Method for preparing bicyclic enol ethers

Abstract

The present invention relates to the field of organic synthesis, and more particularly to a metal complex-catalyzed process for the preparation of compounds of formula (I) starting from compounds of formula (II). TIFF2022528816000015.tif70150

Description

[Technical field]

[0001] The present invention relates to the field of organic synthesis, more specifically to a process for the preparation of compounds of formula (I) catalyzed by metal complexes.

[0002] background The bicyclic enol ether derivatives of formula (I) are typical intermediates to more valuable compounds such as saturated or unsaturated cyclic ketones. For example, 16-oxabicyclo[10.3.1]hexadec-12-ene or 14-methyl-16-oxabicyclo[10.3.1]hexadec-12-ene are important intermediates to highly valued perfume ingredients such as Exaltenone or Muscenone® (trademarks of Firmenich SA). These intermediates have been obtained for decades by double reduction of macrocyclic diones, such as 1,5-cyclopentadecanedione or 3-methylcyclopentadecane-1,5-dione, to the corresponding macrocyclic diols, such as 1,5-cyclopentadecanediol or 3-methylcyclopentadecane-1,5-diol, followed by dehydrogenation and dehydration to form macrocyclic enol ethers. Direct enol ether formation from dione starting materials has not been reported.

[0003] Therefore, there remains a need to develop such more direct approaches to bicyclic enol ethers with improved yields.

[0004] According to the present invention, compounds of formula (I) can be obtained starting from cyclic diketones of formula (II) under transfer hydrogenation conditions using a secondary alcohol as the hydrogen source.

[0005] Summary of the Invention The present invention relates to a novel process which allows the preparation of compounds of formula (I) starting from compounds of formula (II) whilst avoiding the formation and isolation steps of the corresponding diol.

[0006] The subject of the present invention is therefore a compound of formula (I) [ka] [In the formula, R 1 is a linear or branched C 1~5 represents an alkanediyl or alkenediyl group, R 2 is a linear or branched C 1~10 represents an alkanediyl or alkenediyl group] in the form of any one of its stereoisomers or a mixture thereof, said process comprising the steps of: Formula (II) [ka] [In the formula, R 1 and R 2 has the same meaning as defined in formula (I)] in the form of any one of its stereoisomers, in the presence of a hydrogen source with a metal catalyst, except for ruthenium catalysts.

[0007] Description of the Invention Surprisingly, it has now been found that compounds of formula (I) can be advantageously prepared by a one-pot reduction and cyclodehydration type reaction of compounds of formula (II) under transfer hydrogenation conditions. The conditions of the present invention make it possible to avoid the difficult handling of the corresponding diols and are highly selective towards monoreduction. The process of the present invention allows the formation of bicyclic enol ethers in high yields without compromising the conversion. Furthermore, the catalytic system used in the process of the present invention is reusable, making it possible to avoid the use of toxic reagents such as borohydrides, making the aforementioned transformation more sustainable.

[0008] A first subject of the invention is therefore a compound of formula (I) [ka] [In the formula, R 1is a linear or branched C 1~5 represents an alkanediyl or alkenediyl group, R 2 is a linear or branched C 1~10 represents an alkanediyl or alkenediyl group] in the form of any one of its stereoisomers or a mixture thereof, said process comprising the steps of: Formula (II) [ka] [In the formula, R 1 and R 2 has the same meaning as defined in formula (I)], in the form of any one of its stereoisomers, in the presence of a hydrogen source with a metal catalyst, except for ruthenium catalysts.

[0009] According to any embodiment of the present invention, the method of the present invention is a one-step process.

[0010] According to an optional embodiment of the present invention, the process of the present invention is a full conversion process.

[0011] "Complete conversion process" has its usual meaning in the art, i.e. the process of the present invention is carried out until complete conversion of the compound of formula (II).

[0012] According to an optional embodiment of the present invention, a compound of formula (III) [ka] [In the formula, R 1 and R 2 has the same meaning as defined in formula (I), and no compound in any one of its stereoisomeric forms is formed.

[0013] In other words, the method of the present invention can obtain the compound of formula (I) in one step without forming the double reduction product of formula (III). The method of the present invention can obtain mainly the compound of formula (I) without forming the undesired over-hydrogenated diol of formula (III). That is, the method of the present invention is highly selective.

