Acyl anion equivalents: synthesis of ketones and enones from α-phenylthioalkylphosphine oxides

Abstract

The sulphenylated phosphine oxides Ph₂P(O)·CH(SR²)R¹, easily prepared from triphenylphosphine, diphenyl or dimethyl disulphide, and an alkyl halide, form anions which act as acyl anion equivalents. Reaction with aldehydes and ketones gives vinyl sulphides, which can be hydrolysed to carbonyl compounds. Reaction with α-phenylthio- and α-methoxy-aldehydes and ketones gives enone precursors. The scope and limitations of the method are described.