SYNTHESIS OF SOME NEW THIENO[2,3-b]PYRIDINES, PYRIDO[3′,2′:4,5]-THIENO[3,2-d]PYRIMIDINES AND PYRIDO[3′,2′:4,5]THIENO[3,2-d][1,2,3]-TRIAZINES

Abstract

4-Aryl-3-cyano-2-substituted-methyIthiocyclopenta[b]pyridines (3a-c and 4a-i) were prepared by reaction of 4-aryl-3-cyanocyclopenta[b]pyridine-2(1H)-thiones(2a-c) with chloroacetonitrile or chloro-N-arylacetamides, respectively. On treatment of these products with sodium ethoxide in boiling ethanol, they underwent intramolecular Thorpe-Ziegler cyclization to afford the corresponding 3-amino-4-aryl-2-functionallized-cyclopenta[e]thieno [2,3-b]pyridines (5a-c and 6a-i). Most of the latter thienopyridines were used as synthons for the target cyclopenta[5′,6′]pyrido[3′,2′:4.5]thieno[3,2-d]pyrimidines and cyclopenta[5′,6′]. pyrido[3′,2′:4,5]thieno[3,2-d][1,2,3]triazines.