Reactions of Uracils. 6. New Ring Transformations of 6-Aminouracils with Acetylenedicarboxylates to Pyridinedionates and Pyrrolopyridines. Some Revised Constitutions

Article abstract of DOI:10.1021/jo00352a005

Treatment of 6-<(triphenylphosphoranylidene)amino>-1,3-dimethyluracils 8 with dialkyl acetylenedicarboxylates in aprotic solvents affords zwitterionic pyridinedionates 12, involving a novel ring transformation reaction, via cleaving attack of a terminal carbanion to the 2-carbonyl of the uracil.In protic solvents 12 undergo a smooth heterocyclization reaction to give the pyrrolo<3,4-c>pyridines 14.The structures of 12b and 14b have been established by single-crystal X-ray diffraction.By spectroscopic comparison as well as by independent syntheses 12 proved to be closely related (phosphorylated) analogues of previously reported "ureas 17 and 18", while 13 was identical with the "5-propynoyluracil 15".Catalytic hydrogenation of 13a gave carbinol 20, which proved by means of 1H (H-D exchange) and 13C NMR to be identical with "cis-olefin 19".