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

1.1: NaH / dimethylformamide / 1 h / 0 °C 1.2: 77 percent / NaI / dimethylformamide / 5 h / 20 °C 2.1: 91 percent / 2,4,6-collidine; triethylsilyl trifluoromethanesulfonate / CH2Cl2 / 0.5 h / 0 °C View Scheme

1: 97 percent / pyridine / 0 - 20 °C 2: 88 percent / 2,4,6-collidine; triethylsilyl trifluoromethanesulfonate / CH2Cl2 / 0.5 h / 0 °C View Scheme

1H-imidazole; iodine; triphenylphosphine in tetrahydrofuran