FORMATION OF SPIRO[BENZOTHIENO-3,4'-PYRIDINES] BY THE REACTION OF BENZOTHIENO[2,3-c]PYRIDINES WITH ACETYLENE DICARBOXYLIC ESTER

摘要

It has previously been shown that 5-o-chlorobenzyltetrahydrothieno[3,2-c]pyridines react with alkynes only in alcohols to form the products of cleavage of the tetrahydropyridine ring and involving molecules of the solvent and the products of debenzylation (N-vinyltetrahydrothienopyridines) [1]. 2-rifluoroacetamidotetra hydrothieno[2,3-c]pyridines react readily with alkynes both in methanol and in acetonitrile to give a high yield of tetrahydrothieno[3,2-d]azocines [2]. 2-Acetamido-substituted thienopyridines react with alkynes in acetonitrile at 20°C to give modest yields (30-59%) of the thienoazocines. There occur in methanol simul-taneous processes of expansion and cleavage of the tetrahydropyridine fragment to form a mixture of the acetamido-substituted tetrahydrothieno [3 ,2-d] azoc ine s and 2-acetamido-3-ethoxycarbony1-4-(N-vinyl-N-R)aminoethy1-5-methoxy methylthiophenes [2].