Aminomethylation Reaction of <i>ortho</i>-Pyridyl C–H Bonds Catalyzed by Group 3 Metal Triamido Complexes

Tris­[<i>N</i>,<i>N</i>-bis­(trimethylsilyl)­amido] complexes of group 3 metals, especially yttrium and gadolinium, served as catalysts for <i>ortho</i>-C–H bond addition of pyridine derivatives and N-heteroaromatics into the CN double bond of nonactivated imines to afford the corresponding aminomethylated products. Addition of catalytic amounts of secondary amines, such as dibenzylamine, dramatically improved the catalytic activity through the formation of a mixed ligated complex such as [(Me<sub>3</sub>Si)<sub>2</sub>N]<sub>2</sub>Y­(NBn<sub>2</sub>)­(THF) (<b>4</b>). Furthermore, kinetic studies using the isolated complex <b>4</b> provided a plausible reaction mechanism by which coordination of two pyridine derivatives afforded a penta-coordinated species as a key step.