Bis(pentafluorophenyl) Carbonate

Typical Procedure: A 100 mL round bottom flask is charged with 2,2-bis(hydroxymethyl)propionic acid (3.0 g, 22 mmol), bis(pentafluorophenyl) carbonate (21.7 g, 55 mmol), CsF (0.7 g, 4.6 mmol), and 70 mL of anhydrous THF. Initially the reaction mixture is heterogeneous, but after one hour a clear homogeneous solution is formed that is allowed to stir for 20 hours. The solvent is removed in vacuo. The residue is re-dissolved in CH2Cl2 and, after 10 minutes, a byproduct precipitates and could be quantitatively recovered. The filtrate is washed with sodium bicarbonate and water and is dried with MgSO4. The solvent is evaporated in vacuo and the product is recrystallized from ethyl acetate / hexane mixture to give pentafluorophenyl 5-methyl-2-oxo-1,3-dioxane-5-carboxylate (5.5 g, 75%). A THF solution (2 mL) of 2,2,2-trifluoroethanol (320 mg, 3.2 mmol) is slowly added to a mixture of pentafluorophenyl 5-methyl-2-oxo-1,3-dioxane-5-carboxylate (1.0 g, 3.1 mmol) and CsF (193 mg, 1.27 mmol) in anhydrous THF (4 mL) at room temperature. The reaction mixture is stirred for 17 hours before the solvent is removed under vacuum. The residue is then dissolved in CH2Cl2, the insoluble material is filtered, and the filtrate is dried and concentrated in vacuo to give the desired product as a clear oil (616 mg, 82%).