In contrast to the widely explored methods for the asymmetric synthesis of molecules bearing a single stereocenter or adjacent stereocenters, the concurrent construction of 1,3-stereogenic centers in an enantio- and diastereoselective manner remains a challenge, especially in acyclic systems. Herein, we report an enantio- and diastereodivergent construction of 1,3-nonadjacent stereocenters bearing allenyl axial and central chirality through synergistic Pd/Cu-catalyzed dynamic kinetic asymmetric allenylation with racemic allenylic esters. The protocol is suitable for a wide range of substrates including the challenging allenylic esters with less sterically bulky substituents and provided chiral allenylic products bearing 1,3-nonadjacent stereocenters with high levels of enantio- and diastereoselectivities (up to >20:1 dr and >99% ee). Furthermore, several representative transformations involving axial-to-central chirality transfer were conducted, affording useful structural motifs containing nonadjacent stereocenters in a diastereodivergent manner.
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http://dx.doi.org/10.1021/jacs.1c05087 | DOI Listing |
Chemistry
January 2025
Indian Institute of Technology Kharagpur, Chemistry, Paschim Midnapore, 721302, Kharagpur, INDIA.
All-carbon quaternary and tertiary stereocenters connected at the C2-position of functionalizable C3-alkylated indole nucleus are commonly occurring frameworks found in many indole alkaloids of medicinal importance. Their direct access is scarcely reported, a long-standing problem, and developing a unique yet simple method can pave the pathway to an entirely different retrosynthetic route for the total synthesis of these alkaloids. Herein, this problem is addressed by developing an unprecedented branch-selective allylation strategy employing a broad range of structurally and electronically different 3-alkenyl-indoles and allylboronic acids.
View Article and Find Full Text PDFOrg Biomol Chem
January 2025
Department of Chemistry, College of Sciences, Tianjin University of Science and Technology, Tianjin 300457, People's Republic of China.
A sequential [3 + 2]/[2 + 1] annulation reactions of benzimidazole- and indole-derived acrylonitriles with vinylsulfonium salts have been developed for the first time, and shown to provide in yields of 32 to 98% a series of azabicyclo[3.1.0]hexanes containing each a cyano-substituted tetrasubstituted carbon stereocenter with >20 : 1 dr.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Advanced Catalysis Research Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Nat Commun
December 2024
Key Laboratory of Phytochemistry and Natural Medicines, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China.
The functionalized polycycle with densely contiguous tertiary stereocenters is a formidable challenge in synthesizing the parvistemoline family of Stemona alkaloids. We herein report their catalytic, asymmetric total syntheses in 13-14 steps from commercially available 2-(methoxycarbonyl)-pyrrole, featuring the development and deployment of an Ir/Pd-synergistically-catalyzed allylation of α-non-substituted keto esters with secondary aryl-substituted alcohols, stereodivergently accessible to four stereoisomers. Using chiral Pd-enolate and Ir π-allyl complex under neutral conditions, no epimerization occurs.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
State Key Laboratory of Structural Chemistry, Center for Excellence in Molecular Synthesis, Fujian Institute of Research on the Structure of Matter, University of Chinese Academy of Sciences, Fuzhou 350100, China.
Catalytic asymmetric transformation of donor-acceptor cyclopropanes (DACs) has been proven to be a highly valuable and robust strategy to construct diverse types of enantioenriched molecules. However, the use of 1,1,2,2-tetrasubstituted DACs to form products bearing quaternary stereocenters remains a long-term unsolved challenge. Here, we report the copper-catalyzed asymmetric aminative ring opening of tetrasubstituted alkynyl DACs that delivers a myriad of α-tertiary amines with high levels of enantioselectivities.
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