Facile Synthesis of Benzimidazole and Benzothiazole Compounds Mediated by a Zinc Precatalyst Supported by an Iminopyrrole‐Morpholine Ligand
Kulsum Bano, Ajitrao Devadkar, Tarun K. Panda
Abstract
Abstract Three zinc complexes, with the general formula {κ 2 ‐C 4 H 3 NH[2‐CH=NCH 2 CH 2 N(CH 2 CH 2 ) 2 O]ZnX 2 } [X=Cl ( 2 a ), Br ( 2 b ), I ( 2 c )], supported by a neutral iminopyrrole‐morpholine ligand, were synthesized by the reaction between {C 4 H 3 NH‐2‐[CH=NCH 2 CH 2 N (CH 2 CH 2 ) 2 O]} ( 1 ) and anhydrous zinc dihalides (ZnCl 2 , ZnBr 2 , ZnI 2 ) at ambient temperature in dry methanol. The zinc complexes were fully characterized using multinuclear NMR spectroscopic techniques and the molecular structures of complexes 2 a and 2 c in their solid states were determined by single‐crystal X‐ray diffraction analysis. The zinc diiodo complex ( 2 c ) proved to be a competent precatalyst in the formation of a wide range of benzimidazole and benzothiazole compounds, via aerobic oxidative condensation of several benzylamines with o‐ phenylenediamine, N‐ phenyl ‐o‐ phenylene‐diamine, and o‐ mercaptoaniline. The benzimidazole and benzothiazole derivatives were successfully characterized using 1 H and 13 C{ 1 H} NMR spectroscopy.