Preparation of (s)-6-chloro-2,3,4,9-tetrahydro-1h-carbazole-1-carboxamide in enantiomerically enriched form by resolution process

Abstract

The present invention provides for a process for the preparation of (S)-6-Chloro- 2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide in enantiomerically enriched form by resolution of rac-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide. Furthermore, the present invention provides for (S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide in crystalline form as well for the use thereof as a medicament.

Description

[0001]PREPARATION OF (S)-6-CHLORO-2,3,4,9-TETRAHYDRO-1H-CARBAZOLE-1- CARBOXAMIDE IN ENANTIOMERICALLY ENRICHED FORM BY RESOLUTION PROCESS Description The present invention provides for a process for the preparation of (S)-6- Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide in enantiomerically enriched form by resolution of rac-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide. Furthermore, the present invention provides for (S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide in crystalline form. BACKGROUND OF THE INVENTION The compound 6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula also known as Selisistat or EX-527 (CAS-Nr.49843-98-3) is known from WO 2005 / 026112 A2 to possess anti-SIRT1 activity, and as such may be useful in the preparation of medicaments for any condition which may benefit from the inhibition of SIRT1. Such conditions may include, for example, cancer, metabolic diseases such as metabolic syndrome, type I diabetes or type II diabetes, obesity, dislipidemia, hyperlipidemia, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, neurodegenerative conditions that are caused at least in part by polyglutamine aggregation, such as Huntington's disease, spinalbulbar muscular atrophy (SBMA or Kennedy's disease), dentatorubro-pallidoluysian atrophy (DRPLA), spinocerebellar ataxia 1 (SCA1), spinocerebellar ataxia 2 (SCA2), Machado-Joseph disease (MJD;SCA3), spinocerebellar ataxia 6 (SCA6), spinocerebellar ataxia 7 (SCA7), and spinocerebellar ataxia 12 (SCA12). A synthesis for Selisistat in racemic form, hereinafter also referred to as “rac- SLS”, as well as polymorphs of racemic Selisistat has been described in WO 2013 / 057258 A1. The molecule has an asymmetric carbon atom adjacent to the amide functionality and, accordingly, exists in the form of two enantiomers, namely (R)- 6- Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide and (S)-6-Chloro-2,3,4,9- tetrahydro-1H-carbazole-l-carboxamide of formula (S-I), hereinafter also referred to as “(S)-SLS”. While it is known that the enantiomeric forms of Selisistat differ significantly regarding their SIRT1 activity, current clinical trials are performed using the racemic mixture of both enantiomers of Selisistat. So far, enantiopure (S)-Selisistat is available in amorphous form only and can be prepared by chiral high-pressure liquid chromatography (HPLC) in limited amounts only. It is thus an object of the present invention to provide for a new process for the preparation of (S)-Selisistat in enantiomerically enriched form, in particular for a process that is suitable for the preparation of (S)-Selisistat that is suitable for pharmaceutical purposes and that may be prepared conveniently, in large scale and using readily available starting materials and reagents. Furthermore, it is an object of the present invention to provided (S)-Selisistat in a form that provides for improved handling and storage properties. Further objects of the invention will be clear on the basis of the following description of the invention, examples and claims. SUMMARY OF THE INVENTION In a first aspect, the invention relates to a process for the preparation of(S)-6- Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in enantiomerically enriched form by resolution of rac-6-Chloro-2,3,4,9-tetrahydro- 1H-carbazole-1-carboxamide (rac-SLS) of formula (I) In a second aspect, the invention provides for (S)-6-Chloro-2,3,4,9-tetrahydro- 1H-carbazole-1-carboxamide of formula (S-I) in crystalline form. In a third aspect, the present invention provides for a composition comprising (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I) in crystalline form according to the second aspect of the invention and further comprising up to about 20 wt.-% of any other solid-state form of (S)-SLS, based on the weight of the composition. In a fourth aspect, the invention relates to (S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide of formula (S-I) in crystalline form according to the second aspect of the invention for use as a medicament, specifically for use in the prevention or treatment of a disease or condition associated with SIRT1. In a fifth aspect, the present invention provides for the use of (S)-6-Chloro- 2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to the second aspect of the invention for the preparation of a pharmaceutical composition. In a sixth aspect, the invention provides for a pharmaceutical composition comprising (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to the second aspect of the invention and at least one pharmaceutically acceptable excipient. In a seventh aspect, the invention provides for a diastereomeric compound comprising (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide and a tartaric acid derivative of formula (II) In an eighth aspect, the present invention provides for the use of the compound according to the seventh aspect of the invention in the manufacture of (S)- 6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide in enantiomerically enriched form and / or in crystalline form. DESCRIPTION OF THE DRAWINGS Figure 1 depicts a diffractogram of an X-Ray Powder Diffraction (XRPD) analysis of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide in crystalline form (polymorph X). Figure 2 depicts a spectrum of an1H-Nuclear Magnetic Resonance (NMR) analysis of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide in crystalline form (polymorph X). Figure 3 depicts a spectrum of a Differential Scanning Calorimetry (DSC) analysis of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide in crystalline form (polymorph X). Figure 4 depicts a diffractogram of an X-Ray Powder Diffraction (XRPD) analysis of a diastereomeric cocrystal of (S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide with (-)-DTTA. Figure 5 depicts a spectrum of an1H-Nuclear Magnetic Resonance (NMR) analysis of a diastereomeric cocrystal of (S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide with (-)-DTTA. Figure 6 depicts a spectrum of a Differential Scanning Calorimetry (DSC) analysis of a diastereomeric cocrystal of (S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide in crystalline form with (-)-DTTA. Figure 7 depicts the asymmetric unit of (S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide in crystalline form verifying the absolute configuration of the asymmetric carbon (C11) to be “S”. DETAILED DESCRIPTION OF THE INVENTION In a first aspect, the invention provides for a process for the preparation of (S)- 6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) (S-I) in enantiomerically enriched form by resolution of rac-6-Chloro-2,3,4,9-tetrahydro- 1H-carbazole-1-carboxamide (rac-SLS) of formula (I) the process comprising the steps of: a) Providing a first mixture comprising rac-SLS and a compound of formula (II) in enantiomerically enriched form, wherein R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen, C1-C4-haloalkyl, -O-C1- C4-alkyl, -O-C1 - C4- haloalkyl in a first liquid medium; b) exposing the first mixture as formed in step a) to conditions under which rac-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide and the compound of formula (II) at least partly dissolve in the first liquid medium to form an intermediate solution; c) exposing the intermediate solution as formed in step b) to conditions under which a solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals is formed; d) optionally recrystallizing the solid intermediate product as formed in step c) in a second liquid medium to provide the solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals in diastereomerically enriched form; and e) exposing the solid intermediate product as formed in step c) or d) to a base to provide (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (I) in enantiomerically enriched form. The process according to this first aspect of the invention is suitable for the preparation of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)- SLS) of formula (S-I) (S-I) in enantiomerically enriched form, wherein the term “enantiomerically enriched form” as used herein means that (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide may be present in the form of its pure S-enantiomer of formula (S-I) or, in other words, in enantiomerically pure form, or in the form of non-racemic mixtures of the S-enantiomer of formula (S-I) with its corresponding R-enantiomer in which the amount of S-enantiomer is larger than the amount of corresponding R- enantiomer. In some embodiments, the term “(S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide of formula (S-I) in enantiomerically enriched form” may refer to mixtures comprising (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide of formula (S-I) with an enantiomeric excess (ee) of at least about 70 % ee, or at least about 80 % ee, or at least about 90 % ee, such as from about 90 to about 99.9 % ee, or from about 95 to about 99.8 % ee, about 97 to about 99.7 % ee, or from about 98 to about 99.8 % ee. According to the invention, racemic 6-Chloro-2,3,4,9-tetrahydro-1H-carbazole- 1-carboxamide (rac-SLS) of formula (I) (I), is used as a staring material. Racemic SLS (rac-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide) is commercially available or may be prepared according to known procedures, e.g. as described in WO 2013 / 057258 A1. While the chemical purity of rac-SLS as the starting material is not assumed to be critical, in some embodiments, rac-SLS is used in a chemical purity of at least about 90%, 95%, 97% or even 98 or 99% (w / w), based on the total weight of the starting material comprising rac-SLS. The process according to the present invention comprises at least process steps a), b), c) and e). Optionally, a further process step d) may be implemented following step c) and followed by step e). In addition to this, further optional process steps may be comprised by the resolution process of the present invention as described in further detail below. According to the first step a) of the process according to the present invention a first mixture is provided comprising racemic 6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide (rac-SLS) as described above. The first mixture further comprises a first liquid medium such as a solvent or mixture of solvents as described in further detail below and, accordingly, in particular embodiments may be a liquid mixture comprising the first liquid medium and the further constituent such as rac- SLS and / or the compound of formula (II) in undissolved or partly dissolved form. The compound of formula (II) in enantiomerically enriched form comprised by the first liquid mixture, according to the present invention, is a derivative of (-)-tartaric acid (2,3-dihydroxysuccinic acid) in which both hydroxy groups in positions 2 and 3 are esterified with benzoic acid or a derivative thereof. The term “enantiomerically enriched form” as used herein in connection with the tartaric acid derivative of formula (II) means that such tartaric acid derivative of formula (II) may be present in the form of its pure (-)-enantiomer in which both chiral centers are in the R-configuration as depicted in formula (II) or, in other words, or in the form of non-racemic mixtures of the (-)-enantiomer of formula (II) with its corresponding (+)-enantiomer in which the amount of (-)-enantiomer is larger than the amount of corresponding (+)-enantiomer. In some embodiments, the term “compound of formula (I)) in enantiomerically enriched form” may refer to mixtures comprising the (-) enantiomer of the compound of formula (II) with an enantiomeric excess (ee) of at least about 70 % ee, or at least about 80 % ee, or at least about 90 % ee, such as from about 90 to about 99.9 % ee, or from about 95 to about 99.8 % ee, about 97 to about 99.7 % ee, or from about 98 to about 99.8 % ee. In the dibenzoyl tartaric acid derivatives of formula (II) the substituents bound to the aromatic substructures R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen, C1-C4-haloalkyl, -O-C1- C4-alkyl, -O-C1 -C4-haloalkyl. While the compounds of formula (II) may have two aryl rings with different substituents and / or substitution patterns, in preferred embodiments both of the aryl substructures have the same substituents and / or substitution pattern or, in other words, are identical. In some embodiments, the two aryl rings of the compound of formula (II), independently of each other, may be unsubstituted or may carry one or two or three or four or five, preferably one or two or three or just one or two or even just one substituent, wherein in the case of a plurality of substituent these substituents may be the same or different. In the compounds of formula (II) C1-C4-alkyl preferably means a saturated hydrocarbon substituent with one to four carbon atoms such as methyl, ethyl, n- propyl, isopropyl, n-butyl, s-butyl, tert.-butyl; halogen preferably means fluorine, chlorine, bromine, preferably fluorine or chlorine, especially chlorine; C1-C4-haloalkyl preferably means a saturated mono- or polyhalogenated hydrocarbon substituent with one to four carbon atoms such as trifluormethyl, pentafluoroethyl; -O-C1-C4-alkyl preferably means a saturated hydrocarbon substituent with one to four carbon atoms bound via an oxygen atom such as methoxy, ethoxy, n-propoxy, iso- propoxy, n-butoxy, s-butoxy, tert.