Synthesis of Pyrimidines Bearing Sterically Demanding Substituents from Azetes and Nitriles¹

Abstract

Two kinetically stabilized azetes 1a,b react with acceptor-substituted nitrites 2a-g to furnish tetra-substituted pyrimidines 4a-i; the primarily formed Dewar pyrimidines 3 were not detected. In the reactions with α-methylenenitriles, competing 1,4-addition reactions take place and push-pull 1,3-butadiene 6 and 2-aza-1,3-butadiene 8 were prepared from the non-isolable 2-azetines 5.