IRON-CATALYZED HIGHLY EFFICIENT AEROBIC OXIDATIVE SYNTHESIS OF BENZIMIDAZOLES, BENZOXAZOLES, AND BENZOTHIAZOLES DIRECTLY FROM AROMATIC PRIMARY AMINES UNDER SOLVENT-FREE CONDITIONS IN THE OPEN AIR

摘要

Solvent-free oxidative synthesis of benzimidazoles, benzoxazoles, and benzothiazoles from aromatic primary amines and o-phenylenediamine, o-aminophenol, and o-aminothiophenol has been achieved by using Fe(NO_3)_3 and TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxyl). This reaction can use air as an economical and green oxidant, and a wide variety of derivatives were obtained in good to excellent yields. The reaction mechanism was proposed and this method provides a direct, practical, and efficient approach for the preparation of substituted benzimidazoles, benzoxazoles, and benzothiazoles.