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

The reaction of imines with low-valent titanium species, generated in situ by using Ti((OPr)-Pr-i)(4)/2 c-O5H9-MgCI reagent, affords titanium-imine complex, which can couple with nitriles to provide 2,5-diazatitanacyclopentenes. alpha-Aminoketones are obtained in good yields by quenching the corresponding 2,5-diazatitanacyclopentenes with aqueous HC1 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. (c) 2014 Elsevier Ltd. All rights reserved.