Process for a stereoselective polyene cyclization

Abstract

The present invention relates to a process for a stereoselective polyene-cyclization to produce tricyclic compounds of formula (I) where X is CH2 or C=O, which comprises reacting a compound of formula (II) where X is CH2 or C=O and where the curved lines indicate a E- or Z-configuration, in the presence of a catalytic amount of a Brønsted acid having an acidic sulfonamido-moiety.

Description

[0001] Process for a stereoselective polyene cyclization The present invention relates to a process for a stereoselective polyene-cyclization to produce tricyclic compounds of formula (I) where X is CH2or C=O, in particular the enantiomers of formulae (Iatr) and : (Iatr) (ent-Iatr) The compound of formula (Iatr), where X is CH2, is known as ambroxide or by the brand names (-)-Ambrox® and Ambroxan®, respectively. Its enantiomer of formula (ent-Iatr) is also referred to as (+)-ambroxide or (+)-Ambrox®. The IUPAC-Name of the compound of formula (Iatr) is (3aR,5aS,9aS,9bR)-3a,6,6,9a- tetramethyldodecahydronaphtho [2,1-b] furan, however, the numbering of the carbon atoms most often used, that is necessary to define the stereoisomers, follows an older nomenclature, see G. Ohloff, et al., Helv. Chim. Acta 1990, 73, 1935–1947. The compound of formula (Iatr), where X is C=O, is known as (+)- sclareolide, its enantiomer of formula as (-)-sclareolide. Ambroxide is a valuable aroma ingredient that is currently produced based on natural sources (i. e. extraction of sclareol) and was originally produced from ambergris. Due to its olfactory properties with soft musky, animalic, marine and balsamic tonalities ambroxide is among the most valuable odorants in fragrance industry. Although the diastereomers of ambroxide have a comparable scent, the odor threshold differs significantly depending on both relative and absolute stereochemistry (Scheme 1, G. Ohloff, et al., Helv. Chim. Acta 1985, 68, 2022–2029; G. Fráter, et al., Tetrahedron 1998, 54, 7633–7703). Scheme 1: Selected important diastereomers of ambroxide with their respective odor thresholds. odor threshold0.3 ppb 34 ppb 0.15 ppb 2.4 ppb Industrial production of ambroxide starts from the natural product sclareol involving the oxidative cleavage and subsequent cyclization to sclareolide (compound of formula (Iatr), where X is C=O) followed by reduction and cyclization to the ether. A major drawback of this synthesis lies in the unreliability of supply with the natural product sclareol and the need to extract a natural source and to purify the extract (see e. g. B. Schäfer, Natural Products in the Chemical Industry, Springer Verlag Berlin Heidelberg 2014, pp 144 ff. with further references). Therefore, there is the need to design an efficient process for the production of ambroxide in high yield and enantioselectivity starting from well available precursors such as citral and nerolidol via (3E,7E)-homofarnesol or (3E,7E)- homofarnesylic acid (see e. g. M. Schelwies, et al., Chem. Eur. J. 2021, 9263-9266. And references cited therein). The required desired cyclization reaction is an enantio- and diastereoselective polyene-cyclization reaction, wherein the polyene is a 3,7,11-trienic alcohol or carboxylic acid. Polyene-cyclization is a general term that describes reactions that convert polyenes into various cyclized ring systems, for a review on polyene- cyclizations see Johnston et al. in Chem. Rev. 2005, 105, 4730-4756. The type of occurring cyclization, the stereochemistry and the selectivities are a result of the specific polyene, the catalyst (enzymatic or non-enzymatic) and the reaction conditions. Several attempts for the production of ambroxide and sclareolide by polyene- cyclization of (3E,7E)-homofarnesol or (3E,7E)-homofarnesylic acid have been reported in the past – see scheme 2. Scheme 2: Production of ambroxide and sclareolide by polyene-cyclization of (3E,7E)-homofarnesol and (3E,7E)-homofarnesylic acid, respectively: ambroxide Barrero et al., J. Org. Chem 1996, 61, 2215-2218, describe the cyclization of (3E,7E)- homofarnesol to racemic ambroxide in 41% yield using chlorosulfonic acid as achiral catalyst at -78°C. Cassel et al. describe (EP 0553205B1, Henkel) the cyclization of (3E,7E)- homofarnesol to racemic ambroxide with trifluormethanesulfonic acid in nitromethane at -78°C or BF3at 0°C as catalyst. No details on the diastereoselectivities were mentioned. Later Cassel et al.) describe (EP 0680476B1, Henkel) the cyclization of (3E,7E)-homofarnesylic acid to racemic Sclareolide using methanesulfonic acid at -10°C yielding a diastereomeric mixture of sclareolide and 9b-epi-sclareolid (54:46). P. F. Vlad et al. disclose the cyclization of (3E,7E)-homofarnesol to racemic ambroxide with fluorosulfonic acid in nitromethane at -78°C. They also report the cyclization of (3E,7E)-homofarnesylic acid to racemic sclareolide (P. F. Vlad et al., Chem. Heterocycl. Compds., Engl. Transl. 27, 1991, 246). Gulder et al., Nature Communications, (2023)14:813, report the cyclization of (3E,7E)-homofarnesylic acid to racemic sclareolide and 9-epi-sclareolide (75:25 d.r.) with catalytic amounts of DABCO(TfOH)2(1,4-diazabicyclo[2.2.2]octane bistriflate) in perfluoro-tert-butanol (PFTB). The racemic routes have several drawbacks in that they require strongly corrosive acids, low temperatures and toxic solvents and / or result in poor diasteroselectivity. First asymmetric variants of polyene cyclisation to ambroxide and sclareolide require transition metal catalysts but only gave low enantioselectivities. Yamamoto et al., J. Am. Chem. Soc. 1999, 121, 4906-4907, J. Am. Chem. Soc. 2000, 122, 4906–4907 and J. Am. Chem. Soc. 2002, 124, 3647-3655, reported a first asymmetric cyclization (3E,7E)-homofarnesol in the presence of superstoichiometric amounts of tin(IV) chloride-coordinated enantiomerically pure O-(methyl)BINOL to yield 54% of ambroxide (the yield refers to a mix of dia- stereoisomers) with 42 %ee for the major diastereoisomer of formula (I). Later Upar / Bhat et al., Tetrahedron: Asymmetry 2009, 20, 1637-1640, reported a cyclization of (3E,7E)-homofarnesylic acid to sclareolide in 59% yield and with 88 %ee using a variation of the catalyst of Yamamoto et al. Multiple attempts of the inventors to reproduce the conditions reported by Upar and Bhat did not provide sclareolide in the reported yield and enantioselectivity. Rather, only low enantio- and diastereoselectivities were observed. The reported conditions involve the use of a catalytic amount of the chiral ligand alongside superstoichiometric amounts of SnCl4potentially leading to background reactivity, producing racemic product. So far, only a few methods are known for enantioselective polyene-cyclization to ambroxide and sclareolide non-enzymatic syntheses, but all of them require Sn-based catalysts. Recently, the enantioselective production of ambroxide and sclareolide by enzymatic cyclization of (3E,7E)-homofarnesol and (3E,7E)-homofarnesylic acid, respectively, using squalene hopene cyclases (SHCs) have been reported, see for example Hauer et al. in Angew. Chem. 2023, 135, e2023016707; Eichhorn et al. in J. Agric. Food Chem. 2023, 71, 5042-5052 and the references cited therein; Breuer et al. in EP 3417067B1. However, these methods require SHCs that are still very costly. Therefore, there is an ongoing need for a process for the production of racemic or non-racemic ambroxide from homofarnesol and racemic or non-racemic sclareolide from homofarnesylic acid. The processes should at least partly overcome the drawbacks of the prior art processes and should have at least a high diastereoselectivity. Moreover, the process should provide ambroxide and sclareolide, respectively, with at least moderate or high diastereoselectivity and yield. In particular, there is a need for an enantioselective process for producing non-racemic ambroxide from homofarnesol and non-racemic sclareolide from homofarnesylic acid which has both a high diastereoselectivity and a good or high enantioselectivity. It is surprisingly found that these objectives are met by a process for producing a compound of formula (I) as described above, which comprises reacting a compound of formula (II) where X is CH2or C=O and where the curved lines indicate a E- or Z-configuration, in the presence of a catalytic amount of a Brønsted acid having an acidic sulfonamido-moiety of formula (a) -X-NH-S(=O)2-R (a) where R is a fluorinated hydrocarbon radical having 1 to 20 carbon atoms; X represents a -S(=O)2- moiety, a moiety of formula (b) or a moiety of formula (c): -P(=O)(O-)2(b) -P(=N-)(O-)2(c) where the phosphorous atom in moieties (b) and (c) is bound to the NH group of the moiety (a). Therefore, the present invention relates to a process for producing a compound of formula (I) as disclosed herein, which comprises reacting a compound of formula (II) as disclosed herein, in the presence of a catalytic amount of a Brønsted acid having an acidic sulfonamide moiety of formula (a) -X-NH-S(=O)2-R (a) where R is a fluorinated hydrocarbon radical having 1 to 20 carbon atoms, in particular a perfluorinated hydrocarbon radical having 1 to 20 carbon atoms; and X represents a -S(=O)2- moiety, a moiety of formula (b) or a moiety of formula (c) -P(=O)(-O-)2(b) -P(=N-)(-O-)2(c) where the phosphorous atoms of (b) and (c) are bound to the NH group of the moiety of formula (a). The process is associated with several benefits. The process yields the compounds of formula (I) in good yield of frequently > 30% with good diastereoselectivity with respect to the desired diastereomers. In particular, the two 6-membered carbocyclic rings in formula (I) are predominately trans connected to each other, with a ratio of trans : cis > 80:20, in particular > 90:10. More particularly, the reaction yields predominately those diastereomers, where the 6-membered carbocyclic rings in formula (I) are predominately trans connected and the heterocyclic ring is also trans connected to the carbocyclic ring. These diastereomers are also called all- trans-diastereomers (hereinafter also referred to compounds of formula all-trans (I) or (Iatr) and (ent-Iatr)). In particular, the undesired epi-diastereomers of the all trans isomers where the heterocyclic ring is cis connected are not predominately formed. In particular the ratio of the all-trans-diastereomers to the respective epi- diastereomers of the all trans isomers of (I) is > 1:1, especially > 1.2:1. In particular, the following diastereomers and their enantiomers as depicted in the following scheme 4a, are predominately formed: Scheme 4a Desired all-trans diastereomer (Iatr) (enantiomer (ent-Iatr) not shown) Scheme 4b 8-epi diastereomer of (Iatr) (8-epi-I) 9-epi diastereomers of (Iatr) (9-epi-I) (enantiomers (ent-8-epi-I) and (ent-9-epi-I) are not shown) 5β,8α,9β diastereomer (5β,8α,9β-I) (enantiomer not shown) In the present application, the term radical is used interchangeably with the terms, moiety, residue, group or substituent, when defining the variables Rnin the presented formulae. Here and in the following the terms “radical” and “moiety”, “substituent” and “residue” refer to group of atoms in which the atoms are linked to each other by covalent bonds and which in turn are linked to the rest of the molecule by a covalent bond. If not stated otherwise, “radicals” are monovalent, i. e. they are linked to the rest of the molecule by one covalent bond. However, if indicated, radicals may also be di- or trivalent, i. e. they link to 2 or 3 groups of the molecules by 2 or 3 covalent bonds. The organic moieties mentioned in the above definitions of the variables are – like the term halogen – collective terms for individual listings of the individual group members. The term “Cn-Cm” as used herein refers to the range of the number of carbon atoms a moiety may have. The term halogen denotes in each case fluorine, bromine, chlorine or iodine, in particular fluorine, chlorine or bromine. The term "alkyl" as used herein and in the alkyl moieties of alkoxy and the like refers to saturated straight-chain or branched hydrocarbon radicals having 1 to 2 ("C1-C2-alkyl"), 1 to 3 ("C1-C3-alkyl"),1 to 4 ("C1-C4-alkyl"), 1 to 6 ("C1-C6-alkyl") or 1 to 10 ("C1-C10-alkyl") carbon atoms. C1-C2-Alkyl is methyl or ethyl. C1-C3-Alkyl is additionally propyl and isopropyl. C1-C4-Alkyl is additionally n-butyl, 1- methylpropyl (sec-butyl), 2-methylpropyl (isobutyl) or 1,1-dimethylethyl (tert-butyl). C1-C6-Alkyl is additionally also, for example, pentyl, 1-methylbutyl, 2-methylbutyl, 3- methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2- dimethylpropyl, hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4- methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2.2- dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2- trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, or 1-ethyl-2- methylpropyl. C1-C10-Alkyl is additionally also, for example, heptyl, octyl, nonyl and decyl and the isomers thereof. The term "haloalkyl" as used herein, which is also expressed as "alkyl which is partially or fully halogenated", refers to straight-chain or branched alkyl groups having 1 to 2 ("C1-C2-haloalkyl"), 1 to 3 ("C1-C3-haloalkyl"), 1 to 4 ("C1-C4- haloalkyl"), 1 to 6 ("C1-C6-haloalkyl") or 1 to 10 ("C1-C10-haloalkyl") carbon atoms (as mentioned above), where some or all of the hydrogen atoms in these groups are replaced by halogen atoms, in particular by fluorine or chlorine as mentioned above: in particular C1-C2-haloalkyl, such as chloromethyl, bromomethyl, dichloromethyl, trichloromethyl, fluoromethyl, difluoromethyl, trifluoromethyl, chlorofluoromethyl, dichlorofluoromethyl, chlorodifluoromethyl, 1-chloroethyl, 1-bromoethyl, 1- fluoroethyl, 2-fluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl, 2-chloro-2- fluoroethyl, 2-chloro-2,2- difluoroethyl, 2,2-dichloro-2-fluoroethyl, 2,2,2- trichloroethyl or pentafluoroethyl. C1-C3-haloalkyl is additionally, for example, 1- fluoropropyl, 2-fluoropropyl, 3- fluoropropyl, 1,1-difluoropropyl, 2,2-difluoropropyl, 1,2-difluoropropyl, 3,3-difluoropropyl, 3,3,3-trifluoropropyl, heptafluoropropyl, 1,1,1- trifluoroprop-2-yl, 3-chloropropyl and the like. Examples for C1-C4-haloalkyl are, apart those mentioned for C1-C3-haloalkyl, 4-chlorobutyl and the like. Haloalkyl is in particular “Methyl which is substituted by 1, 2 or 3 fluorine atoms” such as fluoromethyl, difluoromethyl or trifluoromethyl. The term "fluorinated alkyl", also expressed as “fluoroalkyl” or "alkyl which is partially or fully fluorinated", indicates saturated straight-chain or branched aliphatic hydrocarbon radicals having for example 1 to 18 (= C1-C18fluoroalkyl) carbon atoms, 1 to 10 (= C1-C10fluoroalkyl) carbon atoms, or (= C1-C8fluoroalkyl) or 1 to 4 (= C1-C4fluoroalkyl) or 1 or 2 (= C1-C2fluoroalkyl) carbon atoms, where some or all of the hydrogen atoms in these groups are replaced by fluorine atoms as mentioned above. "C1-C2Fluoroalkyl" refers to alkyl groups having 1 or 2 carbon atoms (as mentioned above), where some or all of the hydrogen atoms in these groups are replaced by fluorine atoms as mentioned above. "C1-C3Fluoroalkyl" refers to straight-chain or branched alkyl groups having 1 to 3 carbon atoms (as mentioned above), where some or all of the hydrogen atoms in these groups are replaced by fluorine atoms as mentioned above. "C1-C4fluoroalkyl" refers to straight-chain or branched alkyl groups having 1 to 4 carbon atoms (as mentioned above), where some or all of the hydrogen atoms in these groups are replaced by fluorine atoms as mentioned above. "C1-C6fluoroalkyl" refers to straight-chain or branched alkyl groups having 1 to 6 carbon atoms (as mentioned above), where some or all of the hydrogen atoms in these groups are replaced by fluorine atoms as mentioned above. Examples for C1-C2fluoroalkyl are difluoromethyl, trifluoromethyl, 1-fluoroethyl, 2-fluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl or pentafluoroethyl. Examples for C1-C3fluoroalkyl are, in addition to those mentioned for C1-C2flluoroalkyl, 1-fluoropropyl, 2-fluoropropyl, 3-fluoropropyl, 1,1- difluoropropyl, 2,2-difluoropropyl, 1,2-difluoropropyl, 3,3-difluoropropyl, 3,3,3- trifluoropropyl, heptafluoropropyl, 1,1,1-trifluoroprop-2-yl, 1,1,1,3,3,3- hexafluoroprop-2-yl, heptafluoroprop-2-yl and the like. Examples for fluoroalkyl are, in addition to those mentioned for C1-C3fluoroalkyl, 4-fluorobutyl, perfluorobutyl (nonafluorobutyl) and the like. Examples for C1-C8fluoroalkyl are, in addition to those mentioned for C1-C3fluoroalkyl and perfluoropentyl (undecafluoropentyl), perfluorohexyl (tridecafluorohexyl) , perfluoroheptyl (pentadecafluoroheptyl), perfluornonyl (nonadecafluorooctyl) and perfluorodecyl (heneicosafluorooctyl). The term "cycloalkyl" as used herein refers to mono- or bicyclic saturated hydrocarbon radicals having 3 to 10 ("C3-C10-cycloalkyl"), 3 to 8 ("C3-C8-cycloalkyl"), in particular 3 to 6 ("C3-C6-cycloalkyl") carbon atoms. Examples of monocyclic radicals having 3 to 4 carbon atoms are cyclopropyl and cyclobutyl. Examples of monocyclic radicals having 3 to 5 carbon atoms are cyclopropyl, cyclobutyl and cyclopentyl. Examples of monocyclic radicals having 3 to 6 carbon atoms are cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl. Examples of monocyclic radicals having 3 to 8 carbon atoms are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl. Examples of monocyclic radicals having 3 to 10 carbon atoms are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl and cyclodecyl. The bicyclic radicals can be condensed or bridged rings. Examples of bicyclic condensed radicals having 6 to 10 carbon atoms comprise bicyclo[3.1.0]hexyl, bicyclo[3.2.0]heptyl, bicyclo[3.3.0]octyl (1,2,3,3a,4,5,6,6a- octahydropentalenyl), bicyclo[4.2.0]octyl, bicyclo[4.3.0]nonyl (2,3,3a,4,5,6,7,7a- octahydro-1 H-indene), bicyclo[4.4.0]decyl (decalinyl) and the like. Examples of bridged bicyclic condensed radicals having 7 to 10 carbon atoms comprise bicyclo[2.2.1]heptyl, bicyclo[3.1.1 ]heptyl, bicyclo[2.2.2]octyl, 30 bicyclo[3.2.1]octyl and the like. Preferably, the term cycloalkyl denotes a monocyclic saturated hydrocarbon radical. The term "fluorinated cycloalkyl" as used herein, which is also expressed as "cycloalkyl which is partially or fully fluorinated", refers to mono- or bicyclic saturated hydrocarbon groups having 3 to 10 ("fluorinated C3-C10-cycloalkyl") or 3 to 8 ("fluorinated C3-C8-cycloalkyl") or preferably 3 to 6 ("fluorinated C3-C6- cycloalkyl") carbon ring members (as mentioned above) in which some or all of the hydrogen atoms are replaced by fluorine atoms. The term "aryl" as used herein and in the aryl moieties of arylalkyl indicates an aryl group with typically 6 to 18 (C6-C18aryl), in particular 6 to 14 (C6-C14aryl), specifically 6 to 10 carbon atoms (C6-C10aryl) as ring members. Aryl may be a mono-, bi- or polycyclic carbocyclic aromatic radical which does not have heteroatoms as ring members. One example for a monocyclic aryl is phenyl. In bicyclic aryl rings two aromatic rings are condensed or fused or fused by a saturated carbocylce, i.e. the fused rings share two vicinal C atoms as ring members. One example for a bicyclic aromatic radical is naphthyl. In polycyclic aryl rings, three or more rings are condensed. Examples for polycyclic aryl radicals are phenanthrenyl, anthracenyl, tetracenyl, 1-H-benzo[a]phenalenyl, pyrenyl and fluorenyl and the like. “C6-C10-Aryl” is in particular phenyl, 1-naphthyl or 2-naphthyl. The term "fluorinated aryl" as used herein, which is also expressed as "aryl which is partially or fully fluorinated", generally refers to C6-C18aryl, in particular C6-C14aryl, especially C6-C10aryl, as defined above, in which some or all of the hydrogen atoms are replaced by fluorine atoms. Examples include, 4-fluorophenyl, 2,4- difluorophenyl, 2,4,6-trifluorophenyl, 3,5-difluorophenyl, pentafluorophenyl, 1,3,4,5,6,7,8-heptafluoro-2-naphthyl and 2,3,4,5,6,7,8-heptafluoro-1-naphthyl. The term “C6-C10aryl-C1-C4-alkyl” refers to C1-C4-alkyl which is substituted by 1 C6- C10aryl group as defined herein, in particular by phenyl. Examples of C6-C10aryl-C1- C4-alkyl include benzyl, 1-phenylethyl and 2-phenylethyl. The term “fluorinated C6-C10aryl-C1-C4-alkyl” refers to C6-C10aryl-C1-C4-alkyl group as defined herein, where some or all of the hydrogen atoms of the hydrocarbon atom are replaced by fluorine atoms. Examples of C6-C10aryl-C1-C4-alkyl include pentafluorobenzyl, heptafluoronapthylmethyl etc. The term “fluorinated hydrocarbon radical” refers to a hydrocarbon radical, such as alkyl, cycloalkyl, aryl or arylalkyl as defined herein, where some or all of the hydrogen atoms of the hydrocarbon atom are replaced by fluorine atoms. Fluorinated hydrocarbon radicals typically have 1 to 20 carbon atoms, in particular 1 to 14 carbon atoms and include fluorinated C1-C18alkyl, fluorinated C3-C18- cycloalkyl, fluorinated C6-C18aryl and fluorinated fluorinated C6-C10aryl-C1-C4-alkyl. According to the invention, the tricyclic compound of the formula (I), in particular the trans diastereomer, is formed in single reaction step by the acid catalysed cyclization of the compound (II) in the presence of a specific Brønstedt acid having a moiety of formula (a) -X-NH-S(=O)2-R (a) as described herein. In these specific Brønsted acids the sulphur atom of the S(=O)2moiety preferably carries a radical R, which is an electron withdrawing group, where R is in particular represented by the formula R1-CFZ-, where Z is F or fluorinated alkyl, in particular F or CF3and R1is F, fluorinated C1-C18alkyl or fluorinated C6-C18aryl, and where R1is in particular F, perfluorinated C1-C10alkyl or perfluorinated C6-C10aryl. According to one particular group (1) of embodiments, the moiety X is a S(=O)2moiety. The moiety (a) thus can be described by the following formula: (a.1): -S(=O)2-NH-S(=O)2-R (a.1) In this case, the further S(=O)2moiety preferably carries an electron withdrawing group, in particular a group R’, which has one of the meanings given for R. In particular R’ is a group of the formula R2a-CFZ-, where Z is F or fluorinated C1-C4alkyl, in particular F or CF3and R2ais F, fluorinated C1-C18alkyl or fluorinated C6-C18aryl and where R2ais in particular F, perfluorinated C1-C10alkyl or perfluorinated C6-C10aryl. In this group of embodiments, the Brønsted acid can be described by the following formula A.1 R’-S(=O)2-NH-S(=O)2-R (A.1) where R is a fluorinated hydrocarbon radical having 1 to 20 carbon atoms, in particular 1 to 14 carbon atoms, such as fluorinated C1-C18alkyl, fluorinated C3-C10- cycloalkyl, fluorinated C6-C10aryl or fluorinated fluorinated C6-C10aryl-C1-C4- alkyl; in particular a radical R1-CFZ-, where Z is F or fluorinated C1-C4alkyl, in particular F or CF3and R1is F, fluorinated C1-C20alkyl or fluorinated C6-C18aryl, and where R1is in particular F, perfluorinated C1-C10alkyl or perfluorinated C6-C10aryl; R’ is a fluorinated hydrocarbon radical having 1 to 20 carbon atoms, in particular 1 to 14 carbon atoms, such as fluorinated C1-C18alkyl, fluorinated C3-C18- cycloalkyl, fluorinated C6-C18aryl or fluorinated fluorinated C6-C10aryl-C1-C4- alkyl; in particular a radical R1-CFZ-, where Z is F or fluorinated C1-C4alkyl, in particular F or CF3and R1is F, fluorinated C1-C18alkyl or fluorinated C6-C18aryl, and where R1is in particular F, perfluorinated C1-C10alkyl or perfluorinated C6-C10aryl. The Brønsted acids of group (1) of embodiments are usually achiral. In particular, the moieties R1-CFZ and R2a-CFZ are identical. A particular example of group (1) of embodiments is bis(triflimide), i. e. bis(trifluoromethylsulfonyl)imide: HN(SO2-CF3)2. According to another particular group (2) of embodiments, the moiety X is a moiety of the formula (b) -P(=O)(-O-)2(b). The moiety (a) thus can be described by the following formula: (a.2): (-O-)2P(=O)-NH-SO2-R (a.2) In this group (2) of embodiments, the O atoms of the moiety (a.2) carry optionally substituted hydrocarbon radicals having 1 to 30 carbon atoms, e. g. C1-C18alkyl or C6-C18aryl radicals, or together with the P-atom are part of a 1,3,2-dioxaphospha- cycloalkane ring, e. g. 1,3,2-dioxaphosphepane ring, where the 1,3,2-dioxaphospha- cycloalkane ring optionally bears 1 or 2 fused C6-C10arylene radicals which are unsubsituted or substituted, e. g. by 1, 2, 3 or 4 radicals selected from fluorine, SF5, C1-C10alkyl, fluorinated C1-C10alkyl, C5-C10cycloalkyl and C6-C18aryl, where C6-C18aryl usually includes 1, 2 or 3 phenyl rings which are fused to each other or connected by a single bond and where aryl may include a saturated 5- or 6- membered monocycle fused to at least one of the phenyl rings or a saturated 8 to 12 membered spirobicycle fused to at least one of the phenyl rings of C6-C18aryl and where C6-C18aryl is unsubstituted or carries 1, 2 or 3 radicals, such as C1-C10alkyl, fluorine, SF5, fluorinated C1-C10alkyl, C5-C10cycloalkyl, and phenyl. In this group of embodiments, the Brønsted acid can be described by the following formula A.2 (R’’-O-)2P(=O)-NH-S(=O)2-R (A.2) where R is a fluorinated hydrocarbon radical having 1 to 20 carbon atoms, in particular 1 to 14 carbon atoms, such as fluorinated C1-C18alkyl, fluorinated C3-C10- cycloalkyl, fluorinated C6-C10aryl or fluorinated fluorinated C6-C10aryl-C1-C4- alkyl; in particular a radical R1-CFZ-, where Z is F or fluorinated C1-C4alkyl, in particular F or CF3and R1is F, fluorinated C1-C20alkyl or fluorinated C6-C18aryl, and where R1is in particular F, perfluorinated C1-C10alkyl or perfluorinated C6-C10aryl; R’’ are, independently of each other, optionally substituted hydrocarbon radicals having 1 to 30 carbon atoms, e. g. C1-C18alkyl or C6-C18aryl radicals, such as C1-C18alkyl or C6-C18aryl radicals, or together with the P-atom are part of a 1,3,2-dioxaphosphacycloalkane ring, e. g. 1,3,2-dioxaphosphepane ring, where the 1,3,2-dioxaphosphacycloalkane ring optionally bears 1 or 2 fused C6-C10arylene radicals which are unsubstituted or substituted, e. g. by 1, 2, 3 or 4 radicals selected from fluorine, SF5, C1-C10alkyl, fluorinated C1-C10alkyl, C5- C10cycloalkyl and C6-C18aryl, where C6-C18aryl usually includes 1, 2 or 3 phenyl rings which are fused to each other or connected by a single bond and where aryl may include a saturated 5- or 6-membered monocycle fused to at least one of the phenyl rings or a saturated 8 to 12 membered spirobicycle fused to at least one of the phenyl rings of C6-C18aryl and where C6-C18aryl is unsubstituted or carries 1, 2 or 3 radicals, such as C1-C10alkyl, fluorine, SF5, fluorinated C1-C10alkyl, C5-C10cycloalkyl, and phenyl. According to another particular group (3) of embodiments, the moiety X is a tetravalent moiety of formula (c): -P(=N-)(-O-)2(c) In this group (3) of embodiments, the nitrogen atom of the tetravalent moiety (c) preferably bears an electron withdrawing group, e. g. an S(=O)2-R’ moiety, thereby forming a -P(=N-S(O)2R’)(-O-)2moiety, hereinafter group (3a) of embodiments, a further -P(=O)(-O-)2moiety, thereby forming a (-O-)2P(=N-P(=O)(-O-)2)moiety, hereinafter group (3b) of embodiments, or a further moiety -P(=N-)(-O-)2, thereby forming a (-O-)2P(=N-P(O-)2=N)- moiety, hereinafter group (3c) of embodiments. In group (3) of embodiments the moiety (a) thus can be described by the following formulae (a.3), (a.3a), (a.3b), (a3c) or its tautomeric forms (a.3b’), (a.3b’’), (a.3c’) and (a.3c’’) in particular by the formula (a.31c) and its tautomeric forms (a.31c’) and (a.31c’’): In these formulae the “#” refers to a bond connected to a further moiety. In this group (3) of embodiments, the O atoms of the moieties (a.3), (a.3a), (a.3b), (a.3c) and (a.31c) and likewise in the depicted tautomeric forms typically carry a radical R’’ as defined in the context of formula (A.2) In this group (3) of embodiments, the further S(=O)2moiety, if present, preferably carries an electron withdrawing group R’ as defined in the context of formula (A.1), in particular a group of the formula R2a-CFZ-, where Z is F or fluorinated C4alkyl, in particular F or CF3and R2ais F, fluorinated C1-C20alkyl or fluorinated C6-C18aryl and where R2ais in particular F, perfluorinated C1-C10alkyl or perfluorinated C6-C10aryl. In the process of the present invention the catalyst is in particular a Brønsted acid of groups (1) and (3) of embodiments, i. e Brønsted acid catalysts, where X in formula (a) is a S(=O)2moiety or a moiety of the formula (c): -P(=N-)(-O-)2(c) In the process of the present invention the catalyst is a Brønsted acid having preferably a pKaat 20°C and 1 bar in acetonitrile of 14 or lower, in particular a pKain the range of 0 to 14, especially in the range of 0 to 12, 0 to10 or 0 to 8. The pKavalues can be determined by UV-Vis spectrometry of solutions of the Brønsted acid in acetonitrile as described by I. Leito et al. in European J. Org. Chem. 2021, 2021, 1407–1419; J. Org. Chem 2011, 76, 391; Nat. Chem. 2018, 10, 888–894; Angew. Chemie Int. Ed. 2017, 56, 1411–1415; Chem. Sci. 2017, 8, 6964–6973; Angew. Chem. Int. Ed. 2013, 52, 11569–11572. The aforementioned references also give pKavalues of Brønsted acids according to the present invention. A list of pKavalues of Brønsted acids according to the present invention can also be found in the review of Schreyer et al., Angew. Chem. Int. Ed. 2019, 58, 12761–12777. If the catalyst is a Brønsted acid which is chiral, it may impart chirality to the cyclization product of the formula (I). In particular, a noticeable enantiomeric excess of the desired enantiomers of either the formula (I-(+)) or the formula (I-(-)) can be obtained. If the catalyst is a Brønsted acid which is chiral it is preferably used in enantiopure form or has an enantiomeric excess of at least 90%, particular of at least 95% ee. In other words, the molar ratio of Brønsted acid : ent-Brønsted acid is > 95:5 or < 5:95, respectively. Brønsted acids of groups (1), (2) and (3) of embodiments which are suitable as catalysts can be in particular described by formula (III) where R1is F, fluorinated C1-C20alkyl or fluorinated C6-C18aryl, in particular F, perfluorinated C1-C10alkyl or perfluorinated C6-C10aryl; R2is SO2-CFZ-R2aor a moiety of formulae (IVa) or (IVb) where # indicates the bond to the imino nitrogen atom in formula (III); n, m independently of each other are 0, 1 or 2, in particular 0 or 1; R21, R22independently of each other are selected from the group of hydrogen, fluorine and C6-C18aryl, where aryl has 1, 2 or 3 phenyl rings which are fused to each other or connected by a single bond and where aryl may include a saturated 5- or 6-membered monocycle fused to at least one of the phenyl rings or a saturated 8 to 12 membered spirobicycle fused to at least one of the phenyl rings of C6-C18aryl, where C6-C18aryl is unsubstituted or may carry 1, 2 or 3 radicals R29; R23, R24independently of each other are selected from fluorine and fluorinated C1-C4alkyl, such as trifluoromethyl, tetrafluoroethyl, pentafluoroethyl, 1,1,1,3,3,3-hexafluoro-2-propyl or heptafluoro-2-propyl; R3is SO2-CFZ-R3aor a moiety of formula (Va) or (Vb) where # indicates the bond to the imino nitrogen atom in formulae (IVa) and (IVb), respectively; p, q independently of each other are 0, 1 or 2, in particular 0 or 1; R25, R26independently of each other are selected from the group of hydrogen, fluorine and C6-C18aryl, where aryl has 1, 2 or 3 phenyl rings which are fused to each other or connected by a single bond and where aryl may include a saturated 5- or 6-membered monocycle fused to at least one of the phenyl rings or a saturated 8 to 12 membered spirobicycle fused to at least one of the phenyl rings of C6-C18aryl, where C6-C18aryl is unsubstituted or may carry 1, 2 or 3 radicals R30; R27, R28independently of each other are selected from fluorine and fluorinated C1-C4alkyl, such as trifluoromethyl, tetrafluoroethyl, pentafluoroethyl, 1,1,1,3,3,3-hexafluoro-2-propyl or heptafluoro-2- propyl; and where on each occurrence Z is F or fluorinated C1-C4alkyl, in particular F or CF3; R29and R30, independently of each other are selected from C1-C10alkyl, fluorine, SF5, fluorinated C1-C10alkyl, C5-C10cycloalkyl, and phenyl, in particular from C1-C4alkyl, fluorine, SF5, fluorinated C1-C4alkyl and phenyl; R2a, R3aand R4a, independently of each other are selected from fluorine, fluorinated C1-C20alkyl and fluorinated C6-C18aryl, in particular from fluorine, perfluorinated C1-C10alkyl and perfluorinated C6-C10aryl. It is apparent that Brønsted acids of formula (III) where R2is a radical SO2-CFZ-R2aare a particular subgroup of embodiments within group (1) of embodiments, while Brønsted acids of formula (III) where R2is a moiety of formula (IVa) are another particular subgroup of embodiments within group (2) of embodiments. It is also apparent that Brønsted acids of formula (III) where R2is a moiety of formula (IVb) and where R3is a radical SO2-CFZ-R3aare a particular subgroup within group (3a) of embodiments, while Brønsted acids of formula (III) where R2is a moiety of formula (IVb) and where R3is a moiety of formula (Vb) are a particular subgroup within group (3c) of embodiments. It is also apparent that the binaphthyl moieties of formulae (IVa), (IVb), (Va) and (Vb) create centres of chirality in the Brønsted acid of formula (III) due to the hindered rotation of the two naphthyl moieties along the bond connecting them. Therefore, Brønsted acids of formula (III) where R2is a moiety of formulae (IVa) or (IVb) can be used as their racemate or as a non-racemic mixture which preferably has an enantiomeric excess of at least 90%, particular of at least 95% ee. In other words, the molar ratio of Brønsted acid : ent-Brønsted acid is > 95:5 or < 5:95, respectively. Apart from that, Brønsted acids of formula (III) where R2is a moiety of formulae (IVa) or (IVb) favour the formation of the desired all-trans diastereomers and reduce the formation of the less desired 8- and 9-epi-diastereomers and the 5β,8 α,9β diastereomer, in particular, if R2is a moiety of formula (IVb) wherein R3is a moiety of formulae (Va) or (Vb) with particular preference given to those Brønsted acids where R3is a moiety of formula (Vb). Therefore, the present invention preferably relates to a process as described herein, where the Brønsted acid is of the formula (III), where R2is a radical of the formula or (IVb) with R3being a radical SO2-CFZ-R3aor preferably a moiety of the formula (Va) and especially a moiety of formula (Vb). These Brønsted acids are compounds of the formula (IIIa), (IIIb) and (IIIc), including their tautomers, diastereomers and their enantiomers, whith preference given to the compounds of formulae (IIIc) and special preference given to the compounds of formula (IIIc): It is apparent that the Brønsted acids of formula (IIIb) may be present in the tautomeric form depicted in formula (IIIb) or as the following tautomers: It is also apparent that the Brønsted acids of formula (IIIc) may be present in the tautomeric form depicted in formula (IIIb) or as the following tautomers: Brønsted acids of formulae (IIIa), (IIIb) and (IIIc) and their tautomers of formula (IIIb’), (IIIb’’), (IIIc’), (IIIc’’) are preferred as they favour the formation of the desired 3,9-trans diastereomers and suppress the formation of the less desired 8- and 9- epi-diastereomers and the 5β,8α,9β diastereomer. Moreover, if the Brønsted acids of formula (IIIa) and in particular the Brønsted acids of formulae (IIIb) and (IIIc) and their tautomers of formula (IIIb’), (IIIb’), (IIIc’), (IIIc’’) are provided in a non-racemic form, in particular in one of the forms of formulae (R-IIIa) or (S-IIIa), (R,R-IIIb) or (S,S-IIIb), (R,R-IIIc) or (S,S-IIIc), including their tautomers (not shown): (R-IIIa)

