1,2,3-Trizolium-1-unsubstituted methanides, carbon analogues 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

Abstract

A 1,2,3,-triazolium-1-methanide species has been generated and trapped in cycloadditions with alkyne dipolarophiles. The triazolium-1-methanide, a direct carbon analogue of the triazole-N-oxide, is an unstable intermediate prone to ring-opening and re-cyclisation to a 1,2,4-triazine system. New routes to substituted pyrrolo[1,2-c][1,2,3]triazoles, pyrrolo[1,2-d][1,2,4]triazines and substituted 1-aminopyrroles have resulted from this work. X-Ray crystal structures are described for 1,3,3a-triphenyl-4,5-diethoxycarbonyl-3a,6-dihydropyrrolo[1,2-c][1,2,3]triazole 6a, 1-N-anilino-2-phenyl-3,4-diethoxycarbonylpyrrole 9a and 3-(p-methoxyphenyl)-1,8a-diphenyl-8-exo-ethoxycarbonyl-3,4,6,7,8,8a-hexahydropyrrolo[1,2-d][1,2,4]triazine 15d.