Cyanohydrins and cyanohydrin esters, optically active
Resolutions, kinetic enzyme-catalyzed
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Enzyme-Catalyzed Reactions, 71). - Enantioselective Esterification of Racemic Cyanohydrins and Enantioselective Hydrolysis or Transesterification of Cyanohydrin Esters by LipasesPure cyanohydrin enantiomers (S)-1/(R)-1 and their O-acyl derivatives (R)-3/(S)-3 are obtained from three different lipasecatalyzed reactions: i) enantioselective hydrolysis of aliphatic and aromatic racemic cyanohydrin esters 3, ii) enantioselective acylation of racemic cyanohydrins 1, iii) enantioselective transesterification of 3 with primary alcohols. Both the cyanohydrin esters and the free cyanohydrins (which are prone to racemization) are isolated as enantiomers with high optical purity on a preparative scale. Hydrolysis of the racemic butyrates 3b, e with Candida cylindracea lipase and pseudomonas sp. lipase, respectively, for example, affords the free (S)-cyanohydrins (S)-2-hydroxypentanenitril [(S)-1a] and (S)-mandelonitrile [(S)-1b)] in high yield with 97 and 96% ee, respectively. (S)-1a is obtained with the same optical purity by candida sp. lipase-catalyzed transesterification of 3b with 1-octanol.
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