-butoxy, preferably methoxy, iso-propoxy and tert.- butoxy, especially methoxy; and -O-C1-C4-haloalkyl preferably means a saturated and halogenated hydrocarbon substituent with one to four carbon atoms bound via an oxygen atom such as trifluormethoxy, pentafluorethoxy, heptafluor-isopropoxy, especially trifluormethoxy. In particular embodiments of the process according to this aspect of the invention, in the compound of formula (II) R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen and C1-C4- haloalkyl as described above. In further embodiments, in the compound of formula (III) all substituents R1, R2, R3, R4and R5are H. Accordingly, in a preferred embodiment the compound of formula (II) is (2R, 3R)-(-)-Di-O-4-benzoyl-L-tartaric acid (CAS Nr.2743-38-6, herein also referred to as “(-)-DBTA”). In yet further embodiments, in the compound of formula (II) he substituents R1, R2, R4and R5are H and R3is selected from C1-C4-alkyl and C1-C4-haloalkyl as described above, preferably from C1-C4-alkyl, especially methyl. In a preferred embodiment, the compound of formula (II) is (2R, 3R)-(-)-Di-O-4-touyl-L-tartaric acid (CAS Nr.32634-66-5, herein also referred to as “(-)-DTTA”). In further embodiments, further exemplary substituted aryl rings in the compounds of formula (II) comprise, but are not limited to 4-trifluormethylphenyl, 4- tert.-butylphenyl and 3,5-dichlorophenyl. In particular embodiments, rac-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide of formula (I) and the compound of formula (II) may be provided the first liquid mixture to be provided according to process step a) of the process of the invention in a broad variety of molar ratios of from about 1.2 : 1 to about 3 : 1, more specifically from about 1.5 : 1 to about 2.5 to 1, preferably from about 1.9 :1 to about 2.1 to 1. According to process step a), rac-SLS of formula (I) and the chosen compound of formula (II) as well as the first liquid medium may be placed in a suitable reaction vessel which allows for the effective mixture of the components, for example by providing means for effectively mixing the components such as a mechanic or magnetic stirrer. The components of the mixture to be provided according to process step a) may be added to the chosen reaction vessel in parallel or in any order. The first liquid medium comprised by the first mixture to be provided according to process step a), in some embodiments, may be an organic solvent or a mixture of organic solvents. In particular embodiments, the first liquid medium may comprise or essentially consist of a single organic solvent. In further embodiments, the first liquid medium may comprise or essentially consist of a mixture of a plurality of organic solvents, such as two or three or just two organic solvents, herein also referred to as “first organic solvent”, “second organic solvent”, and so on. Suitable organic solvents to be comprised by the first liquid medium comprise, but are not limited to C1-C4 alkyl acetates such as ethyl acetate, propyl acetate, isopropyl acetate isobutyl acetate, and tert.-butyl acetate; acetonitrile, methyl isobutyl ketone, aromatic hydrocarbons such as toluene. In particular embodiments, the first liquid medium comprises or essentially consists of an organic solvent or a mixture of organic solvents selected from the group consisting of C1-C4 alkyl acetates such as ethyl acetate, isobutyl acetate, acetonitrile, methyl isobutyl ketone and aromatic hydrocarbons such as toluene, wherein the term “essentially consist” as used herein means that the compound or mixture it refers to comprises at least about 95 % or at least about 97 % or at least about 98 % or at least about 99 % (all with regard to the total weight of the compound or mixture) of said compound or mixture and up to about 5 % or up to about 3 % or up to about 2 % or up to about 1 % (all with regard to the total weight of the compound or mixture) of further components, such as impurities or water. In particular embodiments of step a) of the process of the invention, the first liquid medium comprises or essentially consists of isobutyl acetate and acetonitrile. In further particular embodiments, in case the first liquid medium comprises a mixture of different solvents, the named solvents may be combined in any suitable amount as long as the miscibility of the corresponding solvents is given. In particular embodiments, especially in cases in which isobutyl acetate and acetonitrile are used, the two solvents may be used in a ratio of from about 60 : 40 (v / v) to about 95 : 5 (v / v), or from about 75 : 25 (v / v) to about 90 : 10 (v / v), or preferably from about 80 : 20 (v / v) to about 90 : 10 (v / v), such as about 85 : 15 (v / v). In further embodiments, in the first liquid mixture to be provided according to process step a) the first liquid medium is used in an amount of about 1 to about 5 or from about 2 to about 4 mL per mmol of rac-SLS. In yet further embodiments, step a) of the process according to the present invention comprises the steps of: a1) providing a first pre-mixture comprising rac-SLS in a first solvent or mixture of solvents, a2) Providing a second pre-mixture comprising of a compound of formula (II) in a second solvent or mixture of solvents, and a3) Combining the first and the second liquid pre-mixtures to form the first intermediate mixture in a first liquid medium. According to this optional embodiment of step a) of the process of the present invention, two separate pre-mixtures may be formed separately of each other (steps a1) and a2), wherein the first pre-mixture comprises rac-SLS and a first solvent or mixture of solvents as described above and wherein the second pre-mixture comprises the chosen compound of formula (II) and a second solvent or mixture of solvents. In a further separate step a3) the two pre-mixtures are the combined to provide the first intermediate mixture in a first liquid medium. According to the second process step b) of the process of the present invention, the first mixture as formed in step a) is exposed to conditions under which rac-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide and the compound of formula (II) at least partly dissolve in the first liquid medium to form an intermediate solution. In preferred embodiments, however, the first mixture is exposed to conditions under which rac-SLS and the compound of formula (II) essentially completely dissolve in the first liquid medium. The conditions to which the first mixture may be exposed to ensure at least partial or, preferably, complete dissolution of the solid constituents rac-SLS and the compound of formula (II) are known to those of skill in the art and may comprise, for example, heating, stirring and / or sonication of the mixture by ultrasound. In particular embodiments, the first liquid mixture is exposed to conditions which comprise heating of the first liquid mixture, preferably until complete dissolution of rac-SLS and the compound of formula (II) is observed. In further embodiments, according to process step b) the first liquid mixture is heated, specifically to a temperature of from about 60 °C or from about 70 °C or from about 80 °C to reflux conditions, or, in other words, to a temperature at which the chosen solvent or mixture of solvents of the first liquid medium boils. As mentioned above, in preferred embodiments the heating of the first liquid mixture may be continued until sufficient or complete dissolution of rac-SLS and the compound of formula (II) is observed to form the first intermediate solution comprising rac-SLS and the compound of formula (II) in dissolved form. According to the third process step c) of the process of the present invention, the intermediate solution as formed in step b) is then exposed to conditions under which a solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals is formed. The terms “solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals” or just “cocrystals” as referred to herein may also be described as solids that are crystalline single-phase materials composed of two or more different molecular or ionic compounds, specifically composed of (S)-SLS and the compound of formula (II), generally in a stoichiometric ratio which are neither solvates nor simple salts. The conditions under which a solid intermediate product, preferably a solid crystalline intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals as described above is formed may, for example, comprise cooling of the intermediate solution as formed in step b), or removal or partial removal of the first liquid medium or a solvent comprised by the first liquid medium, or addition of seed particles or crystals, preferably seed crystals of the solid intermediate product or cocrystals comprising (S)-SLS and the compound of formula (II) as described in further detail below in connection with the seventh aspect of the invention. In particular embodiments, according to process step c) the intermediate solution as formed in step b) may be cooled, optionally under partial removal of the first liquid medium. In further embodiments, the intermediate solution as formed in step b) may be cooled to a temperature within the range of from about 10°C to about 30 °C, or from about 20°C to about 25 °C. Regarding the results of the precipitation and the characteristics of the solid, preferably crystalline intermediate product it might be advantageous to perform the cooling process for an extended period of time. In particular embodiments of process step c), the solution as formed in step b) may be cooled at a cooling rate selected within the range of from about 0.05 °C / min to about 0.6 °C / min, or from about 0.1 °C / min to about 0.5 °C / min, or from about 0.2 °C / min to about 0.4 °C / min. The solid crystalline intermediate product as formed according to process step c) of the invention is obtained in the form of cocrystals may comprise, depending on the actual reaction conditions, predominantly (S)-SLS (with some residual amounts of its R-enantiomer) and the chosen compound of formula (II). In cases in which the compound of formula (II) is used in enantiomerically enriched (but not in the form of a pure enantiomer) the cocrystals usually comprise (S)-SLS and the enantiomer of the compound of formula (II) in which both chiral centers are in the R-configuration. In some embodiments, as described in further detail below in connection with the seventh aspect of the invention, the crystalline intermediate product in the form of diastereomeric cocrystals of (S)-SLS and the compound of formula (II) as formed in step c) comprises (S)-SLS and the compound of formula (II) in a molar ratio of about 2 : 1. The solid crystalline intermediate product of (S)-SLS and the compound of formula (II) as formed in process step c) may then be isolated from the remaining components of the cooled first mixture by standard techniques known to those of skill in the art such as by decantation, filtration, or centrifugation to remove at least a part of the first liquid medium as well as the components dissolved therein from the crystalline intermediate product. Accordingly, in some embodiments process step c) comprises the step of: c1) at least partially removing the first liquid medium from the solid intermediate product. The crystalline intermediate product may then be further purified by washing the isolated cocrystals with a second liquid medium, preferably comprising or essentially consisting of an organic solvent or a mixture of different organic solvents. Accordingly, in some embodiments process step c) further comprises the step of c2) washing the solid intermediate product (comprising diastereomeric cocrystals of (S)-SLS and the compound of formula (II)) with a third liquid medium. Suitable organic solvents for the third liquid medium comprise but are not limited to the solvents as described above in connection with the first and second organic solvents of the first liquid medium. In specific embodiments, the solvents or mixture of solvents used for the second liquid medium essentially correspond to those as used for the first liquid medium. In further particular embodiments, the third liquid medium may comprise or essentially consist of one or more of C1-C4 alkyl acetates such as ethyl acetate, propyl acetate, isopropyl acetate isobutyl acetate, tert.- butyl acetate, acetonitrile, methyl isobutyl ketone, aromatic hydrocarbons such as toluene. Following the isolation and optional washing, the crystalline intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals may then be dried, for example under reduced pressure and / or at elevated temperatures or may be subjected to the further process steps as described below in wet form as a mixture of the intermediate cocrystals with residual amounts of the solvent or mixture of solvents as used in the first and / or third liquid medium. As an optional process step d), the process of the present invention comprises recrystallizing the solid intermediate product as formed in step c) in a second liquid medium to provide the solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals in diastereomerically enriched form. According to the recrystallization of this process step d), the solid intermediate product as formed in step c) in the form of cocrystals may be isolated as described above in connection with process step c) and may then be dissolved in a second liquid medium. As already mentioned, process step d) is optional and, accordingly, may be comprised by the process of the present invention. It should be noted, however, that the process according to the present invention may also be carried out without performing process step d) with process step e) as described in further detail below directly following process step b). In some embodiments, however, the process of the present invention comprises process step d) in which the solid intermediate product (comprising cocrystals of (S)-SLS and the compound of formula (II)) is recrystallized in a second liquid medium. The second liquid medium used as the solvent for the recrystallization according to optional process step d), in some embodiments, may comprise or essentially consist of an organic solvent or a mixture of organic solvents such as a third organic solvent or mixture of different organic solvents. Suitable organic solvents comprise such solvents in which the solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals as formed in step c) is less soluble or sparingly soluble at lower temperatures, for example, at temperatures from about 20 °C to about 40 °C or to about 30°C, and in which the solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals is better soluble at higher temperatures, such as at temperature of above about 30 or 40 °C or of above 50 °C or 60 °C. Suitable solvents for the optional recrystallization according to step d) comprise, but are not limited to the solvents as described above in connection with the first liquid medium. Accordingly, in some embodiments, the second liquid medium may comprise or essentially consist of an organic solvent selected from the group consisting of C1-C4 alkyl acetates such as ethyl acetate, propyl acetate, isopropyl acetate isobutyl acetate, tert.