oxalyl dichloride; dimethyl sulfoxide; triethylamine in dichloromethane T=-60 - 20°C;

1: 66 percent / Na2CO3, NaI / various solvent(s) / 9 h / Heating 2: 91 percent / (COCl)2, Et3N, dimethylsulfoxide (DMSO) / CH2Cl2 / -60 - 20 °C View Scheme

1: 66 percent / Na2CO3, NaI / various solvent(s) / 9 h / Heating 2: 91 percent / (COCl)2, Et3N, dimethylsulfoxide (DMSO) / CH2Cl2 / -60 - 20 °C View Scheme