The conversion of [(4-chloro-5H-1,2,3-dithiazol-5-ylidene)amino]azines into azine fused thiazole-2-carbonitriles

Abstract

The thermolysis of several N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)pyridin-n-amines (where n = 2, 3 and 4) gives a mixture of thiazolopyridine-2-carbonitriles in low to moderate yields. Introduction, by design, of a chlorine substituent at the C2 or C4 position of N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)pyridin-3-amine and other selected azines enables a BnEt₃NI mediated ANRORC style ring transformation that provides fourteen heteroazine fused thiazole-2-carbonitriles in moderate to near quantitative yields. The synthesis described herein therefore provides a facile high yielding two-step route to heteroazine fused thiazole-2-carbonitriles starting from 4,5-dichloro-1,2,3-dithiazolium chloride (Appel salt) and ortho- or para-chloro substituted meta-aminoazines.