Reductive sulfur extrusion reaction of 2,1,3-benzothiadiazole compounds:: a new methodology using NaBH4/CoCl2•6H2O(cat) as the reducing system

A new simple and efficient methodology for reductive sulfur extrusion from 2,1,3-benzothiadiazole compounds has been developed using NaBH4 in the presence of catalytic amounts of ClCl2-6H(2)O (1 mol %). This method is an efficient alternative for the generation of various 1,4-disubstituted-2,3-diaminobenzene derivatives from 4,7-disubstituted-2,1,3-benzothiadiazoles. The diamines can be easily converted into 4,7-disubstitttted-quinoxaline compounds by simple reaction with glyoxal-sodium bisulfite. (c) 2005 Elsevier Ltd. All rights reserved.