Photocyclization of 2-[1]benzothien-3-yl)-3-phenylpropenoic acids

Photocyclization of the substituted 2-(1]benzothien-3-yl)-3-phenylpropenoic acids 3a-c in the presence of iodine and air in a benzene-cyclohexane mixture afforded a separable mixture of three compounds, benzob]naphtho2,1-d]thiophene-6-carboxylic acids 4a-c , 6H-benzob]naphtho2,3-d]thiopyran-6-ones 5a-c , and 10-methoxy-2-methyl-6H-benzob]naphtho2,3-d]pyran-6-one ( 6 ).