In recent years, remarkable progress has been described in the development of methods that simultaneously control vicinal stereochemistry, wherein both stereochemical elements are central chirality; in contrast, methods that control central and axial chirality are comparatively rare. Herein we report that a chiral nickel catalyst achieves the enantioconvergent and diastereoselective coupling of racemic secondary alkyl electrophiles with prochiral 1,3-enynes (in the presence of a hydrosilane) to generate chiral tetrasubstituted allenes that bear an adjacent stereogenic center. A carbon-carbon and a carbon-hydrogen bond are formed in this process, which provides good stereoselectivity and is compatible with an array of functional groups.
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http://dx.doi.org/10.1021/jacs.4c00593 | DOI Listing |
JACS Au
November 2024
Department of Organic Chemistry, Indian Institute of Science, Bangalore560012, India.
Compared to the widely explored enol silanes, the applicability of their extended variants especially as bisvinylogous nucleophiles in enantioselective catalysis has been sparse. Herein, we describe the first enantioselective vinylogous and bisvinylogous allenylic substitution using silyl dienol and trienol ethers, respectively, as a nucleophile. With racemic allenylic alcohols as the electrophile, these enantioconvergent reactions are cooperatively catalyzed by an Ir(I)/(phosphoramidite,olefin) complex and Lewis acidic La(OTf) and display remarkable regio- and diastereoselectivity in most cases.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, 350207, Fuzhou, China.
We present herein a catalytic enantioconvergent diamination of racemic allylic alcohols with the construction of two C-N bonds and 1,3-nonadjacent stereocenters. This iridium/chiral phosphoric acid cooperative catalytic system operates through an atom-economical borrowing hydrogen amination/aza-Michael cascade, and converts readily available phenylenediamines and racemic allylic alcohols to 1,5-tetrahydrobenzodiazepines in high enantioselectivity. An intriguing solvent-dependent switch of diastereoselectivity was also observed.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, 310024, Hangzhou, China.
Transition metal-catalyzed radical-based enantioconvergent reactions have become a powerful strategy to synthesize enantiopure compounds from racemic starting materials. However, existing methods primarily address precursors with central chirality, neglecting those with axial chirality. Herein, we describe the enantioconvergent reductive coupling of racemic allenes with aldehydes, facilitated by a photoredox, chromium, and cobalt triple catalysis system.
View Article and Find Full Text PDFChem Sci
August 2024
Frontiers Science Center for Flexible Electronics (FSCFE), Shaanxi Institute of Flexible Electronics (SIFE), Shaanxi Institute of Biomedical Materials and Engineering (SIBME), Northwestern Polytechnical University (NPU) 127 West Youyi Road Xi'an 710072 China
An efficient and highly enantioconvergent and diastereoselective ternary catalysis in a one-pot process is reported, which represents an integrated strategy for the synthesis of atropisomeric hydrazides with defined vicinal central and axial chirality from readily available racemic α-amino-ynones, azodicarboxylates, and Morita-Baylis-Hillman (MBH) carbonates. This method utilizes -generated racemic pyrrolin-4-ones hydroamination of racemic α-amino-ynones by AuCl catalysis as a novel and versatile C1 synthon, which engage commercially available azodicarboxylates to generate amination products in high yields and uniformly excellent enantioselectivities under the catalysis of a chiral phosphoric acid. Following amination, -alkylation catalyzed by diastereoselective organocatalyst afforded axially chiral hydrazides with excellent diastereoselectivities (>98 : 2 dr).
View Article and Find Full Text PDFJ Am Chem Soc
March 2024
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
In recent years, remarkable progress has been described in the development of methods that simultaneously control vicinal stereochemistry, wherein both stereochemical elements are central chirality; in contrast, methods that control central and axial chirality are comparatively rare. Herein we report that a chiral nickel catalyst achieves the enantioconvergent and diastereoselective coupling of racemic secondary alkyl electrophiles with prochiral 1,3-enynes (in the presence of a hydrosilane) to generate chiral tetrasubstituted allenes that bear an adjacent stereogenic center. A carbon-carbon and a carbon-hydrogen bond are formed in this process, which provides good stereoselectivity and is compatible with an array of functional groups.
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