Journal of the American Chemical Society, Vol.139, No.39, 13660-13663, 2017
Copper-Catalyzed Enantioselective Hydroboration of Unactivated 1,1-Disubstituted Alkenes
We report an efficient and; highly enantio-selective hydroboration of aliphatic 1,1-disubstituted alkenes with pinacolborane using a phosphine-Cu catalyst. The method allows facile preparation of enantiomerically enriched beta-chiral alkyl pinacolboronates from a range of 1,1-disubstituted alkenes with high enantioselectivity up to 99% ee. Unprecedented enantiodiscrimination between the geminal alkyl substituents was observed with functional group compatibility in the hydroboration. Furthermore, a catalyst loading as low as 1 mol % furnished the desired product without a decrease in yield or selectivity, demonstrating its efficiency in gram scale synthesis.