1: oxalyl chloride, DMF / pentane / 1.5 h / 0 - 25 °C 2: 50 percent / triethylamine / pentane / 1.) 25 deg C, 1 - 2 h, 2.) reflux, 15 - 24 h View Scheme

1: oxalyl chloride, DMF / pentane / 1.5 h / 0 - 25 °C 2: 50 percent / triethylamine / pentane / 1.) 25 deg C, 1 - 2 h, 2.) reflux, 15 - 24 h 3: 74 percent / CHCl3 / 24 h / 40 °C View Scheme

1: oxalyl chloride, DMF / pentane / 1.5 h / 0 - 25 °C 2: 50 percent / triethylamine / pentane / 1.) 25 deg C, 1 - 2 h, 2.) reflux, 15 - 24 h 3: 28 percent / CHCl3 / 41 h / 60 °C View Scheme