TRITHIOCYCLOPROPENIUM ION AS A BUILDING BLOCK FOR NITROGEN HETEROCYCLE SYNTHESIS

Article abstract of DOI:10.1016/S0040-4020(01)80147-2

A new methodology for heterocycle synthesis using trithiocyclopropenium salt as a building block is described.Tris(tert-butylthio)cyclopropenium perchlorate (1) reacts with β-amino acids under basic conditions to give 1,2-dihydropyridines, where cyclopropenium salt serves as the three carbon homologator in heterocyclic ring formation.The selective syntheses of 1,5-benzodiazepines and benzimidazoles from 1 are also described.Reaction of 1 with o-phenylenediamines in dimethylformamide gives 1,5-benzodiazepines as a single product but in methanol benzimidazoles.The selective formation of 1,5-benzodiazepines and benzimidazoles could be accounted for by the solvent participation in the cyclization step.