Rh(III)-Catalyzed Oxidant-Free Dehydrogenative Mizoroki–Heck-Type Reaction: Identification of Off-Cycle Processes Potentially Limiting Catalytic Turnover
The Rh(III)-catalyzed dehydrogenative Mizoroki–Heck-type reaction (DMHR) has been extensively studied owing to its diverse synthetic applications. This transformation generally requires stoichiometric amounts of an external oxidant, H<sub>2</sub> acceptor, or internal oxidizing group for...
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| مؤلفون آخرون: | , , , |
| منشور في: |
2025
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| الملخص: | The Rh(III)-catalyzed dehydrogenative Mizoroki–Heck-type reaction (DMHR) has been extensively studied owing to its diverse synthetic applications. This transformation generally requires stoichiometric amounts of an external oxidant, H<sub>2</sub> acceptor, or internal oxidizing group for efficient catalytic turnover. By contrast, the oxidant-free DMHR involving the release of H<sub>2</sub> gas is an ideal method for minimizing waste; however, it remains underdeveloped. Here, we investigated the Rh(III)-catalyzed DMHR of 4-amino-2-quinolones under oxidant-free conditions. A combined experimental and computational study revealed that an off-cycle resting species, formed via the migratory insertion of an alkenylation product into a rhodium hydride species, was involved in the inhibition of catalytic turnover. The highly efficient oxidant-free DMHR of 4-amino-2-quinolones was achieved by excluding the coupling product from the reaction system to suppress the formation of the off-cycle resting species. Furthermore, we revisited the Rh(III)-catalyzed DMHR of aromatic substrates bearing different types of directing groups and demonstrated that substrates bearing representative directing groups such as amides, carbamates, carboxylic acids, 1-naphthol, indoles, pyridines, pyrimidines, and pyrazoles underwent alkenylation in the absence of an oxidizing agent. |
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