Alkylboronic acids and their derivatives have found widespread applications in pharmaceuticals and synthetic chemistry. Accordingly, numerous methods have been developed to prepare these structures. Transition-metal-catalyzed hydroboration of alkenes is one of the most convenient and straightforward methods to synthesize these compounds with chemo- and regioselectivity. Because of the low reactivity of aliphatic internal alkenes and the difficulty of controlling the regioselectivity of hydroboration, only a few examples have been developed for regioselective hydroboration of aliphatic internal alkenes. In particular, the addition of a boryl group to the distal carbon remains a distinct challenge for aliphatic internal alkenes. 

Recently, researchers from the Lanzhou Institute of Chemical Physics of the Chinese Academy of Sciences (LICP) report a highly distal selective hydroboration of aliphatic internal alkenes using readily available iridium dimer precursor [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) as the catalyst in collaboration with Zhengzhou University and Nankai University. This unusual selectivity complements reported copper-, rhodium-, and iridium-catalyzed hydroboration. The current method could tolerate a variety of β,γ- and γ,d-unsaturated carbonyl compounds, affording the borylated products in good to excellent regioselectivity (up to 99:1). DFT calculations reveal the steric effect of Cp* and Bpin gives rise to the observed regioselectivity. In addition, a rare Ir(III/V) mechanism is proposed through calculations that is distinct from the generally accepted Ir(I/III) mechanism in hydroboration of alkenes.