Silylformylation–desilylation of propargyl amides: synthesis of α,β-unsaturated aldehydes

Abstract—a,b-Unsaturated aldehydes are prepared from easily available propargyl amides through a two-step sequence of silylformylation–desilylation reactions. The substituent on the nitrogen atom markedly influences both reactions, b-silylalkenals being formed in the presence of tosyl or tert-butoxycarbonyl protected amines. TBAF is employed to induce the desilylation process that is performed under very mild experimental conditions. A contemporary elimination step occurs when tosylamido aldehydes are reacted affording 2-methylaryl-2-alkenals, while this process can be suppressed changing the functional group to NBOC, thus allowing the formation of b-amino carbonyl compounds.