Studies on Benzo[b]thiophen derivatives. Synthesis and reactions of 2-p-substituted Benzoylbenzo[b]thiophen-3(2H)ones

Abstract

2-p-Substituted benzoylbenzo[b]thiophen-3(2H)-ones were synthesized by cyclization of the corresponding p-substituted 2-(phenacylthio)benzoic acids with different reagents. The behaviour of these diketones toward the action of phenylhydrazine, arylmagnesium bromide and sodium borohydride was investigated. They gave the corresponding monophenylhydrazone derivatives which cyclized to give 1-phenyl-3-aryl- 1H-[1]benzothieno[3,2-c]pyrazoles; 2-bisarylmethylenebenzo[b]-thiophen- 3(2H)-ones; and 2-arylmethylenebenzo[b]thiophen-3(2H)-ones respectively. The structure of the above reaction products was confirmed by synthesis through other routes.