Computational Exploration of the Nature of Li+-Ureide Anion Catalysis on Formation of Highly Reactive Vinyl Carbocations and Subsequent C-C Bond Forming Reactions

Woojin Lee; Hosea M Nelson; K N Houk

doi:10.1021/acs.joc.2c02178

Computational Exploration of the Nature of Li⁺-Ureide Anion Catalysis on Formation of Highly Reactive Vinyl Carbocations and Subsequent C-C Bond Forming Reactions

J Org Chem. 2023 Mar 17;88(6):3403-3408. doi: 10.1021/acs.joc.2c02178. Epub 2023 Feb 23.

Authors

Woojin Lee¹, Hosea M Nelson², K N Houk¹

Affiliations

¹ Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States.
² Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.

PMID: 36820472
DOI: 10.1021/acs.joc.2c02178

Abstract

The mechanisms of the C-H insertion reactions of vinyl carbocations formed by heterolysis of vinyl trifluoromethanesulfonates (triflates) by catalytic lithiated 1,3-bis[3,5-bis(trifluoromethyl)phenyl]urea (Li⁺-ureide) have been studied with ωB97X-D density functional theory. The ionization promoted by the Li⁺-ureide forms a metastable intimate ion pair complex of Li⁺-ureide-triflate anion and vinyl cation. The relative thermodynamic stabilities of isomeric alkyl cations are impacted by ion-pairing with the Li⁺-ureide-triflate anion. We show that the C-H insertion reaction of the vinyl cation intermediate is the rate-determining step and explain the effect of the aryl substituents on the formation of the vinyl cation and its C-H insertion reactivity as well as the regioselectivity of C-H activation by the vinyl cation.