tetrabutyl ammonium fluoride in tetrahydrofuran T=20°C; Hydrolysis; 10 h;

oxalyl dichloride; dimethyl sulfoxide; triethylamine 1.) ether, from -40 deg C to -35 deg C, 1 h, 2.) ether, a) -78 deg C, 1 h, b) 0 deg C, 2 h; Yield given. Multistep reaction;