Synthesis of heterocyclic compounds using amidines as their ene-1,1-diamine tautomers. II. Synthesis of 2,3-dihydropyridine, 3,4-dihydropyridine and 3,4-dihydropyrrol-2-one derivatives by the reaction of amidines with alpha,beta-unsaturated carbonyl

摘要

N-t-Butylacetamidines I on heating with methyl vinyl ketone, acrolein or crotonaldehyde gave the 2,3-dihydropyridine derivatives 4, 5 or 6 via N-alkylation of the acetamidines 1. Reaction of amidines, 1 with phenyl 1-propenyl ketone, benzalacetone or chalcone gave 3,4-dihydropyridine derivatives 8, 9 or 10. These were obtained by C-alkylation, achieved by Michael addition of the acetamidines 1 as their N,C-tautomers ene-1,1-diamines 1' to alpha,beta-unsaturated carbonyl compounds, and subsequent cyclodehydration of adducts. Reaction of 1 with ethyl 3-benzoylacrylate gave 3,4-dihydropyrrol-2-one derivatives 13.