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J. Am. Chem. Soc. 2000, 122, 7294-7307
Mechanism of SN2 Alkylation Reactions of Lithium Organocuprate Clusters with Alkyl Halides and Epoxides. Solvent Effects, BF3 Effects, and Trans-Diaxial Epoxide Opening Seiji Mori,§,‡ Eiichi Nakamura,*,§ and Keiji Morokuma*,‡ Contribution from Department of Chemistry, The UniVersity of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan, and Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory UniVersity, Atlanta, Georgia 30322 ReceiVed January 19, 2000
Abstract: The B3LYP density functional studies on the mechanism of the SN2-substitution reaction of methyl halides and epoxides with lithium organocuprates(I), (CH3)2CuLi‚LiCl and [(CH3)2CuLi]2, revealed the energetics and the geometries of important transition states and intermediates along the reaction pathway. In the absence of solvent coordination on the copper atom, the reaction takes place in a single step through rate determining cleavage of the C-X bond (X ) leaving group) involving nucleophilic participation of the CH3-Cu bond composed of the copper 3dz2 orbital and carbon 2s+2p orbitals. Consideration of solvent polarity and coordination of an explicit (CH3)2O molecule to a lithium atom in the cuprate cluster lowers the activation energy to
