Improvement in the Palladium-Catalyzed Miyaura Borylation Reaction by Optimization of the Base: Scope and Mechanistic Study
Santiago Barroso, Markus Joksch, Pim Puylaert, Sergey Tin, Stephen J. Bell, Luke Donnellan, Stewart Duguid, Colin Muir, Peichao Zhao, Vittorio Farina, Duc N. Tran* and Johannes G. de Vries*
*Janssen Pharmaceutica, 2340 Beerse, Belgium; Universität Rostock, Albert-Einstein-Straße 29a, 18059 Rostock, Germany, Email: ntran25its.jnj.com, johannes.devriescatalysis.de
S. Barroso, M. Joksch, P. Puylaert, S. Tin, S. J. Bell, L. Donnellan, S. Duguid, C. Muir, P. Zhao, V. Farina, D. N. Tran, J. G. de Vries, J. Org. Chem., 2021, 86, 103-109.
DOI: 10.1021/acs.joc.0c01758 (free Supporting Information)
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By using lipophilic bases such as potassium 2-ethyl hexanoate, the palladium-catalyzed Suzuki-Miyaura borylation of a wide range of substrates could be achieved at 35°C in less than 2 h with very low catalyst loading. A mechanistic study shows a hitherto unrecognized inhibitory effect by the acetate anion on the catalytic cycle, whereas use of bulky 2-ethyl hexanoate minimizes this inhibitory effect.
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Inhibitory effect of acetate