Synthesis of heterocyclic compounds using amidines as their ene-1,1-diamine tautomers.: I.: Synthesis of 4,5-dihydro-3H-pyridin-2-one, 3,4-dihydropyrrol-2-one and 1,3-dihydropyrrol-2-one derivatives by the reaction of amidines with α,β-unsaturated esters

N-t-Butylacetamidines I on heating with methyl acrylate (2) at 200 degrees gave the 4,5-dihydro-3H-pyridin-2-one derivatives 5. Michael addition of the acetamidines 1 as their ene-1,1-diamine tautomers 1' to 2 and the subsequent cyclization of the adducts gave derivatives 5. Amidines 1 on reaction with trimethyl ethylenetri-carboxylate (9) or dimethyl acetylenedicarboxylate (12) afforded 3,4-dihydropyrrol-2-one 11 or 1,3-dihydropyrrol-2-one derivatives 13.