Enantiomer-Pure Hexahydro-Pyrrolocyclopenta-Pyridine Derivatives

A compound further defined as an enantiomerically pure [3aα,8bα]-1,2,3,3a,4,8b-hexahydropyrrolocyclopentapyridine derivative or pharmaceutically usable salt thereof of formula:

• wherein:
• Z is a single bond or CH2;
• R1 is a hydrogen or a straight-chain or branched lower alkyl residue;
• R2 and R3 are independently a hydrogen, a straight-chain or branched lower alkyl residue, a lower alkoxy, a lower alkylthio, or a halogen;
• and
• X and Y alternately are CH or N.

A method for producing a compound of formula (I) comprising:

• reductively converting into a compound of formula (I) a compound of the general formula (II)
• wherein:
• Z is a single bond;
• R1 is hydrogen;
• R2 and R3 are independently a hydrogen, a straight-chain or branched lower alkyl residue, a lower alkoxy, a lower alkylthio, or a halogen;
• and
• X and Y alternately are CH or N;
• to obtain a diastereomer mixture;
• recovering a less readily soluble diastereomer from the diastereomer mixture by crystallization to obtain a diastereomerically pure compound of the general formula (III):
• and
• cleaving the diastereomerically pure compound of the general formula (III) under suitable conditions to give the enantiomerically pure compound of the general formula (I).