SYNTHESIS OF N3-SUBSTITUTED QUINAZOLINE-2,4-DIONES VIA C-4 AMINATION-CYCLIZATION OF ISATOIC ANHYDRIDES

Abstract

A direct approach for the synthesis of N3-substituted quinazoline-2,4-diones via condensation of isatoic anhydrides with amines mediated by Ph3P-I2 was reported. Instead of the expected benzoxazinones, the reaction proceeds with an amine attack at the C-4 position of isatoic anhydrides leading to quinazoline-2,4-diones upon heating in the presence of base. This one-pot process enables a rapid construction of a broad range of quinazoline-2,4-dione derivatives using simple, readily available, and low-cost reagents with no extra carbonylating agent needed.