A highly efficient multicomponent synthesis of pyridones and pyrimidones by a [2+2+2] strategy

:The reaction of N-silylated iminoethers with 2-substituted acetyl chloride s yields activated 2-azadienes. These were shown to react with electron-def icient acetylenic dienophiles to yield pyridones. They also react with quin ones to give the corresponding aromatized cycloadducts in good yields. The reaction of a-azadienes with activated nitriles provided a very practical r oute towards polysubstituted pyrimidones. A multicomponent protocol is repo rted which combines a N-t-butyldimethylsilyl iminoether, an acetyl chloride derivative and a dienophile in the presence of triethylamine without isola tion of any intermediate. This provides an extremely practical and versatil e route to various mono- and polycyclic azaaromatics with a predictable sub stitution pattern. Yields ranged from 43 % to 94 % for the complete sequenc e. (C) 1999 Elsevier Science Ltd. All rights reserved.