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[ASAP] Enantioselective Synthesis of γ-Oxycarbonyl Motifs by Conjugate Addition of Photogenerated α-Alkoxy Radicals
[ASAP] Iron-Catalyzed Enantioselective Radical Carboazidation and Diazidation of α,β-Unsaturated Carbonyl Compounds
MRVLigands Fe(II)
[ASAP] α-Heteroarylation of Thioethers via Photoredox and Weak Brønsted Base Catalysis
MRVComme azote
Convenient C(sp3)–H bond functionalisation of light alkanes and other compounds by iron photocatalysis
DOI: 10.1039/D1GC01563J, Paper
A practical and green iron-catalyzed photoredox system for C–H functionalization of ethane, propane, and other light alkanes was developed.
The content of this RSS Feed (c) The Royal Society of Chemistry
[ASAP] Direct C(sp3)–H Cyanation Enabled by a Highly Active Decatungstate Photocatalyst
[ASAP] Mechanism of Electrochemical Generation and Decomposition of Phthalimide-N-oxyl
[ASAP] Ni-Catalyzed Aryl Sulfide Synthesis through an Aryl Exchange Reaction
Dynamic parallel kinetic resolution of α-ferrocenyl cation initiated by chiral Brønsted acid catalyst
DOI: 10.1039/D1SC02122B, Edge Article
The dynamic parallel kinetic resolution (DPKR) of an enantiomeric α-ferrocenyl cation using a chiral phosphate anion of an acid catalyst was accomplished by the combination of the PKR and the racemization through the formation of vinylferrocene.
The content of this RSS Feed (c) The Royal Society of Chemistry
[ASAP] Enantioselective Intermolecular C–H Amination Directed by a Chiral Cation
[ASAP] State-of-the-Art Biocatalysis
[ASAP] Synthesis of 3,3-Dialkyl-Substituted Isoindolinones Enabled by Nickel-Catalyzed Reductive Dicarbofunctionalization of Enamides
[ASAP] Biocompatible Photoinduced Alkylation of Dehydroalanine for the Synthesis of Unnatural α-Amino Acids
[ASAP] Pd-Catalyzed Etherification of Nitroarenes
[ASAP] Oxidative Cleavage of Alkenes by O2 with a Non-Heme Manganese Catalyst
Electrooxidative dearomatization of biaryls: synthesis of tri- and difluoromethylated spiro[5.5]trienones
DOI: 10.1039/D1SC02682H, Edge Article
Radical spirocyclization via dearomatization has emerged as an attractive strategy for the rapid synthesis of structurally diverse spiro molecules.
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[ASAP] Radical Chain Reduction via Carbon Dioxide Radical Anion (CO2•–)
Easy access to drug building-blocks through benzylic C–H functionalization of phenolic ethers by photoredox catalysis
DOI: 10.1039/D1CC01756J, Communication
A visible light-mediated photocatalyzed C–C-bond benzylic functionalization of phenolic ether-containing drug-like compounds is presented.
The content of this RSS Feed (c) The Royal Society of Chemistry
[ASAP] Electrochemical Synthesis of Fluorinated Ketones from Enol Acetates and Sodium Perfluoroalkyl Sulfinates
[ASAP] The Application of Pulse Radiolysis to the Study of Ni(I) Intermediates in Ni-Catalyzed Cross-Coupling Reactions
[ASAP] N-Ammonium Ylide Mediators for Electrochemical C–H Oxidation
MRVElectrochemical CH activation
Photocatalytic C-H activation and the subtle role of chlorine radical complexation in reactivity
MRVCerium power
The functionalization of methane, ethane, and other alkanes derived from fossil fuels is a central goal in the chemical enterprise. Recently, a photocatalytic system comprising [CeIVCl5(OR)]2– [CeIV, cerium(IV); OR, –OCH3 or –OCCl2CH3] was disclosed. The system was reportedly capable of alkane activation by alkoxy radicals (RO•) formed by CeIV–OR bond photolysis. In this work, we present evidence that the reported carbon-hydrogen (C–H) activation of alkanes is instead mediated by the photocatalyst [NEt4]2[CeCl6] (NEt4+, tetraethylammonium), and RO• are not intermediates. Spectroscopic analyses and kinetics were investigated for C–H activation to identify chlorine radical (Cl•) generation as the rate-limiting step. Density functional theory calculations support the formation of [Cl•][alcohol] adducts when alcohols are present, which can manifest a masked RO• character. This result serves as an important cautionary note for interpretation of radical trapping experiments.
Carbon dioxide based methodologies for the synthesis of fine chemicals
DOI: 10.1039/D1OB00755F, Review Article
Rapid environmental changes triggered by the increase in the concentration of heat-absorbing gases such as CO2 in the atmosphere have become a major cause of concern.
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Synthesis of methanesulfone-containing tetrasubstituted carbon stereocenters
DOI: 10.1039/D1OB00071C, Paper
Synthesis of sulfone-containing tetrasubstituted carbon stereocenters.
