D. Seebach, P. Renaud, W. Schweizer
Nov 7, 1984
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0
Influential Citations
74
Citations
Quality indicators
Journal
Helvetica Chimica Acta
Abstract
Reduction of ethyl 4,4,4-trichloro- and 4,4,4-trifluoro-3-oxobutanoate by fermenting baker's yeast (Saccharomyces cerevisiae) on a preparative scale (20–50 g in ca. 3 1 of H2O) gave 70–80% yields of the trichloro- [(−)-(S)-1a] and trifluoro-hydroxyesters [(+)-(R)2a] of ca. 85 and 45% ee, respectively. Both, (−)-1a and (+)-2a could be obtained in > 98% ee by subsequent crystallization (of(−)-1, (+)-2a or the 3,5-dinitrobenzoate (+)-2b. The absolute configuration of both hydroxyesters was determined (a) by chemical correlation ((−)-1a), (b) from the melting diagrams and mixed melting points (differential-scanning calorimetry Fig. 1) of the dinitrobenzoates of the CF3-derivative (+)-2a and its CH3-analogue 8, and c) by X-ray analysis of the ester 2f from (+)-2a and (−)-camphanoyl chloride (Fig. 2 and 3).