Vilsmeier cyclization of α-acetyl-α-aroyl ketene-N,S-acetals: direct and efficient synthesis of halogenated pyridin-2(1H)-ones

Abstract

An efficient synthetic route to 3-aroyl-5-formyl-4-halo pyridin-2(1H)-ones has been developed via Vilsmeier cyclization of 2-(ethylthio(arylamino)methylene)-1-alkylbutane-1,3-dione. The synthetic protocol has demonstrated the first example of Vilsmeier cyclization of α-acetyl-α-aroylketene-N,S-acetals, providing a novel route to 4-bromo/chloro pyridin-2(1H)-ones.