Substrate scope of carboxylic acids and terminal alkynes^a.

^aReaction conditions: carboxylic acid 1 (0.2 mmol), terminal alkyne 2 (0.4 mmol, 2.0 equiv.), PdCl₂ (5 mol%), TFP (10 mol%), Piv₂O (0.28 mmol, 1.4 equiv.), dioxane (2.0 mL), N₂, 160 °C, 12 h. Isolated yield. GC yield is shown in parentheses.

^bTerminal alkyne 2 (4.0 equiv.) is used.

^cLiI instead of LiBr.