Markovnikov‐Selective Cobalt‐Catalyzed Wacker‐Type Oxidation of Styrenes into Ketones under Ambient Conditions Enabled by Hydrogen Bonding - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Angewandte Chemie International Edition Année : 2023

Markovnikov‐Selective Cobalt‐Catalyzed Wacker‐Type Oxidation of Styrenes into Ketones under Ambient Conditions Enabled by Hydrogen Bonding

Résumé

The replacement of palladium catalysts for Wacker‐type oxidation of olefins into ketones by first‐row transition metals is a relevant approach for searching more sustainable protocols. Besides highly sophisticated iron catalysts, all the other first‐row transition metal complexes have only led to poor activities and selectivities. Herein, we show that the cobalt‐tetraphenylporphyrin complex is a competent catalyst for the aerobic oxidation of styrenes into ketones with silanes as the hydrogen sources. Remarkably, under room temperature and air atmosphere, the reactions were exceedingly fast (up to 10 minutes) with a low catalyst loading (1 mol%) while keeping an excellent chemo‐ and Markovnikov‐selectivity (up to 99% of ketone). Unprecedently high TOF (864 h‐1) and TON (5,800) were reached for the oxidation of aromatic olefins under these benign conditions. Mechanistic studies suggest a reaction mechanism similar to the Mukaiyama‐type hydration of olefins with a change in the last fundamental step, which controls the chemoselectivity, thanks to a unique hydrogen bonding network between the ethanol solvent and the cobalt peroxo intermediate.

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Chimie
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Origine : Publication financée par une institution

Dates et versions

hal-04322780 , version 1 (06-12-2023)

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Naba Abuhafez, Andreas Ehlers, Bas de Bruin, Rafael Gramage-Doria. Markovnikov‐Selective Cobalt‐Catalyzed Wacker‐Type Oxidation of Styrenes into Ketones under Ambient Conditions Enabled by Hydrogen Bonding. Angewandte Chemie International Edition, 2023, ⟨10.1002/anie.202316825⟩. ⟨hal-04322780⟩
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