1: With oxalyl dichloride; dimethyl sulfoxide in dichloromethane T=-30°C; 0.75 h; Cooling with dry ice; 2: With triethylamine in dichloromethane T=-30 - 20°C; 12 h;

diisobutylaluminium hydride in diethyl ether; toluene T=-78°C; 16 h;