-butyl acetate, acetonitrile, methyl isobutyl ketone, aromatic hydrocarbons such as toluene, preferably isobutyl acetate and / or acetonitrile. In some embodiments, the second liquid medium comprises or essentially consists of isobutyl acetate and acetonitrile. The organic solvents can be used in the firm of a single solvent or in the form of a mixture of two or even more of the named solvents. In connection with the present recrystallization according to step d), however, it may be advantageous to use just one solvent in pure form, such as pure acetonitrile. Accordingly, in some embodiments, the second liquid medium comprises or essentially consists of acetonitrile. While the absolute amount of solvent used for the recrystallization according to optional process step d) is not critical and may be varied within a broad range, in some embodiments, the second liquid medium may be used in an amount within the range of from about 10 mL to about 40 mL or from about 15 mL to about 30 mL or to about 20 mL per g of the crystalline intermediate product. In further embodiments, the recrystallization according to optional process step d) may further comprise the steps of d1) providing a mixture of the solid intermediate product (comprising (S)-SLS and the compound of formula (II) in the form of cocrystals) in a second liquid medium comprising or essentially consisting of a third solvent or mixture of solvents as described above, d2) exposing the mixture as formed in step d1) to conditions under which the solid intermediate product at least partly dissolves in the second liquid medium, and d3) exposing the mixture as formed in step d2) in which the solid intermediate product is (at least partly) dissolved in the second liquid medium to conditions under which the dissolved intermediate product recrystallizes. The mixture of the solid intermediate product (comprising (S)-SLS and the compound of formula (II) in the form of diastereomeric cocrystals) in a second liquid medium to be provided according to process step d1) may be provided in a suitable rection vessel with suitable means for mixing a solid and a liquid component as described above in connection with process step a), such as a magnetic or mechanic stirrer. According to process step d2), the mixture as provided in process step d1) may then be heated. Accordingly, in some embodiments, process step d2) comprises heating of the mixture as provided in step d1) to an elevated temperature, such as a temperature within the range of from about 60 °C to about 90 °C or from about from about 70 °C to about 85 °C. It should be noted that the absolute temperature to which the mixture is heated is not critical and, in some embodiments, may be limited by the boiling point of the chosen second liquid medium or organic solvent contained therein. In preferred embodiments, the conditions according to process step d2) may be selected such that the solid intermediate product completely or substantially completely dissolves in the second liquid medium, for example to an amount of at least 95 % or at least 98 % or at least 99 % or even at least 99.9 % or 100 % (with regard to the total amount of solid intermediate added to the mixture) is dissolved. After complete or at least sufficient dissolution of the solid intermediate product in the second liquid medium, the heated mixture or solution as prepared according to process step d2) may then be exposed to conditions under which the dissolved intermediate product recrystallizes. These conditions may comprise cooling of the intermediate mixture or solution as formed in step d2), or removal or partial removal of the second liquid medium or a solvent comprised by the second liquid medium, or addition of seed particles or crystals, preferably seed crystals of the solid intermediate product or cocrystals comprising (S)-SLS and the compound of formula (II) as described in further detail below in connection with the seventh aspect of the invention. In particular embodiments, process step d3) comprises cooling of the mixture as formed in step d2), preferably to a temperature within the range of from about 10 °C to about 30 °C, preferably at a cooling rate selected within the range of from about 0.05 °C / min to about 0.6 °C / min, or from about 0.1 °C / min to about 0.5 °C / min, or from about 0.2 °C / min to about 0.4 °C / min. In further particular embodiments, process step d3) comprises addition of seed particles or crystals, preferably seed crystals of the solid intermediate product or cocrystals comprising (S)-SLS and the compound of formula (II), especially seed crystals with a high enantiomeric and / or diastereomeric purity. During the cooling process and, optionally in the presence of seed crystals as described above usually a solid precipitate in crystalline form (comprising the solid intermediate product in crystalline form) is formed which may, after completion of the cooling process may be isolated by standard techniques such as by filtration, decantation or by centrifugation. The solid recrystallized intermediate product may then be further purified by washing of the isolated precipitate, preferably with an organic solvent or mixture of organic solvents, such as the solvent or solvents used in the recrystallization process. The washing step may be conducted just once or a plurality of times as deemed necessary. In particular embodiments, the isolated and washed recrystallized intermediate product may then be dried to remove residual solvent, if necessary, under reduced pressures and / or at elevated temperatures. Accordingly, in further embodiments optional process step d) of the process of the present invention may further comprise as a further step d4) isolating and washing of the recrystallized intermediate product. The recrystallized intermediate product as isolated according to process step 6) is usually obtained in high diastereomeric and enantiomeric purity such as with an enantiomeric excess of usually at least about 95 % ee, or at least about 97 % ee, or at least about 98 % ee or even at least about 99 % ee, such as from about 99 % ee to about 99.9 % ee. The solid intermediate product as formed in step c) or d) comprising cocrystals of (S)-SLS and the compound of formula (II), according to a further process step e) are then exposed to a base wherein the term “base” as used herein means a basic regent capable of reacting with the intermediate comprising cocrystals of (S)- SLS and the compound of formula (II) such that free (S)-6-Chloro-2,3,4,9-tetrahydro- 1H-carbazole-1-carboxamide of formula (I) is provided, for example by deprotonation of the protonated (S)-SLS comprised in the solid intermediate product. Accordingly, the process of the invention further comprises the further process step e) exposing the solid intermediate product as formed in step c) or d) to a base to provide (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I) in enantiomerically enriched form. (S)-SLS of formula (S-I) may then be, in an additional process step, isolated in enantiomerically enriched form. Accordingly, process step e) may further comprises, as an additional process step e1) the step of e1) isolating (S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide of formula (S-I) in enantiomerically enriched form. In some embodiments the base to which the solid intermediate product may be exposed, or, in other words, with which the solid intermediate product may be contacted or reacted with may be an inorganic base. In other embodiments, however, the solid intermediate product may also be exposed to a suitable organic base. In preferred embodiments, however, the organic or preferable inorganic base, more specifically the strength of the chosen organic or preferable inorganic base is chosen such that it does not lead to the partial or complete racemization of the prepared (S)- 6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I) in enantiomerically enriched form. The chosen organic or preferably inorganic base to which the solid intermediate product is exposed according to process step e) may be provided in the form of a solution, such as a solution in a suitable organic solvent or in a mixture of solvents. In further embodiments, especially in cases in which the base is an inorganic base, such base may be provided in the form of a solution in water or an aqueous mixture of an organic solvent with water. In yet further preferred embodiments, the base is an inorganic base and is provided in an aqueous solution. Accordingly, in some embodiments of process step e) the intermediate product is exposed to an aqueous solution of an inorganic base. Suitable examples for inorganic bases comprise but are not limited to carbonates, hydrogen carbonates or hydroxides of alkaline or earth alkaline metals, such as sodium hydrogen carbonate (NaHCO3), potassium hydrogen carbonate (KHCO3), sodium carbonate (Na2CO3) or potassium carbonate (K2CO3), preferably sodium hydrogen carbonate (NaHCO3). In particular embodiments, the solid intermediate product is exposed to an aqueous solution of sodium or potassium hydrogen carbonate or of sodium or potassium carbonate preferably to an aqueous solution of NaHCO3. The chosen organic or preferably inorganic base may be added to the solid intermediate product in an amount of at least 1.5 equivalents with regard to the molar amount of intermediate cocrystals of (S)-SLS and the compound of formula (II), preferably in a molar amount of at least about 1.8, or 1,9, or of at least about 2.0 equivalents with regard to the molar amount of intermediate cocrystals of (S)-SLS and the compound of formula (II), such as from about 2.0 to about 3.0 molar equivalents with regard to the molar amount of intermediate cocrystals of (S)-SLS and the compound of formula (II). The chosen base, as described above, may be provided in the form of a solution in the chosen solvent and the solid intermediate compound may be added to said solution. In general, however, the order of addition is not critical as long as the solid intermediate and the chosen base may be brought in direct contact. In a particular embodiment, a mixture is prepared comprising the solid intermediate as obtained from step c) or d) as described above and the chosen base preferably in an aqueous solvent such as water. The reactants and the solvent may be placed in a suitable rection vessel equipped with suitable means for an effective mixing of the components such as a mechanic or magnetic stirrer. In particular embodiments, a mixture is provided comprising the solid intermediate comprising the diastereomeric cocrystals of (S)-SLS and the compound of formula (II) and water or an aqueous solvent, preferably water, and an aqueous solution of sodium hydrogen carbonate is added to the mixture. The dissociation of the solid intermediate comprising the diastereomeric cocrystals of (S)-SLS and the compound of formula (II) usually occurs readily upon contact and reaction with the chosen inorganic or organic base and is usually completed after a reaction time of up to about 5 h or up to about 3 or 2 h at room temperature (approx.22 °C) or slightly above. Especially in cases in which the dissociation according to step e) is performed using an aqueous solvent or mixture of solvents, preferably when water is used as the solvent or liquid medium (S)-6-Chloro- 2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I) in enantiomerically enriched form may be obtained in the form of a mixture, more specifically in the form of a aqueous suspension of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide of formula (S-I) in the form of white crystals. These crystals may then be isolated, washed and dried using standard techniques, for example as described above in connection with the isolation of the solid intermediate, such as by filtration, decantation or centrifugation. From the aqueous solvent or mixture of solvents separated from (S)-SLS in crystalline form as described above, the compound of formula (II) may be recovered, for example by treatment with a suitable acid to neutralize potential remains of the inorganic or organic acid used in the dissociation process according to step e) and to protonate the deprotonated tartaric acid derivative of formula (II) which may then be isolated in crystalline form. In a second aspect, the invention provides for (S)-6-Chloro-2,3,4,9-tetrahydro- 1H-carbazole-1-carboxamide of formula (S-I) (S-I) in crystalline form. As described in detail above, (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide according to this second aspect of the invention may be prepared according to the process of the first aspect of the invention. Accordingly, the