Transition metal-free hydroarylation of unactivated alkynes was achieved by combining a Brønsted acid catalyst and a two-phase solvent system consisting of 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) and cyclohexane. This protocol is applicable to a wide variety of 2-alkynylbiaryls which leads to the synthesis of substituted phenanthrenes via 6-endo-selective ring closure. The biphasic system achieves