Cooperative heterobimetallic substrate activation enhances catalytic activity and amplifies regioselectivity in 1,4-hydroboration of pyridines

Regioselective 1,4-hydroboration of pyridine derivatives and quinoline with pinacolborane is catalyzed efficiently by the heterobinuclear catalyst, (IPr)CuFeCp(CO)2, at only 2 mol% loading, providing access to valuable 1,4-dihydropyridine (1,4-DHP) products. A variety of reactive functional groups are tolerated in the pyridine 3-position, and sufficient catalytic activi-ty was obtained for reduction of sterically hindered cases such as 3,5-disubstituted pyridines and even 4-substituted pyri-dines. Mechanistic experiments indicate that the superior catalytic activity and 1,4-regioselectivity of the Cu/Fe heterobinu-clear catalyst compared to the corresponding mononuclear Cu catalyst derives from cooperative chemistry of two key catalyt-ic intermediates derived from the biphilic catalyst: electrophilic CpFe(CO)2(Bpin) activates the pyridine substrates towards regioselective nucleophilic addition by (IPr)CuH.