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Note | Regular issue | Vol 65, No. 11, 2005, pp.2729-2740
Published online, 2nd September, 2005
DOI: 10.3987/COM-05-10440
A Facile Synthesis of 2-Aminothiazolo[5,4-b]pyridines and 2-Aminobenzoxazoles via Cyclization of Thioureas

Ju Hee Yoon, Hyunmin Song, Sang Wong Kim, Gyoonhee Han, and Hea-Young Park Choo*

*Ewha Womans University, School of Pharmacy, Seoul 120-750, Korea

Abstract

2-Aminothiazolo[5,4-b]pyridines and 2-aminobenzoxazoles have been synthesized from 2-hydroxy-3-thioureidopyridine and 2-hydroxy-3- thioureidobenzene respectively via acid catalyzed cyclization, which were prepared by the reaction of isothiocyanates with 2-hydroxy-3-aminopyridine or 2-aminophenol. The hydroxyl group of N-(2-hydroxy-5-phenyl)- N’-phenyl thiourea reacted as nucleophile to thioureido carbon to give 2-aminobenzoxazoles, whereas that of N-(2-hydroxypyridino)-N’-phenylthiourea was reacted as leaving group upon nuclephillic sulfur of thiourea group in the presence of trifluoroacetic acid or phosphoric acid.