STEREOSELECTIVE AMIDOALKYLATION REACTIONS VIA N,O-ACETALS

The isomerization of N,O-acetals 1 yields N-acyl-O-vinyl acetals 2 or 2-aminomethyl-1,3-butadienes 10, depending on the nature of the nitrog en substituents. In the presence of trimethylsilyl trifluoromethanesul fonate (TMSOTf) the N,O-acetals 2h-u are converted stereoselectively i nto beta-(N-acyl-amino)aldehydes 3. The relative configurations of the products 3 have been determined by X-ray analysis and H-1-NMR experim ents. The mechanism of the reaction is discussed. Crossover experiment s indicate an intermolecular course of the rearrangement.