[0002] With respect to the desired selectivity of the Brønsted acid with respect to the desired cyclization products, in particular with respect to the desired stereoisomers, it is preferred that the radicals R21, R22, R25, R26in formulae (IIIa), (IIIb), (IIIc), (R- IIIa), (S-IIIa), (R,R-IIIb), (S,S-IIIb), (R,R-IIIc), (S,S-IIIc), (IVa), (IVb), (Va) and (Vb) are C6-C18aryl, where aryl includes 1, 2 or 3 phenyl rings which are fused or connected by a single bond and where aryl may include a saturated 5- or 6- membered monocycle fused to at least one of the phenyl rings or a saturated 8 to 12 membered spirobicycle fused to at least one of the phenyl rings, where C6-C18aryl is unsubstituted or may carry 1, 2 or 3 radicals R30as defined herein. Particular preference is given to Brønsted acids where R2is a moiety of formula (IVa) or (IVb) with R3being preferably a moiety of formulae (Va) or (Vb), where R21, R22, R25, R26in formulae (IIIa), (IIIb), (IIIc), (R-IIIa), (S-IIIa), (R,R-IIIb), (S,S-IIIb), (R,R-IIIc), (S,S-IIIc), (IVa), (IVb), (Va) and (Vb) are selected from - phenyl, which is substituted with 1, 2, or 3 radicals selected from C1-C10alkyl, C1-C10fluorinated alkyl and SF5, in particular from fluorinated C1-C4alkyl, C1- C4fluorinated alkyl and SF5; - naphthyl, which is unsubstituted or substituted with 1, 2, or 3 radicals selected from C1-C10alkyl, C1-C10fluorinated alkyl and phenyl, in particular from fluorinated C1-C4alkyl, C1-C4fluorinated alkyl and phenyl; - biphenyl, which is unsubstituted or substituted with 1, 2, or 3 radicals selected from C1-C10alkyl, C1-C10fluorinated alkyl and phenyl, in particular from fluorinated C1-C4alkyl, C1-C4fluorinated alkyl and phenyl; - fluorenyl, which is unsubstituted or substituted with 1, 2, or 3 radicals selected from C1-C10alkyl, C1-C10fluorinated alkyl and phenyl, in particular from fluorinated C1-C4alkyl, C1-C4fluorinated alkyl and phenyl, where 2 of the substitutents located in the 9 position of fluorenyl may form a saturated 4-7 membered spirocarbocyle. Special preference is given to Brønsted acids where R2is a moiety of formula (Iva) or (IVb) with R3being preferably a moiety of formulae (Va) or (Vb), where R21, R22, R25, R26in formulae (IIIa), (IIIb), (IIIc), (R-IIIa), (S-IIIa), (R,R-IIIb), (S,S-IIIb), (R,R- IIIc), (S,S-IIIc), (IVa), (IVb), (Va) and (Vb) is a spiro[cyclo-C4-C7-alkane-1,9’- fluorene]-2’-yl radical, which is optionally substituted by one radical selected from C1-C10alkyl, C1-C10fluorinated alkyl and phenyl, in particular from C1-C4alkyl, C1-C4fluorinated alkyl and phenyl. Such radicals are in particular a radical of formula A where # indicates the point of attachment of A to the binaphthyl moieties formulae (IIIa), (IIIb), (IIIc), (R-IIIa), (S-IIIa), (R,R-IIIb), (S,S-IIIb), (R,R-IIIc), (S,S-IIIc), (IVa), (IVb), (Va) and (Vb), k is 1, 2, 3 or 4, in particular 1, 2 or 3; x is 0 or 1 Rxis selected from C1-C10alkyl, C1-C10fluorinated alkyl and phenyl, in particular from C1-C4alkyl, C1-C4fluorinated alkyl and phenyl. Examples of preferred meanings of R21, R22, R25, R26include, but are not limited to phenyl, 4-methylphenyl, 4-(pentafluorosulfanyl)phenyl, 4-tert.-butylphenyl, 4-(2- propyl)phenyl, 4-(1-methylbut-2-yl)phenyl, 4-(1,2,2-trimethylbut-2-yl)phenyl, 4- trifluoromethylphenyl, 4-(1,1,2,2,3,3,3-heptafluoro-n-propyl)phenyl, 3,5- bis(trifluoromethyl)phenyl, 3,5-bis(pentafluorosulfanyl)phenyl, 3,5-bis(1,1,2,2,3,3,3- heptafluoro-n-propyl)phenyl, 1-naphthyl, 2-naphtyl, 3-biphenyl, 4-biphenyl, 4’-n- propyl-3-biphenyl, spiro[cyclobutane-1,9’-fluorene]-2’-yl, spiro[cyclopoentane-1,9’- fluorene]-2’-yl, spiro[cyclohexane-1,9’-fluorene]-2’-yl, 7’-methyl- spiro[cyclohexane-1,9’-fluorene]-2’-yl, 7’-phenylspiro[cyclohexane-1,9’-fluorene]- 2’-yl, 2,4,6-trimethylphenyl, 2,4,6-trsi(2-propyl)phenyl, 4-(1- methylcyclopentyl)phenyl and 4-(1-methylcyclohexyl)phenyl. Apart from that, the variables m, n, p, q, Z, R1, R2a, R3a, R4a, R23, R24, R27, R28, R29, R30in formulae (III), (IIIa), (IIIb), (IIIc), (R-IIIa), (S-IIIa), (R,R-IIIb), (S,S-IIIb), (R,R-IIIc), (S,S-IIIc), (IVa), (IVb), (Va) and (Vb) alone or in particular in combination preferably have the following meanings: m, n are identical and in particular 0 or 1; p, q are identical and in particular 0 or 1; Z is F or CF3; R1is selected from fluorine, perfluorinated C1-C10alkyl and perfluorinated C6-C10aryl; in particular from fluorine and perfluorinated C1-C10alkyl; R2ais selected from fluorine, perfluorinated C1-C10alkyl and perfluorinated C6-C10aryl; in particular from fluorine and perfluorinated C1-C10alkyl; R3ais selected from fluorine, perfluorinated C1-C10alkyl and perfluorinated C6-C10aryl; in particular from fluorine and perfluorinated C1-C10alkyl; R4ais selected from fluorine, perfluorinated C1-C10alkyl and perfluorinated C6-C10aryl; in particular from fluorine and perfluorinated C1-C10alkyl; R23, R24if present, are identical or different and selected from trifluoromethyl, tetrafluoroethyl, pentafluoroethyl, 1,1,1,3,3,3-hexafluoro-2-propyl and heptafluoro-2-propyl; R27, R28if present, are identical or different and selected from trifluoromethyl, tetrafluoroethyl, pentafluoroethyl, 1,1,1,3,3,3-hexafluoro-2-propyl and heptafluoro-2-propyl; R29, R30if present, are identical or different and selected from alkyl, fluorine, SF5, fluorinated alkyl and phenyl. The meanings of R21, R22, R25, R26in formulae (IIIa), (IIIb), (IIIc), (R-IIIa), (S-IIIa), (R,R-IIIb), (S,S-IIIb), (R,R-IIIc), (S,S-IIIc), (IVa), (IVb), (Va) and (Vb) may be identical or different and frequently are identical. The meanings of R23, R24, R27, R28in formulae (IIIa), (IIIb), (IIIc), (R-IIIa), (S-IIIa), (R,R-IIIb), (S,S-IIIb), (R,R-IIIc), (S,S-IIIc), (IVa), (IVb), (Va) and (Vb), if present, may be identical or different and frequently are identical. If m and n or p and q in are 1, the radicals R23, R24, R27, R28, respectively, are preferably located in the 6 and 6’ positon of the binaphtyl moiety. The meanings of m, n, p and q in formulae (IIIa), (IIIb), (IIIc), (R-IIIa), (S-IIIa), (R,R- IIIb), (S,S-IIIb), (R,R-IIIc), (S,S-IIIc), (IVa), (IVb), (Va) and (Vb) may be identical or different and frequently are identical. The meanings of Z in formulae (IIIc), (R,R-IIIc), (S,S-IIIc), may be identical or different and frequently are identical. The meanings of R1and R4ain formulae (IIIc), (R,R-IIIc) and (S,S-IIIc) may be identical or different and frequently are identical. A preferred group of catalysts are those of the following formulae (IIIa-1), (R,R-IIIa- 1) and (S,S-IIIa-1): 1) A particular preferred group of catalysts are those of the following formulae (IIIb-1), An especially preferred group of catalysts are those of the following formulae (IIIc- 1), (R,R-IIIc-1) and (S,S-IIIc-1): where Raare identical and correspond to the moieties CFZ-R1and CFZ-R4a, respectively, where Z, R1and R4aare as defined herein and in particular have the preferred meanings; Rbare identical and have the meanings defined for R21, R22, R25, R26, respectively, and in particular have the preferred meanings; Rcare identical and are H or have the meanings defined for R23, R24, R27, R28, respectively, and in particular have the preferred meanings. Examples of preferred Brønsted acid catalysts, are those of the formulae (IIIa-1), (R-IIIa-1) and (S-IIIa-1), where Ra, Rband Rchave the meanings given in the following table A. Further examples of particularly preferred Brønsted acid catalysts, are those of the formulae (IIIb-1), (R,R-IIIb-1) and (S,S-IIIb-1), where Ra, Rband Rchave the meanings given in the following table A. Further examples of especially preferred Brønsted acid catalysts, are those of the formulae (IIIc-1), (R,R-IIIc-1) and (S,S-IIIc-1), where Ra, Rband Rchave the meanings given in the following table A. Table A: Meanings of Ra, Rband Rcin formulae (IIIc-1), (R,R-IIIc-1) and (S,S-IIIc-1) The Brønsted acid catalysts of formula (III) are principally known in the art and in case of catalysts according to group (1) of embodiments commercially available. Catalysts of formulae (IIIa) and (IIIb) and their enantiomers (S,S-IIIa), (S,S-IIIb), (R,R-IIIa) and (R,R-IIIb) are known and disclosed e. g. in WO 2017 / 037141, WO 2022 / 144436, P.S.J. Kaib, B. List, Synlett 2016, 27, 156–158 and Angew. Chem. Int. Ed. 2016, 55, 13200–13203 or can be prepared by the methods described therein. The Brønsted acid catalysts are highly reactive in the cyclization reaction according to the invention can be used in low catalytic amounts with respect to the compound of the formula (II), in particular in amounts of at most 0.3 mol, preferably at most 0.2 mol and especially at most 0.1 mol per 1 mol of the compound formula (II). Frequently, acceptable reaction rates are achieved at amounts of at least 0.00001 mol, preferably at most 0.00005 mol and especially at most 0.0001 mol per 1 mol of the compound formula (II). In the process of the present invention, the compound of formula (II) may be used as its 3E-isomer or as its 3Z-isomer or as a mixture of the 3E- and the 3Z-isomer. The 3E / 3Z-ratio of the compound of formula (II) affect the epimeric ratio in the obtained products – see e. g. the results summarized in table 23 of the example section. Therefore, it is principally possible to affect the epimeric ratio in the compound of formula (I), in particular the epimeric ratio at carbon atoms 8 and 9 in the compound of formula (I) by the 3E / 3Z-ratio in the compound of formula (II) subjected to the cyclization reaction of the invention. In order to increase ratio of the all-trans diastereomers of (I), herein all-trans-(I) including (Iatr) and (ent-Iatr), to the 9-epi diastereomers of all-trans-(I), i. e. the ratio all-trans-(I) : 9-epi-(I), it was found beneficial if the compounds of formula (II) have a high 3E / 3Z-ratio, e. g. a ratio of at least 1.5:1, in particular at least 2:1 and especially at least 5:1 or higher. However, it is also possible to use a mixture of the 3E and the 3Z-stereoisomer of a compound of formula (II). However, it is preferred, if the compounds of formula (II) have an 3E / 3Z-ratio with respect to the double bond in the 3-position of at least 1:1, in particular at least 1.1:1, e. g. in the range of 1:1 to 100:1, in particular in the range of 1:1 to 95:1, preferably in the range 1.1:1 to 100:1 or in the range 1.1:1 to 95:1. Regarding the double bond in the 7-position of the compounds of formula (II), a high 7E / 7Z ratio is required for achieving a high trans ratio in (I) with respect to the central double bond linking the two 6-membered rings. Therefore, compounds (II) are used, where the 7E / 7Z ratio with respect to the double bond in the 7-position is preferably at least 1.5:1, in particular at least 2:1, especially at least 5:1, e. g. in the range of 1.5:1 to 1000:1, in particular in the range of 2:1 to 1000:1, especially in the range 5:1:1 to 1000:1. Of course, it may be of interest to react compounds of formula (II) have a low 3E / 3Z-ratio, e. g. a ratio of lower than 1:1, in particular lower than 1.5:1 to selectively produce epimers of the all trans diastereromers (Iatr) and (ent-Iatr), in particular the interesting 9-epi isomer of (Iatr) or (ent-Iatr), respectively. 2E / 7E and 2Z / 7E-Isomers can be included as minor isomers depending on the technical grade of formula (II) used. It was found that in the process of the invention initially one or more of the following monocyclic compounds of the following formulae (VI-α), (VI-β) and (VI- γ) can be formed which further react to the compound of the formula (I), presumably they are formed from the carbenium-ion-intermediate of formula (VII): Therefore, the invention also includes processes, where mixtures of at least one compound of formula (II) and at least one compound of the formulae (VI-α), ) and / or (VI-γ) reacted in the presence of the Brønsted acid catalyst as described herein. As a consequence, it will also be possible to use one or more of the compounds of the formulae (VI-α), (VI-β) and / or (VI-γ) as a starting material for producing the compound of formula (I). Acids other than the Brønsted acid catalysts having the moiety of formula (a) may be present in the reaction mixture. In some cases they increase the conversion rate. However, formation of the undesired epi-diastereomers, in particular the 8-epi diastereomers and the 5β,8α,9β-diastereomer, may increase. Suitable acids other than the Brønsted acid catalysts having the moiety of formula (a) are in particular carboxylic acids, in particular those of the groups of C1-C6alkane mono- and dicarboxylic acids, such as acetic acid or propionic acid, fluorinated and C1-C6alkanecarboxylic acids, such as trifluoroacetic acid, C6-C10arylcarboxylic acids, such as benzoic acid, fluorinated C6-C10arylcarboxylic acids, such as 2,4,6-trifluorobenzoic acid and perfluorobenzoic acid and hydroxy-C2-C6alkane mono- and dicarboxylic acids, such as lactic acid and tartaric acid, C1-C6alkanesulfonic acids, such as methane sulfonic acid, C6-C10arylsulfonic acids, such as toluene sulfonic acid. If present, they may be present in amounts of 0.01 to 5 mol per 1 mol, in particular in amounts of 0.1 to 2 mol per 1 mol of the compound of formula (II). Preferably, they are absent or essentially absent, i. e. they are present in amounts of less than 0.01 mol per 1 mol of the compound of formula (II). The reaction is preferably carried out in an organic solvent or solvent mixture. Preferred are non-aqueous solvents. Suitable organic solvents include aprotic solvents and fluorinated alkanols having 2 to 10 carbon, in particular fluorinated alkanols having 2 to 10 carbon atoms, where all carbon atoms, except those carrying the hydroxyl group, are perfluorinated, and perfluorinated alkanols having 2 to 10 carbon atoms. Examples of preferred fluorinated alkanols include hexafluoroisopropanol, perfluoro-tert-butanol 1H,1H- perfluorooctan-1-ol. Suitable aprotic solvents include in particular halogenated hydrocarbons, in particular chlorinated alkanes having in particular 1 to 10 carbon atoms, fluororinated alkanes having in particular 3 to 10 carbon atoms, esters of carboxylic acids with fluorinated alkanols, in particular with prefluorinated alkanols having 2 to 20 carbon atoms, and alkanes having 5 to 10 carbon atoms, such as pentane, hexane, heptane and mixtures thereof, cycloalkanes having 5 to 10 carbon atoms such as cyclohexane, aromatic hydrocarbons, such as toluene and xylenes, aliphatic and cycloaliphatic ethers, such as methyl-tert.