Reactions of N‐Phenylamide and Phenyl (Thio)esters of 3‐Phenylpropiolic Acid with Benzene under Superelectrophilic Activation.

N-Phenylamide and phenyl (thio)esters of 3-phenylpropiolic acid add benzene in the presence of CF3SO3H or AlX3 (X = Cl, Br) to give 4,4-diphenyl-3,4-dihydroquinolin-2-one, 4,4-diphenyl-3,4-dihydrocoumarin, and 4,4-diphenyl-3,4-dihydrothiocoumarin, respectively.