present invention also relates to (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide of formula (S-I) obtained or obtainable according to the process of the first aspect of the invention. As mentioned above, (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide of formula (S-I) may be prepared or obtained by the process of the first aspect of the invention in enantiomerically pure or enantiomerically enriched form or, in other words, in the form of non-racemic mixtures with residual amounts of its R-enantiomer. In preferred embodiments, however, the present invention provides for (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide having an enantiomeric purity of at least about 97 % ee or of at least about 98 % ee or of at least about 99 % ee or even above such as from about 99 % ee to about 100 % ee or to about799.9 % ee or to about 99.8 % ee. As the process of the first aspect of the invention provides for (S)-6-Chloro- 2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide with high chemical purity, in some embodiments, the present invention, according to this second aspect provides for (S)- 6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide with a chemical purity of at least about 90 % or at least about 95 % (w / w) or even at least about 97 % (w / w), or even at least about 98 % (w / w), or even at least about 99 % (w / w) or above such as from about 95 to about 100 % (w / w), or from about 97 to about 99.9 % (w / w), or from about 98 to about 99.8 % (w / w), or from about 99 to about 99.5 % (w / w). The crystals of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I) according to this aspect of the invention have been analyzed by X-ray powder diffraction (hereinafter also referred to as “XRPD” or “Powder X-Ray Diffraction analysis, “PXRD” as used herein synonymously) in which a specific diffraction pattern for the crystalline (S)-SLS as prepared according to the process of the first aspect of the invention was found as described in detail in Example 2 below. The XRPD spectrum showed prominent signals or, in other words, reflections at 2- theta (2- ^) angle values of 16.4, 19.8, 21.9 and 32.6 degrees (with a deviation of + / - 0.2 degree or preferably 0.1 degree) when measured at a temperature range of 20 °C to 30 °C, more specifically of 20 °C to 25 °C with Cu-K ^ radiation having a wavelength of 0.15406 nm; for details of the analysis see Example 2.1). The term "reflection" with regard to powder X-ray diffraction as used herein, means peaks in an X-ray diffractogram, which are caused at certain diffraction angles (Bragg angles) by constructive interference from X-rays scattered by parallel planes of atoms in solid material, which are distributed in an ordered and repetitive pattern in a long-range positional order. Such a solid material is classified as “crystalline” material or, as used herein, “in crystalline form”, whereas amorphous material is defined as solid material, which lacks long-range order and only displays short-range order, thus resulting in broad scattering. According to literature, long-range order e.g. extends over approximately 100 to 1000 atoms, whereas short-range order is over a few atoms only (see "Fundamentals of Powder Diffraction and Structural Characterization of Materials” by Vitalij K. Pecharsky and Peter Y. Zavalij, Kluwer Academic Publishers, 2003, page 3). Accordingly, in a particular embodiment the present invention provides for (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I) in crystalline form having an X-ray powder diffraction pattern comprising 2-theta angle values (with a deviation of + / - 0.2 degree) of 16.4, 19.8, 21.9 and 32.6 degrees (herein also referred to as “polymorph X”). The term “polymorph” as used herein refers to a crystalline form of a compound, for example to a crystalline form of (S)-SLS, having the same chemical composition but different spatial arrangements of the molecules, atoms, and / or ions forming the crystal. In further particular embodiments, the present invention relates to (S)-6- Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form having an X-ray powder diffraction pattern comprising 2-theta angle values (with a deviation of + / - 0.2 degree) of 14.8, 16.4, 19.8, 21.9, 24.9, 30.4 and 32.6 degrees (polymorph X) when measured as described above. Even more specifically, polymorph X of (S)-SLS showed signals or reflections at 2-theta (2- ^) angle values substantially as listed in Table 1 (see Example 2.1) and as shown in the XRPD diffractogram as depicted in Fig.1. The (S)-SLS in enantiomerically enriched form of the present invention has been further analysed by1H-Nuclear magnetic resonance. The1H-NMR spectrum of (S)-SLS in enantiomerically enriched form according to this aspect of the invention was recorded using a dilute solution comprising about 5 to about 10 mg of the respective polymorph in about 0.7 mL deuterated dimethylsulfoxide (DMSO-d6) (using a Varian Mercury 400 MHz spectrometer, equipped with a broadband probe ATB 1H / 19F / X of 5 mm). The1H-NMR spectrum of (S)-SLS in enantiomerically enriched form (see Fig.2,1H-NMR spectrum of polymorph X of (S)-SLS) was identical to the1H-NMR spectrum of racemic Selesistat and showed no residual organic solvents or other organic compounds. (S)-SLS in crystallin form (polymorph X) of the present invention has been further characterized by Differential Scanning Calorimetry (DSC). The corresponding spectrum is depicted in Fig.3. When heated from 25 °C to about 300 °C at a rate of about 10 °C / min (for details see Example 2.3), the DSC spectrum of polymorph X showed an endothermic peak within the range of from about 170 °C to about 190 °C, specifically from about 183 °C to about 190 °C with an onset of about 185 °C. Accordingly, in a further embodiment the present invention provides for (S)-6- Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form having a melting point (melting onset) of about 183 °C to about 186 °C, specifically of about 185 °C (+ / - 2.5 °C, or + / - 1.5, or + / - 1 °C or + / - 0.5 °C as the standard deviation). The corresponding melting enthalpy ( ^H) was determined as - 106.7 J / g (calculated as the area under curve of the endothermic peak and normalized to sample weight). Accordingly, in a further embodiment the present invention provides for (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form having a melting enthalpy ( ^H) within the range of from about -104 J / g to about -109 J / g or from about -105 J / g to about - 108 J / g. As described in detail in Example 5 below, the absolute configuration the asymmetric carbon atom (C11) of 6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide as prepared according to the process of the first aspect of the invention has been determined to be “S” as depicted in formula (S-I) as well as in the asymmetric unit of the molecule as depicted in Figure 7. Crystalline (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide according to this aspect of the invention as described above, particularly polymorph X, may be prepared in a form which does not comprise considerable amounts of water or organic solvents enclosed or incorporated in the crystal structure, except for residual amounts of water or organic solvents of up to about 2.0 wt.-% or up to about 1 wt.-% or up to about 0.5 wt.-% with regard to the total weight of the respective crystalline material which may be, for example, associated to the surface of the crystalline material. Furthermore, polymorph X of crystalline (S)-6-Chloro-2,3,4,9- tetrahydro-1H-carbazole-1-carboxamide as described above has been found to be non-hygroscopic or, in other words, not to attract or incorporate water under defined storage conditions. Accordingly, in particular embodiments, the crystalline (S)-SLS as disclosed herein, specifically polymorph X, is solvent free and / or non-hygroscopic. Furthermore, crystalline (S)-SLS as disclosed herein, specifically polymorph X, has been found to be stable under defined storage conditions such as the storage conditions defined by the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH). More specifically, of (S)-SLS in crystalline form as disclosed herein has been found stable under accelerated ICH conditions for at least 7 days when stored in a suitable climate chamber at 40 °C + / - 2 °C at 75 % + / - 5 % relative humidity (RH) as described in Example 3 below. Accordingly, in specific embodiments, the present invention provides for (S)-SLS in crystalline form, specifically polymorph X, which is stable at a temperature of 40 °C + / - 2 °C and a relative humidity (RH) of 75% + / - 5 % (accelerated ICH conditions) for a period of at least 7 days, wherein the term “stable” as used in this context means that at least 90 wt.-% or at least 95 wt.-% or at least 98 wt.-% or at least 99 wt.-% of the specific polymorph remains in the specific polymorphic form without degradation or conversion to another polymorphic or amorphous form. Accordingly, (S)-SLS in crystalline form as disclosed herein, specifically polymorph X, is especially useful for pharmaceutical purposes and applications. In a third aspect, the present invention provides for a composition comprising (S)-SLS of formula (S-I) in crystalline form, specifically in crystalline polymorphic form X of (S)-SLS as described above and further comprising up to about 20 wt.-%, 10 wt.-%, 5 wt.-%, 4 wt.-%, 3 wt.-%, 2 wt.-% or 1 wt.-% of any other solid-state form of (S)-SLS, based on the weight of the composition. The term “solid-state form” as used in this context is to be understood as a form of (S)-SLS other than polymorph X as described herein, such as potential further polymorphs or solvates or an amorphous solid form of (S)-SLS. In a fourth aspect, the present invention provides for (S)-SLS in crystalline form, specifically polymorph X as described above, for use as a medicament. In this context, the present invention also relates to the use of (S)-SLS in crystalline form, specifically polymorph X, in the manufacture of a medicament. Furthermore, in this context the present invention also relates to a method of using (S)-SLS in crystalline form, specifically polymorph X, as a medicament or for the treatment or prevention of a medical condition, preferably a medical condition of a warm-blooded animal or human, specifically of a human. In some embodiments of this fourth aspect of the invention, a medical condition that may be treated or prevented may be a medical condition or disease associated with or mediated by sirtuin, specifically a medical condition or disease associated with or mediated by SIRT1. Accordingly, the present invention also provides for (S)-SLS of formula (S-I) in crystalline form according to the second aspect of the invention as described above or the composition according to the third aspect of the invention for use in the prevention or treatment of a disease or condition associated with or mediated by sirtuin, for example SIRT1. In some embodiments, a disease or medical condition associated with or mediated by SIRT1 as referred to above that may be treated or prevented by administration of (S)-SLS in crystalline form or the compositions of the present invention comprising such (S)-SLS in crystalline form may be selected from cancer, metabolic diseases such as metabolic syndrome, type I diabetes or type II diabetes, obesity, dislipidemia, hyperlipidemia, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, neurodegenerative conditions that are caused at least in part by polyglutamine aggregation, such as Huntington's disease, spinalbulbar muscular atrophy (SBMA or Kennedy's disease), dentatorubro-pallidoluysian atrophy (DRPLA), spinocerebellar ataxia 1 (SCA1), spinocerebellar ataxia 2 (SCA2), Machado- Joseph disease (MJD; SCA3), spinocerebellar ataxia 6 (SCA6), spinocerebellar ataxia 7 (SCA7), and spinocerebellar ataxia 12 (SCA12), specifically Huntington’s disease. In a fifth aspect, the present invention relates to the use of (S)-SLS of formula (S-I) in crystalline form of according to the second aspect of the invention, specifically of polymorph X of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide or the composition according to the third aspect of the invention for the preparation of a pharmaceutical composition. Accordingly, in a sixth aspect, the present invention relates to a pharmaceutical composition comprising (S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide in crystalline form, specifically polymorph X, according to the second aspect of the invention as described above or the composition comprising such (S)-SLS in crystalline form, specifically polymorph X, preferably in a predetermined and / or pharmaceutically effective amount, and at least one pharmaceutically acceptable excipient wherein the term “pharmaceutically effective amount” as used herein means that amount which, when administered to a warm- blooded animal or human for treating or preventing a disease, is sufficient to effect such treatment or prevention for the disease. In some embodiments, the predetermined and / or effective amount of the preferably anhydrous and non-solvated crystalline form of (S)-SLS of the present invention or the composition comprising the same as defined in any one of the above- described aspects and their corresponding embodiments may be selected within the range of from about 1 mg to about 300 mg, or from about 20 mg to about 250 mg, or from about 1 mg to about 20 mg or from about 100 to about 200 mg per single dose amount, calculated as anhydrous and non-solvated (S)-6-Chloro-2,3,4,9-tetrahydro- 1H-carbazole-1-carboxamide in crystalline form. Ther term “excipient” as used herein means a pharmaceutically acceptable auxiliary substance, carrier or material that enables or facilitates the formulation of an active pharmaceutical ingredient such as (S)-SLS in a crystalline form as described herein as a composition or dosage form that may be manufactured according to