Hydrazinolysis of N-(3-Oxo-1-isoindolinyliden)alanin Ethyl Ester, Structure of the Product
Treatment of N-(3-oxo-1-isoindolinyliden)alanin ethyl ester (6) with hydrazine hydrate leads to 4-methyl-2,3,4,6-tetrahydro[1,2,4]triazino[3,4-a]isoindole-3,6-dione (8, Scheme 3) and not to the previously postulated 6-hydroxy-2-methyl-2,3-dihydroimidazo [2,1-a]phthalazin-3-one (7, cf. ). The structure of 8 has been established by an independent synthesis as well as by the X-ray analysis of the reaction product 11 from 8 and 3-dimethylamino-2,2-dimethyl-2H-azirine (1, Scheme 4). A reaction mechanism for the formation of 8 from 6 is suggested in Scheme 5.