The Metalation of (tert-Butyldimethylsilyl)(2-pyridylmethyl)amine with Dimethylzinc and Subsequent Zinc-Mediated Carbon−Carbon Coupling Reaction

Abstract

The lithiation of 2-(aminomethyl)pyridine and the subsequent reaction with ClSiMe2tBu yields (tert-butyldimethylsilyl)(2-pyridylmethyl)amine (1). The metalation of 1 with dimethylzinc gives colorless dimeric methylzinc 2-pyridylmethyl(tert-butyldimethylsilyl)amide (2), which crystallizes in the triclinic space group P1¯. The solvent-free thermal decomposition of 2 at 150 °C leads to the evolution of methane, the precipitation of zinc metal and the formation of amine 1, bis(methylzinc)—1,2-dipyridyl-1,2-bis(tert-butyldimethylsilylamido)ethane (3), and bis[(tert-butyldimethylsilyl)(2-pyridylmethyl)amido]zinc (4). Compound 3 can be obtained in good yield by reacting 2 with dimethylzinc at elevated temperatures in toluene. During this reaction, zinc metal precipitates and methane is evolved. The C−C coupling product 3 crystallizes in the tetragonal space group I41cd. The lithiation of 1 and the subsequent metathesis reaction with anhydrous ZnCl2 yields complex 4 almost quantitatively.