HETEROCYCLIC SYSTEMS CONTAINING BRIDGEHEAD NITROGEN ATOM: PART LXVI. STUDIES OF ORIENTATION OF CYCLIZATION IN THE SYNTHESIS OF 8-FLUOROTHIAZOLOBENZIMIDAZOL-3(2H)-ONE

Article abstract of DOI:10.1016/S0022-1139(00)82753-0

2-Fluoro-6-nitroaniline, obtained by nitration of 2-fluoroacetanilide, on reduction with Raney nickel and hydrazine hydrate followed by treatment of the resulting diamine with carbon disulphide in situ gives 4-fluorobenzimidazolyl-2-thione.This thione on condensation with chloroacetic acid gives 4-fluorobenzimidazol-2-thiolacetic acid which on cyclization with a mixture of acetic anhydride and pyridine furnished 8-fluorothiazolo<3,2-a>benzimidazol-3(2H)-one as revealed by 1H-NMR spectroscopy.The condensation of 4-fluorobenzimidazolyl-2-thione with 1,2-dibromoethane yields 2,3-dihydro-8-fluorothiazolo<3,2-a>benzimidazole and sym-bis-(4-fluorobenzimidazol-2-ylmercapto)ethane.