Electrochemical homocoupling of 2-bromomethylpyridines catalyzed by nickel complexes.
2,2'-Bipyridine (bpy) and a series of dimethyl-2,2'-bipyridines were synthesized from 2-bromopyridine and 2-bromomethylpyridines, respectively, using an electrochemical process catalyzed by nickel complexes. The method is simple and efficient, with isolated yields between 58 and 98% according to the structure. We first studied the influence of the presence and the position of the methyl group on the yield, using N,N-dimethylformamide (DMF) or acetonitrile (AN) as the solvent, NiBr(2)bpy as the catalyst, and Zn as the sacrificial anode, in an undivided cell and at ambient temperature. On the basis of a better understanding of the reaction mechanism based on electroanalytical studies, we could improve the dimerization both by substituting the catalyst ligand (bpy) by the reagent itself, i.e., 2-bromomethylpyridine or 2-bromopyridine, and by using Fe instead of Zn as the sacrificial anode.
de França
Kelnner W R
KW
Departamento de Química Fundamental, Universidade Federal de Pernambuco, CCEN, 50670-901, Recife, PE, Brasil.
Navarro
Marcelo
M
Léonel
Eric
E
Durandetti
Muriel
M
Nédélec
Jean-Yves
JY