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. 2019 Mar 29;5(3):eaav9839.
doi: 10.1126/sciadv.aav9839. eCollection 2019 Mar.

Intermolecular dialkylation of alkenes with two distinct C(sp3)─H bonds enabled by synergistic photoredox catalysis and iron catalysis

Xuan-Hui Ouyang  1 , Yang Li  1 , Ren-Jie Song  1 , Ming Hu  1 , Shenglian Luo  1 , Jin-Heng Li  1   2   3
Affiliations

Intermolecular dialkylation of alkenes with two distinct C(sp3)─H bonds enabled by synergistic photoredox catalysis and iron catalysis

Xuan-Hui Ouyang et al. Sci Adv. .

Abstract

The functionalization of unactivated C(sp3)─H bonds represents one of the most powerful and most atom-economical tools for the formation of new carbon-based chemical bonds in synthesis. Although cross-dehydrogenative coupling reactions of two distinct C─H bonds for the formation of carbon-carbon bonds have been well investigated, controlled functionalizations of two or more different C(sp3)─H bonds across a functional group or a molecule (e.g., an alkene or alkyne) in a single reaction remain challenging. Here, we present a three-component dialkylation of alkenes with common alkanes and 1,3-dicarbonyl compounds via synergistic photoredox catalysis and iron catalysis for the synthesis of two functionalized 1,3-dicarbonyl compounds. Mechanistic studies suggest that the photoredox catalysis serves as a promotion system to allow the dialkylation to proceed under mild conditions by reducing the oxidation and reduction potentials of the iron intermediates and the reaction partners.

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Figures

Fig. 1
Fig. 1. 1,2-Dialkylation of alkenes with two distinct C(sp3)─H bonds.
Synergistic photoredox catalysis and iron catalysis for the intermolecular dialkylation of alkenes with alkanes and 1,3-dicarbonyl compounds to synthesize two functionalized 1,3-dicarbonyl compounds.
Fig. 2
Fig. 2. Control experiments.
(A) Loadings of Eosin Y on the reaction. (B) Trapping experiment with a stoichiometric amount of radical inhibitor. (C) Reaction between alkene 1a and cyclohexane 2a in the absence of dicarbonyl compounds.
Fig. 3
Fig. 3. Possible mechanism.
The generation of cyclohexyl sp3-hybridized carbon-centered radical A and new alkyl radical intermediate B is supported by experimental evidence, and subsequent single-electron oxidation and nucleophilic reaction with 1,3-keto ester 3a afford 4aaa.
See this image and copyright information in PMC

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