Silica Supported Fluoroboric Acid: An Efficient and Reusable Heterogeneous Catalyst for Facile Synthesis of 2-Aliphatic Benzothiazoles, Benzoxazoles, Benzimidazoles and Imidazo[4,5-b]pyridines

Abasaheb V. Patil, Babasaheb P. Bandgar, Soo-Hyoung Lee
2010 Bulletin of the Korean Chemical Society (Print)  
NH 2 SH + CH 3 C(OCH 2 CH 3 ) 3 N S HBF 4 -SiO 2 (2 mol %) Neat, rt 1a 2b 3b 3EtOH Scheme 1. Synthesis of 2-methylbenzothiazole under various conditions Benzothiazole, benzoxazole, benzimidazole and imidazo [4,5-b]pyridine moieties have attracted a great deal of interest in diverse field of chemistry. 1,2 These heterocycles have achieved significance in pharmacology as antibacterial, 3 antiviral, 4 antifungal, 5 anticancer, 6 anticonvulsant 7 and immunosuppressant agents. 8 Quite a plethora of
more » ... uite a plethora of methods have been developed for the preparation of these heterocycles including the condensation of carboxylic acids, 9 acid chlorides, 10,11 orthoesters, 12-14 esters, 15 and aldehydes 16-21 with o-aminophenols, o-aminothiophenols and o-phenylenediamines, dehydration of o-acylaminophenols, 22 the reaction of o-quinones with amines 23 and Beckmann rearrangement of o-acylphenoloximes. 24
doi:10.5012/bkcs.2010.31.6.1719 fatcat:wanuvcwvfrdizotdb5mlotdohu