-butyl ether and tetrahydrofurane, nitroalkanes such as nitromethane and mixtures thereof. In this context, suitable chlorinated hydrocarbons are in particular dichloromethane, dichloroethane, trichloroethane etc. In particular, the organic solvent comprises or is a fluorinated alkanol. In particular, the organic solvent does not contain any solvents other than aprotic organic solvents and fluorinated alkanols. Preferably, the reaction is carried out in an organic solvent where the total amount of the compound of the formula (II) in the organic solvent subjected to the reaction is in the range of 0.05 to 3.0 mol per 1 L of the organic solvent. In general, the process of the invention is performed under temperature control. The reaction temperature of reaction of depends on different factors, such as the reactivity of the Brønsted acid catalyst and can be determined by the person skilled in the art in the individual case, for example by simple preliminary tests. In general, the reaction of the invention is performed at a temperature in of not more than 40 °C, in particular of not more than 30 °C to achieve a high selectivity. Suitable conversion rates are achieved at temperatures of -60 °C or higher, in particular at -50 °C or higher. In particular the reaction of the compound (II) is carried out at a temperature in the range of -60 to 40 °C, preferably in the range of -50 to 30 °C, more preferably in the range from -40 to 25 °C. It may be benefical to run the reaction under the atmosphere of an inert gas, such as nitrogen, argon or a mixture thereof. However, it is not necessary to carry out the reaction under an inert atmosphere. The pressure during the reaction is of minor importance and is typically carried out at ambient pressure, i. e. at about 1 bar. However, a higher pressure of generally >1 to 5 bar and preferably of >1 to 2 bar may be established during the reaction. The reaction of the process according to the present invention as described herein may be carried out continuously or batchwise. The reaction is usually carried out in a reaction vessel customary for such reactions. The reaction is typically effected in a reaction vessel with stirring apparatus. Suitable reactors for a continuous and batchwise reaction are known to those skilled in the art and are described, for example, in Ullmanns Enzyklopädie der technischen Chemie, vol. 1, 3rd Edition, 1951, p. 743 ff. Preference is given to using a cascade of stirred vessels or a tube reactor for the continuous variant of the process of the present invention. Suitable reactors for the semicontinuous or continuous embodiment, which may be pressure-rated, are known to those skilled in the art and are described, for example, in Ullmanns Enzyklopädie der technischen Chemie, volume 1, 3rd Edition, 1951, p. 769 ff. The reaction can be carried out in a continuous, semicontinuous or batchwise manner. Preference is given to a continuous process. In principle, the reaction can be performed under a pressure in the range of 0.1 to 50 bar, preferably in the range of 0.5 to 2 bar and more preferably under ambient pressure. The work-up of the reaction mixtures obtained in the reaction of process of the invention and the isolation of the compound (I), are effected in a customary manner, for example by a distillative separation of the product from the catalyst or an aqueous extractive work-up or by removing the solvent, for example under reduced pressure. The compound of formula (I) may be obtained in sufficient purity by applying such measures or a combination thereof. Further purification can be effected by methods commonly used in the art, such as distillation, crystallization or chromatography or by a combination of 2 or all of these measures. Preferably the reaction mixture obtained in the reaction of the process of the invention, for work-up, is concentrated by removing all or most of the solvent and then the obtained raw product is subjected to one or more purification steps, such as especially distillation or silica gel column chromatography using a gradient eluent. In one embodiment the work-up of the reaction mixture obtained in the reaction of the process according to the invention involves recycling of the Brønsted acid catalyst and / or the organic solvent. Examples The invention is to be illustrated by the following examples. 1. Abbreviations: conv. conversion of starting material iso isotherm equiv.: molar equivalent e.e.: enantiomeric excess e.r.: enantiomeric ratio HFIP: 1,1,1,3,3,3-hexafluoropropan-2-ol HNTF2: bis(trifluoromethane)sulfonimide (bistriflimide) IDPi: imidodiphosphorimidate MTBE: methyl tert.-butyl ether NEt3triethylamine n.d.: not determined. PADI: phosphoramidimiate PFTB: perfluoro-tert-butanol PTFE: polytetrafluoroethylene r.t.: room temperature (about 23 °C) Tf: triflyl group (−SO2CF3) TFA: trifluoroacetic acid Tf2O: trifluoromethanesulfonic anhydride (triflic anhydride) TfOH: trifluoromethanesulfonic acid (triflic acid) THF: tetrahydrofuran 2. Analytics Thin-Layer Chromatography (TLC) and Preparative TLC (pTLC): Monitoring reactions, analysis of column fractions and determination of retardation factors (Rfvalues) was performed by thin-layer chromatography on silica gel 60 or aluminum oxide coated glass plates (0.20 mm) with F254fluorescence indicator from Machery-Nagel. Qualitative analysis and visualization was accomplished by irradiation with UV light at λ = 254 nm and / or by immersion in different staining reagents (specified for each compound in the respective experimental procedure) followed by heating with a heat-gun at 300 °C until dryness. The following CAM or PMA stains were typically used for the visualization of the cyclized lactone and ether products): - Cerium ammonium molybdate (CAM) stain: Ce(SO4)2(cerium sulfate: 5.0 g) and (NH4)6Mo7O24⋅ 4 H2O (ammonium molybdate 25.0 g) were dissolved in H2O (450 mL) and concentrated H2SO4(50 mL) - Phosphomolybdic acid (PMA) stain: Phosphomolybdic acid (10 g) was dissolved in 100 mL absolute ethanol. NMR:1H,13C,31P nuclear magnetic resonance (NMR) spectra were acquired on a Bruker AV-600, AV-500, or AV-300 spectrometer in the specified deuterated solvent.1H chemical shifts are reported in ppm (δ) relative to tetramethylsilane (TMS) with the residual solvent resonance employed as the internal reference (δ 7.26 ppm for CDCl3; δ 5.32 ppm for CD2Cl2).13C chemical shifts are reported in ppm from tetramethylsilane (TMS) with the solvent resonance as the internal standard (CDCl3δ 77.16 ppm; CD2Cl2δ 53.84 ppm). Gas Chromatography (GC): GC was performed on HP 6890 and 5890 Series instruments equipped with a split- mode capillary injection system and a flame ionization detector (FID) using hydrogen (H2) or helium (He) as carrier gas. Enantiomeric ratios were determined by comparing the sample with an appropriate corresponding racemic mixture. The (chiral) stationary phases, mobile phases and detailed conditions are provided in the individual experiment. For quantitative GC-analysis of the reaction mixtures, the response factors of starting materials, identified intermediates, products and the internal standard were determined and the quantification was validated using the calibration curve method for each respective component. 3. Preparation of starting compounds 3.1 Preparation of (3E,7E) / (3Z,7E)-homofarnesol An isomeric mixture of homofarnesylic acid (obtained from the low-pressure carbonylation of nerolidol as described e.g. in M. Schelwies et al., Chem. Eur. J. 2021, 27, 9263–9266; WO 2018 / 153727; and WO 2018 / 154048) having a ratio 3E,7E : 3Z,7E : 2E,7E = 54:40:6 (1.25 g, 5.00 mmol) was transferred to a flame- dried 100 mL Schlenk flask equipped with a rubber septum under argon. The starting material was dissolved in anhydrous tetrahydrofuran (THF, 20 mL) and the resulting colorless solution was cooled to 0 °C using an ice / water bath. LiAlH4(1Msolution in THF, 5.00 mL, 5.00 mmol) was added dropwise over 5 min. The reaction mixture was stirred for 90 min at 0 °C. Afterwards1H NMR and TLC (hexanes / ethyl acetate 4:1 v / v) indicated complete consumption of the starting material and the formation of a less polar product. A Fieser workup, as described in L. F. Fieser, M. Fieser, Reagents Org. Synth. 1967, 1, 584, was performed: the reaction mixture was diluted with methyl tert.-butyl ether (MTBE, 20 mL), 0.2 mL water was added carefully at 0 °C, followed by 0.2 mL of 15% aqueous NaOH and 0.6 mL water, and the resulting cloudy solution was stirred at room temperature for 30 min. Afterwards, anhydrous MgSO4was added and the suspension was stirred for additional 15 min. The resulting suspension was filtered over a pad of Na2SO4 / Celite®545, and concentrated under reduced pressure to afford the crude product as an oil. Purification by flash column chromatography on silica gel (Merck, 40-63 µm) using hexanes / MTBE as eluent (isocratic elution with 4:1 v / v) afforded an isomeric mixture of homofarnesols as a colorless oil (3E,7E : 3Z,7E : 2E,7E : 2Z,7E = 54:40:4:2; 1.00 g, yield: 85%). TLC (SiO2, hexanes / MTBE 4:1 v / v): Rf(3Z,7E) = 0.31, Rf(3E,7E) = 0.25 (CAM stain). NMR data for (3E,7E : 3Z,7E)-homofarnesol with 3E:3Z = 57:43: NMR (501 MHz, CDCl3): δ 5.23–5.02 (m, 3H), 3.61 (q, J = 6.1 Hz, 2H), 2.29 (q, J = 6.8 Hz, 2H), 2.14–2.01 (m, 6H), 1.98 (dd, J = 9.2, 6.1 Hz, 2H), 1.73 (q, J = 1.3 Hz, 1H; 3Z,7E-isomer), 1.68 (s, 3H), 1.65 (d, J = 1.3 Hz, 2H; 3E,7E-isomer), 1.62–1.58 (m, 6H), 1.40–1.33 (m, 1H, OH).13C NMR (126 MHz, CDCl3): δ 139.1, 139.1, 135.6, 135.4, 131.5, 131.5, 127.4, 124.5, 124.5, 124.1, 124.0, 120.8, 120.0, 64.1, 62.8, 62.6, 39.9, 39.9, 39.9, 37.2, 37.0, 36.0, 32.1, 31.7, 31.6, 26.9, 26.8, 26.7, 26.6, 25.8, 25.8, 23.7, 17.8, 16.4, 16.2, 16.1. Diagnostic peaks for (2E,7E)-homofarnesol with 2Z:7E = 66:34: (m, 2H), 4.10 (t, J = 4.9 Hz, 2H), 0.99 (d, J = 6.8 Hz, 3H), 0.89 (d, J = 6.6 Hz, 2H). Gas Chromatography: Column Optima-350.25 mm / 0.25mm, 29.0 m; tempera- ture: 220 °C (injector) temperature gradient from 60 °C with 5 °C / min to 300 °C / 350 °C (detector), 0.60 bar H2, sample size: 0.2 µL, t(2E,7E)= 25.18 min (3.47%), t(2Z,7E)= 25.55 min (1.79%), t(3Z,7E)= 25.71 min (39.74%), t(3E,7E)= 26.00 min (53.70%). 3.2 Preparation of (S,S)-IDPi catalysts The following preparation of the (S,S)-IDPi catalysts were performed according to literature procedures, such as P. S. J. Kaib et al., Angew. Chem. Int. Ed. 2016, 55, 13200–13203. In a flame-dried Schlenk under argon, a suspension of 3,3’-substituted (S,S)-BINOL (0.2 mmol, 2.0 equiv.) in toluene (0.8 mL) was treated with the respective phosphazene reagent (0.2 mmol, 2.0 equiv.) and triethylamine (1.6 mmol, 16 equiv.). The reaction mixture was stirred for 2 h at room temperature (r.t.), then 1,1,1,3,3,3- hexamethyldisilazane (HMDS, 0.1 mmol, 1.0 equiv.) and 4-dimethylaminopyridine (DMAP, 0.1 mmol, 1.0 eq.) were added. The reaction mixture was stirred for additional 15 min at r.t., then the Schlenk tube was subsequently sealed and heated to 130 °C for 3 d. After cooling to r.t., an aqueous solution of HCl (10%) was added and the mixture was extracted with dichloromethane. The combined organic layers were washed with brine, dried over MgSO4and concentrated under reduced pressure. The crude material was purified by column chromatography on silica gel to afford the desired product as a salt. The salt was dissolved in 5 mL dichloromethane, then an aqueous solution of HCl (6 M, 8 mL) was added, and the mixture was stirred vigorously for 10 minutes. The organic layer was separated and the aqueous phase was extracted with dichloromethane for several times until no product could be detected by TLC in the last dichloromethane extract. The organic layers were combined and the solvent was removed under reduced pressure. The obtained solid (S,S)-IDPi catalyst was dried under high vacuum for 16 hours at r.t.. 4. Preparation Examples General procedure 1: An oven-dried screw-cap glass vial under argon equipped with a PTFE-coated magnetic stir bar was charged with the respective polyene substrate. The starting material was dissolved in the respective solvent and the solution was cooled to the indicated temperature. The Brønsted acid catalyst, if liquid, was added with a syringe through the screw-cap, the pierced screw-cap was sealed with Parafilm® or replaced with a new one and the vial was placed inside a cryostat at the indicated temperature or immersed inside an ice / NaCl bath at −18 °C. In case of solid Brønsted acid catalysts, the catalyst was transferred to the reaction vessel and dissolved in the respective solvent. The solution was cooled to the indicated temperature and the substrate was added via syringe. Yields and diastereomeric ratios for the respective cyclized products were determined by1H NMR spectroscopic analysis of the crude reaction mixture using 1,3,5-trimethylbenzene and / or triethylamine as internal standard and / or by gas chromatography (GC) using hexadecan-1-ol as internal standard. Enantiomeric ratios were determined by GC on a chiral stationary phase. Examples 1 to 6 and Comparative Example C1 Evaluation of strong achiral Brønsted acids as catalysts in the cyclization of (3E,7E)-homofarnesylic acid to sclareolide sclareolide 8- epi-sclareolide A B The reactions of Examples 1 to 6 and comparative example C1 were carried out according to General Procedure 1 using the reaction scale, solvent, reaction temperature, initial concentration of (3E,7E)-homofarnesylic acid, reaction time, Brønsted acid catalyst and catalyst loading specified in Table 1 below. Sclareolide A and 8-epi-sclareolide were obtained as racemic mixtures. Table 1 aAddition of the catalyst was performed at −78 °C and the reaction vessel was transferred to a cooling bath or to a cryostat adjusted to the indicated temperature. As can be seen from Table 1, the reaction in the presence of the Brønsted acid catalyst according to the invention (HNTf2) not only affords the sclareolide compounds A and B in a higher overall yield than the reaction in the presence of triflic anhydride, but also affords the preferred sclareolide A in a higher yield than 8-epi-sclareolide B. Epimerization of the desired sclareolide to 8-epi-sclareolide can be further suppressed by adjusting reaction time and temperature (lower temperature and / or shorter reaction time). Examples 7 to 9 Effect of added trifluoroacetic acid on the Brønsted acid-catalyzed cyclization of (3E,7E)-homofarnesylic acid to sclareolide An oven-dried screw-cap glass vial under argon equipped with a PTFE-coated magnetic stir bar was charged with 0.1 mmol (3E,7E)-homofarnesylic acid and commercially available (3aR)-(+)-sclareolide (0.1 mmol), if applicable (see Table 2). The starting material was dissolved in dry dichloromethane to give a 0.25 M of (3E,7E)-homofarnesylic acid and the solution was cooled a temperature of -78°C. The Brønsted acid catalyst (10 mol-% of HNTf2), and TFA (0.1 mmol), if applicable, was added (see Table 2), the pierced screw-cap was sealed with Parafilm® or replaced with a new one and the vial was immersed inside an ice / NaCl bath at −18 °C. After 3 h at this temperature, the reaction mixture was treated with triethylamine and 1,3,5-trimethylbenzene was added as internal standard. Conversions and yields for sclareolide (A) and 8-epi-sclareolide (B) were determined by1H NMR spectroscopic analysis of the crude reaction mixture using 1,3,5-trimethylbenzene as internal standard. Table 2 As can be seen from Table 2, addition of commercial (3aR)-(+)-sclareolide indeed led to product inhibition. However, by also adding TFA, the conversion rate was nearly restored to the previously observed level, presumably due to promoted dissociation of the catalyst from the product. Examples 10 to 15 and Comparative Example C2 Effect of TFA on the cyclization of (3E,7E)-homofarnesylic acid to sclareolide using HNTF2as catalyst The reactions of these Examples were carried out according to General Procedure 1 using (3E,7E)-homofarnesylic acid as a starting material on a 0.1 mmol scale. TFA was added to the reaction mixture together with the Brønsted acid catalyst HNTf2(or instead of HNTf2in Comparative Example C3) in an amount given in Table 3. The reactions were conducted at a temperature of -78 °C to -18 °C over a time period of 2 h. The solvent and catalyst loading used in each case are given in Table 3 below. Table 3: As can be seen from Table 3, very high amounts of TFA decrease the yield of sclareolide, likely due to increased epimerization (see Examples 12-14). Conversion and yield are however still satisfactory; the yields of A are in all cases higher than in the experiments carried out without TFA (see tables 1 and 2). Using TFA in the absence of HNTf2as catalyst did not provide much product, thus confirming the necessity of a Brønsted acid catalyst with sufficient acidity (see Comparative Example C2). Nitromethane was also found to be a suitable solvent for the cyclization reaction, giving results that are comparable to those obtained with dichloromethane (see Example 15). Examples 16 to 19 Effect of trifluoroacetic acid (TFA) on cyclization of (3E,7E)-homofarnesylic acid to sclareolide using HNTf2as catalyst in different solvents The reactions of these Examples were carried out according to General Procedure 1 using (3E,7E)-homofarnesylic acid as a starting material on a 0.1 mmol scale. The initial concentration of (3E,7E)-homofarnesylic acid was 0.25 M each. TFA (1 equiv.) was added to the reaction mixture together with the Brønsted acid catalyst HNTf2, which was applied in an amount of 10 mol%. The reactions were conducted in the solvent and at the temperature indicated in Table 4 below. The reaction time was 3 h in each case. Table 4 aAddition of the catalyst was performed at −78 °C and the reaction vessel was transferred to a cooling bath or to a cryostat adjusted to the indicated temperature. As can be seen from Table 4, hydrocarbon solvents are also suitable solvents for the purpose of the invention. Although slightly lower conversions were observed compared to the results obtained in dichloromethane, the yield towards sclareolide was comparable. Remarkably, fluorinated alkanols like 1,1,1,3,3,3- hexafluoropropan-2-ol were identified as particularly suitable reaction solvent. Examples 20 to 24 Use of Brønsted acids other than TFA as additives along with HNTf2as Brønsted acid catalyst The reactions of these examples were carried out according to General Procedure 1 using (3E,7E)-homofarnesylic acid as a starting material on a 0.1 mmol scale. The initial concentration of (3E,7E)-homofarnesylic acid in the solvent dichloromethane was 0.25 M each. The additives listed in Table 5 below were each added to the reaction mixture in an amount of 1 molar equivalent together with the Brønsted acid catalyst HNTf2, which was used in an amount of 10 mol%. The reactions were conducted at the temperature of -78 °C to -18 °C and over a reaction time of 2 h in each case. Yields for sclareolide were determined by NMR from the crude reaction mixture using 1,3,5-trimethylbenzene as internal standard and are summarized in Table 5 below. Table 5: As can be seen from table 5, various other Brønsted acids show similar results to TFA. Example 25 Cyclization reaction of (3E,7E)-homofarnesylic acid to sclareolide with HNTf2as catalyst and TFA as additive sclareolide 9- epi-sclareolide 5β,8 ^,9β-sclareolide 8- epi-sclareolide A B CDTo a 10 mL oven-dried pear-shaped two-neck flask equipped with a PTFE-coated magnetic stir bar under an argon atmosphere (3 x vacuum / argon cycle) was added a 0.5 M stock solution of HNTf2in CD2Cl2(0.15 mmol, 0.10 equiv.), trifluoroacetic acid (1.50 mmol, 1.00 equiv.) and CH2Cl2(2.70 mL, 0.5 M with respect to homofarnesylic acid). The colorless solution was cooled to −18 °C (ice / NaCl bath) and stirred (700 rpm) for 10 min. Then neat homofarnesylic acid (HMFS, 1.50 mmol) was transferred via a syringe pump (13.3 µL / min) over 30 min to the stirred solution of the catalyst. After the addition was complete, the resulting pale brown- red solution was stirred for an additional hour at −18 °C. After 90 min reaction time, the mixture was treated with triethylamine (3.60 mmol, 2.40 equiv.) and then mesitylene (1.51 mmol, 1.01 equiv.) was added as internal standard. Full consumption of the starting material is observed by TLC and NMR analysis of an aliquot (approx. 0.1 mL) of the pale yellow crude reaction mixture indicated approximately 52% yield of the desired product. The crude reaction mixture was transferred to a flask containing Celite®(approx. 2 g) and concentrated under reduced pressure. The resulting free-flowing off-white powder was subjected to purification by flash column chromatography on silica gel (Merck, 60 Å, 40-63 µm, 230-400 mesh, 20 g) using hexanes / ethyl acetate as eluent (gradient elution withhexanes / ethyl acetate). Fractions containing the product were pooled, concentrated under reduced pressure and filtered over sand / cotton wool to remove traces of silica gel. The least polar fractions typically consist of a mixture of completely cyclized tricyclic lactones (267 mg, 1.07 mmol, 71% yield; 62% yield of identified compounds A, B, C and D with a d.r. (A:B:C:D) of 17:4:2.7:1, other lactone diastereomers <10%). The more polar fractions contained a more complex mixture of partially cyclized compounds. After chromatography of the mixture, the combined yield was 375 mg (1.50 mmol, 99.6%) thus indicating excellent mass balance. A detailed report of the chromatography are summarized in Table 6 below. Sclareolide A and its diastereomers were obtained as their racemic mixtures. Table 6: Details on the fractions isolated after flash column chromatography * In the formula or the main components the dashed lines means that one of the dashed line represents a C=C double bond while the other dashed lines represent C-C single bonds. The combined lactone fractions were analyzed by gas chromatography as follows: Column FFAP 0.25 mm / 0.25 mm,15.0 m; temperature: 220 °C (injector), temperature gradient from 60 °C 5 °C / min to 250 °C iso 5 °C / min / iso / 350 (detector), 0.50 bar H2, sample size: 0.2 µL, tR(D)= 27.69 min (D, 8-epi-sclareolide, 0.91%), tR(B)= 28.87 min (B, 9-epi-sclareolide, 13.35%), tR(A)= 29.06 min (A, sclareolide, 67.33%), tR(C)= 29.56 min (C, 5β,8α,9β-sclareolide, 10.25%). Examples 26 to 29 Cyclization of (3Z,7E)-homofarnesylic acid to 9-epi-sclareolide using HNTf2as catalyst and TFA as additive The reactions of these Examples were carried out according to General Procedure 1 using (3Z,7E)-homofarnesylic acid as a starting material on a 0.1 mmol scale. The initial concentration of (3Z,7E)-homofarnesylic acid in the solvent dichloromethane is given for each case in Table 7 below. As indicated in Table 7, TFA was added in an amount of 1.0 equiv. to the reaction mixtures of Examples 28 and 29 together with the Brønsted acid catalyst HNTf2, which in all cases was used in an amount of 10 mol%. The reactions were conducted in each case at the temperature of -78 °C to -18 °C over a period of 2 h. Conversation rates and yields were determined by1H NMR spectroscopy of the crude reaction mixture using 1,3,5- trimethylbenzene as internal standard. The results are summarized in Table 7 below. Table 7: Example 30 Cyclization reaction of (3Z,7E)-homofarnesylic acid to 9-epi-sclareolide with HNTf2as catalyst and TFA as additive A flame-dried 10 mL Schlenk tube under argon equipped with a PTFE-coated magnetic stir bar was charged with a solution of (3Z,7E)-homofarnesylic acid (1 mL of a 2Msolution in CH2Cl2; flask rinsed with 1 mL and 1.6 mL CH2Cl2). The solution was cooled to −78 °C (dry ice / acetone cooling bath) and TFA (2.01 mmol, 1.0 equiv.) was transferred to the reaction vessel followed by dropwise addition of HNTf2(0.40 mL of a 0.5 M stock solution in CD2Cl2; 0.20 mmol, 0.10 equiv.). The resulting pale yellow solution was placed inside a cryostat at −20 °C and stirred at this temperature for 20 h. The reaction mixture was then neutralized with triethylamine (0.5 mL, 363 mg, 3.59 mmol, 1.8 equiv.), whereupon the color changed from orange-red to pale yellow, and the reaction mixture was concentrated onto Celite®. Purification by flash column chromatography on silica gel eluting with hexanes / ethyl acetate (gradient elution with hexanes / ethyl acetate) afforded a fraction of tricyclic lactones (255 mg, 51% yield, d.r. A:B:C:D ca. 155:29:2.1:1) and a fraction containing mainly partially cyclized compounds (112 mg, 22% yield), as determined from the following GC analysis. GC analysis: Column: FFAP 0.25 mm / 0.25 mm, 15.0 m; temperature: 220 °C (injector) temperature gradient from 60 °C 5 °C / min to 250 °C iso 5 °C / min / iso / 350 (detector), 0.50 bar H2, sample size: 0.2 µL, tR(D)= 27.50 min (8- epi-sclareolide, 0.50%), tR(A)= 28.77 min (B, 9-epi-sclareolide, 77.35%), tR(A)= 28.91 min (C, sclareolide, 1.05%), tR(B)= 29.16 min (B, 5β,8α-sclareolide, 14.49%). Examples 31 to 37 General procedure 2: The respective PADI or IDPi catalyst (5 mol% catalyst loading) was transferred to an oven-dried 1.5 mL screw-cap glass vial equipped with a PTFE-coated magnetic stir bar under ambient atmosphere and dissolved in the respective solvent. Neat (3E,7E)-homofarnesylic acid (5.01 mg, 0.02 mmol) was added to the magnetically stirred (250 rpm) colorless solution, the vial was closed with a screw-cap and the reaction mixture was stirred for the indicated time at the specified temperature. The reaction mixture was monitored using TLC (silica gel, hexanes / ethyl acetate 4:1 v / v, visualization with CAM stain) and NMR. After the indicated reaction time, triethylamine (20 µL) was added, the reaction mixture was diluted with hexanes or n-pentane to precipitate the catalyst and the resulting colorless suspension was filtered (elution with hexanes / dichloromethane 1:1, v / v or hexanes / ethyl acetate 9:1, v / v) through a pipette filled with a small pad of silica gel (d × l = 0.5 × 1 cm), sand and cotton wool. Concentration under reduced pressure afforded the crude product as a colorless oil or as a colorless solid. Alternatively, the reaction mixture was directly applied onto a 10 x 10 cm glass plate coated with 0.25 mm silica gel and purified by preparative TLC (elution with hexanes / ethyl acetate 9:1 or 4:1 v / v, typically one elution was sufficient to accomplish separation of lactones from partially cyclized compounds and the catalyst). A small (approximately 0.5 × 10 cm) center part of the TLC plate was cut, immersed in CAM stain and subsequently heated to dryness to visualize the dark blue product band. The product band was marked, collected, filtered over sand / cotton wool (elution with MTBE or dichloromethane, 3 × 1 mL) and concentrated under reduced pressure to afford the crude product. Mesitylene (1,3,5-trimethylbenzene, for quantitative NMR analysis) or cetyl alcohol (hexadecan-1-ol, for quantitative GC analysis) were added as internal standard respectively. Yields and conversion rates were determined via NMR and / or GC accordingly. Examples 31 to 33 Use of phosphoramidimidate (PADI) catalysts for the cyclization of (3E,7E)- homofarnesylic acid to sclareolide 1 The reactions of these examples were carried out according to General Procedure 2 using (3E,7E)-homofarnesylic acid as a starting material having an initial concentration in the solvent dichloromethane of 0.2 M. As Brønsted acid catalyst the (S)-PADI catalyst 1 depicted above is used, which is the S-enantiomer of a compound of formula (III) of the present invention, wherein R2is a radical of formula (IVb). The substituents Ra, Rband Rcof the (S)-PADI catalyst 1 have the meanings outlined in Table 8 below. The respective reaction temperatures are also given in Table 8 and the reaction time was 24 h in all cases. The yields for sclareolide were determined by GC using 1-hexadecanol as internal standard. The enantiomeric ratio (e.r.) was determined by gas chromatography on a chiral stationary phase. Table 8: Examples 34 to 37 Imidodiphosphorimidate (IDPi) catalysts for the cyclization of (3E,7E)- homofarnesylic acid to sclareolide The reactions of these examples were carried out according to General Procedure 2 using (3Z,7E)-homofarnesylic acid as a starting material having an initial concentration in the solvent dichloromethane as given in table 9 below. With the exception of Example 79, the (S,S)-IDPi catalyst 1 depicted above is used as Brønsted acid catalyst, which is a compound of formula (S,S-IIIa) of the present invention, wherein the substituents Rd, Reand Rfthe have the meanings outlined in table 9 below. In Example 34 the respective (R,R)-enantiomer of this catalyst was used instead. The reaction temperature and reaction time used in each case are summarized in Table 9. The yields for sclareolide were determined by GC using 1- hexadecanol as internal standard. The enantiomeric ratio (e.r.) was determined by gas chromatography on a chiral stationary phase. Table 9: *) (R,R)-enantiomer of (S,S)-IDPi catalyst 1 was used Examples 38 and 39a to 39c Scale-up, solvent screening and catalyst recycling studies of asymmetric polyene cyclization of (3E,7E)-homofarnesylic acid to sclareolide Example 38: The (S,S)-IDPi catalyst 1 with Rd= 3,5-(CF3)2-phenyl, Re= Tf and Rf= H, (89.4 mg, 0.05 mmol, 5 mol%) was transferred to an oven-dried 4 mL screw-cap glass vial equipped with a PTFE-coated magnetic stir bar. The vial was closed with a screw- cap containing a silicone / PTFE septum, evacuated and purged with argon (3 ×). Dry toluene (1.0 mL) was added, and the vial was placed in an ice / NaCl bath at –18 °C. After 5 min, a solution of (3E,7E)-homofarnesylic acid (250 mg, 1.00 mmol) in dry toluene (1.0 mL) was added via syringe to the solution, the vial was sealed with parafilm and placed inside a cryostat at –5 °C and the resulting pale yellow solution was stirred at this temperature for 6 days. Afterwards the orange-yellow reaction mixture was neutralized with triethylamine (20 µL, 14.5 mg, 0.14 equiv.), and concentrated onto Celite®. Purification by flash column chromatography on silica gel using hexanes / ethyl acetate as eluent afforded a lactone fraction (50.2 mg, yield: 20%) as a mixture of diastereomers. Details on the diastereomeric and enantiomeric ratios are given in table 12 and the GC data below. The catalyst was recovered after elution with ethyl acetate