1: 96 percent / tetrabutylammonium fluoride / tetrahydrofuran / 72 h / 20 °C 2: 56 percent / oxalyl chloride; DMSO; Et3N / CH2Cl2 / 0.5 h / -65 °C View Scheme

tetrabutyl ammonium fluoride in tetrahydrofuran T=20°C; 72 h;