New routes for the synthesis of pyrrolo-[3,2-d]- and -[2,3-d]-pyrimidine systems starting from a common pyrrole derivative

New routes for the synthesis of pyrrolo-[3,2-d]- and -[2,3-d]-pyrimidines from a common 2,3-dicarboxypyrrole derivative are described. The common starting material, 3-ethoxycarbonyl-2-carboxy-4-methylpyrrole (1) is conveniently functionalized to give 2- or 3-azidocarbonylpyrroles (4), (17), and (22) which on Curtius rearrangement followed by treatment with ammonia or amines give the pyrrolylurea (6a) or its derivatives (6b–d), or (23). These, in basic medium cyclise to 7-methylpyrrolo[3,2-d]pyrimidine-2,4-diones (7a), its 3-substituted derivatives (7b–d), or to 5-methylpyrrolo[2,3-d]pyrimidine-2,4-diones (19)