Synthesis of γ-Benzopyranone by TfOH-Promoted Regioselective Cyclization of <i>o</i>-Alkynoylphenols Masahito Yoshida Yuta Fujino Takayuki Doi 10.1021/ol2016934.s001 Regioselective cyclization of <i>o</i>-alkynoylphenols forming γ-benzopyranones has been demonstrated. Trifluoromethanesulfonic acid (TfOH) induced 6-<i>endo</i> cyclization of <i>o</i>-alkynoylphenols without forming 5-<i>exo</i> cyclized benzofuranone derivatives to provide the corresponding γ-benzopyranones in high yields. 2011-09-02 00:00:00 Regioselective cyclized Cyclization TfOH Benzopyranone benzofuranone cyclization benzopyranone derivative Synthesi endo exo yield Trifluoromethanesulfonic acid