Synthesis of γ-Benzopyranone by TfOH-Promoted Regioselective Cyclization of o-Alkynoylphenols
摘要:
Regioselective cyclization of o-alkynoylphenols forming gamma-benzopyranones has been demonstrated. Trifluoromethanesulfonic acid (TfOH) induced 6-endo cyclization of o-alkynoylphenols without forming 5-exo cyclized benzofuranone derivatives to provide the corresponding gamma-benzopyranones in high yields.