orthoformic acid triethyl ester; boron trifluoride diethyl etherate in benzene 18 h; Heating;

sodium periodate in methanol; water 11 h; Ambient temperature;

1: 3 g / p-toluenesulphonic acid / benzene / Heating 2: 1.) diisopropylamine, 2M BuLi, 2.) hexamethylphosphoramide / 1.) THF, hexane, -78 deg C, 20 min; 2.) THF, -78 deg C to -20 deg C, 2 h 3: 1 g / NaIO4 / methanol; H2O / 11 h / Ambient temperature View Scheme

1: 1.) diisopropylamine, 2M BuLi, 2.) hexamethylphosphoramide / 1.) THF, hexane, -78 deg C, 20 min; 2.) THF, -78 deg C to -20 deg C, 2 h 2: 1 g / NaIO4 / methanol; H2O / 11 h / Ambient temperature View Scheme

2: 3 g / p-toluenesulphonic acid / benzene / Heating 3: 1.) diisopropylamine, 2M BuLi, 2.) hexamethylphosphoramide / 1.) THF, hexane, -78 deg C, 20 min; 2.) THF, -78 deg C to -20 deg C, 2 h 4: 1 g / NaIO4 / methanol; H2O / 11 h / Ambient temperature View Scheme