Abstract
Biarylboronic esters are generally prepared by directed ortho-metalation or by Miyaura borylation and hence rely on the presence of a directing group or pre-functionalization. In this paper, the preparation of biarylboronic esters by direct C-H borylation of biaryl substrates is reported. Sterically governed regioselectivities were observed in the borylation of appropriately substituted biaryls by using [Ir(OMe)(COD)](2)precatalyst and di-tert-butylbipyridyl ligand. The resulting biarylboronic esters were isolated in 38-98% yields. The synthesized biarylboronic esters were further successfully employed in C-O, C-Br, and C-C coupling reactions.