1: 94 percent / NOCl / pyridine / 2 h / -15 - -10 °C 2: 78 percent / Al2O3 / diethyl ether; CH2Cl2 / 2 h / 0 °C 3: 82 percent / triethylamine / acetonitrile / 27 h / Ambient temperature 4: 32 percent / acetonitrile / 48 h / Heating View Scheme