in tetrahydrofuran; diethyl ether T=-78 - 20°C; 1 h;

1: 51 percent / KMnO4 / pyridine; H2O / 2 h / 50 °C 2: SOCl2 / 4 h / Heating 3: 67 percent / diethyl ether; tetrahydrofuran / 1 h / -78 - 20 °C View Scheme

1: SOCl2 / 4 h / Heating 2: 67 percent / diethyl ether; tetrahydrofuran / 1 h / -78 - 20 °C View Scheme

1: 1.) aq. NaNO2, 21percent aq. HBF4, 2.) NaF / 2.) 1,2,4-trichlorobenzene, 150 deg C 2: 51 percent / KMnO4 / pyridine; H2O / 2 h / 50 °C 3: SOCl2 / 4 h / Heating 4: 67 percent / diethyl ether; tetrahydrofuran / 1 h / -78 - 20 °C View Scheme