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Updated: Apr 8, 2026

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Published on: July 27, 2022
Rh(III) -catalyzed C(sp(3))-H bond activation by an external base metalation/deprotonation mechanism: a theoretical
Julong Jiang1, Romain Ramozzi1, Keiji Morokuma2
1Fukui Institute for Fundamental Chemistry, Kyoto University, Takano-Nishihiraki-cho 34-4, Kyoto 606-8103 (Japan).
Abstract:
The C(sp(3) )H bond activation of 8-methylquinoline followed by alkyne insertion catalyzed by a Rh(III) complex has been studied by using density functional theory (DFT) calculations. Contrary to common belief, the CH bond activation of methylquinoline does not occur by the traditional intramolecular concerted metalation/deprotonation (CMD) mechanism but by an external base CMD mechanism. The use of free acetate or copper(II) acetate as base permits the CH activation step, as observed experimentally. However, the following insertion is possible only if copper(II) acetate is used. The insertion followed by metathesis occurs via a cationic Rh(III) complex and is irreversible, which ensures the efficiency of the entire process. Therefore the use of copper is crucial for completing the catalytic cycle. The present work should help to rationalize the origins of the experimental results described in the literature.
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