Palladium(II)-Catalyzed ortho Arylation of 2-Phenylpyridines with Potassium Aryltrifluoroborates by C-H Functionalization

An efficient one-pot synthesis of ortho-arylated 2-phenylpyridine and pyridine derivatives by use of potassium aryltrifluoroborates is presented. The optimal reaction conditions are as follows: the 2-phenylpyridine or pyridine derivative is treated with 2.5 equivalents of a potassium aryltrifluoroborate in the presence of 10 mol% palladium(II) acetate, three equivalents of copper(II) acetate, and two equivalents of p-benzoquinone in 1,4-dioxane at 120 degrees C for 24 hours. p-Benzoquinone is an important co-oxidant in the transmetalation-reductive elimination step. The kinetic isotope effect (k(H)/k(D)) for the C-H bond activation was determined to be 1.09. It indicates that the C-H bond cleavage does not Occur in the rate-determining step.