chromium dichloride in tetrahydrofuran 0.75 h; Ambient temperature;

chromium dichloride in tetrahydrofuran T=0°C; 0.75 h; Yield given. Yields of byproduct given;

N,N,N',N',N'',N''-hexamethylphosphoric triamide; sodium hexamethyldisilazane in tetrahydrofuran T=-78°C; 1 h; Yield given. Yields of byproduct given;