Design, Generation, and Synthetic Application of Borylzincate: Borylation of Aryl Halides and Borylzincation of Benzynes/Terminal Alkyne
Yuki Nagashima, Ryo Takita*, Kengo Yoshida, Keiichi Hirano and Masanobu Uchiyama*
*Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Email: takitamol.f.u-tokyo.ac.jp, uchiyamamol.f.u-tokyo.ac.jp
Y. Nagashima, R. Takita, K. Yoshida, K. Hirano, M. Uchiyama, J. Am. Chem. Soc., 2013, 135, 18730-18733.
DOI: 10.1021/ja409748m (free Supporting Information)
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Borylzincate can be generated in situ from dialkylzinc, diboron, and metal alkoxide. Model DFT calculations show that although the formation of borylzincate is kinetically favorable, it is thermodynamically unfavorable. A successive reaction sequence, that provides a compensating energy gain, therefore enables Zn-catalyzed borylation of aryl halides and borylzincation of benzynes and terminal alkyne from diborons without the need for any cocatalyst.
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