Enantioconvergent Hydroboration of E/ Z-Mixed Trisubstituted Alkenes

J Am Chem Soc. 2024 Jul 31;146(30):21089-21098. doi: 10.1021/jacs.4c06585. Epub 2024 Jul 12.

Abstract

The lack of mode for chirality recognition makes it particularly challenging to carry out asymmetric transformations on E/Z-mixed minimally functionalized trisubstituted alkenes. Here, we report a catalytic enantioconvergent hydroboration of minimally functionalized trisubstituted E/Z-mixed alkenes to construct chiral organoboronic esters with excellent enantioselectivity using chiral radical cobalt catalyst. This C(sp3)-H borylation protocol showed good functional group tolerance and products could be converted to valuable compounds via C-B derivatizations. The mechanistic studies, which included control experiments, nonlinear effect experiments, deuterated labeling experiments, and X-ray diffraction, demonstrated that the favorable compatibility between the thermodynamically unfavorable isomerization and hydroboration was the key factor in achieving convergent transformation.