Search of analgesic activity of N-substituted 2-((3-R-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)amino)-4-oxo-4-phenylbut-2-enamides

A series of ethyl 2-((1-(R-amino)-1,4-dioxo-4-phenylbut-2-en-2-yl)amino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate was synthesized by decyclization of ethyl 2-((2-oxo-5-phenylfuran-3(2H)-ylidene)amino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate with aliphatic amines. All the compounds synthesized were found to have analgesic activity at or above the levels of the reference compounds.