N-acylimidates are readily silylated with t-butyldimethylsilyl triflate in the presence of triethylamine to give 2-aza-1,3-dienes . These react with activated nitriles to yield pyrimidin-4-ones .
:The reaction of N-silylated iminoethers with 2-substituted acetyl chlorides yields activated 2-azadienes. These were shown to react with electron-deficient acetylenic dienophiles to yield pyridones. They also react with quinones to give the corresponding aromatized cycloadducts in good yields. The reaction of a-azadienes with activated nitriles provided a very practical route towards polysubstituted pyrimidones. A multicomponent protocol is reported which combines a N-t-butyldimethylsilyl iminoether, an acetyl chloride derivative and a dienophile in the presence of triethylamine without isolation of any intermediate. This provides an extremely practical and versatile route to various mono- and polycyclic azaaromatics with a predictable substitution pattern. Yields ranged from 43 % to 94 % for the complete sequence. (C) 1999 Elsevier Science Ltd. All rights reserved.