Dehydrogenative Silylation of Alkenes for the Synthesis of Substituted Allylsilanes by Photoredox, Hydrogen‐Atom Transfer, and Cobalt Catalysis

Yu, Wancong; Luo, Yong‐Chun; Yan, Lei; Liú, Dan; Wang, Zhu‐Yin; Xu, Peng‐Fei

doi:10.1002/ange.201904707

Cited by 14 publications

(6 citation statements)

References 72 publications

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“…The direct alkenylation of aldehydes represents a highly attractive and sustainable strategy for the synthesis of this important family of compounds. We were excited to find that various primary and secondary aldehydes were effective substrates under the optimal alkenylation conditions, providing α,β-unsaturated ketones in decent yields with exclusive E selectivity (33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43). Notably, excellent site selectivity was observed for aldehyde C-H bonds, while other activated C-H bonds, such as benzylic (34), allylic (38), propargylic (39) and α-heteroatom C-H bonds (42 and 43), were not functionalized.…”

Section: Resultsmentioning

confidence: 99%

“…In this context, we were inspired by direct hydrogen atom transfer (HAT) photocatalysts that could achieve the straightforward activation of C-H bonds 33 decatungstate anion ([W 10 O 32 ] 4− ), a polyoxometalate photocatalyst that has been broadly applied in various functionalizations of alkanes and aldehydes [34][35][36][37][38][39] . On the other hand, photocatalytic dehydrogenative cross-coupling reactions with concomitant hydrogen evolution have recently been developed through cooperative photoredox and cobaloxime catalysis, as pioneered by the Wu and Lei groups [40][41][42][43][44] . Inspired by these studies, we proposed that the combination of decatungstate anion and a cobaloxime catalyst could enable the direct activation and alkenylation of alkanes and aldehydes using alkenes as the feedstocks.…”

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confidence: 99%

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Photoinduced site-selective alkenylation of alkanes and aldehydes with aryl alkenes

et al. 2020

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The dehydrogenative alkenylation of C-H bonds with alkenes represents an atom-and stepeconomical approach for olefin synthesis and molecular editing. Site-selective alkenylation of alkanes and aldehydes with the C-H substrate as the limiting reagent holds significant synthetic value. We herein report a photocatalytic method for the direct alkenylation of alkanes and aldehydes with aryl alkenes in the absence of any external oxidant. A diverse range of commodity feedstocks and pharmaceutical compounds are smoothly alkenylated in useful yields with the C-H partner as the limiting reagent. The late-stage alkenylation of complex molecules occurs with high levels of site selectivity for sterically accessible and electron-rich C-H bonds. This strategy relies on the synergistic combination of direct hydrogen atom transfer photocatalysis with cobaloxime-mediated hydrogen-evolution cross-coupling, which promises to inspire additional perspectives for selective C-H functionalizations in a green manner.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Photoinduced site-selective alkenylation of alkanes and aldehydes with aryl alkenes

et al. 2020

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“…However, the substrates were invariably limited to phenylsilanes or (TMS) 3 SiH with labile Si-H bonds (Scheme 1b). 11,[29][30][31][32][33][34][35] As pioneered by Fagnoni et al, 36 decatungstate was found to be an effective hydrogen atom transfer (HAT) photocatalyst for aromatic tertiary silanes activation (Scheme 1c). Nevertheless, only poor selectivities were observed for trialkylsilanes owing to the comparably high bond dissociation energies (BDEs) of Si-H and α-Si-C-H bonds (>92 kcal mol −1 ).…”

Section: Introductionmentioning

confidence: 99%

Electrophotocatalytic Si–H Activation Governed by Polarity-Matching Effects

Jiang

Zeng

2022

CCS Chem

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Trialkylsilanes are important building blocks in organic synthesis; however, their widespread use in redox chemistry is limited by their high oxidation potentials and comparably high bond dissociation energies (BDEs) of Si-H and α-Si-C-H bonds (>92 kcal mol −1 ). Herein, we report a new strategy for Si-H bond homolysis enabled by the synergistic combination of electrooxidation, photoinduced ligand-to-metal charge transfer (LMCT), and radical-mediated hydrogen atom transfer (HAT). Governed by the polarity-matching effect, the HAT to electrophilic MeO• or [Cl-OHCH 3 ]• from the more hydridic Si-H instead of a C-H bond allows the selective generation of silyl radicals. This electrophotocatalytic protocol provides rapid access to Si-functionalized benzimidazo-fused isoquinolinones with broad functional-group compatibility. Mechanistic studies have shown that n-Bu 4 NCl is essential to the electrooxidation of CeCl 3 to form the Ce (IV) species.

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“…It is proposed that overoxidation of the products is inhibited by a rapid electron back transfer between the product and the photocatalyst. Other challenging dehydrogenative bond-forming reactions (e.g., C-N [64-66], C-O [64,67-69], C-P [70-72], C-S [62,73], C-Si[74]) by CCHE have also been reported, providing further evidence for the versatility of this strategy to construct C-heteroatom bonds.…”

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confidence: 99%