[0014] According to any embodiment of the present invention, regardless of the specific aspect, compound (I) and the corresponding compound (II) may be in the form of any one of its stereoisomers or mixtures thereof. For the sake of clarity, the term stereoisomer contemplates any diastereoisomers, enantiomers, racemates.

[0015] Indeed, compounds (I) or (II) may have at least one stereocenter that may have a different stereochemistry (i.e., if two stereocenters are present, compounds (I) or (II) may have the (R,R) or (R,S) configuration). Each of these stereocenters may be in the relative or absolute configuration R or S, or a mixture thereof; in other words, these compounds of formula (II) or (I) may be in the form of pure enantiomers or diastereoisomers, or in the form of a mixture of stereoisomers.

[0016] According to any one of the above embodiments of the present invention, the compound of formula (II) is 20 It is a compound.

[0017] According to any one of the above embodiments of the invention, compound (I) has the formula [ka] [In the formula, R 2 has the same meaning as defined in formula (I), R 3 represents a hydrogen atom or a methyl group] in the form of any one of its stereoisomers.

[0018] According to any one of the above embodiments of the invention, compound (II) has the formula [ka] [In the formula, R 2 has the same meaning as defined in formula (I), R 3 represents a hydrogen atom or a methyl group] in the form of any one of its stereoisomers.

[0019] According to an optional embodiment of the present invention, R 1 is a linear or branched C 1~5 It represents an alkanediyl or alkenediyl group. Preferably, R 1 is linear or branched C 1~4 It represents an alkanediyl group. Preferably, R 1 is linear or branched C 2~3 Even more preferably, R 1 represents a 1,2-propanediyl group or a 1,2-ethanediyl group. Even more preferably, R 1 represents a 1,2-propanediyl group.

[0020] According to an optional embodiment of the present invention, R 2 is a linear or branched C 1~10 It represents an alkanediyl or alkenediyl group. Preferably, R 2 is linear or branched C 1~10 It represents an alkanediyl group. Preferably, R 2 is linear or branched C 4~9 It represents an alkanediyl group. Preferably, R 2 is linear or branched C 6~9 Even more preferably, R 2 represents a 1,8-octanediyl group.

[0021] According to an optional embodiment of the present invention, R3 represents a hydrogen atom or a methyl group. 3 can represent a methyl group.

[0022] Non-limiting examples of suitable compounds of formula (I) include 12-oxabicyclo[6.3.1]dodec-8-ene, 10-methyl-12-oxabicyclo[6.3.1]dodec-8-ene, 13-oxabicyclo[7.3.1]tridec-9-ene, 11-methyl-13-oxabicyclo[7.3.1]tridec-9-ene, 14-oxabicyclo[8.3.1]tetradec-10-ene, 12-methyl-14-oxabicyclo[8.3.1]tetradec-10-ene, 15-oxabicyclo[8.3.1]tetradec-10-ene, 16-oxabicyclo[8.3.1]tetradec-10-ene, 17-oxabicyclo[8.3.1]tetradec-10-ene, 18-oxabicyclo[8.3.1]tetradec-10-ene, 19-oxabicyclo[8.3.1]tetradec-10-ene, 20-oxabicyclo[8.3.1]tetradec-10-ene, 21-oxabicyclo[8.3.1]tetradec-10-ene, 22-oxabicyclo[8.3.1]tetradec-10-ene, 23-oxabicyclo[8.3.1]tetradec-10-ene, 24-oxabicyclo[8.3.1]tetradec-10-ene, 25-oxabicyclo[8.3.1]tetradec-10-ene, 26-oxabicyclo[8.3.1]tetradec-10-ene, 27-oxabicyclo[8.3.1]tetradec-10-ene, 28-oxabicyclo[8.3.1]tetradec-10-ene, 29-oxabicyclo[8.3.1]tridec-9-ene, 30-oxabicyclo[8.3.1]tridec-10-ene, 31 5-oxabicyclo[9.3.1]pentadec-11-ene, 13-methyl-15-oxabicyclo[9.3.1]pentadec-11-ene, 16-oxabicyclo[10.3.1]hexadec-12-ene, 14-methyl-16-oxabicyclo[10.3.1]hexadec-12-ene, 17-oxabicyclo[11.3.1]heptadec-13-ene, or 15-methyl-17-oxabicyclo[11.3.1]heptadec-13-ene. Preferably, the compound of formula (I) may be 16-oxabicyclo[10.3.1]hexadec-12-ene, 14-methyl-16-oxabicyclo[10.3.1]hexadec-12-ene, 17-oxabicyclo[11.3.1]heptadec-13-ene, or 15-methyl-17-oxabicyclo[11.3.1]heptadec-13-ene. Preferably, the compound of formula (I) may be 16-oxabicyclo[10.3.1]hexadec-12-ene, or 14-methyl-16-oxabicyclo[10.3.1]hexadec-12-ene. Even more preferably, the compound of formula (I) may be 14-methyl-16-oxabicyclo[10.3.1]hexadec-12-ene.

[0023] Non-limiting examples of suitable compounds of formula (II) may include cycloundecane-1,5-dione, 3-methylcycloundecane-1,5-dione, cyclododecane-1,5-dione, 3-methylcyclododecane-1,5-dione, cyclotridecane-1,5-dione, 3-methylcyclotridecane-1,5-dione, cyclotetradecane-1,5-dione, 3-methylcyclotetradecane-1,5-dione, cyclopentadecane-1,5-dione, 3-methylcyclopentadecane-1,5-dione, cyclohexadecane-1,5-dione, or 3-methylcyclohexadecane-1,5-dione. Preferably, the compound of formula (II) may be cyclopentadecane-1,5-dione, 3-methylcyclopentadecane-1,5-dione, cyclohexadecane-1,5-dione, or 3-methylcyclohexadecane-1,5-dione. Preferably, the compound of formula (II) may be cyclopentadecane-1,5-dione, or 3-methylcyclopentadecane-1,5-dione. Even more preferably, the compound of formula (II) may be 3-methylcyclopentadecane-1,5-dione.

[0024] Compounds of formula (II) are commercially available compounds or can be prepared by several methods such as those reported in Helvetica Chimica Acta 1967, 50, 705, or in WO2016104474 or WO2016184848.

[0025] According to any embodiment of the present invention, the catalyst is a metal catalyst. Preferably, the metal catalyst is represented by the formula [M(O) m (X) n ] (IV) [In the formula, M is a metal selected from the group consisting of transition or post-transition metals, m is 0, 1 or 2, X represents an anionic ligand, and n is an integer from 1 to 6.

[0026] According to any of the above embodiments of the invention, M may be a metal selected from the group consisting of metals of groups IIIA (such as Al), IVA, IIIB, IVB (such as Ti or Zr), VB (such as V), VIB and VIIB of the periodic table. Preferably, M may be selected from the group consisting of aluminum, titanium, zirconium and vanadium.

[0027] According to any of the above embodiments of the present invention, n may be an integer from 1 to 4. Preferably, n may be an integer from 2 to 4. Even more preferably, n may be 3 or 4.

[0028] According to any of the above embodiments of the invention, X represents an anionic ligand, a non-limiting list of which includes a hydrogen or halogen atom, a hydroxy, oxy or β-diketonato group, or an alkoxy or carboxylic acid group.

[0029] The term "β-diketonate" has its usual meaning in the art, i.e., a compound of the formula R a (COCHCO) - R a [In the formula, R a are independent of each other, C1 to C 18 represents a group represented by the formula: [alkyl group, and the negative charge is delocalized].

[0030] According to any of the above embodiments of the present invention, in formula (III), each X is simultaneously or independently a hydrogen or a fluorine, a chlorine, a bromine or an iodine atom, a hydroxy or an acetylacetonate group, a C1-C 18 Alkoxy groups, such as methoxy, ethoxy or isopropoxy, s-butoxy groups, or C1-C 18 It represents a carboxylic acid group, for example a HCOO, CH3COO, CH3CH2COO or phenylCOO group. Preferably, each X simultaneously or independently represents a hydroxy, methoxy, ethoxy, propoxy, butoxy, isopropoxy or acetylacetonate group.

[0031] Non-limiting examples of suitable metal catalysts of formula (III) can include [Al(OR)3], [Al(OAc)3], [Al(acac)3], [Ti(OR)4], [Ti(O)(acac)2], [Zr(OR)4], [Zr(acac)4], [V(O)(acac)2], [V(acac)3], [V(O)(OR)3] (wherein R is a C1-C6 alkyl group, preferably R is a C1-C4 alkyl group).

[0032] The metal catalyst can be added to the reaction medium of the process of the invention in a wide range of concentrations. As non-limiting examples, metal concentration values ​​can be mentioned ranging from 1000 ppm to 100000 ppm relative to the total amount of substrate. Preferably, the metal concentration is comprised between 5000 ppm and 15000 ppm. Of course, the process also works with more catalysts than this. However, the optimum concentration of the metal depends on the nature of the metal, the nature of the substrate, the temperature and the desired reaction time, as known to those skilled in the art.

[0033] According to any one of the above embodiments of the present invention, the hydrogen source is a hydrocarbon containing at least one secondary alcohol functional group and having a boiling point of 80° C. or more, preferably 110° C. or more, even more preferably 120° C. or more. The hydrogen source incorporates hydrogen in the ketone production. The incorporated hydrogen source may be a secondary alcohol. In particular, the incorporated hydrogen source may be a hydrogen source of the formula [ka] [In the formula, R 4 and R 5 each independently represents a C which may be substituted by a hydroxy group or an aryl group; 1~10 C, optionally substituted with a linear alkyl group, a hydroxyl group or an aryl group 2~10 C optionally substituted with a linear alkenyl group, a hydroxy group or an aryl group 3~10 Branched or cyclic alkyl or alkenyl groups, 1 to 5 C 1~3represents an alkyl or alkoxy group, a hydroxy group, or a phenyl group which may be substituted with a halogen atom, or R 4 and R 5 When taken together, C optionally substituted with a hydroxy group or an aryl group 2~10 The hydrogen source of formula (V) may be one of the following: 4~10 It is a compound.

[0034] The term "aryl group" has its usual meaning in the art, i.e., an aromatic hydrocarbon group, such as an optionally substituted phenyl or naphthyl group. Non-limiting examples of optional substituents for the aryl group include C 1~3 It may contain alkyl or alkoxy groups, hydroxy groups or halogen atoms.

[0035] According to any one of the above embodiments, R 4 C may be substituted with a hydroxy group or an aryl group. 1~10 C which may be substituted with a linear alkyl group, a hydroxy group or an aryl group 3~10 A branched or cyclic alkyl group or 1 to 5 C 1~3 It can represent a phenyl group which may be substituted with an alkyl or alkoxy group, a hydroxy group or a halogen atom. 4 is C, which may be substituted with a hydroxy group; 1~10 C, optionally substituted with a linear alkyl group or a hydroxy group 3~10 It can represent a branched or cyclic alkyl group. Preferably, R 4 is C, which may be substituted with a hydroxy group; 3~8 It may represent a linear or branched alkyl group. Even more preferably, R 4 can represent a methyl, ethyl, propyl, isopropyl, butyl, or octyl group which may be substituted with a hydroxy group.

[0036] According to any one of the above embodiments, R5 C may be substituted with a hydroxy group or an aryl group. 1~10 C which may be substituted with a linear alkyl group, a hydroxy group or an aryl group 3~10 It can represent a branched or cyclic alkyl group. Preferably, R 5 can represent a methyl, ethyl or propyl group.

[0037] According to any one of the above embodiments, R 4 and R 5 When taken together, C may be substituted with a hydroxy group. 4~7 It can represent a linear or branched alkanediyl or alkenediyl. Preferably, R 4 and R 5 If taken together, C 4~7 It may represent a linear alkanediyl. Even more preferably, R 4 and R 5 If taken together, C 4~5 It may represent a linear alkanediyl.

[0038] Non-limiting examples of suitable hydrogen sources may include 1-phenylethan-1-ol, 2-methyl-2,4-pentanediol, cyclohexanol, 4-methylpentan-2-ol, cyclopentanol, or octan-2-ol. Preferably, the hydrogen source may be cyclopentanol or 4-methylpentan-2-ol.

[0039] The hydrogen source can be added to the reaction medium of the method of the present invention in a wide range of concentrations. As a non-limiting example, hydrogen source concentration values ​​can be mentioned ranging from 1 equivalent to 50 equivalents, or even from 1 equivalent to 5 equivalents, relative to the amount of compound of formula (II). Of course, the optimal concentration of the hydrogen source depends on the nature of the hydrogen source, the nature of the substrate, the temperature and the catalyst used in the method, as well as the desired reaction time, as known to those skilled in the art.

[0040] According to any embodiment of the present invention, the process of the present invention can be carried out in the presence of a cocatalyst. Non-limiting examples of suitable cocatalysts include tertiary amines, such as pyridine, bispyridine, trimethylamine, lutidine, N,N-diisopropylethylamine, or 1,8-diazabicyclo[5.4.0]undec-7-ene, or tertiary phosphines, or optionally substituted phenols, or optionally substituted bisphenols. Preferably, the cocatalyst can be a tertiary amine or pyridine or a substituted bisphenol. Even more preferably, the cocatalyst can be a methylpyridine, or a dihydroxybiphenyl component, such as 2,2'-dihydroxydiphenylmethane, 2,2'-dihydroxybiphenyl.

[0041] The cocatalyst can be added to the reaction medium of the method of the present invention in a wide range of concentrations. As a non-limiting example, the cocatalyst concentration value can be in the range of 0.1 equivalent to 2 equivalents relative to the catalyst. Of course, the optimal concentration of the cocatalyst depends on the nature of the cocatalyst, the nature of the substrate, the temperature and the catalyst used in the method, as well as the desired reaction time, as known to those skilled in the art.

[0042] The process of the present invention may be carried out under batch or continuous conditions.

[0043] The reaction can be carried out in the absence of a solvent.

[0044] The temperature of the process of the invention may be comprised between 120° C. and 300° C., more preferably between 150° C. and 250° C. Of course, the person skilled in the art will also be able to select the preferred temperature as a function of the melting and boiling points of the hydrogen source and the starting and final products, as well as the desired reaction or conversion time.

[0045] The process of the invention can be carried out at atmospheric pressure or under a slight vacuum. The process of the invention can be carried out under an inert atmosphere such as nitrogen or argon.

[0046] According to any one of the above embodiments of the present invention, the relatively volatile compounds produced during the process of the present invention are continuously removed during the process of the present invention. The removal of these relatively volatile compounds, such as water and ketones produced during the process of the present invention, can be distilled during the process of the present invention.

[0047] Working Example The invention will now be described in further detail by the following examples, in which the abbreviations have their usual meaning in the art, temperatures are given in degrees Celsius (° C.), and (unless otherwise noted) NMR spectroscopic data are 1 H and 13 Recorded in CDCl3 on a 360 or 400 MHz instrument for C, chemical shifts 6 are given in ppm relative to TMS as standard, coupling constants J are expressed in Hz.

[0048] Example 1 Preparation of compounds of formula (I) starting from compounds of formula (II) A 1 liter glass reactor equipped with a mechanical stirrer, a packed column and a reflux condenser was charged with 250 g of 3-methyl-1,5-cyclopentadecanedione (0.99 mol), 50 g of hydrogen source (see Table 1) and V(acac)3 (17.2 g, 0.049 mol) at atmospheric pressure. The mixture was stirred and heated to reflux, after which the remaining hydrogen source (450 g) was metered in over 22 hours, while the light fractions formed during the reaction (water and the resulting ketone) were distilled into the flask. The resulting mixture was cooled to 100 °C and the remaining solvent was concentrated under vacuum. The remaining oil (230 g) was flash distilled (170 °C, 1 mbar) and the distillate was analyzed by GC (see Table 1).

[0049] [Table 1]

[0050] Example 2 Preparation of compounds of formula (I) starting from compounds of formula (II) A 1 liter glass reactor equipped with a mechanical stirrer, a packed column and a reflux condenser was charged with 250 g of 3-methyl-1,5-cyclopentadecanedione (0.99 mol), 50 g of cyclohexanol, Zr(OPr)4 (4.63 g, 0.0098 mol, 70% in PrOH) and 2,2'-dihydroxydiphenylmethane (1.59 g, 0.0098 mol) at atmospheric pressure. The mixture was stirred and heated to reflux, after which the remaining hydrogen source (450 g) was metered in over 22 hours while the light fractions formed during the reaction (water, cyclohexanol, cyclohexanone) were distilled into the flask. The resulting mixture was cooled to 100 °C and the remaining solvent was concentrated under vacuum. The remaining oil (242 g) was flash distilled (170° C., 1 mbar) and the distillate was analyzed by GC (compound I, 92.7% purity, 91.2% yield). No 3-methyl-1,5-cyclopentadecanediol was formed and 3-methyl-1,5-cyclopentadecanedione was completely converted.

