Two-electron transfer to haloarenes constitutes one of the most reliable synthetic methodologies for the generation of aryllithiums. In addition to the conventional halides, readily available aryl ethers can function as potent substrates. However, it is known that the reductive cleavage of alkoxides is plagued by insufficient selectivity concerning the cleaving bond adjacent to the ether oxygen, resulting in decreased reliability of these alkoxyarene substrates. In the present study, we discovered that naphthalenes bearing readily installable -butyldimethylsilyl ethers undergo two-electron reduction with lithium metal, resulting in lithiation at the position of the original siloxy group. DFT calculations elucidated the rationale for the change in selectivity upon incorporation of the siloxy group. Our results underscore the practical utility of a siloxy group as a leaving group for reductive transformations involving electron transfer.
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http://dx.doi.org/10.1021/jacsau.4c00448 | DOI Listing |
Phys Chem Chem Phys
November 2024
Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education, Department of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
Carbenes are highly reactive intermediates central to various organic transformations, particularly within photochemistry. This study investigates siloxy carbenes generated from acyl silanes a 1,2-silyl shift, focusing on their generation and reactivity in excited states, using the multiconfiguration perturbation theory (CASPT2//CASSCF/PCM). Our findings reveal that the presence of an aryl group conjugated with the carbonyl moiety substantially lowers the excitation energy of the singlet nπ* state, enabling the 1,2-Brook rearrangement to proceed directly on the singlet hypersurface.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
State Key Laboratory of Organometallic Chemistry and Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, CAS, 345 Lingling Road, Shanghai, 200032, P. R. China.
The transition metal-catalyzed direct coupling reactions involving electron-rich Fischer carbene species are largely underdeveloped and remain a big challenge. Here, a direct coupling reaction of azoles and azine N-oxides is reported with Fischer copper carbene species bearing an α-siloxy group i, which can be in situ generated from acylsilanes catalytically under photoirradiation and redox-neutral conditions. This coupling reaction between electron-rich α-siloxy Fischer Cu-carbene species with hard carbanion nucleophiles may undergo a bimetallic relay process, which is confirmed by the kinetic analysis and in situ NMR analysis.
View Article and Find Full Text PDFJACS Au
August 2024
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
Two-electron transfer to haloarenes constitutes one of the most reliable synthetic methodologies for the generation of aryllithiums. In addition to the conventional halides, readily available aryl ethers can function as potent substrates. However, it is known that the reductive cleavage of alkoxides is plagued by insufficient selectivity concerning the cleaving bond adjacent to the ether oxygen, resulting in decreased reliability of these alkoxyarene substrates.
View Article and Find Full Text PDFOrg Lett
March 2024
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
The palladium-catalyzed addition of trifluoroacetylsilanes to alkenes and allenes via the cleavage of the C-Si bonds is reported. When alkenes are used, cyclopropanation occurs to afford cyclopropane derivatives bearing CF and siloxy groups with a high degree of stereoselectivity. When allenes are used, silylacylation occurs to form alkenylsilane derivatives bearing a trifluoroacetyl group at the allylic position with complete regioselectivity.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
May 2024
Key Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China.
Chiral trisubstituted vicinal diols are a type of important organic compounds, serving as both common structure units in bioactive natural products and chiral auxiliaries in asymmetric synthesis. Herein, by using siloxypropadienes as the precursors of allyl copper(I) species, a copper(I)-catalyzed diastereoselective and enantioselective reductive allylation of ketones was achieved, providing both syn-diols and anti-diols in good to excellent enantioselectivity. DFT calculations show that cis-γ-siloxy-allyl copper species are generated favorably with either 1-TBSO-propadiene or 1-TIPSO-propadiene.
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