1,2,3-TRIAZOLIUM-1-UNSUBSTITUTED METHANIDES, CARBON ANALOGS OF TRIAZOLE-N-OXIDES - A 1,3-DIPOLE CASCADE FROM 1,2,3-TRIAZOLIUM-1-METHANIDE TO 1,2,4-TRIAZINIUM-4-METHANIDE - NEW ROUTES TO PYRROLO[1,2-C][1,2,3]TRIAZOLES, PYRROLO[1,2-D][1,2,4]TRIAZINES AND SUBSTITUTED 1-AMINOPYRROLES, AZOLIUM 1,3-DIPOLES

A 1,2,3-triazolium-1-methanide species has been generated and trapped in cycloadditions with alkyne dipolarophiles. The triazolium-1-methani de, a direct carbon analogue of the triazole-N-oxide,is an unstable in termediate prone to ring-opening and re-cyclisation to a 1,2,4-triazin e system. New routes to substituted pyrrolo[1,2-c][1,2,3]triazoles, py rrolo[1,2-d][1,2,4]triazines and substituted 1-aminopyrroles have resu lted from this work. X-Ray crystal structures are described for 1,3;3a -triphenyl-4,5; carbonyl-3a,6-dihydropyrrolo[1,2-c][1,2,3]triazole 6a, 1-N-anilino-2-phenyl-3,4-diethoxycarbonylpyrrole 9a and 8-exo-ethoxyc arbonyl-3,4,6,7,8,8a-hexahydropyrrolo [1,2-d][1,2,4]triazine 15d.