An efficient synthesis of trifluoromethyl-containing 2, 3-allenols via carbonyl-yne reaction of 3, 3, 3-trifluoropyruvates with acetylenes is described. In the presence of MgBr2· Et2O the reaction of methyl trifluoropyruvate with hex-1-yne proceeds diastereoselectively. Trifluoromethyl-substituted 2, 3-allenols can be stereoselectively transformed into trifluoromethyl-substituted 2, 5-dihydrofurans on treatment with AgNO3.
