14381-42-1Relevant articles and documents
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House,H.O.,Frank,G.A.
, p. 2948 - 2956 (1965)
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Catalytic α-Deracemization of Ketones Enabled by Photoredox Deprotonation and Enantioselective Protonation
Chen, Shuming,Gao, Anthony Z.,Ivlev, Sergei I.,Meggers, Eric,Nie, Xin,Ye, Chen-Xi,Zhang, Chenhao
supporting information, p. 13393 - 13400 (2021/09/03)
This study reports the catalytic deracemization of ketones bearing stereocenters in the α-position in a single reaction via deprotonation, followed by enantioselective protonation. The principle of microscopic reversibility, which has previously rendered this strategy elusive, is overcome by a photoredox deprotonation through single electron transfer and subsequent hydrogen atom transfer (HAT). Specifically, the irradiation of racemic pyridylketones in the presence of a single photocatalyst and a tertiary amine provides nonracemic carbonyl compounds with up to 97% enantiomeric excess. The photocatalyst harvests the visible light, induces the redox process, and is responsible for the asymmetric induction, while the amine serves as a single electron donor, HAT reagent, and proton source. This conceptually simple light-driven strategy of coupling a photoredox deprotonation with a stereocontrolled protonation, in conjunction with an enrichment process, serves as a blueprint for other deracemizations of ubiquitous carbonyl compounds.
Mechanistic Investigation of the Nickel-Catalyzed Carbonylation of Alcohols
Comba, Peter,Ghosh, Tamal,Hashmi, A. Stephen K.,Krieg, Saskia,Menche, Maximilian,Paciello, Rocco,Rück, Katharina S. L.,Sabater, Sara,Sch?fer, Ansgar,Schaub, Thomas
supporting information, (2020/03/19)
The carbonylation of alcohols represents a straightforward and atom-efficient methodology for the preparation of carboxylic acids. It is desirable to perform these reactions under precious metal-free and low-pressure conditions, with regioselectivity control. In this work, we present a detailed mechanistic study of a catalytic system based on NiI2, which can carbonylate benzylic alcohols in a highly regioselective manner to the corresponding branched carboxylic acids, core motifs for nonsteroidal drugs. The combination of catalytic amounts of nickel and iodide is crucial for efficient catalytic and regioselective conversion. Quantum-chemical computations were used to evaluate the underlying mechanistic processes. They revealed that a combination of two mechanisms is responsible for the observed reactivity and that the oxidative addition of alkyl halides to the Ni(0) species follows a radical oxidation pathway via two one-electron steps.
Electrogenerated Sm(II)-Catalyzed CO2 Activation for Carboxylation of Benzyl Halides
Bazzi, Sakna,Schulz, Emmanuelle,Mellah, Mohamed
supporting information, p. 10033 - 10037 (2019/12/24)
Sm(II)-catalyzed carboxylation of benzyl halides is reported through the electrochemical reduction of CO2. The transformation proceeds under mild reaction conditions to afford the corresponding phenylacetic acids in good to excellent yields. This user-friendly and operationally simple protocol represents an alternative to traditional strategies, which usually proceeds through the C(sp3)-halide activation pathway.