generally accepted quality standards, stored at common storage conditions and administered conveniently to subjects in need thereof, such as human patients. In this context, the term “pharmaceutically acceptable” means that the compound or mixture it refers to is useful in preparing a pharmaceutical composition that is generally safe, non-toxic and neither biologically nor otherwise undesirable and includes that which is acceptable for human pharmaceutical use. The at least one pharmaceutically acceptable excipient, which is comprised in the pharmaceutical composition of the present invention, is preferably selected from the group consisting of fillers, binders, disintegrants, lubricants, glidants, and combinations thereof as known to those of skill in the art and as described, for example, in current pharmacopoeias, such as the European Pharmacopoeia or the United States Pharmacopeia. Preferably, the at least one pharmaceutically acceptable excipient is selected from the group consisting of one or more fillers, binders, disintegrants and lubricants. More preferably, the at least one pharmaceutically acceptable excipient is selected from the group consisting of microcrystalline cellulose, colloidal silicon dioxide, croscarmellose sodium, magnesium stearate and combinations thereof. In some embodiments, the pharmaceutical compositions of this aspect of the invention comprising (S)-SLS in crystalline form, preferably polymorph X, especially in anhydrous and non-solvated form may be a solid dosage form, such as a solid dosage form for oral administration. Examples for such solid dosage forms that are suitable for oral administration may comprise but are not limited to tablets, capsules, granules and oral films. More preferably, the oral solid dosage form is a tablet or a capsule, such as a soft capsule or a hard capsule. In the case of a hard capsule, this may be filled with a powder mixture or with granules or pellets comprising (S)-SLS. Optionally, the granules, the tablet or the capsule may be coated. The pharmaceutical compositions of the present invention as defined in any one of the above-described embodiments may be produced by standard manufacturing processes, which are well-known to the skilled person including, for example, blending, granulation (wet or dry granulation), tablet compression, film- coating or capsule filling and packaging. For example, the tablet may be prepared by mixing the crystalline form of (S)-SLS of the present invention or the composition comprising the same as defined in any one of the above-described aspects and their corresponding embodiments with at least one excipient such as fillers, binders, disintegrants, lubricants, glidants or combinations thereof. Optionally, a granulation step such as a dry or wet granulation step is performed before compression. The tablet cores may be additionally film-coated. In a seventh aspect, the invention provides for a diastereomeric compound comprising (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S)-I and a tartaric acid derivative of formula (II) in enantiomerically enriched form or preferably in enantiomerically pure form, wherein R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen, C1-C4-haloalkyl, -O-C1- C4-alkyl, -O-C1-C4- haloalkyl. The diastereomeric compound according to this aspect of the invention corresponds to the “solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals” or just “cocrystals” as referred to and described in connection with the process of the first aspect of the invention. As already mentioned above, these compounds may also be described as solids that are crystalline single-phase materials composed of two or more different molecular or ionic compounds, specifically composed of (S)-SLS and the compound of formula (II), generally in a stoichiometric ratio which are neither solvates nor simple salts. It should be noted that all features, definitions, embodiments as disclosed in connection with the first aspect of the invention and irrespective of being disclosed as “particular”, “specific”, “preferred” or in any other way may be combined with any one of the other aspects of the invention, including this seventh aspect of the invention. Accordingly, in the compounds of formula (II) according to this aspect of the invention C1-C4-alkyl preferably means a saturated hydrocarbon substituent with one to four carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, tert.-butyl; halogen preferably means fluorine, chlorine, bromine, preferably fluorine or chlorine, especially chlorine; C1-C4-haloalkyl preferably means a saturated mono- or polyhalogenated hydrocarbon substituent with one to four carbon atoms such as trifluormethyl, pentafluoroethyl, heptafluor-isopropyl; -O-C1-C4-alkyl preferably means a saturated hydrocarbon substituent with one to four carbon atoms bound via an oxygen atom such as methoxy, ethoxy, n-propoxy, iso- propoxy, n-butoxy, s-butoxy, tert.-butoxy, preferably methoxy, iso-propoxy and tert.- butoxy, especially methoxy; and -O-C1-C4-haloalkyl preferably means a saturated and halogenated hydrocarbon substituent with one to four carbon atoms bound via an oxygen atom such as trifluormethoxy, pentafluorethoxy, heptafluor-isopropoxy, especially trifluormethoxy. In particular embodiments of the compounds according to this aspect of the invention, in the compound of formula (II) R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen and C1-C4- haloalkyl as described above. In further embodiments, in the compound of formula (III) all substituents R1, R2, R3, R4and R5are H. In yet further embodiments, both asymmetric carbon atoms of the chosen tartaric acid derivative of formula (II) may be in the R-configuration. Accordingly, in a preferred embodiment the compound of formula (II) is (2R, 3R)-(-)-Di-O-4-benzoyl-L-tartaric acid (CAS Nr.2743-38-6, herein also referred to as “(-)-DBTA”). In yet further embodiments, in the compound of formula (II) the substituents R1, R2, R4and R5are H and R3is selected from C1-C4-alkyl and C1-C4-haloalkyl as described above, preferably from C1-C4-alkyl, especially methyl. In a preferred embodiment, the compound of formula (II) is (2R, 3R)-(-)-Di-O-4-toluoyl-L-tartaric acid (CAS Nr.32634-66-5, herein also referred to as “(-)-DTTA”). As described in detail above, the compounds of this aspect of the invention may be prepared according to the process of the first aspect of the invention, specifically according to process steps a), b), c) and optionally d) of the process of the first aspect of the invention in which they are also referred to as “a solid intermediate product comprising (S)-SLS and the compound of formula (II)”. In some embodiments, such solid intermediate product is in the form of a compound comprising (S)-6-Chloro- 2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide and the tartaric acid derivative of formula (II) in a molar ratio of 2 : 1. In further embodiments, the compounds according to this aspect of the invention comprising (S)-SLS and the compound of formula (II), preferably in a molar ratio of 2:1 are in crystalline form, or, in other words, in the form of cocrystals comprising (S)-SLS and the compound of formula (II), preferably in a molar ratio of 2:1. The cocrystals of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide of formula (S-I) and (2R, 3R)-(-)-Di-O-4-toluoyl-L-tartaric acid as the compound of formula (II) according to this aspect of the invention have also been analyzed by X-ray powder diffraction in which a specific diffraction pattern was found as described in detail in Example 4 below. The XRPD spectrum showed prominent signals or, in other words, reflections at 2-theta (2- ^) angle values of 6.2, 10.7, 12.5 and 16.2 degrees. (with a deviation of + / - 0.2 degree or preferably 0.1 degree) when measured at a temperature range of 20 °C to 30 °C, more specifically of 20 °C to 25 °C with Cu-K ^ radiation having a wavelength of 0.15406 nm; for details of the analysis see Example 4.2). Accordingly, in a particular embodiment the present invention provides for cocrystals of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I) and (2R, 3R)-(-)-Di-O-4-toluoyl-L-tartaric acid as the compound of formula (II) having an X-ray powder diffraction pattern comprising 2-theta angle values (with a deviation of + / - 0.2 degree or preferably 0.1 degree) of 6.2, 10.7, 12.5 and 16.2 degrees. In a further particular embodiment, the present invention relates to a cocrystal of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) and (2R, 3R)-(-)-Di-O-4-toluoyl-L-tartaric acid as the compound of formula (II) having an X-ray powder diffraction pattern comprising 2-theta angle values (with a deviation of + / - 0.2 degree or preferably 0.1 degree) of 6.2, 10.7, 10.9, 12.5, 14.3, 16.2, 20.9 and 21.3 degrees when measured as described above. Even more specifically, the cocrystals of (S)-SLS and (2R, 3R)-(-)-Di-O-4-toluoyl-L-tartaric acid as the compound of formula (II) showed signals or reflections at 2-theta (2- ^) angle values of substantially as listed in Table 2 (see Example 4.2) and as shown in the XRPD diffractogram as depicted in Fig.4. The diastereomeric cocrystals of (S)-SLS and (2R, 3R)-(-)-Di-O-4-toluoyl-L- tartaric acid as the compound of formula (II) of the present invention have been further analysed by1H-Nuclear magnetic resonance using a dilute solution comprising about 5 to about 10 mg of the respective cocrystals in about 0.7 mL deuterated dimethylsulfoxide (DMSO-d6) (using a Varian Mercury 400 MHz spectrometer, equipped with a broadband probe ATB 1H / 19F / X of 5 mm). The1H- NMR spectrum of the cocrystals of (S)-SLS and (2R, 3R)-(-)-Di-O-4-toluoyl-L-tartaric acid as the compound of formula (II) is shown in Fig.5 and showed no residual organic solvents or other organic compounds. The cocrystals of (S)-SLS and (2R, 3R)-(-)-Di-O-4-touyl-L-tartaric acid as the compound of formula (II) of the present invention has been further characterized by Differential Scanning Calorimetry (DSC). The corresponding spectrum is depicted in Fig.6. When heated from 25 °C to about 300 °C at a rate of about 10 °C / min (for details see Example 4.4), the DSC spectrum of the cocrystals of (S)-SLS and (2R, 3R)-(- )-Di-O-4-toluoyl-L-tartaric acid as the compound of formula (II) showed an endothermic peak within the range of from about 190 °C to about 205 °C, specifically from about 195 °C to about 205 °C with an onset of about 197 °C corresponding to the melting point of the cocrystals of (S)-SLS and (2R, 3R)-(-)-Di-O-4-toluoyl-L-tartaric acid as the compound of formula (II). Finally in an eight aspect, the present invention provides for the use of the diastereomeric cocrystals according to the seventh aspect of the invention comprising (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S)-I and a tartaric acid derivative of formula (II) in enantiomerically enriched form or preferably in enantiomerically pure form, as described in connection with the first and seventh aspect of the invention for the manufacture of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide in enantiomerically enriched form and / or in crystalline form. According to some embodiments, the use according to this aspect of the invention refers to the preferred cocrystals of as described in connection with the seventh aspect of the invention, especially the cocrystals of (S)-SLS and (2R, 3R)-(-)- Di-O-4-touyl-L-tartaric acid as the compound of formula (II) and the cocrystals of (S)- SLS and (2R, 3R)-(-)-Di-O-4-benzoyl-L-tartaric acid as the compound of formula (II). The following list of numbered items are embodiments comprised by the present invention: 1. A process for the preparation of(S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole- 1-carboxamide ((S)-SLS) of formula (S-I) (S-I) in enantiomerically enriched form by resolution of rac-6-Chloro-2,3,4,9- tetrahydro-1H-carbazole-1- carboxamide (rac-SLS) of formula (I) the process comprising the steps of: a) Providing a first (liquid) mixture comprising rac-SLS and a compound of formula (II) in enantiomerically enriched form, wherein R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen, C1-C4-haloalkyl, -O-C1- C4-alkyl and -O-C1 -C4-haloalkyl in a first liquid medium, b) exposing the first (liquid) mixture as formed in step a) to conditions under which rac-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide and the compound of formula (II) at least partly dissolve in the first liquid medium to form an intermediate solution, c) exposing the intermediate solution as formed in step b) to conditions under which a solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals is formed, d) optionally recrystallizing the solid intermediate product as formed in step c) in a second liquid medium to provide the solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals in diastereomerically enriched form, and e) exposing the solid intermediate product as formed in step c) or d) to a base to provide (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide of formula (S-I) in enantiomerically enriched form. 2. The process for the preparation of(S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in enantiomerically enriched form according to item 1, wherein process step a) comprises the steps of: a1) Providing a first pre-mixture comprising rac-SLS in a first solvent or mixture of solvents, a2) Providing a second pre-mixture comprising of a compound of formula (II) in a second solvent or mixture of solvents, a3) Combining the first and the second liquid pre-mixtures to form the first intermediate mixture in a first liquid medium. 3. The process according to item 1 or 2, wherein process step c) comprises the step of: c1) at least partially removing the first liquid medium from the solid intermediate product. 