TsNBr2 Mediated Synthesis of 2-Acylbenzothiazoles and Quinoxalines from Aryl Methyl Ketones under Metal Free Condition

An efficient one pot strategy has been developed for the synthesis of 2-acylbenzothiazoles and quinoxalines from aryl methyl ketones. A variety of heterocycles of these two categories could be prepared in a two-step sequence in excellent yields. The reaction was performed starting from aromatic ketones via an aryl gloxal intermediate which, on further condensation with 2-aminobenzenethiol or o-phenylenediamine, produces the corresponding heterocyclic skeleton. Aromatic ketones are initially treated with TsNBr2 in DMSO at 65 degrees C for 3 h and the crude reaction mixture was treated with 2-aminobenzenethiol (at 80 degrees C) or o-phenylenediamine (at RT) to generate the final compound.