Cyanohydrin esters reactions with carbonyl compounds

Protected cyanohydrin anions also behave as acyl carbanion equivalents, and this method can be extended to aj3-unsaturated derivatives (5). The reaction of yet another type of acyl carbanion equivalent (6) with esters gives products of type (7), which are useful for the synthesis of novel heterocyclic compounds. Species of type (8 Y = 0,S), are further modified acyl carbanion equivalents, and behave towards carbonyl compounds as synthetic equivalents of the Wittig reagents PhaP = C(YR)CHO. Compounds (9) are j8-acylvinyl anion equivalents. ... 

The most general methods for the syntheses of 1,2-difunctional molecules are based on the oxidation of carbon-carbon multiple bonds (p. 117) and the opening of oxiranes by hetero atoms (p. 123fl.). There exist, however, also a few useful reactions in which an a - and a d -synthon or two r -synthons are combined. The classical polar reaction is the addition of cyanide anion to carbonyl groups, which leads to a-hydroxynitriles (cyanohydrins). It is used, for example, in Strecker s synthesis of amino acids and in the homologization of monosaccharides. The ff-hydroxy group of a nitrile can be easily substituted by various nucleophiles, the nitrile can be solvolyzed or reduced. Therefore a large variety of terminal difunctional molecules with one additional carbon atom can be made. Equally versatile are a-methylsulfinyl ketones (H.G. Hauthal, 1971 T. Durst, 1979 O. DeLucchi, 1991), which are available from acid chlorides or esters and the dimsyl anion. Carbanions of these compounds can also be used for the synthesis of 1,4-dicarbonyl compounds (p. 65f.). 

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