Organocatalyzed direct and asymmetric functionalization of benzylic C(sp3)-H bond is attractive yet challenging. Herein, we report the enantioselective acylation of benzylic C(sp3)-H bond via a cooperative photoredox and N-heterocyclic carbene (NHC) catalysis, affording the corresponding chiral α-aryl ketones in moderate to good yields with good to excellent enantioselectivities (up to 99:1 er). The rational design of novel NHCs guided by initial evaluation of available catalysts and their application promote the asymmetric transformation. Mechanistic experiments and density functional theory (DFT) calculations support the formation of benzyl radical and ketyl radical intermediates, and rationalize the coupling of these radical species via open-shell singlet transition states to be the enantiodetermining step. This redox neutral protocol features mild conditions, and free of transition-metals and pre-functionalized radical precursors.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/anie.202421151 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Recent advances in the copper-catalyzed aerobic C-H oxidation strategy.
Org Biomol Chem
April 2021
Center for Metareceptome Research, Graduate School of Pharmaceutical Sciences, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea.
The interplay between copper catalysts and molecular oxygen provides the opportunity to control the promiscuous catalytic behaviors in aerobic Csp3-H bond oxidations without using stoichiometric amounts of oxidants. This mini-review aims to cover the Cu-catalyzed aerobic benzylic and α-carbonyl Csp3-H oxidations and that of the carbon next to an amine group in the past five years. The development of tandem multicomponent reactions employing aerobic Csp3-H bond oxidations will be discussed to highlight the controlled catalyst behaviors and the catalyst interactions between multiple reaction components.
View Article and Find Full Text PDFCooperative Light-Activated Iodine and Photoredox Catalysis for the Amination of Csp3 -H Bonds.
Angew Chem Int Ed Engl
June 2017
Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain.
An unprecedented method that makes use of the cooperative interplay between molecular iodine and photoredox catalysis has been developed for dual light-activated intramolecular benzylic C-H amination. Iodine serves as the catalyst for the formation of a new C-N bond by activating a remote Csp3 -H bond (1,5-HAT process) under visible-light irradiation while the organic photoredox catalyst TPT effects the reoxidation of the molecular iodine catalyst. To explain the compatibility of the two involved photochemical steps, the key N-I bond activation was elucidated by computational methods.
View Article and Find Full Text PDFModular Approach to Reductive C(sp2)-H and C(sp3)-H Silylation of Carboxylic Acid Derivatives through Single-Pot, Sequential Transition Metal Catalysis.
J Org Chem
May 2015
Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, United States.
We report a modular approach to catalytic reductive Csp2-H and Csp3-H silylation of carboxylic acid derivatives encompassing esters, ketones, and aldehydes. Choice of either an Ir(I)/Rh(I) or Rh(I)/Rh(I) sequence leads to either exhaustive reductive ester or reductive ketone/aldehyde silylation, respectively. Notably, a catalyst-controlled direct formation of doubly reduced silyl ethers is presented, specifically via Ir-catalyzed exhaustive hydrosilylation.
View Article and Find Full Text PDFToward a synthetically useful stereoselective C-H amination of hydrocarbons.
J Am Chem Soc
January 2008
Institut de Chimie des Substances Naturelles, UPR 2301, CNRS, Avenue de la Terrasse, F-91198 Gif-sur-Yvette, France.
Reaction between a sulfur(VI) compound and an iodine(III) oxidant in the presence of a catalytic quantity (<=3 mol %) of a rhodium(II) catalyst leads to the formation of a chiral metallanitrene of unprecedented reactivity. The latter allows intermolecular C-H amination to proceed in very high yields up to 92% and excellent diastereoselectivities up to 99% with C-H bond containing starting materials as the limiting component. The scope of this C-H functionalization includes benzylic and allylic substrates as well as alkanes.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!