Selective synthesis of α-sulphenyl-, α-sulphinyl-, and α-sulphonyl-α,β-unsaturated carbonyl compounds by the knoevenagel reaction

Abstract

Simple treatment of aldehydes with the carbonyl compounds (1)[R²COCH₂S(O)_nAr; n= 0,1,2] and piperidine stereoselectively produces the condensation products (7), the stereochemistry of which is controlled by the steric requirements of two functional groups COR² and S(O)_nAr in a sulphur-stabilized carbanion intermediate.