title: The molecular mechanism of palladium-catalysed cyanoesterification of methyl cyanoformate onto norbornene.
abstract: Potential energy surface mapping was completed for the entire catalytic cycle of palladium-catalysed cyanoesterification onto norbornene (NBE) using density functional theory calculations. We found that after the oxidative addition step of the reagent methyl cyanoformate, the reaction proceeds through an insertion of olefin into a Pd(II)-COOMe bond first. Subsequently, reductive elimination occurs by transferring the cyanide group from the Pd center to NBE. This rearrangement is triggered by the rotation of the ester group into a π-interaction with the Pd(II) centre. The regioselectivity of olefin insertion is controlled by ionic and covalent interactions in the precursor π-complex formation step. Importantly, all of the intermediates and transition states along the exo pathway were found to be more stable than the corresponding structures of the endo pathway without any sign of crossing over between the two surfaces via isomerization. The rate-determining step is the reductive elimination despite the fact that the corresponding activation barrier is reduced by conformational changes via the rotation of a MeOOC-C(NBE) bond.
authors.affiliation: Faculty of Science, Ibaraki University, 2-1-1, Bunkyo, Mito, Ibaraki 310-8512, Japan. smori@mx.ibaraki.ac.jp.
authors.forename: Takuya
authors.initials: T
authors.lastname: Ishitsuka
authors.affiliation: Division of Earth, Life, and Molecular Sciences, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan. ynishiha@okayama-u.ac.jp.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Okuda
authors.affiliation: Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA and MTA-ELTE Chemical Structure & Function "Momentum" Laboratory, Budapest, Hungary.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Szilagyi
authors.affiliation: Faculty of Science, Ibaraki University, 2-1-1, Bunkyo, Mito, Ibaraki 310-8512, Japan. smori@mx.ibaraki.ac.jp and Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, 2-1-1, Bunkyo, Mito, Ibaraki 310-8512, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Mori
authors.affiliation: Division of Earth, Life, and Molecular Sciences, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan. ynishiha@okayama-u.ac.jp.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nishihara