Regioselective synthesis of new imidazo[4,5‐e][1,3]thiazino[2,3‐c][1,2,4]triazines via reaction of imidazo[4,5‐e][1,2,4]triazinethiones with ethyl phenylpropiolate

Abstract

A method for the regioselective synthesis of imidazo[4,5‐e][1,3]thiazino[2,3‐c][1,2,4]triazine derivatives has been developed by the reaction of imidazotriazinethiones with ethyl phenylpropiolate upon treatment with potassium carbonate or sodium methoxide in methanol. The synthesis was accomplished by Michael‐type addition of the imidazotriazinethiones to the triple bond of ethyl phenylpropiolate followed by subsequent intramolecular cyclization.