tetrabutyl ammonium fluoride in tetrahydrofuran T=20°C; 3 h; Inert atmosphere;

1: 90 percent / Jones' reagent / acetone / 0.5 h / 0 °C 2: 95 percent / oxalyl chloride / benzene / 3 h / Ambient temperature 3: 81 percent / AlCl3 / CH2Cl2 / 1.) 0 deg C, 45 min, 2.) r.t., 30 min 4: 71 percent / SiO2 / petroleum ether; diethyl ether View Scheme