Reactions of 2-methyl-3,1-benzoxazin-4-one with active methylene compounds: a new route to 3-substituted 4-hydroxyquinolin-2(1H)-ones

Abstract

A new route to 3-substituted 4-hydroxyquinolin-2(1H)-ones, compounds of great biological importance, is described. The C-acylation of active methylene compounds 2 with the 2-methyl-3,1-benzoxazin-4-one 1, under basic conditions, leads to the formation of the new products 3–10, which have been isolated and characterized. Cyclization of the above intermediates furnishes the 3-substituted 4-hydroxyquinolin-2(1H)-ones. Spectral data and physical characteristics for all compounds are reported.