sodium tetrahydroborate in methanol T=0 - 20°C; Overall yield = 70 percent;

1: With potassium tri-sec-butyl-borohydride in tetrahydrofuran T=-78°C; 4 h; Inert atmosphere; 2: With water in ethanol T=20°C; 3: With dihydrogen peroxide; sodium hydroxide

1.1: chromium(VI) oxide; sulfuric acid / water; acetone / 20 - 35 °C 2.1: potassium tri-sec-butyl-borohydride / tetrahydrofuran / 4 h / -78 °C / Inert atmosphere 2.2: 20 °C View Scheme

1.1: potassium hydrogen difluoride / diethylene glycol / 1 h / 175 °C 2.1: chromium(VI) oxide; sulfuric acid / water; acetone / 20 - 35 °C 3.1: potassium tri-sec-butyl-borohydride / tetrahydrofuran / 4 h / -78 °C / Inert atmosphere 3.2: 20 °C View Scheme

1: triethylamine tris(hydrogen fluoride) 2: oxalyl dichloride; dimethyl sulfoxide; triethylamine / dichloromethane / -70 - 0 °C 3: sodium tetrahydroborate / methanol / 0 - 20 °C View Scheme

fluorine in acetic acid Yield given. Further byproducts given. Yields of byproduct given;