New class of reactive intermediate: Beta-lithio carbon-centered radicals

ORGN 314

Lawrence M. Pratt1, Steven R. Kass2, Alireza Fattahi2, and Lev Lis2. (1) Department of Chemistry, Fisk University, 1000 17th Ave. N, Nashville, TN 37211, (2) Department of Chemistry, University of Minnesota, 207 Pleasant St. S.E, Minneapolis, MN 55455
Ab initio and DFT calculations indicate that beta-C-H bonds in organolithiums (RLi) are greatly reduced compared to their corresponding RH compounds. For example, the calculated LiCH2CH2–H bond dissociation energy is 74 kcal/mol as opposed to 100 kcal/mol for ethane. Why are these bonds so weak? What effect do substituents have on these bond energies? Will aggregates behave differently than monomeric species? Can these bifunctional radicals be used to advantage in synthetic chemistry? These issues and others will be addressed in this presentation.