New heterospiro-ring systems by condensation of some heterocyclic o-dicarboxylates with 1,3-diphenylguanidine

Abstract

The behaviour of some heterocyclic o-dicarboxylates towards 1,3-diphenylguanidine and sodium hydride was investigated. Whereas the pyridine and isothiazole derivatives (11) and (22) gave the amides (12) and (13), and (23), respectively, as the main products, the pyrimidine and isoxazole esters (17) and (24) afforded, through a spiro-cyclization reaction, the heterospiro-compounds (20) and (26). The structures of these new ring systems were established on the basis of chemical and spectroscopic data.