potassium carbonate in tetrahydrofuran; methanol; water 1 h; Ambient temperature;

(i) (COCl)2, DMF, CH2Cl2, (ii) /BRN= 1718733/, Py; Multistep reaction;

oxalyl dichloride; N,N-dimethyl-formamide in dichloromethane T=0°C; 3.5 h;

1.1: N,N-dimethyl-formamide; oxalyl dichloride / dichloromethane / 1 h / 0 - 20 °C 1.2: 15 h / 20 °C 2.1: tetrabutyl ammonium fluoride / tetrahydrofuran; water / 0.02 h / 20 °C View Scheme