Corey's method reduced titanium in tetrahydrofuran

amalgamated magnesium; titanium tetrachloride in tetrahydrofuran T=-10 - 0°C; 2 h; other cyclic ketones, var. temperature; ring-size and alkyl substituent effect in mixed pinacol coupling reaction; Product distribution;

sulfuric acid T=0°C; 2 h; Mechanism;