4. The process according to any one of the preceding items, wherein process step e) comprises the step of e1) isolating (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide of formula (I) in enantiomerically enriched form. 5. The process according to any one of the preceding items, wherein in the compound of formula (II) R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen and C1-C4-haloalkyl. 6. The process according to any one of the preceding items, wherein in the compound of formula (II) R1, R2, R3, R4and R5are H. 7. The process according to any one of the preceding items, wherein in the compound of formula (II) R1, R2, R4and R5are H and R3is selected from C1 - C4-alkyl and C1-C4-haloalkyl. 8. The process according to any one of the preceding items, wherein in the compound of formula (II) R1, R2, R4and R5are H and R3is selected from C1 - C4-alkyl. 9. The process according to any one of the preceding items, wherein in the compound of formula (II) R1, R2, R4and R5are H and R3is methyl. 10. The process according to any one of the preceding items, wherein in the first liquid mixture rac-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (I) and the compound of formula (II) are provided in a molar ratio of about 1.5 : 1 to about 2.5 : 1, preferably from about 1.9 : 1 to about 2.1 : 1. 11. The process according to any one of the preceding claims, wherein the first liquid medium and / or the second liquid medium is an organic solvent or a mixture of organic solvents. The process according to any one of claims 2 to 11, wherein the first and / or the second solvent is an organic solvent or mixture of organic solvents. The process according to any one of the preceding items, wherein the first and / or the second liquid medium comprises or essentially consists of an organic solvent or a mixture of organic solvents selected from the group consisting of C1-C4 alkyl acetates such as ethyl acetate, propyl acetate, isopropyl acetate isobutyl acetate, and tert.-butyl acetate; acetonitrile, methyl isobutyl ketone, aromatic hydrocarbons such as toluene. The process according to any one of the preceding items, wherein the first and the second liquid medium comprises or essentially consists of isobutyl acetate and acetonitrile. The process according to any one of the preceding items, wherein the second liquid medium comprises or essentially consists of acetonitrile. The process according to any one of the preceding items, wherein the first liquid medium is used in an amount of about 1 to about 5 or from about 2 to about 4 mL per mmol of rac-SLS. The process according to any one of the preceding items, wherein according to step b) the first liquid mixture is heated. The process according to any one of the preceding items, wherein according to step b) the first liquid mixture is heated to a temperature within the range of from about 60 °C or from about 80 °C to reflux conditions. The process according to any one of the preceding items, wherein according to step c) the intermediate solution as formed in step b) is cooled. The process according to any one of the preceding items, wherein according to step c) the intermediate solution as formed in step b) is cooled to a temperature within the range of from about 10 °C to about 30 °C, or from about 20 °C to about 25 °C. The process according to any one of the preceding items, wherein according to step c) the intermediate solution as formed in step b) is cooled at a cooling rate selected within the range of from about 0.05 °C / min to about 0.6 °C / min, or from about 0.1 °C / min to about 0.5 °C / min, or from about 0.2 °C / min to about 0.4 °C / min. 22. The process according to any one of the preceding items, wherein the crystalline intermediate product of (S)-SLS and the compound of formula (II) in the form of cocrystals as formed in step c) comprises (S)-SLS and the compound of formula (II) in a molar ratio of 2 : 1. 23. The process according any one of the preceding items, wherein process step c) further comprises the step of c2) washing the solid intermediate product (comprising the diastereomeric cocrystals of (S)-SLS and the compound of formula (II) ) with a third liquid medium. 24. The process according to any one of the preceding items, wherein according to process step d) the solid intermediate product (comprising the diastereomeric cocrystals of (S)-SLS and the compound of formula (II)) is recrystallized in a second liquid medium. 25. The process according to any one of the preceding items, wherein the second liquid medium is used in an amount within the range of from about 10 mL to about 40 mL or from about 15 mL to about 30 mL or to about 20 mL per g of the crystalline intermediate product. 26. The process according to any one of the preceding items, wherein the recrystallization according to process step d) comprises the steps of d1) providing a mixture of the solid intermediate product (comprising the diastereomeric cocrystals of (S)-SLS and the compound of formula (II)) in a second liquid medium comprising or essentially consisting of a third solvent or mixture of solvents, d2) exposing the mixture as formed in step d1) to conditions under which the solid intermediate product (at least partly) dissolves in the second liquid medium, and d3) exposing the mixture as formed in step d2) in which the solid intermediate product is (at least partly) dissolved in the second liquid medium to conditions under which the dissolved intermediate product (comprising the diastereomeric cocrystals of (S)-SLS and the compound of formula (II)) recrystallizes. 27. The process according to item 26, wherein step d2) comprises heating of the mixture as provided in step d1) to a temperature within the range of from about 60 °C to about 90 °C or from about from about 70 °C to about 85 °C. 28. The process according to item 26 or 27, wherein step d3) comprises cooling of the mixture as formed in step d2), preferably to a temperature within the range of from about 10 °C to about 30 °C, preferably at a cooling rate selected within the range of from about 0.05 °C / min to about 0.6 °C / min, or from about 0.1 °C / min to about 0.5 °C / min, or from about 0.2 °C / min to about 0.4 °C / min. 29. The process according to any one of items 26 to 28, wherein the recrystallization according to process step d) further comprises the step of d4) isolating and washing of the recrystallized intermediate product (comprising the diastereomeric cocrystals of (S)-SLS and the compound of formula (II)). 30. The process according to any one of the preceding items, wherein according to step e) the intermediate product is exposed to an inorganic base. 31. The process according to any one of the preceding items, wherein according to step e) the intermediate product is exposed to an aqueous solution of an inorganic base. 32. The process according to any one of the preceding items, wherein according to step e) the base is selected from the group of carbonates, hydrogen carbonates or hydroxides of alkaline or earth alkaline metals. 33. The process according to any one of the preceding items, wherein according to step e) the base is sodium hydrogen carbonate. 34. The process according to any one of the preceding items, wherein according to step e) the base is used in an amount of at least 1.5 equivalents with regard to the molar amount of intermediate cocrystals of (S)-SLS and the compound of formula (II). 35. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I) (S-I) in crystalline form. 36. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide according to item 35, prepared according to the process of any one of items 1 to 34. 37. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide according to item 35 or 36 having an enantiomeric purity of at least 97 % ee or of at least 98 % ee or of at least 99 % ee. 38. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I) in crystalline form according to any one of items 35 to 37, having an X-ray powder diffraction pattern comprising 2-theta angle values (with a deviation of + / - 0.2 degree) of 16.4, 19.8, 21.9 and 32.6 degrees (polymorph X). 39. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to any one of items 35 to 38, having an X-ray powder diffraction pattern comprising 2-theta angle values (with a deviation of + / - 0.2 degree) of 14.8, 16.4, 19.8, 21.9, 24.9, 30.4 and 32.6 degrees (polymorph X). 40. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (I) in crystalline form according to any one of items 35 to 39 having a melting point (melting onset) of about 185 °C (polymorph X). 41. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to any one of items 35 to 40, having a melting enthalpy ( ^H) within the range of from about -104 J / g to about -109 J / g or from about -105 J / g to about -108 J / g. 42. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to any one of items 35 to 41, wherein the crystalline form of (S)-SLS is solvent-free and / or non- hygroscopic. 43. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to any one of items 35 to 42, wherein the crystalline form of (S)-SLS is stable at a temperature of 40 °C + / - 2 °C and a relative humidity (RH) of 75% + / - 5 % (accelerated ICH conditions) for a period of at least 7 days. 44. A composition comprising of (S)-SLS of formula (S-I) in crystalline form according to any one of items 35 to 43 and further comprising up to about 20 wt.-%, 10 wt.-%, 5 wt.-%, 4 wt.-%, 3 wt.-%, 2 wt.-% or 1 wt.-% of any other solid-state form of (S)-SLS, based on the weight of the composition. 45. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to any one of items 35 to 43 or the composition according to item 44 for use as a medicament. 46. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to any one of items 35 to 43 or the composition according to item 44 for use in the prevention or treatment of a disease or condition associated with SIRT1. 47. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to any one of items 35 to 43 or the composition according to item 44 for use in the prevention or treatment of cancer, metabolic diseases such as metabolic syndrome, type I diabetes or type II diabetes, obesity, dislipidemia, hyperlipidemia, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, neurodegenerative conditions that are caused at least in part by polyglutamine aggregation, such as Huntington's disease, spinalbulbar muscular atrophy (SBMA or Kennedy's disease) dentatorubro-pallidoluysian atrophy (DRPLA), spinocerebellar ataxia 1 (SCA1), spinocerebellar ataxia 2 (SCA2), Machado-Joseph disease (MJD;SCA3), spinocerebellar ataxia 6 (SCA6), spinocerebellar ataxia 7 (SCA7), and spinocerebellar ataxia 12 (SCA12). 48. Use of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to any one of items 35 to 43 or the composition according to item 44 for the preparation of a pharmaceutical composition. 49. A pharmaceutical composition comprising (S)-6-Chloro-2,3,4,9-tetrahydro-1H- carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to any one of items 35 to 43 or the composition according to item 44 and at least one pharmaceutically acceptable excipient. 50. The pharmaceutical composition according to item 49, wherein the pharmaceutical composition is a solid dosage form for oral administration. 51. The pharmaceutical composition according to item 49 or 50, wherein the composition is in the form of a tablet, a capsule, a granule or an oral film. 52. A compound comprising (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide and a tartaric acid derivative of formula (II) in enantiomerically enriched form, wherein R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen, C1-C4-haloalkyl, -O-C1- C4-alkyl and -O-C1 -C4-haloalkyl. 53. The compound according to item 52 comprising (S)-6-Chloro-2,3,4,9- tetrahydro-1H-carbazole-1-carboxamide and the tartaric acid derivative of formula (II) in a molar ratio of 2 : 1. 54. The compound according to item 52 or 53, wherein in the compound of formula (II) R1, R2, R4and R5are H and R3is methyl. 55. The compound according to item 52 or 53, wherein in the compound of formula (II) R1, R2, R3, R4and R5are H. 56. The compound according to any one of items 52 to 55 in crystalline form, preferably in the form of a cocrystal. 57. The compound according to item 54 having an X-ray powder diffraction pattern comprising 2-theta angle values (with a deviation of + / - 0.2 degree) of 6.2, 10.7, 12.5 and 16.2 degrees. 58. The compound according to item 57 having an X-ray powder diffraction pattern comprising 2-theta angle values (with a deviation of + / - 0.2 degree) of 6.2, 10.7, 10.9, 12.5, 14.3, 16.2, 20.9 and 21.3 degrees.59. The use of the compound according to any one of claims 52 to 58 for the manufacture of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide in enantiomerically enriched form and / or in crystalline form. The following examples serve to illustrate the invention, however, should not be understood as restricting the scope of the invention. EXAMPLES Example 1: Resolution of rac-Selisistat (rac-SLS) using (-)- di-O,O’-para-toluoyl- tartaric acid ((-)-DTTA) 1.1 Cocrystal formation of (S)-Selisistat ((S)-SLS) with (-)-DTTA 100.0 g (402.0 mmol) rac-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide (rac-SLS) and 400 mL isobutyl acetate (2-methylpropyl ethanoate; CAS- Nr.110-19-0) were added to a reactor having a volume of 2 L equipped with a mechanical stirrer, a thermometer and a condenser. To the resulting white suspension was added a solution of 77.7 g (201.0 mmol) (-)-DTTA ((2R, 3R)-(-)-Di-O- 4-toluoyl-L-tartaric acid; CAS Nr.32634-66-5) in 188 mL of acetonitrile followed by 660 mL of isobutyl acetate. The suspension was heated under stirring to a temperature of 92 °C at which the formation of a clear yellowish solution was observed. Following that, the solution was slowly cooled to room temperature (approx. 