Regiodivergent and Enantioselective Hydroboration of Dienol Ethers

Transition metal-catalyzed asymmetric hydroboration of alkenes is one of the most straightforward methods for the synthesis of chiral organoboron compounds and has been well-established. While significant progress has been made in the catalytic enantioselective hydroboration of simple dienes, the development of regiodivergent and enantioselective hydroboration of more challenging substrates such as heteroatom-substituted or trisubstituted dienes remains limited. Here, we disclose a cobalt-catalyzed regiodivergent and enantioselective hydroboration of dienol ethers using a commercially available Co(acac)₂ catalyst and chiral ligands. The reaction exhibits good functional group compatibility and broad substrate scope, selectively affording 1,2-, 4,1-, 1,4-, and 4,3-hydroboration products in good yields and high regio- and enantioselectivities (up to >99%). Mechanistic studies, including deuterium-labeling, kinetic, and UV-vis experiments, suggest the involvement of Co-H species as active catalysts in the reactions. The powerful conversion capabilities of the products are demonstrated by various downstream transformations and the efficient preparation and late-stage elaboration of bioactive compounds.