1.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 2 h / 0 - 20 °C 2.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 0.58 h / -78 °C 2.2: 0.08 h / -78 - 0 °C View Scheme

tetrabutyl ammonium fluoride in tetrahydrofuran 0.5 h;