Titanium-mediated reductive cross-coupling reactions of imines with nitriles: an efficient route for the synthesis of α-aminoketones or 1,2-diketones

The reaction of imines with low-valent titanium species, generated in situ by using Ti(OiPr)4/2 c-C5H9MgCl reagent, affords titanium–imine complex, which can couple with nitriles to provide 2,5-diazatitanacyclopentenes. α-Aminoketones are obtained in good yields by quenching the corresponding 2,5-diazatitanacyclopentenes with aqueous HCl solution. However, when the reaction is first quenched with MeOH in air followed by addition of aqueous HCl solution, 1,2-diketones are formed in good to high yields.