Preparation by yeast reduction and determination of the sense of chirality of enantiomerically pure ethyl (−)-4,4,4-trichloro-3-hydroxy- and (+)-4,4,4-trifluoro-3-hydroxybutanoate

✍ Scribed by Dieter Seebach; Philippe Renaud; W. Bernd Schweizer; Max F. Züger; Marie-Josèphe Brienne

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: German
• Weight: 709 KB
• Volume: 67
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19840670721

✦ Synopsis

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 H~2~O) 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 CF~3~‐derivative (+)‐2a and its CH~3~‐analogue 8, and c) by X‐ray analysis of the ester 2f from (+)‐2a and (−)‐camphanoyl chloride (Fig. 2 and 3).