4-AMINO-1-AZADIENES IN HETEROCYCLIC CHEMISTRY - SILICON-ASSISTED SYNTHESIS OF SUBSTITUTES 6-MEMBERED AND 8-MEMBERED NITROGEN-HETEROCYCLES

4-Amino-1-azabutadienes 1 react succesively with substituted dichloros ilanes and esters of acetylenecarboxylic acid to yield 1,5-diazocines 4 and pyridines 5 in high yields. Chemo- and regioselective insertion of the activated acetylene into the nitrogen-silicon bond of diazasili ne 2 and/or [4+2] cycloaddition of 2 to the carbon-carbon triple bond are proposed to be involved in the course of the reaction.