22 °C) at a cooling rate of about 0.3 °C / min. At an internal temperature of the solution of 80 °C some seed crystals of a cocrystal of (S)-SLS with (-)-DTTA with an enantiomeric excess of 99 % ee were added. After completion of the cooling process the resulting suspension was stirred for 1 h at room temperature and then filtered with a sintered funnel (porosity 3). The resulting solid was washed four times with 200 mL (each) of a mixture of isobutyl acetate and acetonitrile (85:15 (v / v)) to afford 113 g of a crude product comprising 70 g of solid cocrystals of (S)-6-Chloro-2,3,4,9- tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) with (-)-DTTA (as estimated by1H-NMR) in the form of white crystals having an enantiomeric excess of 84.5 % ee containing residual amounts of isobutyl ethanoate and acetonitrile. 1.2 Recrystallization of the cocrystals of (S)-SLS with (-)-DTTA 112 g of the crude product comprising 70 g of the solid cocrystals of (S)-SLS with (-)-DTTA as prepared under step 1.1 above was filled into a 2 L reaction vessel equipped with a mechanical stirrer, a thermometer and a condenser together with 1200 mL of acetonitrile. The resulting white suspension was heated to a temperature of 80 °C at which the formation of a clear solution was observed. Following that, the solution was slowly cooled to room temperature (approx. 22 °C) at a cooling rate of about 0.3 °C / min. At an internal temperature of the solution of 75 °C some seed crystals of a cocrystal of (S)-SLS with (-)-DTTA with an enantiomeric excess of 99 % ee were added. After completion of the cooling process the resulting suspension was stirred for 1 h at room temperature and then filtered with a sintered funnel (porosity 3). The resulting solid was washed two times with 144 mL (each) of acetonitrile and dried at a pressure of approx.1 mbar at room temperature for approx.12 h to afford 46.1 g of cocrystals of (S)-SLS with (-)-DTTA in the form of white crystals having an enantiomeric excess of 99.3 % ee. 1.3 Dissociation of cocrystals of (S)-SLS with (-)-DTTA 45.0 g (102 mmol) of the cocrystals of (S)-SLS with (-)-DTTA were charged to a 2 L reaction vessel equipped with a mechanical stirrer together with 900 mL of water to afford a white emulsion. To the emulsion 235 ml of a 0.86 M aqueous solution of sodium hydrogen carbonate (NaHCO3) (comprising 2 equivalents of NaHCO3 with regard to the amount of cocrystals of (S)-SLS with (-)-DTTA) were added and the resulting mixture was stirred at room temperature for 2 h to provide a white suspension. The suspension was filtered with a sintered funnel (porosity 3) and the resulting filter cake was washed 5 times with 180 mL of water (each). The resulting solid was dried at a pressure of approx.1 mbar at room temperature for approx.12 h to afford 24.5 g of (S)-Selisistat ((S)-SLS) in the form of white crystals having an enantiomeric excess of 99.3 % ee. 1.4 Recovery of (-)-DTTA 1.8 L of the aqueous phases received from the filtration step as well as subsequent washing as described under item 1.3 above were provided in a reaction vessel with a volume of 2 L and being equipped with a mechanical stirrer.155 mL of a 1M aqueous solution of hydrochloric acid were added to provide a mixture with a pH- value of 3 which was stirred at room temperature for a period of 1 h to afford a white suspension. The suspension was slowly filtered with a sintered funnel (porosity 3) and the resulting filter cake was wished twice with 180 mL of water (each) and dried under vacuum (approx.1 mbar) for about 12 h to afford 5.6 g (-)-DTTA in the form of a white solid. Example 2: Characterization of (S)-Selisistat in crystalline form (S)-Selisistat in crystalline form having an enantiomeric purity of 99.3 % ee as prepared according to Example 1 above was characterized by X-Ray powder diffraction (XRPD),1H-NMR, Differential Scanning calorimetry (DSC) and chiral High- Pressure Liquid Chromatography (chiral HPLC). 2.1 XPRD analysis of (S)-Selisistat in crystalline form XPRD analysis of (S)-Selisistat in crystalline form was performed at ambient conditions on a PANalytical X'Pert PRO ^-^ diffractometer of 240 mm of radius in reflection geometry, equipped with Cu Kα radiation and a PIXcel detector, operated at 45 kV and 40 mA. The crystalline sample was mounted on a zero-background silicon holder and allowed to spin at 0.25 rev / s during the data collection. The measurement angular range was 3.0-40.0° (2^) with a step size of 0.013°. The scanning speed was 0.082 (40.80 s / step). The XPRD pattern measured for (S)-Selisistat in crystalline form (polymorph X) accordingly showed good crystallinity (see Fig.1) and peaks as listed in Table 1 below: Table 1: Pos. [°2Th.]d-spacing [Å] Rel. Int. [%] 11.5 7.70 2 13.1 6.75 2 14.8 6.00 19 16.4 5.41 54 18.5 4.78 2 19.8 4.49 25 20.8 4.27 8 21.9 4.06 100 22.4 3.97 7 23.1 3.84 6 24.3 3.66 8 24.9 3.57 16 25.0 3.57 5 27.2 3.27 9 27.7 3.22 15 28.8 3.09 8 29.0 3.07 1 29.3 3.04 9 29.8 2.99 1 30.4 2.94 17 31.2 2.86 1 32.6 2.74 25 33.6 2.67 1 33.9 2.64 2 34.5 2.59 6 35.6 2.52 1 36.2 2.48 1 36.7 2.45 1 38.3 2.35 1 2.21H-NMR analysis of (S)-Selisistat in crystalline form A1H-Nuclear magnetic resonance (1H NMR) spectrum of (S)-Selisistat in crystalline form (polymorph X) was recorded in deuterated DMSO in a Varian Mercury 400 MHz spectrometer, equipped with a broadband probe ATB 1H / 19F / X of 5 mm (see Fig.2). The spectrum was acquired dissolving approx.5 to10 mg of sample in 0.7 mL of deuterated solvent. The1H NMR spectrum of (S)-Selisistat in crystalline form was identical to the spectrum of the racemic starting material and showed no residual organic solvents. 2.3 Differential Scanning calorimetry (DSC) analysis of (S)-Selisistat in crystalline form A DSC analysis of (S)-Selisistat in crystalline form (polymorph X) was recorded with a Mettler Toledo DSC2. The sample was weighed into a 40 μL aluminium crucible with a pinhole lid and heated from 25 to 300 °C at a rate of 10 °C / min, under nitrogen (50 mL / min). The recorded spectrum (see Fig.3) showed an endothermic peak with an onset at about 185 °C corresponding to the melting point of (S)-Selisistat in crystalline form (polymorph X). 2.4 Chiral HPLC analysis of (S)-Selisistat in crystalline form A chiral HPLC analysis of (S)-Selisistat in crystalline form was performed using an Agilent HP1100 HPLC system equipped with a vacuum degasser, a quaternary pump, an autosampler, a thermostatic column and a VW detector. The enantiomeric excess of (S)-Selisistat in crystalline form was determined under the following conditions: Chiralpak IA 250 x 4.6 mm, 5 µm; sample concentration: 1 mg / mL in heptane / isopropyl alcohol (1:1); mobile phase: isopropyl alcohol:ethanol-0.2% diethyl amine (50:50); temperature: 25 °C; flow rate: 0.4 mL / min; wavelength: 210 nm; injection: 5 µL; run time: 30 min. The chromatogram displayed an enantiomeric purity of 99.3 % ee (peaks at retention times of 15.16 and 19.86 min). Example 3: Stability of (S)-Selisistat in crystalline form A sample (S)-Selisistat in crystalline form as prepared and characterized in Examples 1 and 2 above (polymorph X) was subjected to a accelerated stability test under conditions as defined by the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH; accelerated ICH conditions: storage at 40 + / - 2 °C at 75 + / - 5 % relative humidity) as follows: A crystal of (S)-Selisistat as prepared according to Example 1 above was placed on an XRPD silicon sample holder and exposed to the above defined accelerated ICH conditions in a suitable climatic chamber. The sample was periodically analyzed by XRPD analysis (as described under Example 2.1 above) to observe potential crystalline conversion or amorphization. The tested sample of (S)-Selisistat in crystalline form (polymorph X) remained stable at 40 + / - 2 °C at 75 + / - 5 % relative humidity (RH) for at least 1 week. Example 4: Characterization of cocrystals of (S)-Selisistat with (-)-DTTA 4.1 Preparation of seed cocrystals of (S)-Selisistat with (-)-DTTA To a test tube equipped with magnetic stirrer and containing a mixture of racemic Selisistat (25 mg, 0.101 mmol) and (-)-DTTA (19.4 mg, 0.050 mmol, 0.5 eq.), 0.25 mL of ethyl acetate was added. The resulting suspension was stirred at room temperature for 15 hours. Then, the suspension was centrifuged, decanted and dried under vacuum at room temperature overnight to afford cocrystals of (S)-Selisistat with (-)-DTTA ((S)-SLS:(-)-DTTA) in the form of an an off-white solid. The obtained solid was analyzed by XRPD in wet as described below. 4.2 XPRD analysis of cocrystal of (S)-SLS:(-)-DTTA (1:0.5) XPRD analysis of cocrystal (S)-SLS:(-)-DTTA as prepared according to step 4.1 above was performed at ambient conditions on a PANalytical X'Pert PRO ^-^ diffractometer of 240 mm of radius in reflection geometry, equipped with Cu Kα radiation and a PIXcel detector, operated at 45 kV and 40 mA. The crystalline sample was mounted on a zero-background silicon holder and allowed to spin at 0.25 rev / s during the data collection. The measurement angular range was 3.0-40.0° (2^) with a step size of 0.013°. The scanning speed was 0.082 (40.80 s / step). The XPRD pattern measured for the cocrystal of (S)-SLS:(-)-DTTA showed good crystallinity (see Fig.4) and peaks as listed in Table 2 below (only peaks with a relative intensity higher than 1% are given): Table 2: Pos. [°2θ] d-spacing [Å] Rel. Int. [%] 3.6 24.75 8 5.4 16.29 16 6.2 14.15 100 7.4 11.93 10 8.8 10.06 2 10.3 8.62 7 10.4 8.49 10 10.7 8.26 47 10.9 8.14 26 11.6 7.66 2 11.9 7.45 12 12.5 7.07 76 13.5 6.54 2 14.3 6.19 25 15.5 5.71 7 15.8 5.60 15 16.2 5.47 48 16.3 5.43 9 16.9 5.25 3 17.5 5.05 1 17.8 4.97 6 18.3 4.85 1 18.8 4.72 1 19.1 4.64 1 19.9 4.46 10 20.4 4.36 4 20.9 4.25 17 4.31H-NMR analysis of a cocrystal of (S)-SLS:(-)-DTTA (1:0.5) A1H-Nuclear magnetic resonance (1H-NMR) spectrum of (S)-SLS:(-)-DTTA in crystalline form was recorded in deuterated DMSO in a Varian Mercury 400 MHz spectrometer, equipped with a broadband probe ATB 1H / 19F / X of 5 mm (see Fig.5). The spectrum was acquired dissolving approx.5 to10 mg of sample in 0.7 mL of DMSO-d6. Compared to the1H-Nuclear magnetic resonance spectrum of (S)-SLS as depicted in Fig.2 (see Example 2.2 above), the1H-Nuclear magnetic resonance spectrum of (S)-SLS:(-)-DTTA comprised characteristic signals at about 7.85 ppm (m, 2 H), about 7.4 ppm (m, 2H), about 5.8 ppm (m, 1H) and 2.4 ppm (s, 3H). 4.4 Differential Scanning calorimetry (DSC) analysis of a cocrystal of (S)-SLS:(-)- DTTA (1:0.5) A DSC analysis of a cocrystal of (S)-SLS:(-)-DTTA (1:0.5) was recorded with a Mettler Toledo DSC2. The sample was weighed into a 40 μL aluminium crucible with a pinhole lid and heated from 25 to 300 °C at a rate of 10 °C / min, under nitrogen (50 mL / min). The recorded spectrum (see Fig.6) showed an endothermic peak with an onset at about 196 °C corresponding to the melting point of the cocrystal of (S)-SLS:(-)-DTTA (1:0.5). Example 5: Determination of the absolute configuration of (S)-Selisistat 5.1 Preparation of single crystals of (S)-SLS 11 mg of (S)-SLS prepared according to Example 1 above with an enantiomeric excess of 99.3 % ee was dissolved in 1 mL ethanol in a vessel with a volume of 2 mL equipped with a screw cap for closure. The screw cap was placed on the opening of the vessel but was not screwed to allow slow evaporation of the ethanol. The solution was allowed to stand undisturbed at room temperature (approx.22°C). After 10 days bipyramidal shaped single crystals were obtained. XRPD analysis of a milled sample of the obtained single crystals conducted as described in Example 2.1 above confirmed that the material of the single crystals corresponds to the polymorph of (S)-SLS as described in Example 2.1 above (polymorph X). 5.2 Single-crystal X-ray structure determination of (S)-SLS The single crystal prepared according to Example 5.1 above was mounted for measurement immersed in inert Fomblin-Y as protecting oil. Intensity measurements were carried out at the XALOC beamline at ALBA synchrotron at 17 keV radiation (λ = 0.72931 Å) using a channel-cut Si(111) monochromator and KB mirrors coated with Rh. Data collection was performed using a Bruker MD2M diffractometer and the multi-axis MK2 miniKappa goniometer by Arinax. The data were recorded using a Pilatus 26M area detector at room temperature. The used dataset was collected using multiple single-axis sweeps at kappa = 0. Systematic absences were consistent with the chiral space group P212121 (No.19). The program used for the data collection is an in-house software (Collect) and the programs used for processing were autoPROC1 and xia2 / DIALS. The structure was solved by direct methods using the program SHELXS 2013 / 1 and refined by full-matrix least-squares on F2 using the program SHELXL- 2018 / 3. H atoms were introduced in calculated positions and refined as riding on their parent atoms with idealized geometries and with restrained isotropic displacement parameters. Table 3 summarizes the experimental and refinement parameters applied: Table 3: crystal size (µm) 200 × 100 × 45 measurement temperature 293 K kappa (°) 0 phi (°) 0 Δ rotation (°) 0.5 exposure (s) 0.1 transmission (%) 9.74 distance to detector (mm) 123 λ / resolution (Å) 0.72931 / 0.733 a (Å) 9.4774(1) b (Å) 9.5509(1) c (Å) 13.0936(1) α (°) 90 β (°) 90 γ (°) 90 V (Å3) 1185.20(2) GES P212121 d (g / cm3) 1.394 R(int) / R(σ) 0.0738 / 0.1201 R1 Fo>4σ(Fo) 0.0487 wR2 0.1333 GooF 1.081 residual (e / Å3) 0.50 / -0.36 The recorded intensities were used to solve and refine the structure in the orthorhombic P212121 space group. All the non-hydrogen atoms of the (S)-SLS molecule were found from the electronic density maps. The final agreement indices were: R1 = 0.049 (Fo > 4σ(Fo)) and wR2 = 0.133 Flack parameter = 0.03(2) (calculated according to (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259)) According to the Flack parameter close to 0 the results indicate that the absolute structure given by the refinement is to be assumed as correct. Figure 7 shows the resulting asymmetric unit of the SLS structure verifying the absolute configuration of the asymmetric carbon (C11) to be “S”.

