Malic Acid Diesters and Amides

Another interesting approach to the less readily accessible diethyl ( S)-malate (3) is enan-tioselective bioreduction of sodium diethyl oxalacetate (4) with baker s yeast Saccharomyces cerevisiae). Under fermenting conditions, 3 is produced in high yield with 98% ee [10]. 

Dimethyl (5)-malate (2), when exposed to ammonia, forms ( S)-( —)-hydroxysuccinamide [( S)-malamide] (5) in nearly quantitative yield [11]. 

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