Enantioselective addition of methyllithium to aromatic imines catalyzed by C2 symmetric tertiary diamines

Enantioselective addition of methyllithium to aromatic imines catalyzed by C2 symmetric tertiary diamines is described. Eleven diamines have been tested, for which dramatic effect of the nitrogen substitution has been observed. Diamines bearing hindered group close to the nitrogen led to racemic product while homologous hindered diamines led to the best results. Enantiomeric excess up to 74% could be achieved. An explanation of the absolute configuration of the product obtained is given considering the mechanism of the reaction.

Graphical Abstract