1: 88 percent / aq. ammonia / 1) 6 h, RT, 2) toluene, 15 h, reflux 2: 440 mg / NaBH4, 2M HCl / tetrahydrofuran; ethanol 3: 95 percent / triethylsilane / trifluoroacetic acid / 0.5 h 4: 72 percent / toluene-p-sulphonic acid / CH2Cl2 / 15 h / Ambient temperature 5: 54 percent / triphenylphosphine / various solvent(s) / 40 h / Heating 6: 80 percent / 2M H2SO4 / tetrahydrofuran / 2 h / 50 °C View Scheme