1: trifluoromethanesulfonic anhydride; 4-(dimethylamino)pyridine / CH2Cl2 / 2 h / 20 °C 2: 1.1 g / LiBr; BF3*OEt2 / dioxane; diethyl ether / 0.5 h / 50 °C 3: 94 percent / 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile); tributyltin hydride / CH2Cl2 / 0.25 h / 20 °C 4: 96 percent / tetrabutylammonium fluoride; acetic acid / tetrahydrofuran / 1.5 h / 0 °C View Scheme