Photochemical enantioselective nickel‐catalyzed cross‐coupling reactions are difficult to implement. We report a visible‐light‐mediated strategy that successfully couples symmetrical anhydrides and 4‐alkyl dihydropyridines (DHPs) to afford enantioenriched α‐substituted ketones under mild conditions. The chemistry does not require exogenous photocatalysts. It is triggered by the direct excitation of DHPs, which act as a radical source and as a reductant, facilitating the turnover of the chiral catalytic nickel complex.
Some rights reserved. The terms and conditions for the reuse of this version of the manuscript are specified in the publishing policy. For all terms of use and more information see the publisher's website. This is the final peer-reviewed author's accepted manuscript (postprint) of the following publication:This item was downloaded from IRIS Università di Bologna (https://cris.unibo.it/).When citing, please refer to the published version.
Photochemical enantioselective nickel-catalyzed cross-coupling reactions are difficult to implement. We report avisible-light-mediated strategy that successfully couples symmetrical anhydrides and 4-alkyld ihydropyridines (DHPs) to afforde nantioenriched a-substituted ketones under mild conditions.T he chemistry does not require exogenous photocatalysts.Itistriggered by the direct excitation of DHPs,which act as ar adical source and as ar eductant, facilitating the turnover of the chiral catalytic nickel complex.Nickel catalysis has experienced great advances in the past decade,w ith valuable cross-coupling processes being developed to produce natural products,p olymers,a nd pharmaceuticals. [1] Recent efforts have also demonstrated how nickel-catalyzed cross-coupling strategies can be used to prepare chiral molecules. [2] Fore xample,t here are effective methods for achieving enantioconvergent carbon-carbon bond formation using racemic alkyl electrophiles and traditional [3] or reductive [4] cross-coupling processes ( Figure 1a). However,t hese methods require highly nucleophilic organometallic reagents or stoichiometric reductants,r espectively. This reduces their practicality.R ecently,t he combination of nickel catalysis and photoredox catalysis [5] has provided av ersatile tool to mitigate some of these issues (Figure 1b). This approach exploits the ability of visible-light-activated photocatalysts to generate,one xcitation, alkyl radicals upon single-electron transfer (SET) activation of low-energy, bench-stable substrates and under mild conditions. [6] Crucially,t he photoredox catalyst also modulates the oxidation state of nickel complexes by SET reduction, which is essential for catalyst turnover. Despite the potential practical advantages of this approach, only af ew asymmetric catalytic examples has been developed to date. [7] [*] Prof. Dr.P.Melchiorre ICREA Passeig LluísC ompanys 23,
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.