title: How and Why Does Ni(0) Promote Smooth Etheric C-O Bond Cleavage and C-C Bond Formation? A Theoretical Study.
abstract: Ni-catalyzed cross-coupling between aryl alkyl ethers (ArOR) and Grignard reagents (RMgBr), known since 1979, proceeds under mild conditions in many cases. Although the reaction routes of various synthetic protocols involving transition-metal-catalyzed C-O bond activation have been elucidated, the mechanism of this etheric Kumada-Tamao-Curriu reaction remains enigmatic. This is because oxidative addition of inert etheric C-O to Ni(0) is thermodynamically and kinetically unfavorable, making it hard to explain the observed high reactivity of ether toward Ni catalysts. In this work, we used DFT calculations to identify a plausible reaction pathway by the Ni(0)-ate complex, which enables smooth C-O bond cleavage and R-group transfer with reasonable activation barriers; this mechanism also accounts for the ineffectiveness of Pd catalysts. These results throw new light on both C-O activation and cross-coupling, and should be valuable for further rational development of the methodologies.
authors: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo-to 113-0033 (Japan).|The Advanced Elements Chemistry Research Team, RIKEN CSRS and the Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama-ken, 351-0198 (Japan).
authors: Hiroyuki
authors: H
authors: Ogawa
authors: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo-to 113-0033 (Japan).|The Advanced Elements Chemistry Research Team, RIKEN CSRS and the Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama-ken, 351-0198 (Japan).
authors: Hiroki
authors: H
authors: Minami
authors: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo-to 113-0033 (Japan).|The Advanced Elements Chemistry Research Team, RIKEN CSRS and the Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama-ken, 351-0198 (Japan).
authors: Takashi
authors: T
authors: Ozaki
authors: The Advanced Elements Chemistry Research Team, RIKEN CSRS and the Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama-ken, 351-0198 (Japan).|Faculty of Pharmaceutical Science at Kagawa Campus, Tokushima Bunri University, 1314-1 Shido, Sanuki-shi, Kagawa-ken 769-2193 (Japan).
authors: Shinsuke
authors: S
authors: Komagawa
authors: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo-to 113-0033 (Japan). chaowang@mol.f.u-tokyo.ac.jp, chaowang@riken.jp.|The Advanced Elements Chemistry Research Team, RIKEN CSRS and the Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama-ken, 351-0198 (Japan). chaowang@mol.f.u-tokyo.ac.jp, chaowang@riken.jp.
authors: Chao
authors: C
authors: Wang
authors: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo-to 113-0033 (Japan). uchiyama@mol.f.u-tokyo.ac.jp, uchi_yama@riken.jp.|The Advanced Elements Chemistry Research Team, RIKEN CSRS and the Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama-ken, 351-0198 (Japan). uchiyama@mol.f.u-tokyo.ac.jp, uchi_yama@riken.jp.
authors: Masanobu
authors: M
authors: Uchiyama
keywords: DFT calculations; aryl alkyl ether; cross-coupling; nickel; reaction mechanism