Claims

Claims 1. A process for the preparation of (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole- 1-carboxamide ((S)-SLS) of formula (S-I)in enantiomerically enriched form by resolution of rac-6-Chloro-2,3,4,9- tetrahydro-1H-carbazole-1- carboxamide (rac-SLS) of formula (I)the process comprising the steps of: a) Providing a first mixture comprising rac-SLS and a compound of formula (II)in enantiomerically enriched form,wherein R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen, C1-C4-haloalkyl, -O-C1- C4-alkyl and -O-C1-C4-haloalkyl in a first liquid medium, b) exposing the first mixture as formed in step a) to conditions under which rac-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide and the compound of formula (II) at least partly dissolve in the first liquid medium to form an intermediate solution, c) exposing the intermediate solution as formed in step b) to conditions under which a solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals is formed, d) optionally recrystallizing the solid intermediate product as formed in step c) in a second liquid medium to provide the solid intermediate product comprising (S)-SLS and the compound of formula (II) in the form of cocrystals in diastereomerically enriched form, and e) exposing the solid intermediate product as formed in step c) or d) to a base to provide (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide of formula (S-I) in enantiomerically enriched form.

2. The process according to claim 1, wherein in the compound of formula (II) R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen and C1-C4-haloalkyl.

3. The process according to any one of the preceding items, wherein in the compound of formula (II) R1, R2, R4and R5are H and R3is selected from C1- C4-alkyl.

4. The process according to any one of the preceding claims, wherein in the first liquid mixture rac-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (I) and the compound of formula (II) are provided in a molar ratio of about 1.5 : 1 to about 2.5 to 1, preferably from about 1.9 :1 to about 2.1 to 1.

5. The process according to any one of the preceding claims, wherein the first and / or the second liquid medium comprises or essentially consists of an organic solvent or a mixture of organic solvents selected from the group consisting of C1-C4 alkyl acetates such as ethyl acetate, propyl acetate, isopropyl acetate isobutyl acetate, and tert.-butyl acetate; acetonitrile, methyl isobutyl ketone, aromatic hydrocarbons such as toluene.

6. The process according to any one of the preceding claims, wherein the first and the second liquid medium comprises or essentially consists of isobutyl acetate and acetonitrile.

7. The process according to any one of the preceding claims, wherein the recrystallization according to process step d) comprises the steps of d1) providing a mixture of the solid intermediate product in a second liquid medium comprising or essentially consisting of a third solvent or mixture of solvents, d2) exposing the mixture as formed in step d1) to conditions under which the solid intermediate product at least partly dissolves in the second liquid medium, and d3) exposing the mixture as formed in step d2) in which the solid intermediate product is at least partly dissolved in the second liquid medium to conditions under which the dissolved intermediate product comprising (S)- SLS and the compound of formula (II) in the form of cocrystals in diastereomerically enriched form recrystallizes.

8. The process according to any one of the preceding claims, wherein according to step e) the base is selected from the group of carbonates, hydrogen carbonates or hydroxides of alkaline or earth alkaline metals.

9. The process according to any one of the preceding claims, wherein according to step e) the base is sodium hydrogen carbonate.

10. The process according to any one of the preceding items, wherein according to step e) the base is used in an amount of at least 1.5 equivalents with regard to the molar amount of intermediate cocrystals of (S)-SLS and the compound of formula (II).

11. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I)(S-I) in crystalline form.

12. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide according to claim 11 having an enantiomeric purity of at least 97 % ee or of at least 98 % ee or of at least 99 % ee.

13. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide of formula (S-I) in crystalline form according to claim 11 or 12, having an X-ray powder diffraction pattern comprising 2-theta angle values (with a deviation of + / - 0.2 degree) of 16.4, 19.8, 21.9 and 32.6 degrees (polymorph X).

14. (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide ((S)-SLS) of formula (S-I) in crystalline form according to any one of claims 11 to 13 for use as a medicament.

15. A compound comprising (S)-6-Chloro-2,3,4,9-tetrahydro-1H-carbazole-1- carboxamide and a tartaric acid derivative of formula (II)in enantiomerically enriched form, wherein R1, R2, R3, R4and R5can be the same or different and can independently be selected from H, C1-C4-alkyl, halogen, C1-C4-haloalkyl, -O-C1- C4-alkyl and -O-C1 -C4-haloalkyl.

16. The compound according to claim 15 comprising (S)-6-Chloro-2,3,4,9- tetrahydro-1H-carbazole-1-carboxamide and the tartaric acid derivative of formula (II) in a molar ratio of 2 :

1.

17. The compound according to claim 15 or 16, wherein in the compound of formula (II) R1, R2, R4and R5are H and R3is methyl.

18. The compound according to any one of claims 15 to 17 in crystalline form, preferably in the form of a cocrystal.

19. The compound according to claim 18 having an X-ray powder diffraction pattern comprising 2-theta angle values (with a deviation of + / - 0.2 degree) of 6.2, 10.7, 12.5 and 16.2 degrees.

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