Phosphonium Ylide

(Triphenylphosphoranylidene)acetonitrile (1) is a stable phosphonium ylide, which reacts as a Wittig reagent with a variety of carbonyl compounds to give α,β-unsaturated nitriles.¹⁾ 1 can also react with carboxylic acids, in the presence of EDCI and DMAP, to form cyanoketophosphoranes (2). Ozonolysis of 2, and subsequent addition of nucleophiles such as amines or alcohols, gives α-keto amides, α-keto esters, etc.²⁾

Recently, α-keto amides have been of increasing interest as the pharmacophore for an enzyme activity inhibitor.³⁾ This is a convenient and effective method of synthesis using 1, to obtain α-keto amides from carboxylic acids.