Palladium-catalyzed and ligand-enabled C-H functionalization methods have emerged as a powerful approach for the preparation of therapeutically important motifs and complex natural products. Olefins, owing to their natural abundance, have been extensively employed for the formation of C-C and C-X bonds and the generation of various heterocycles. Traditionally, activated as well as starting materials with preinstalled functional groups, and also halide substrates under transition metal catalysis, have been employed for olefin difunctionalization. However, strategies for employing unactivated C-H bond functionalization to achieve alkene difunctionalization have rarely been explored. A possible solution to this challenge is the application of bulky ligands which enhances the reductive elimination pathway and inhibits β-hydride elimination to selectively yield difunctionalized alkene products. This feature article summarizes the utilization of unreactive C-H bonds in the Pd-catalyzed and ligand-enabled difunctionalization of alkenes.
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http://dx.doi.org/10.1039/d1cc04397h | DOI Listing |
Org Lett
December 2024
Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China.
Highly enantioselective allylic amination and alkylation of racemic sterically hindered aryl-substituted Morita-Baylis-Hillman (MBH) adducts have been achieved by using an in situ formed Pd-catalyst from an axially chiral phenanthroline ligand. This dynamic kinetic asymmetric transformation (DYKAT) is compatible with cyclic and acyclic secondary amines, dialkyl malonates, β-keto esters, acetylacetone, and malononitrile, affording the corresponding chiral products, such as β-amino acid esters, in up to 95% yield and with up to a 99:1 enantiomeric ratio.
View Article and Find Full Text PDFJ Am Chem Soc
September 2024
Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China.
The synthesis of complex polysubstituted aromatic molecules from simple precursors is a central goal in organic chemistry. In this study, we developed an approach for the -alkylation of iodoarenes utilizing a dual ligand catalytic system. By combining Pd/olefin ligand cooperative catalysis with bulky trialkylphosphine ligand-promoted C(sp)-I reductive elimination, we have established an -alkylative Catellani-type reaction with the aryl-iodine bond reconstruction as the final step, which opens new synthetic opportunities within the Catellani-type reactions.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
The development of simplified synthetic strategy to create structurally and functionally diverse pseudo-natural macrocyclic molecules is highly appealing but poses a marked challenge. Inspired by natural scaffolds, herein, we describe a practical and concise ligand-enabled Pd(II)-catalyzed sp C-H alkylation, olefination and arylation macrocyclization, which could offer a novel set of pseudo-natural macrocyclic sulfonamides. Interestingly, the potential of ligand acceleration in C-H activation is also demonstrated by an unprecedented enantioselective sp C-H alkylation macrocyclization.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2024
Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Pd(II)-catalyzed enantioselective C-H activation has emerged as a versatile platform for constructing point, axial, and planar chirality. Herein, we present an unexpected discovery of a Pd-catalyzed enantioselective cascade β,γ-methylene C(sp)-H diarylation of free carboxylic acids using bidentate chiral mono-protected amino thioether ligands (MPAThio), enabling one-step synthesis of a complex chiral 9,10-dihydrophenanthrene scaffolds with high enantioselectivity. In this process, two methylene C(sp)-H bonds and three C(sp)-H bonds were activated, leading to the formation of four C-C bonds and three chiral centers in one pot.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
April 2023
Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China.
Amide is one of the most widespread functional groups in organic and bioorganic chemistry, and it would be valuable to achieve stereoselective C(sp )-H functionalization in amide molecules. Palladium(II) catalysis has been prevalently used in the C-H activation chemistry in the past decades, however, due to the weakly-coordinating feature of simple amides, it is challenging to achieve their direct C(sp )-H functionalization with enantiocontrol by Pd catalysis. Our group has developed sulfoxide-2-hydroxypridine (SOHP) ligands, which exhibited remarkable activity in Pd-catalyzed C(sp )-H activation.
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