[0051] Example 3 Preparation of compounds of formula (I) starting from compounds of formula (II) A 1 liter glass reactor equipped with a mechanical stirrer, a packed column and a reflux condenser was charged with 250 g of 3-methyl-1,5-cyclopentadecanedione (0.99 mol), 50 g of 2-octanol, Zr(OPr)4 (9.26 g, 0.0196 mol, 70% in PrOH) and 2,2'-dihydroxybiphenyl (3.7 g, 0.0196 mol) at 200 mbar. The mixture was stirred and heated to reflux, after which the remaining hydrogen source (250 g) was metered in over 16 hours, while the light fractions formed during the reaction (water, 2-octanol, 2-octanone) were distilled into the flask. The resulting mixture was cooled to 100 °C and the remaining solvent was concentrated under vacuum. The remaining oil (230 g) was flash distilled (180° C., 1 mbar) and the distillate was analyzed by GC (compound I, 89.2% purity, 94.1% yield). No 3-methyl-1,5-cyclopentadecanediol was formed and 3-methyl-1,5-cyclopentadecanedione was completely converted.

[0052] Example 4 Preparation of compounds of formula (I) starting from compounds of formula (II) A 1 liter glass reactor equipped with a mechanical stirrer, a packed column and a reflux condenser was charged with 250 g of 3-methyl-1,5-cyclopentadecanedione (0.99 mol), 50 g of hydrogen source (see Table 2), Ti(OiPr)4 (5.6 g, 0.02 mol) and 2,2'-dihydroxybiphenyl (3.7 g, 0.02 mol) at the pressures indicated in Table 2. The mixture was stirred and heated to reflux, after which the remaining hydrogen source (450 g) was metered in over 22 hours while the light fractions formed during the reaction (water and the resulting ketone) were distilled into the flask. The resulting mixture was cooled to 100 °C and the remaining solvent was concentrated under vacuum. The remaining oil (approximately 230 g) was flash distilled (170 °C, 1 mbar) and the distillate was analyzed by GC (see Table 2).

[0053] [Table 2]

[0054] Example 5 Preparation of compounds of formula (I) starting from compounds of formula (II) A 1 liter glass reactor equipped with a mechanical stirrer, a packed column and a reflux condenser was charged with 250 g of 3-methyl-1,5-cyclopentadecanedione (0.99 mol), 50 g of cyclopentanol, Al(OBu)3 (12.3 g, 0.05 mol) and 2,2'-dihydroxydiphenylmethane (8 g, 0.05 mol) at atmospheric pressure. The mixture was stirred and heated to reflux, after which the remaining hydrogen source (450 g) was metered in over 22 hours while the light fractions formed during the reaction (water, cyclopentanol, cyclopentanone) were distilled into the flask. The resulting mixture was cooled to 100 °C and the remaining solvent was concentrated under vacuum. The remaining oil (247 g) was flash distilled (170 °C, 1 mbar) and the distillate was analyzed by GC (compound I, 85% purity, 85% yield). No 3-methyl-1,5-cyclopentadecanediol was formed and 3-methyl-1,5-cyclopentadecanedione was completely converted.

Claims

1. Formula (I) 【Chemistry 1】 [In the formula, R １ is a linear or branched C １～５ represents an alkanediyl or alkenediyl group; R ２ is a linear or branched C １～１０ represents an alkanediyl or alkenediyl group] in the form of any one of its stereoisomers or a mixture thereof, said process comprising the steps of: Formula (II) 【Chemistry 2】 [In the formula, R １ and R ２ has the same meaning as defined in formula (I)] in the form of any one of its stereoisomers, in the presence of a hydrogen source, using a metal catalyst, except a ruthenium catalyst, of the formula [M(O) m (X) n ] (IV) [In the formula, M is a metal selected from the group consisting of transition metals or post-transition metals, m is 0, 1 or 2, X represents an anionic ligand and n is an integer from 1 to 6, and in the presence of a co-catalyst selected from the group consisting of tertiary amines, tertiary phosphines, optionally substituted phenols and optionally substituted bisphenols, said process being a one-pot reduction and cyclodehydration type reaction of a compound of formula (II) under transfer hydrogenation conditions.