followed by acidification with the ion exchange resin DOWEX 50WX8 (50-100 mesh). GC (achiral stationary phase): Column FFAP 0.25 mm / 0.25 mm, 15.0 m; temperature: 220 °C (injector) temperature gradient 60 °C 5 °C / min, 250 °C iso 5 °C / min / iso / 350 (detector) 0.50 bar H2, sample size: 0.2 µL, tR(D)= 28.05 min (D, 8-epi-sclareolide, 1.58%), tR(C)= 29.24 min (C, 9-epi-sclareolide, 1.20%), tR(A)= 29.46 min (A, sclareolide, 80.90%), tR(B)= 29.93 min (B, 5β,8α,9β-sclareolide, 13.47%). GC (chiral stationary phase) Column Hydrodex-beta-TBDAc-CD 0.25 mm / 0.25 , 25.0 m; temperature: 220 °C (injector) temperature gradient 80 °C 0.8 °C / min, 200 °C 10 °C / min 220 °C 5 min iso / 350 (detector), 0.60 bar H2, sample size: 1.0 µL, tR(A, major)= 137.75 min (A, sclareolide, 52.77%), tR(B, minor)= 140.37 min (B, 5β,8α,9β-sclareolide, 4.01%), tR(A, minor)= 143.64 min (A, sclareolide, 31.31%), tR(B, major)= 146.58 min (B, 5β,8α,9β-sclareolide, 10.37%). Example 39a: The (S,S)-IDPi catalyst 1 with Rd= 3,5-(CF3)2-phenyl, Re= Tf and Rf= H, (0.05 mmol) was transferred to an oven-dried 4 mL screw-cap glass vial equipped with a PTFE-coated magnetic stir bar. The vial was closed with a screw-cap containing a silicone / PTFE septum, evacuated and purged with argon (3 ×). Dry dichloromethane (1.0 mL) was added, and the vial was placed in an ice / NaCl bath at –18 °C. After 5 min, a solution of (3E,7E)-homofarnesylic acid (1.00 mmol) in dry dichloromethane (1.0 mL, 1 M, 0.5 M final concentration) was added via syringe to the solution, the vial was sealed with parafilm and placed inside a cryostat at –5 °C and the resulting pale yellow solution was stirred at this temperature for 5 days. Afterwards the orange-yellow reaction mixture was neutralized with triethylamine (109 mg, 1.0 equiv.), and the resulting pale yellow to colorless solution was concentrated onto Celite®. Purification by automated flash column chromatography on spherical silica gel (Biotage®SFär 25 g, Biotage®HP-Sphere 25 µm) using hexanes / ethyl acetate as eluent afforded a lactone fraction (96.5 mg, 385 µmol, yield: 39%) as a mixture of diastereomers. Details on the diastereomeric and enantiomeric ratios are given in table 10 and the GC data below. The catalyst was recovered after elution with ethyl acetate followed by acidification with DOWEX 50WX8 (50-100 mesh), and obtained as an off-white solid after drying under reduced pressure (87.1 mg, 48.7 µmol, 97% recovery). GC (achiral stationary phase): Column: FFAP 0.25 mm / 0.25 mm, 15.0 m, temperature: 220 °C (injector) temperature gradient 60 °C 5 °C / min, 250 °C iso 5 °C / min / iso / 350 (detector), 0.50 bar H2, sample size: 0.2 µL, tR(D)= 28.08 min (D, 8-epi-sclareolide, 0.50%), tR(C)= 29.27 min (C, 9-epi-sclareolide, 2.23%), tR(A)= 29.51 min (A, sclareolide, 81.51%), tR(B)= 29.95 min (B, 5β,8α,9β-sclareolide, 11.90%). GC (chiral stationary phase): Column: Hydrodex-beta-TBDAc-CD 0.25 mm / 0.25 mm, 25.0 m; temperature: 220 °C (injector) temperature gradient 80 °C 0.8 °C / min, 200 °C 10 °C / min 220 °C 5 min iso / 350 (detector), 0.60 bar H2, sample size: 1.0 µL, tR(A, major)= 137.76 min (A, sclareolide, 56.34%), tR(B, minor)= 140.42 min (B, 5β,8α,9β-sclareolide, 4.54%), tR(A, minor)= 143.72 min (A, sclareolide, 30.42%), tR(B, major)= 146.67 min (B, 5β,8α,9β-sclareolide, 8.24%). Example 39b: The reaction was carried out with recycled (S,S)-IDPi catalyst 1 recovered in Example 39a (87.1 mg, 48.7 µmol, 4.9 mol%) for 6 days according to the procedure of Example 39a. Yield of the lactone fraction: 87.9 mg, 351 µmol, 35%. The (S,S)- IDPi catalyst 1 was recovered as described in Example 39a (76.7 mg, 42.9 µmol, 86% recovery). The results are summarized in table 10. GC (achiral stationary phase): FFAP 0.25 mm / 0.25 mm, 15.0 m, temperature: 220 °C (injector) temperature gradient 60 °C 5 °C / min, 250 °C iso 5 °C / min / iso / 350 (detector), 0.50 bar H2, sample size: 0.2 µL, tR(D)= 28.05 min (D, 8-epi-sclareolide, 0.97%), tR(C)= 29.26 min (C, 9-epi-sclareolide, 2.26%), = 29.55 min (A, sclareolide, 77.66%), tR(B)= 29.96 min (B, 5β,8α,9β-sclareolide, 13.95%). GC (chiral stationary phase): Hydrodex-beta-TBDAc-CD 0.25 mm / 0.25 mmm df G / 68125.0 m, temperature: 220 °C (injector) temperature gradient 80 °C 0.8 °C / min, 200 °C 10 °C / min 220 °C 5 min iso / 350 (detector), 0.60 bar H2, sample size: 1.0 µL, tR(A, major)= 138.33 min (A, sclareolide, 54.80%), tR(B, minor)= 140.32 min (B, 5β,8α,9β-sclareolide, 5.20%), tR(A, minor)= 143.31 min (A, sclareolide, 29.79%), tR(B, major)= 146.40 min (B, 5β,8α,9β-sclareolide, 9.32%). Example 39c: The transformation was carried out with recycled (S,S)-IDPi catalyst 1 recovered in Example 39b (76.7 mg, 42.9 µmol, 4.3 mol%) for 3 days according to the procedure described in Example 39a. Yield of the lactone fraction: 77.5 mg, 310 µmol, 31%. The (S,S)-IDPi catalyst 1 was recovered as described in Example 90a (76.7 mg, 42.9 µmol, 86% recovery). The results are summarized in table 10. GC (achiral stationary phase): FFAP 0.25 mm / 0.25 mm, 15.0 m, temperature: 220 °C (injector) temperature gradient 60 °C 5 °C / min, 250 °C iso 5 °C / min / iso / 350 (detector), 0.50 bar H2, sample size: 0.2 µL, tR(D)= 28.01 min (D, 8-epi-sclareolide, 0.46%), tR(C)= 29.22 min (C, 9-epi-sclareolide, 1.71%), tR(A)= 29.47 min (A, sclareolide, 81.06%), tR(B)= 29.90 min (B, 5β,8α,9β-sclareolide, 8.12%). GC (chiral stationary phase): Hydrodex-beta-TBDAc-CD 0.25 mm / 0.25 mm, 25.0 m, temperature: 220 °C (injector) temperature gradient 80 °C 0.8 °C / min, 200 °C 10 °C / min 220 °C 5 min iso / 350 (detector), 0.60 bar H2, sample size: 1.0 µL, tR(A, major)= 137.88 min (A, sclareolide, 57.55%), tR(B, minor)= 140.34 min (B, 5β,8α,9β-sclareolide, 3.05%), tR(A, minor)= 143.54 min (A, sclareolide, 32.94%), tR(B, major)= 146.59 min (B, 5β,8α,9β-sclareolide, 6.14%). Table 10: a)Yield refers to the isolated yield of the lactone fraction after flash column chromatography on silica gel.b)The diastereomeric ratio (d.r.) was determined by gas chromatography.c)The enantiomeric ratio (e.r.) was determined by gas chromatography on a chiral stationary phase, d) loading refers to the molar amount of catalyst based on the starting material The compound B obtained from the lactone fractions isolated from the cyclizations of (3E,7E)-homofarnesylic acid in the presence of (S,S)-IDPi catalyst 1 according to Examples 38 and 39a to 39c was confirmed to be 5β,8α,9β-sclareolide by comparing its13C NMR with those disclosed in S. Escher et al., Helv. Chim. Acta. 1990, 73, 1935 –1947, as shown below in table 11. Table 11: Examples 40 and 41 Preparation of sclareolide from (3E,7E)-homofarnesylic acid in the presence of HFIP. A screw-cap vial was charged with a magnetic stir bar, the respective (S,S)-IDPi catalyst 2 depicted above and specified in table 14 (0.50 µmol 0.02 equiv.), perfluorooctan-1-ol (40.0 mg, 0.10 mmol) as additive and 1,1,1,3,3,3- hexafluoropropan-2-ol (HFIP, 0.5 mL) as solvent. Thus, the (S,S)-IDPi catalyst 2 is a Brønsted acid of formula (S,S-IIIa) according to the present invention, wherein the substituents Rdand Rehave the meanings outlined in table 12. The reaction solution was cooled to the reaction temperature specified in table 12 and stirred for 10 min. (3E,7E)-homofarnesylic acid (6.26 mg, 25.0 µmol) was added to the reaction vial, and the reaction was stirred at the temperature indicated in table 12 for 7 days. The reaction mixture was treated with triethylamine and slowly warmed to room temperature, followed by evaporation of the solvent under reduced pressure. The yields of sclareolide and the diastereomeric ratios (d.r.) were determined by GC using 1-hexadecanol as internal standard. The enantiomeric ratios (e.r.) were determined by gas chromatography on a chiral stationary phase. These results are summarized in table 12. Table 12: Achiral GC: DB-5MS 0.25 mm / 0.25 mm, 30.0 m, temperature: 220 °C (injector) 50 °C iso 5 min, 15 °C / min, 340 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 19.80 min (sclareolide), tR2= 19.90 min (5β,8α,9β-sclareolide). Chiral GC: Ivadex-1 0.25 mm / 0.25 mm, 30.0 m, temperature: 220 °C (injector) temperature gradient 180 °C, 0.5 °C / min, 200 °C, 10 °C / min, 220 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 27.87 min (sclareolide, minor), tR2= 28.52 min (sclareolide, major). tR3= 29.28 min (5β,8α,9β-sclareolide, minor), tR4= 29.68 min (5β,8α,9β -sclareolide, major). Example 42 Preparation of sclareolide from (3E,7E)-homofarnesylic acid in the presence of PFTB sclareolide5 ^ ,8 ^,9 ^-sclareolide (S,S)-IDPi catalyst 3 A screw-cap vial was charged with a magnetic stir bar, the respective IDPi catalyst 3 depicted above and specified in table 15 (0.50 µmol, 2 mol%), and perfluoro-tert- butanol (PFTB, 0.02 mL). Thus, the (S,S)-IDPi catalyst 3 is a Brønsted acid of formula (S,S-IIIa) according to the present invention, wherein the substituents Rd, Reand Rfhave the meanings outlined in table 13. The reaction solution was cooled to the reaction temperature of -30°C and stirred for 10 min. (3E,7E)- homofarnesylic acid (0.025 mmol) was added to the reaction vial, and the reaction was stirred at -30°C for 12 hours. The reaction mixture was treated with triethylamine and slowly warmed to room temperature, followed by evaporation of the solvent under reduced pressure. The yield of sclareolide and the diastereomeric ratio (d.r.) were determined by NMR using CH2Br2as internal standard. The enantiomeric ratio (e.r.) was determined by gas chromatography on a chiral stationary phase. These results are summarized in table 13. Table 13: Chiral GC: vadex-10.25 mm / 0.25 mmm, 30.0 m, temperature: 220 °C (injector) temperature gradient 180 °C, 0.5 °C / min, 200 °C, 10 °C / min, 220 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 27.87 min (sclareolide, major), tR2= 28.52 min (sclareolide, minor). Examples 43 to 46 Brønsted acids as additives for the IDPi-catalyzed cyclization of (3E,7E)- homofarnesylic acid to sclareolide The reactions of these Examples were carried out according to General Procedure 2 using (3E,7E)-homofarnesylic acid as a starting material having an initial concentration in the solvent dichloromethane of 0.2 M. As Brønsted acid catalyst the (S,S)-IDPi catalyst 2 (see formula in examples 40 / 41) was used, wherein Rdis 3,5-(CF3)2-phenyl and Re= Tf. The respective additive listed in Table 14 was added in each case together with the catalyst in an amount of one molar equivalent. The reactions were all carried out at a reaction temperature of 0°C for a reaction period of 64 hours. The yields were determined by1H NMR analysis using mesitylene as internal standard. The diastereomeric ratios (d.r.) were determined by GC and the enantiomeric ratios (e.r.) by gas chromatography on a chiral stationary phase. These results are summarized in table 14. Table 14: Example 47 IDPi-catalyzed polyene cyclization of (3E,7E)-homofarnesylic acid esters to sclareolide The reaction of this example was carried out according to General Procedure 2 using the tert-butyl ester of (3E,7E)-homofarnesylic acid as starting material having an initial concentration in the solvent dichloromethane of 0.2 M. As Brønsted acid catalyst the (S,S)-IDPi catalyst 2 (see formula in examples 40 / 41) was used, wherein Rdis 3,5-(CF3)2-phenyl and Reis Tf. TFA was added as carboxylic acid additive in an amount given in table 15 together with the catalyst. The reaction was carried out at a reaction temperature of 0°C for a reaction period of 48 hours. The yield of sclareolide was determined NMR analysis using mesitylene as internal standard. The diastereomeric ratio (d.r.) was determined by GC and the enantiomeric ratios (e.r.) by gas chromatography on a chiral stationary phase. These results are summarized in table 15. Table 15: Examples 48 to 96 The following General Procedure 3 is especially intended for use of phosphoramidimiate (PADI) and imidodiphosphorimidate (IDPi) as catalysts for preparing ambroxide from (3E,7E)-homofarnesol. General procedure 3: The respective PADI or IDPi catalyst (5 mol% catalyst loading) was transferred to an oven-dried 1.5 mL screw-cap glass vial equipped with a PTFE-coated magnetic stir bar under ambient atmosphere and dissolved in the respective solvent. Neat (3E,7E)-homofarnesol (10.0 mg, 0.04 mmol) was added to the magnetically stirred (250 rpm) colorless solution, the vial was closed with a screw-cap and the reaction mixture was stirred for the indicated time at the specified temperature. The reaction mixture was monitored using TLC (silica gel, hexanes / ethyl acetate 4:1 v / v, visualization with CAM stain) and1H NMR. After the indicated reaction time, triethylamine (20 µL) was added, the reaction mixture was diluted with hexanes or n-pentane to precipitate the catalyst and the resulting colorless suspension was filtered (elution with hexanes / dichloromethane 1:1, v / v or hexanes / ethyl acetate 9:1, v / v) through a pipette filled with a small pad of silica gel (d x l = 0.5 x 1 cm), sand and cotton wool. Concentration under reduced pressure afforded the crude product as a colorless oil or as a colorless solid. Alternatively, the reaction mixture was directly applied onto a 10 x 10 cm glass plate coated with 0.25 mm silica gel and purified by preparative TLC (elution with hexanes / ethyl acetate, typically one elution was sufficient to accomplish separation of lactones from partially cyclized compounds and the catalyst). A small (approximately 0.5 x 10 cm) center part of the TLC plate was cut, immersed in CAM stain and subsequently heated to dryness to visualize the dark blue product band. The product band was marked, collected, filtered over sand / cotton wool (elution with MTBE or dichloromethane, 3 x 1 mL) and concentrated under reduced pressure to afford the crude product. Mesitylene (1,3,5-trimethylbenzene, for quantitative NMR analysis) or cetyl alcohol (hexadecan-1-ol, for quantitative GC analysis) were added as internal standard respectively. Yields and conversions were determined via NMR and / or GC accordingly. Examples 48 to 54 Use of PADI catalysts for the polyene cyclization of (3E,7E)-homofarnesol to ambroxide ambrox(S)-PADI catalyst 2 The reactions of these examples were carried out according to General Procedure 3 using (3E,7E)-homofarnesol as a starting material having an initial concentration in the solvent dichloromethane indicated in table 16 below. As Brønsted acid catalyst the (S)-PADI catalyst 2 depicted above is used, which is the S-enantiomer of a compound of formula (III) of the present invention, wherein R2is a radical of formula (IVb). The substituents Raand Rbof the (S)-PADI catalyst 2 have the meanings outlined in Table 16. The reactions were conducted at room temperature over a period of 1 day. The yields of ambroxide were determined by GC using 1- hexadecanol as internal standard or by NMR using 1,3,5-trimethylbenzene or dibromomethane as internal standard. The enantiomeric