Synthesis and DFT calculations of 2-thioxo-1,2-dihydropyridine-3-carbonitrile as versatile precursors for novel pharmacophoric hybrid molecules

Abstract

Pyridine-2-(1H)-thiones were prepared by the reaction of the appropriate 1,3-diones with cyanothioacetamide. Based on DFT calculations, a molecular level understanding for this reaction mechanism gives for the first time a strong evidence for the preferential formation of one of the expected pyridinethione regioisomers. The latter compounds were utilized as intermediates for the synthesis of novel thieno[2,3-b]pyridines and bis(thieno[2,3-b]pyridines) via reaction with bromoacetylbenzofurans, bromoacetylbenzothiazole as well as the appropriate bis-bromoacetyl derivatives in ethanolic sodium ethoxide at reflux.