We report the development of a new class of guanidine-containing peptides as multifunctional ligands for transition-metal catalysis and its application in the remote desymmetrization of diarylmethanes via copper-catalyzed Ullman cross-coupling. Through design of these peptides, high levels of enantioinduction and good isolated yields were achieved in the long-range asymmetric cross-coupling (up to 93:7 er and 76% yield) between aryl bromides and malonates. Our mechanistic studies suggest that distal stereocontrol is achieved through a Cs-bridged interaction between the Lewis-basic C-terminal carboxylate of the peptides with the distal arene of the substrate.
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http://dx.doi.org/10.1021/jacs.6b03444 | DOI Listing |
Angew Chem Int Ed Engl
October 2024
Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
Chiral tetrasubstituted allenes have emerged as important architectures for engineering biologically active compounds. The construction of unique tetrasubstituted allene scaffolds with precise control of continuous central and axial chirality remains yet to be developed. Here, we report a remote enantioselective ϵ-alkylation of yne-propargylic acetates with enals enabled by NHC and copper cooperative catalysis, leading to a series of tetrasubstituted allenes with excellent enantioselectivities (up to >99 % ee) and diastereoselectivities (up to >95 : 5 dr).
View Article and Find Full Text PDFAcc Chem Res
July 2024
Department of Chemistry, University of California─Davis, 1 Shields Avenue, Davis, California 95616, United States.
ConspectusRhL catalysts have risen in popularity in the world of organic synthesis, being used to accomplish a variety of reactions, including C-H insertion and cyclopropanation, and often doing so with high levels of stereocontrol. While the mechanisms and origins of selectivity for such reactions have been examined with computational quantum chemistry for decades, only recently have detailed pictures of the dynamic behavior of reacting RhL-complexed molecules become accessible. Our computational studies on RhL catalyzed reactions are described here, with a focus on C-H insertion reactions of RhL-carbenes.
View Article and Find Full Text PDFJ Am Chem Soc
August 2023
Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Synthetic application of asymmetric catalysis relies on strategic alignment of bond construction to creation of chirality of a target molecule. Remote desymmetrization offers distinctive advantages of spatial decoupling of catalytic transformation and generation of a stereogenic element. However, such spatial separation presents substantial difficulties for the chiral catalyst to discriminate distant enantiotopic sites through a reaction three or more bonds away from a prochirality center.
View Article and Find Full Text PDFJ Am Chem Soc
July 2023
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, Shaanxi 710072, China.
Novel-substituted pyrrolidine derivatives are widely used in drugs and bioactive molecules. The efficient synthesis of these valuable skeletons, especially enantiopure derivatives, is still recognized as a key bottleneck to overcome in chemical synthesis. Herein, we report a highly efficient catalyst-tuned regio- and enantioselective hydroalkylation reaction for the divergent synthesis of chiral C2- and C3-alkylated pyrrolidines through desymmetrization of the readily available 3-pyrrolines.
View Article and Find Full Text PDFChem Sci
May 2023
Department of Industrial Chemistry 'Toso Montanari', University of Bologna 40136 Bologna Italy
Herein, we report a photochemical organocatalytic method for the asymmetric introduction of perfluoroalkyl fragments (including the valuable trifluoromethyl moiety) at the remote γ-position of α-branched enals. The chemistry exploits the ability of extended enamines (dienamines) to form photoactive electron donor-acceptor (EDA) complexes with perfluoroalkyl iodides, which under blue light irradiation generate radicals through an electron transfer mechanism. The use of a chiral organocatalyst, derived from -4-hydroxy-l-proline, secures a consistently high stereocontrol while inferring complete site selectivity for the more distal γ position of the dienamines.
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