1,3-γ-Silyl-elimination in electron-deficient cationic systems

Michael A. Mercadante; Christopher B. Kelly; Trevor A. Hamlin; Kayla R. Delle Chiaie; Michael D. Drago; Katherine K. Duffy; Megan T. Dumas; Diana C. Fager; Bryanna L. C. Glod; Katherine E. Hansen; Cameron R. Hill; Rebecca M. Leising; Catherine L. Lynes; Allyson E. MacInnis; Madeline R. McGohey; Stephanie A. Murray; Marc C. Piquette; Shaina L. Roy; Ryan M. Smith; Katherine R. Sullivan; Bao H. Truong; Kristina M. Vailonis; Vitaliy Gorbatyuk; Nicholas E. Leadbeater; Leon J. Tilley

doi:10.1039/C4SC01732C

1,3-γ-Silyl-elimination in electron-deficient cationic systems†

Michael A. Mercadante,^b Christopher B. Kelly,^b Trevor A. Hamlin,^b Kayla R. Delle Chiaie,^a Michael D. Drago,^a Katherine K. Duffy,^a Megan T. Dumas,^a Diana C. Fager,^a Bryanna L. C. Glod,^a Katherine E. Hansen,^a Cameron R. Hill,^a Rebecca M. Leising,^a Catherine L. Lynes,^a Allyson E. MacInnis,^a Madeline R. McGohey,^a Stephanie A. Murray,^a Marc C. Piquette,^a Shaina L. Roy,^a Ryan M. Smith,^a Katherine R. Sullivan,^a Bao H. Truong,^a Kristina M. Vailonis,^a Vitaliy Gorbatyuk,^b Nicholas E. Leadbeater*^bc and Leon J. Tilley*^a

Author affiliations

* Corresponding authors

^a Department of Chemistry, Stonehill College, 320 Washington Street, Easton, Massachusetts 02357, USA
E-mail: ltilley@stonehill.edu

^b Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, USA
E-mail: nicholas.leadbeater@uconn.edu

^c Department of Community Medicine & Health Care, University of Connecticut Health Center, The Exchange, 263 Farmington Ave, Farmington, USA

Abstract

Placement of an electron-withdrawing trifluoromethyl group (–CF₃) at a putative cationic centre enhances γ-silyl neighbouring-group participation (NGP). In stark contrast to previously studied γ-silyl-substituted systems, the preferred reaction pathway is 1,3-γ-silyl elimination, giving ring closure over solvent substitution or alkene formation. The scope of this cyclopropanation reaction is explored for numerous cyclic and acyclic examples, proving this method to be a viable approach to preparing CF₃-substituted cyclopropanes and bicyclic systems, both containing quaternary centres. Rate-constants, kinetic isotope effects, and quantum mechanical calculations provided evidence for this enhancement and further elaborated the disparity in the reaction outcome between these systems and previously studied γ-silyl systems.

Chemical Science

1,3-γ-Silyl-elimination in electron-deficient cationic systems†

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1,3-γ-Silyl-elimination in electron-deficient cationic systems

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