Asymmetric synthesis of (S)-and (R)-malic acid from ketene and chloral

H Wynberg, EGJ Staring

Index: Wynberg, Hans; Staring, Emiel G. J. Journal of the American Chemical Society, 1982 , vol. 104, # 1 p. 166 - 168

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Citation Number: 254

Abstract

Abstract: Quinidine (5) catalyzes the addition of ketene (1) to chloral (2) at-50 OC in toluene. The@(trichloromethyl)-0-propiolactone 3 is formed virtually optically pure (98% enantiomeric excess). A mechanism for this reaction, accounting for the high enantiomeric excess, is proposed. Known hydrolytic procedures convert the lactone 3 to malic acid (6). By proper choice of catalyst both (R)-and (S)-malic acid can be obtained optically pure.