1: triethylamine / dichloromethane / 1 h / 0 °C 2: diisobutylaluminium hydride / tetrahydrofuran; toluene / 0.33 h / -40 - 20 °C View Scheme

oxalyl dichloride; N,N-dimethyl-formamide in dichloromethane T=20°C; 1 h;