alpha, beta-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, beta-silyalkenals 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 beta-amino carbonyl compounds. (c) 2005 Elsevier Ltd. All rights reserved.
- rhodium-catalysed silylformylation
- alpha,beta-unsaturated aldehydes
- RHODIUM-CATALYZED TRANSFORMATION
- EFFICIENT SILYLFORMYLATION
- ALDOL CONDENSATION
- TERMINAL ALKYNES