2. R １ is a linear or branched C １～４ The method of claim 1 , wherein the moiety represents an alkanediyl group.

3. R １ is a linear or branched C ２～３ 3. The method according to claim 1 or 2, wherein the moiety represents an alkanediyl group.

4. R １ The process according to any one of claims 1 to 3, wherein represents a 1,2-propanediyl group or a 1,2-ethanediyl group.

5. R ２ is a linear or branched C ４～９ 5. The process according to claim 1, wherein the alkanediyl group is an alkanediyl group.

6. R ２ is a linear or branched C ６～９ 6. The process according to claim 1, wherein the alkanediyl group is an alkanediyl group.

7. R ２ The process according to any one of claims 1 to 6, wherein represents a 1,8-octanediyl group.

8. The compounds of formula (I) are 12-oxabicyclo[6.3.1]dodec-8-ene, 10-methyl-12-oxabicyclo[6.3.1]dodec-8-ene, 13-oxabicyclo[7.3.1]tridec-9-ene, 11-methyl-13-oxabicyclo[7.3.1]tridec-9-ene, 14-oxabicyclo[8.3.1]tetradec-10-ene, 12-methyl-14-oxabicyclo[8.3.1]tetradec-10-ene, 15-oxabicyclo[9.3.1]pentadeca- 8. The method of claim 1, wherein the aryl group is selected from the group consisting of 11-ene, 13-methyl-15-oxabicyclo[9.3.1]pentadec-11-ene, 16-oxabicyclo[10.3.1]hexadec-12-ene, 14-methyl-16-oxabicyclo[10.3.1]hexadec-12-ene, 17-oxabicyclo[11.3.1]heptadec-13-ene, and 15-methyl-17-oxabicyclo[11.3.1]heptadec-13-ene.

9. 9. The process of any one of claims 1 to 8, wherein the compound of formula (II) can be selected from the group consisting of cycloundecane-1,5-dione, 3-methylcycloundecane-1,5-dione, cyclododecane-1,5-dione, 3-methylcyclododecane-1,5-dione, cyclotridecane-1,5-dione, 3-methylcyclotridecane-1,5-dione, cyclotetradecane-1,5-dione, 3-methylcyclotetradecane-1,5-dione, cyclopentadecane-1,5-dione, 3-methylcyclopentadecane-1,5-dione, cyclohexadecane-1,5-dione, and 3-methylcyclohexadecane-1,5-dione.

10. 10. The method of any one of claims 1 to 9, wherein M is selected from the group consisting of aluminum, titanium, zirconium and vanadium.

11. The metal catalyst is [Al(OR) ３ ], [Al(OAc) ３ ], [Al(acac) ３ ], [Ti(OR) ４ ], [Ti(O)(acac) ２ ], [Zr(OR) ４ ], [Zr(acac) ４ ], [V(O)(acac) ２ ], [V(acac) ３ ], and [V(O)(OR) ３ wherein R is selected from the group consisting of C １ ~C ６ 11. The method of claim 1, wherein the alkyl group is an alkyl group.

12. 12. The method of claim 1, wherein the hydrogen source is a hydrocarbon containing at least one secondary alcohol functional group and having a boiling point of 80° C. or greater.

13. The hydrogen source has the formula 【Chemistry 3】 [In the formula, R ４ and R ５ each independently represents a C which may be substituted by a hydroxy group or an aryl group; １～１０ C which may be substituted with a linear alkyl group, a hydroxyl group or an aryl group ２～１０ C which may be substituted with a linear alkenyl group, a hydroxy group or an aryl group ３～１０ A branched or cyclic alkyl or alkenyl group, 1 to 5 C １～３ represents an alkyl or alkoxy group, a hydroxy group, or a phenyl group which may be substituted with a halogen atom, or R ４ and R ５ When taken together, C optionally substituted with a hydroxy group or an aryl group ２～１０ 13. The process according to claim 1, wherein the alkanediyl or alkenediyl is a linear or branched alkanediyl.

14. 14. The method of any one of claims 1 to 13, wherein the hydrogen source is 1-phenylethan-1-ol, 2-methyl-2,4-pentanediol, cyclohexanol, 4-methylpentan-2-ol, cyclopentanol, or octan-2-ol.

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