Remote Site-Selective C(sp3)-H Monodeuteration of Unactivated Alkenes via Chain-Walking Strategy

The installation of deuterium atoms at distal C(sp3)-H bonds is a longstanding synthetic challenge. Through the synergistic combination of chain-walking strategy and transfer hydrodeuteration, we present the remote transfer hydrodeuteration of unactivated alkenes at distal C(sp3)-H sites, aided by native directing groups, using readily available pinacolborane (HBpin) and D2O as H- and D+ sources, respectively. Significantly, this tactic offers a complementary pattern to conventional hydro-deuteration methods that adduct H-D, or its surrogate, to unsaturated bonds. Both experimental data and density functional theory (DFT) studies demonstrated the critical role of the directing group in guiding the olefin isomerization process. DFT calculations suggest that it was the in situ-generated Ni(II)- hydride rather than Ni(I)-hydride that performed as active intermediates in the olefin insertion and isomerization steps.