Enantioselective palladium-catalyzed diboration of 1,1-disubstituted allenes.

ABSTRACT: A practical and enantioselective palladium-catalyzed diboration of 1,1-disubstituted allenes is developed by employing a P-chiral monophosphorus ligand, BI-DIME. A series of diboronic esters containing a chiral tertiary boronic ester moiety are formed in excellent yields and ee's with the palladium loading as low as 0.2 mol%. DFT calculations revealed a concerted mechanism of oxidative addition of bis(pinacolato)diboron and allene insertion, as well as a critical dispersion effect on the origins of the enantioselectivity. The method is successfully applied to the concise and enantioselective synthesis of brassinazole.

SUBMITTER: Liu J 

PROVIDER: S-EPMC5615263 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature