Patent ID: 8574876

Claim:
A method of preparing a substantially stereomerically pure compound according to structural formula II(a): including salts and hydrates thereof, wherein: A is O, CR 1 R 2 , —C═C—, or —CH 2 —CH 2 —, wherein R 1 and R 2 are each independently selected from —H, COOH, —X, NH 2 , CH 2 NHC(NH)NH 2 , —CX 3 , —CH 3 , —CH 2 CH 3 , and wherein X is selected from F, Cl, and Br; M and M′ may both be present or may both be absent and when both M and M′ are present M and M′ are the same and are selected from O and CR 3 R 4 wherein R 3 and R 4 are H, or R 3 or R 4 of M and R 3 or R 4 of M′ form a methylene bridge; with the provisos that (a) when M and M′ are O, A is not O; and when A is O, M and M′ are not O; (b) A can be —CH═CH— or —CH 2 —CH 2 — when M and M′ are CR 3 R 4 ; and (c) when M and M′ are CR 3 R 4 and have one or more stereocenters, the stereocenters of M and M′ are of opposite stereochemistry; the method comprising contacting an amine compound according to structural formula I wherein A, M and M′ are as defined for structural formula II(a), with oxygen in the presence of a monoamine oxidase enzyme with a cofactor under conditions in which the monoamine oxidase enzyme oxidizes the amine compound of structural formula I to a corresponding imine compound of structural formula II(a).