ratio (e.r.) was determined by gas chromatography on a chiral stationary phase. These results are summarized in table 16. Table 16: Examples 55 to 56 Evaluation of IDPi catalysts and solvents in the cyclization of (3E,7E)-homofarnesol to ambroxide The reactions of these Examples were carried out on a 0.02 or 0.05 mmol scale according to General Procedure 3 using (3Z, 7E)-homofarnesol as a starting material having an initial concentration in the solvent listed in table 19 below of 0.1 M. In example 55 the (S,S)-IDPi catalyst 2 (see formula in examples 40 / 41) was used as Brønsted acid catalyst, which is a compound of formula (S,S-IIIa) of the present invention, wherein the substituents Rdand Rethe have the meanings outlined in table 17 below. In Example 56 the respective (R,R)-enantiomer of this catalyst was used instead. The reactions were conducted at room temperature for a reaction time given in table 17. The yields for ambroxide were determined by GC using 1-hexadecanol as internal standard. The enantiomeric ratio (e.r.) was determined by gas chromatography on a chiral stationary phase. These results are summarized in table 17. Table 17: *) (R,R)-enantiomer of (S,S)-IDPi catalyst 2 was used Examples 57 to 59 Use of Brønsted-acidic additives in the IDPi-catalyzed cyclization of (3E,7E)- homofarnesol to ambroxide -IDPi dichloromethane ambrox (A) 8-epi-ambrox (B)The reactions of these Examples were carried out on a 0.02 mmol scale according to General Procedure 3 using (3Z,7E)-homofarnesol as a starting material having an initial concentration in dichloromethane as solvent of 0.2 M. As Brønsted acid catalyst the (S,S)-IDPi catalyst 2 (see formula in examples 40 / 41) was used, wherein Rdis 3,5-(CF3)2-phenyl and Re= Tf. The respective carboxylic acid additive listed in table 18 was added together with the catalyst in an amount of 1 equiv. The reactions were conducted at a temperature of 0°C over a period of 64 hours. The yields for ambroxide were determined by1H NMR using mesitylene as internal standard. The diastereomeric ratios (d.r.) were determined by GC and the enantiomeric ratios (e.r.) by GC on a chiral stationary phase. These results are summarized in table 18. Table 18: Examples 60 to 76 Cyclization of (3E,7E)-homofarnesol to ambroxide and 5β,8α,9β-ambroxide using HFIP as solvent A screw-cap vial was charged with a magnetic stirrer bar, the respective IDPi catalyst (catalyst loading as indicated in the respective table and HFIP or PFTB. The reaction solution was cooled to the corresponding temperature and stirred for 10 min. (3E,7E)-homofarnesol (0.025 mmol) was added to the reaction vial and the reaction was stirred at the respective temperature. After the specified time, the reaction mixture was treated with Et3N and slowly warmed to room temperature. Then, the solvent was evaporated under reduced pressure. The reported yields (ambrox) and d.r. (ambrox:5β,8α,9β-ambrox) were determined by gas chromatography (GC) using 1-hexadecanol or NMR spectroscopy using dibromomethane as internal standard. The enantiomeric ratio (e.r.) was determined by gas chromatography on a chiral stationary phase. In the reaction optimization and for screening purposes, the known compounds ambrox and 5β,8α,9β-ambrox were not isolated, and their identity was confirmed by comparison of their1H and 13C NMR data with those of authentic samples and / or reported literature data. These results are summarized in table 19. Table 19: Examples 77 to 96 Cyclization of (3E,7E)-homofarnesol to ambroxide and 5β,8α,9β-ambroxide using PFTB as solvent The reactions of these Examples were carried out on a 0.025 mmol scale according to the protocol of examples 60 to 76. Details are given in table 20 below. Example 96 was set up for 12 hours at −40oC then 8 hours at 0oC. The yields for ambroxide and the d.r. (ambroxide : 5β,8α,9β-ambroxide) were determined NMR using dibromomethane as internal standard. The enantiomeric ratios (e.r.) were determined by GC on a chiral stationary phase. These results are summarized in table 20. Table 20: *) A = ambroxide and B = 5β,8α,9β-ambroxide Example 97 Exemplary protocol for the asymmetric polyene cyclization of (3E,7E)-homofarnesol to ambroxide using an IDPi catalyst A screw-cap vial was charged with a magnetic stirrer bar, an IDPi catalyst 3 (see formula in example 42) and HFIP or PFTB as solvent. The loading of the IDPi catalyst 3 was was in the range of 1 to 5 mol%, and the substituents Rd, Reand Rfof the catalyst typically corresponded to one of the combinations of these substituents given in Tables 19 or 20. The reaction solution was cooled to the reaction temperature in the range of -50°C to r.t. and stirred for 10 min. (3E,7E)- homofarnesol (0.025 mmol) was added to the reaction vial and the reaction was stirred at the respective reaction temperature. After a reaction time of 10 hours to 7 days, the reaction mixture was treated with triethylamine and slowly warmed to room temperature. Then, the solvent was evaporated under reduced pressure. The reported yields (ambroxide) and d.r. (ambroxide:5β,8α,9β-ambroxide) were determined by1H NMR using dibromomethane as internal standard. The enantiomeric ratio (e.r.) was determined by gas chromatography on a chiral stationary phase. In the reaction optimization and for screening purposes, the known compounds ambroxide and 5β,8α,9β-ambroxide were not isolated, and their identity was confirmed by comparison of their1H and13C NMR data with those of authentic samples and / or as reported in S. Escher et al., Helv. Chim. Acta. 1990, 73, 1935 –1947 GC: DB-5MS 0.25 mm / 0.25mm, 30.0 m, temperature: 220 °C (injector) temperature gradient 50 °C iso 5 min, 15 °C / min, 340 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 19.06 min (ambroxide), tR2= 19.16 min (5β,8α,9β- ambroxide). Chiral GC: BGB 1760.25 mm / 0.25 mm, 30.0 m, temperature: 220 °C (injector) temperature gradient 150 °C iso 60 min, 20 °C / min, 220 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 44.51 min (ambroxide, minor), tR2= 46.17 min (ambroxide, major). tR3= 47.82 min (5β,8α,9β-ambroxide, minor), tR4= 49.17 min (5β,8α,9β-ambroxide, major).13C NMR (126 MHz, CDCl3) δ (ambroxide) 79.9, 65.0, 60.1, 57.3, 42.5, 40.0, 39.8, 36.2, 33.6, 33.1, 22.7, 21.2, 20.7, 18.4, 15.1. (5β,8α,9β-ambroxide) 78.9, 64.4, 58.6, 52.5, 38.7, 37.7, 35.5, 34.1, 33.3, 31.4, 29.7, 27.1, 25.1, 23.4, 20.6, 19.0. Example 98 Procedure for the polyene cyclization of (3E,7E)-homofarnesol to ambroxide using an IDPi catalyst The (R,R)-enantiomer of an IDPi catalyst 2 (see formula in examples 40 / 41) with Rd= 4-tert.-butylphenyl and Re= SO2C8F17(0.02 mmol, 0.02 equiv.) was dissolved in HFIP (20 mL) in a round-bottom flask at 0 °C. To the mixture was added (3E,7E)- homofarnesol (1.0 mmol) via syringe with stirring. The reaction mixture was stirred at 0 °C until full consumption of the starting material (3E,7E)-homofarnesol was achieved as indicated by TLC. The resulting mixture was quenched with triethylamine, the solvent was evaporated under reduced pressure and the residue was subjected to column chromatography on a silica gel (hexanes / ethyl acetate 20:1 v / v) to give the product as a mixture of diastereoisomers (ambroxide and 5β,8α,9β-ambroxide) in 64% yield (152 mg, 0.64 mmol, d.r. of 73:27 ambroxide:5β,8α,9β-ambroxide, and e.r. 89.4:10.6 for ambroxide). To recover the IDPi catalyst, the column was eluted with hexanes / ethyl acetate (4:1 v / v) to afford the IDPi catalyst as a salt. The IDPi was obtained after acidification in DCM with aq. HCl (6M) and evaporation of the solvent followed by drying under high vacuum as a colorless solid (IDPi recovery >99%). The purity of the recovered catalyst was verified Examples 99 to 101 and Comparative Example C3 Catalytic cyclization of homofarnesol isomers to ambroxide and its isomers using PFTB as solvent (S,S)-IDPi catalyst 4A screw-cap vial was charged with a magnetic stirrer bar, the (S,S)-IDPi catalyst 4 depicted above (catalyst loading: 2 mol%) and PFTB. The reaction solution was cooled to the corresponding temperature and stirred for 10 min. The homofarnesol substrate (0.025 mmol, 0.05 M) was added to the reaction vial and the reaction was stirred at a temperature of -30°C for 12 hours. Afterwards the reaction mixture was treated with triethylamine and slowly warmed to room temperature. Then, the solvent was evaporated under reduced pressure. The reported yields and diastereomeric ratios (d.r.) were determined by NMR using CH2Br2as internal standard. The enantiomeric ratios (e.r.) were determined by gas chromatography on a chiral stationary phase. The respective results are summarized in table 21. The obtained compounds ambroxide, 5β,8α,9β-ambroxide, 9-epi-ambroxide and the interrupted products depicted above were not isolated. Table 21: *) ratios roughly estimated by GC GC: DB-5MS 0.25 mm / 0.25 mm, 30.0 m, temperature: 220 °C (injector); 159 °C isotherm for 50 min, temperature gradient 20 °C / min to 340 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 19.66 min (γ-interrupted), tR2= 20.75 min (α-interrupted), tR3= 22.90 min (β-interrupted), tR4= 33.70 min (9-epi-ambroxide), tR5= 36.91 min (ambroxide), tR6= 39.05 min (5β,8α,9β-ambroxide). Chiral GC: BGB 1760.25 mm / 0.25 mm, 30.0 m, temperature: 220 °C (injector); 150 °C isotherm for 60 min, temperature gradient 20 °C / min to 220 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 38.40 min (9-epi-ambroxide, major), tR2= 39.00 min (9-epi-ambroxide, minor). tR3= 44.51 min (ambroxide, major), tR4= 46.17 min (ambroxide, minor). tR5= 47.82 min (5β,8α,9β-ambroxide, major), tR6= 49.17 min (5β,8α,9β-ambroxide, minor). Example 102 Catalytic cyclization of 3E / 7E-homofarnesol to ambroxide and its isomers (-) ambroxide 5 ^,8 ^,9 ^-ambroxide A 100 mL Schlenk flask under argon equipped with a PTFE-coated magnetic stir bar was charged with homofarnesol (1.180 g, 5.0 mmol, 1.0 equiv.) and IDPi catalyst of example 99 (0.1 mmol, 0.02 equiv.). The mixture was cooled to -40oC and stirred for 10 min. 4 mL PFTB was added and the reaction was stirred for 12 h until full consumption of the starting material was observed as indicated by TLC. Then the reaction solution was stirred at 0oC for another 8 h. The resulting mixture was quenched with Et3N, the solvent was evaporated under reduced pressure and the residue was subjected to column chromatography on a silica gel (hexanes / ethyl acetate 50:1 v / v) to give ambroxide in 51% yield (603 mg, 2.55 mmol, ambroxide:5β,8α,9β-ambroxide >20:1, e.r. of ambroxide 95:5). To recover the IDPi catalyst, the column was eluted with hexanes / ethyl acetate (1:4 v / v) to afford the IDPi catalyst as a salt. The IDPi was obtained after acidification in DCM with aq. HCl (6 M) and evaporation of the solvent followed by drying under high vacuum as a colorless solid 253 mg (IDPi recovery >99%). The purity of the recovered catalyst was verified by and31P NMR. GC: DB-5MS 0.25 mm / 0.25 mm, 30.0 m, temperature: 220 °C (injector) 159 °C iso 50 min, temperature gradient 20 °C / min, 340 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 36.9 min (ambroxide), tR2= 39.0 min (5β,8α,9β- ambroxide). Chiral GC: BGB 1760.25 / 0.25df, 30.0 m, temperature: 220 °C (injector) 150 °C iso 60 min, 20 °C / min, 220 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 44.6 min (ambroxide, major), tR2= 46.2 min (ambroxide, minor). Example 103 Catalytic cyclization of homofarnesol isomer mixture to ambroxide and its isomers A 100 mL Schlenk flask under argon equipped with a PTFE-coated magnetic stir bar was charged with mixture 3E,7E and 3Z,7E-homofarnesol (3E,7E:3Z,7E= 63:37, 1.63 mmol, 1.0 equiv.) and IDPi catalyst of example 99 (0.033 mmol, 0.02 equiv.). The mixture was cooled to -40oC and stirred for 10 min. 1.3 mL PFTB (Perfluoro- tert-butanol) was added and the reaction was stirred for 12 h until full consumption of the starting material was observed as indicated by TLC. Then the reaction solution was stirred at 0oC for another 8 h. The resulting mixture was quenched with Et3N, the solvent was evaporated under reduced pressure and the residue was subjected to column chromatography on a silica gel (hexanes / ethyl acetate 50:1 v / v) to give mixture ambroxide and 9-epi ambroxide in 39% yield (ambroxide:9-epi- ambroxide 63:37, e.r. of ambroxide 94:6, e.r. of 9-epi-ambroxide 92:8) To recover the IDPi catalyst, the column was eluted with hexanes / ethyl acetate (1:4 v / v) to afford the IDPi catalyst as a salt. The IDPi was obtained after acidification in DCM with aq. HCl (6 M) and evaporation of the solvent followed by drying under high vacuum as a colorless solid 83 mg (IDPi recovery >99%). The purity of the recovered catalyst was verified by and31P NMR. GC: DB-5MS 0.25 mm / 0.25 mm, 30.0 m, temperature: 220 °C (injector) 159 °C iso 50 min, temperature gradient 20 °C / min, 340 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 33.7 min (9-epi-ambroxide), tR2= 36.92 min (ambroxide). Chiral GC: BGB 1760.25 mm / 0.25 mm, 30.0 m, temperature: 220 °C (injector) 150 °C iso 60 min, temperature gradient 20 °C / min, 220 °C iso 5 min, 0.60 bar H2, sample size: 0.2 µL, tR1= 38.3 min (9-epi-ambroxide, major), tR2= 39.1 min (9- epi-ambroxide, minor). tR1= 44.5 min (ambroxide, major), tR2= 46.1 min (ambroxide, minor). Example 104 Catalytic cyclization of (3E,7E) homofarnesol to ambroxide and a by-product NP A 100 mL Schlenk flask under argon equipped with a PTFE-coated magnetic stir bar was charged with (3E,7E) homofarnesol (42.3 mmol, 1.0 equiv.) and IDPi catalyst of example 99 (0.85 mmol, 0.02 equiv.). The mixture was cooled to -40oC and stirred for 10 min. 33.8 mL PFTB (Perfluoro-tert-butanol) was added and the reaction was stirred for 12 h. Then the reaction solution was stirred at 0oC for another 8 h until full consumption of monocyclic intermediates. To recover the solvent, the resulting mixture was distilled under reduced pressure. To this end, a distillation bridge with a Schlenk tube immersed in dry-ice and connected to a membrane vacuum pump was attached to the reaction vessel. The temperature of the reaction mixture was kept at 0 °C, PFTB was collected at p ≈ 1 mbar and obtained as a clear colorless liquid. The residue was subjected to column chromatography on silica gel (gradient elution with hexanes / ethyl acetate 50:1 to 1:4 v / v) to give ambrox in 52% yield (5.18 g, 22.0 mmol, 92:8 d.r., ambrox:5β,8α,9β-ambrox >20:1, e.r. of ambrox 95:5), and a mixture of partially cyclized product NP in 47% yield (4.70 g, 19.9 mmol, α:β:γ 14:9:1). To recover the IDPi catalyst, the column was eluted with hexanes / ethyl acetate (1:4 v / v) to afford the IDPi catalyst as a salt. The protonated IDPi was obtained after acidification in DCM with aq. HCl (6 M) and evaporation of the solvent, followed by drying under high vacuum as a colorless solid (2.14 g, 0.85 mmol, IDPi recovery >99%). The purity of the recovered catalyst was verified by and31P NMR spectroscopy.

