Synthesis and reactions of azido-benzothiazoles and -benzo[b]thiophens; novel thiazolo[4,5-g]benzoxazoles and dihydrothieno[3,2-g]benzoxazoles

Abstract

6-Azidobenzothiazole and its 2-methyl and 2-methylthio-derivatives were prepared from the corresponding amine and gave the thiazolo[4,5-g]benzoxazoles, (8)–(10), on thermolysis in a polyphosphoric-acetic acid mixture. 6,7-Dihydro-2-methylthieno[3,2-g]benzoxazole 8,8-dioxide (12) was prepared similarly. An improved method of synthesis of 2-fluoro-6-nitrobenzothiazole is reported.