PREPARATION OF BOTH ENANTIOMERS OF MALIC AND CITRAMALIC ACID AND OTHER HYDROXYSUCCINIC ACID-DERIVATIVES BY STEREOSPECIFIC HYDRATIONS OF CIS OR TRANS 2-BUTENE-1,4-DIOIC ACIDS WITH RESTING CELLS OF CLOSTRIDIUM-FORMICOACETICUM

(R)-Malic, (S)-malic, (R)-citramalic, (S)-citramalic, (2R,3S)-2-hydroxy-3-methylsuccinic and (2R,3S)-2,3-dimethyl-2-hydroxysuccinic acid were prepared on scales up to 25 mmol by stereospecific addition of water to different 2-butene-1,4-dioic acid derivatives catalyzed by resting cells of Clostridium formicoaceticum (Scheme 1). The (3R)-monodeuterio (R)- and (S)-malic acid as well as (R)- and (S)-citramalic acid were prepared using freeze-dried cells in (H2O)-H-2-buffer. The stereochemical purity of the products was in most cases greater than or equal to 99%.