2-AZA-1,3-DIENES - METHODS OF SYNTHESIS AND STEREOCHEMICAL STUDIES

2-Aza-1,3-dienes bearing an activating trialkylsilyloxy group at C-3 h ave been prepared via three routes. The first route involves the silyl ation of N-acylimidates which are readily available from iminoether hy drochlorides and acid chlorides. According to a more general route tow ards these doubly activated dienes, N-trialkylsilylimidates and N-tria lkylsilylimines derived from non-enolizable aldehydes were convenientl y converted in a one-pot sequence into the corresponding azadienes by reaction with an acid chloride in the presence of triethylamine. Final ly, cyclic dienes could be prepared by direct silylation of glutarimid e on both oxygens with trialkylsilyltriflate in the presence of trieth ylamine. The configuration and conformation of 2-azadienes have been e stablished by H-1, C-13 and N-15 NMR spectroscopy.