Combined intra-intermolecular criss-cross cycloaddition reactions leading to perfluoroalkylated fused tricyclic nitrogen heterocycles
Résumé
Perfluoroalkylated hydrazones 1a–ewere preparedfrom diethyl hydrazinophosphate andwere engaged in the reaction with 3-substitutedhomoallenyl aldehydes according to Zwierzak’smethod. The resulting non-symmetrical perfluoroalkyl-derived azines reacted in combined intra-intermolecular criss-cross cycloaddition with phenyl isocyanate, phenyl isothiocyanate and dimethyl acetylenedicarboxylate producing fused tricyclic heterocycles. Besides, the thermal cyclization of perfluoroalkylated non- symmetrical azines, without added dipolarophile, was carried out providing fused bicyclic systems.