molecular sieve; pyridinium chlorochromate in dichloromethane 36 h; Ambient temperature;

1: 71 percent / pyridinium chlorochromate, molecular sieves / CH2Cl2 / 36 h / Ambient temperature 2: 93 percent / methanol / 12 h / Ambient temperature 3: 94 percent / lithium aluminium hydride / tetrahydrofuran / 0.33 h / 0 °C 4: 1.) p-toluenesulfonic acid, paraformaldehyde; 2.) BF3*Et2O / 1.) acetone, water, rt, 4 h; 2.) rt, 15 h View Scheme

1: 71 percent / pyridinium chlorochromate, molecular sieves / CH2Cl2 / 36 h / Ambient temperature 2: 93 percent / methanol / 12 h / Ambient temperature 3: 94 percent / lithium aluminium hydride / tetrahydrofuran / 0.33 h / 0 °C 4: 1.) p-toluenesulfonic acid, paraformaldehyde; 2.) BF3*Et2O / 1.) acetone, water, rt, 4 h; 2.) rt, 15 h 5: 90 percent / 1percent NaOH / diethyl ether; H2O / 72 h View Scheme