Claims

Claims 1. The process for preparing a tricyclic compound of the formula (I)which comprises reacting a compound of the formula (II)where in formulae (I) and (II) X is CH2or C(=O) and where the curved lines in formula (II) indicate an E- or Z-configuration; in the presence of a catalytic amount of a Brønsted acid having a moiety of the formula (a) -X-NH-S(=O)2-R (a) where X represents a -S(=O)2- moiety, a -P(=O)(O-)2moiety or a -P(=N-)(O-)2moiety, where the phosphorous atoms of these moieties are bound to the NH group in the moiety of formula (a) and where R is a fluorinated hydrocarbon moiety having 1 to 20 carbon atoms.

2. The process of claim 1, where the Brønsted acid has a pKaat 20°C and 1 bar in acetonitrile of 14 or lower than 14.

3. The process of any one of the preceding claims, where the X in formula (a) represents a -S(=O)2- moiety or a -P(=N-)(O-)2moiety.

4. The process of any one of the preceding claims, where the Brønsted acid is of the formula (III)where R1is F, fluorinated C1-C18alkyl and fluorinated C6-C18aryl; R2is S(=O)2-CFZ-R2aor a moiety of formulae (IVa) or (IVb)where # indicates the bond to the sulfonamide nitrogen atom in formula (III); n, m independently of each other are 0, 1 or 2; R21, R22independently of each other are selected from the group of hydrogen, fluorine and C6-C18aryl, where aryl has 1, 2 or 3 phenyl rings which are fused to each other or connected by a single bond and where aryl may include a saturated 5- or 6-membered monocycle fused to at least one of the phenyl rings or a saturated8 to 12 membered spirobicycle fused to at least one of the phenyl rings of C6-C18aryl, where C6-C18aryl is unsubstituted or may carry 1, 2 or 3 radicals R29; R23, R24independently of each other are selected from fluorine and fluorinated C1-C4alkyl; R3is S(=O)2-CFZ-R3aor a moiety of formulae (Va) or (Vb)where # indicates the bond to the imino nitrogen atom in formulae (IVa) and (IVb), respectively; p, q independently of each other are 0, 1 or 2; R25, R26independently of each other are selected from the group of hydrogen, fluorine and C6-C18aryl, where aryl has 1, 2 or 3 phenyl rings which are fused to each other or connected by a single bond and where aryl may include a saturated 5- or 6-membered monocycle fused to at least one of the phenyl rings or a saturated 8 to 12 membered spirobicycle fused to at least one of the phenyl rings of C6-C18aryl, where C6-C18aryl is unsubstituted or may carry 1, 2 or 3 radicals R30;R27, R28independently of each other are selected from fluorine and fluorinated C1-C4alkyl; and where on each occurrence Z is F or fluorinatedalkyl, in particular F or CF3; R29and R30, independently of each other are selected from C1-C10alkyl, fluorine, SF5, fluorinated C1-C10alkyl, C5-C10cycloalkyl, and phenyl; R2a, R3aand R4a, independently of each other are selected from fluorine, F, fluorinated C1-C18alkyl and fluorinated C6-C18aryl.

5. The process of claim 4, where R2is S(=O)2-CFZ-R2aor a moiety of formula (IVb).

6. The process of claim 5, where R2a moiety of formula (IVb), where R3is a moiety of formulae (Va) or (Vb).

7. The process of any one of the preceding claims, where the Brønsted acid is chiral.

8. The process of claims 4 to 7, where formula (III) is represented by formula (IIIb), including its tautomers, diastereomers and its enantiomers:

9. The process of claim 8, where the Brønsted acid is of the formulae (R,R-IIIb) or (S,S-IIIb):

10. The process of any one of claims 7, 8 or 9, where the chiral Brønsted acid is used in is enantiopure form or has an enantiomeric excess of at least 90% ee.

11. The process of claims 4-6, 8, 9 or 10, where m, n, p and q in formulae (IIIb), (R,R-IIIb), (S,S-IIIb), (IVa), (IVb), (Va) and (Vb) are 0 or 1.

12. The process of at least one of claims 4-7, 8, 9, 10 or 11, where R21, R22, R25, R26in formulae (IIIb), (R,R-IIIb), (S,S-IIIb), (IVa), (IVb), (Va) and (Vb) are selected from - phenyl, which is substituted with 1, 2, or 3 radicals selected from C1-C10alkyl, C1-C10fluorinated alkyl and SF5; - naphthyl, which is unsubstituted or substituted with 1, 2, or 3 radicals selected from C1-C10alkyl, C1-C10fluorinated alkyl and phenyl;- biphenyl, which is unsubstituted or substituted with 1, 2, or 3 radicals selected from C1-C10alkyl, C1-C10fluorinated alkyl and phenyl; - fluorenyl, which is unsubstituted or substituted with 1, 2, or 3 radicals selected from C1-C10alkyl, C1-C10fluorinated alkyl and phenyl, where 2 of the substituents located in the 9 position of fluorenyl may form a saturated 4-7 membered spirocarbocyle.

13. The process of claim 12, where R21, R22, R25, R26in formulae (IIIb), (R,R-IIIb), (S,S-IIIb), (IVa), (IVb), (Va) and (Vb) are of the following formula Awhere # indicates the point of attachment k is 1, 2, 3 or 4; x is 0 or 1 Rxis selected from C1-C10alkyl, C1-C10fluorinated alkyl and phenyl.

14. The process of any one of the preceding claims, where the amount of the Brønsted acid is in the range of 0.00001 to 0.3 mol, in particular in the range of 0.00005 to 0.1 mol per 1 mol of the compound formula (II).

15. The process of any one of the preceding claims, where the compound of formula (II) has an E / Z ratio with respect to the double bond in the 3-position of at least 1:1, in particular at least 1.1:

1.

16. The process of any one of the preceding claims, where the reaction is carried out in an organic solvent which is selected from aprotic solvents and fluorinated alkanols and mixtures thereof.

17. The process of claim 16, where the organic solvent comprises or is a fluorinated alkanol.

18. The process of any one of claims 16 or 17, where the reaction is carried out in an organic solvent and where the concentration of the compound of the formula (II) in the organic solvent is in the range of 0.05 to 3.0 mol / l.

19. The process of any one of the preceding claims, where the reaction is carried out at a temperature in the range of -80 to +40°C, in particular in the range of -60 to +30°C.

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