Enantioselective Vanadium-Catalyzed Oxidative Coupling: Development and Mechanistic Insights.

ABSTRACT: The evolution of a more reactive chiral vanadium catalyst for enantioselective oxidative coupling of phenols is reported, ultimately resulting in a simple monomeric vanadium species combined with a Brønsted or Lewis acid additive. The resultant vanadium complex is found to effect the asymmetric oxidative ortho-ortho coupling of simple phenols and 2-hydroxycarbazoles with good to excellent levels of enantioselectivity. Experimental and quantum mechanical studies of the mechanism indicate that the additives aggregate the vanadium monomers. In addition, a singlet to triplet crossover is implicated prior to carbon-carbon bond formation. The two lowest energy diastereomeric transition states leading to the enantiomeric products differ substantially with the path to the minor enantiomer involvin

SUBMITTER: Kang H 

PROVIDER: S-EPMC6467780 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature