Pyrimidines. LI. Synthesis of Pyrimido [1, 6-α] benzimidazole-1, 3 (2H, 5H)-dione Derivatives by the Reaction of 6-Chloro-2H-1, 3-oxazine-2, 4 (3H)-diones with o-Phenylenediamines

Abstract

The reaction of 6-chloro-1, 3-oxazine-2, 4-diones (1) with o-phenylenediamines (2) in the presence of acetic acid afforded pyrimido [1, 6-α] benzimidazole-1, 3 (2H, 5H)-dione derivatives (3) via a 1, 3-oxazine-to-pyrimidine ring transformation.