Disclosed herein is a novel, redox-neutral protocol for the visible-light-induced radical alkynylation of unactivated olefins. The intramolecular migration of an alkynyl group, by cleaving an inert C-C σ bond, is realized for the first time. A wide range of synthetically useful trifluoroethylated linear alkynes are readily obtained under mild reaction conditions.
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http://dx.doi.org/10.1002/anie.201700413 | DOI Listing |
Chemistry
November 2024
Frontiers Science Center for Transformative Molecules, Zhangjiang Institute for Advanced Study, and Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
The daunting challenges in converting alcoholic O-H bonds with high bond-dissociation energy (BDE) to alkoxy radicals and harnessing those unruly reaction species largely limit exploiting free alcohols in C(sp)-H functionalization. Herein we describe a novel radical alkynylation and allylation of unactivated C(sp)-H bonds with unmodified aliphatic alcohols. The use of phenyliodine bis(trifluoroacetate) (PIFA) enables the formation of alkoxy radicals under mild photochemical conditions.
View Article and Find Full Text PDFChemistry
November 2024
College of Chemistry and Chemical Engineering, Henan University, Kaifeng, 475004, P.R. China.
Polyfluoroaryl ethers represent an important framework of biologically active molecules and materials. Owing to the strong bond dissociation energy of C-F bond, selectivity and other issues, transition metal-catalyzed synthesis of polyfluoroaryl ethers from perfluoroarenes via the activation of C-F bond is challenging and underdeveloped, as compared to the well-documented C-O bond formation starting from aryl iodides, aryl bromides or aryl chlorides. Herein, an unprecedented Pd-catalyzed defluorinative etherification for the synthesis of polyfluoroaryl ether skeletons using hydrobenzoxazoles as phenol surrogate, has been reported.
View Article and Find Full Text PDFChem Commun (Camb)
August 2024
Department of Chemistry, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
A novel deoxygenative alkynylation of amides promoted by a synergistic action of a divalent rare-earth element and a transition metal has been developed. In this method, α-alkynyl substituted amines are synthesized from unactivated amides and alkynes in a single transformation. Broad substrate scope and excellent selectivity for CO cleavage has been demonstrated.
View Article and Find Full Text PDFJ Am Chem Soc
June 2024
Tianjin Key Laboratory of Structure and Performance for Functional Molecules, College of Chemistry, Tianjin Normal University, Tianjin 300387, P. R. China.
Enantioselective three-component difunctionalization of alkenes with boron reagents represents an attractive strategy for assembling three-dimensional chiral organoboron compounds. However, regio- and enantiocontrol comprise the pivot challenges in these transformations, which predominantly require the use of activated conjugated alkenes. Herein, by utilizing various carbonyl directing groups, including amides, sulfinamides, ketones, and esters, we succeed in realizing a nickel-catalyzed 1,2-borylalkynylation of unactivated alkenes to enable the simultaneous incorporation of a boron entity and an sp-fragment across the double bond.
View Article and Find Full Text PDFNat Commun
May 2024
Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, China.
Herein, we disclose a highly efficient cobalt-catalyzed cross-electrophile alkynylation of a broad range of unactivated chlorosilanes with alkynyl sulfides as a stable and practical alkynyl electrophiles. Strategically, employing easily synthesized alkynyl sulfides as alkynyl precursors allows access to various alkynylsilanes in good to excellent yields. Notably, this method avoids the utilization of strong bases, noble metal catalysts, high temperature and forcing reaction conditions, thus presenting apparent advantages, such as broad substrate scope (72 examples, up to 97% yield), high Csp-S chemo-selectivity and excellent functional group compatibility (Ar-X, X = Cl, Br, I, OTf, OTs).
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