The content of this RSS Feed (c) The Royal Society of Chemistry
Electrochemically driven desaturation of carbonyl compounds
MRVnice
Nature Chemistry, Published online: 23 March 2021; doi:10.1038/s41557-021-00640-2
Excising hydrogen adjacent to a carbonyl group—one of the most basic and widely employed transformations in organic synthesis—is traditionally achieved using metals and/or stoichiometric oxidants. Now, it has been shown that an electrochemically driven approach removes such requirements, resulting in a more sustainable and easily scalable method with wide substrate scope.[ASAP] Cyclization by C(sp3)–H Arylation with a Transient Directing Group for the Diastereoselective Preparation of Indanes
Nickel‐Catalyzed C‐Heteroatom Cross‐Coupling Reactions under Mild Conditions via Facilitated Reductive Elimination
MRV!
The generation of NiIII and excited NiII intermediates facilitates the reductive elimination step leading to the mild cross-couplings. This review provides an overview of the state-of-the-art approaches for mild C-heteroatom bond formations via homo- and heterogeneous photoredox and nickel dual catalysis, electro- and nickel dual catalysis, as well as conventional zinc and nickel dual catalysis.
Abstract
The formation of C-heteroatom bonds represents an important type of bond-forming reaction in organic synthesis and often provides a fast and efficient access to privileged structures found in pharmaceuticals, agrochemical and materials. In contrast to conventional Pd- or Cu-catalyzed C-heteroatom cross-couplings under high-temperature conditions, recent advances in homo- and heterogeneous Ni-catalyzed C-heteroatom formations under mild conditions are particularly attractive from the standpoint of sustainability and practicability. The generation of NiIII and excited NiII intermediates facilitate the reductive elimination step to achieve mild cross-couplings. This review provides an overview of the state-of-the-art approaches for mild C-heteroatom bond formations and highlights the developments in photoredox and nickel dual catalysis involving SET and energy transfer processes; photoexcited nickel catalysis; electro and nickel dual catalysis; heterogeneous photoredox and nickel dual catalysis involving graphitic carbon nitride (mpg-CN), metal organic frameworks (MOFs) or semiconductor quantum dots (QDs); as well as more conventional zinc and nickel dual catalyzed reactions.
Electrochemical Arylation of Aldehydes, Ketones, and Alcohols: from Cathodic Reduction to Convergent Paired Electrolysis
MRVnice
Electrochemical approaches to the direct arylation of carbonyls and alcohols through less‐explored cathodic reduction and convergent paired electrolysis are presented. This protocol features: excellent functional group (including ester, amide, amine, thioether, borate) tolerance, mild conditions (metal catalyst‐ and external reductant‐free), good scalability (>10 gram‐scale), and site‐selectivity.
Abstract
Arylation of carbonyls, one of the most common approaches toward alcohols, has received tremendous attention, as alcohols are important feedstocks and building blocks in organic synthesis. Despite great progress, there is still a great gap to develop an ideal arylation method featuring mild conditions, good functional group tolerance, and readily available starting materials. We now show that electrochemical arylation can fill the gap. By taking advantage of synthetic electrochemistry, commercially available aldehydes (ketones) and benzylic alcohols can be readily arylated to provide a general and scalable access to structurally diverse alcohols (97 examples, >10 gram‐scale). More importantly, convergent paired electrolysis, the ideal but challenging electrochemical technology, was employed to transform low‐value alcohols into more useful alcohols. Detailed mechanism study suggests that two plausible pathways are involved in the redox neutral α‐arylation of benzylic alcohols.
Photocatalytic Giese‐Type Reaction with Alkylsilicates Bearing C,O‐Bidentate Ligands
MRV:)
Shine on me! Photocatalytic Giese‐type reactions with alkylsilicates bearing C,O‐bidentate ligands as alkyl radical precursors are reported. Not only primary, secondary, and tertiary alkyl radicals, but also elusive methyl radicals, can be generated under the present reaction system. This radical generation process is investigated by theoretical calculations.
Abstract
Herein, a photocatalytic Giese‐type reaction with alkylsilicates bearing C,O‐bidentate ligands as stable alkyl radical precursors has been reported. The alkylsilicates were prepared in one step from organometallic reagents. Not only primary, secondary, and tertiary alkyl radicals, but also elusive methyl radicals, could be generated by using the present reaction system. The generated radicals were trapped by electron‐deficient olefins bearing various functional groups to give the desired alkyl adducts. The silicon byproduct can be recovered after the photoreaction. The radical generation process was investigated by theoretical calculations, which provided an insight into the facile generation of methyl radicals from methylsilicate bearing C,O‐bidentate ligands.
Chemodivergence between Electrophiles in Cross‐Coupling Reactions
In cross‐coupling reactions, chemoselectivity becomes a concern when two or more (pseudo)halides are present in the substrates. This minireview surveys cases in which divergent chemoselectivity between electrophiles can be achieved under different reaction conditions. Particular emphasis is placed on discussing the possible mechanistic origins of selectivity control.
Abstract
Chemodivergent cross‐couplings are those in which either one of two (or more) potentially reactive functional groups can be made to react based on choice of conditions. In particular, this review focuses on cross‐couplings involving two different (pseudo)halides that can compete for the role of the electrophilic coupling partner. The discussion is primarily organized by pairs of electrophiles including chloride vs. triflate, bromide vs. triflate, chloride vs. tosylate, and halide vs. halide. Some common themes emerge regarding the origin of selectivity control. These include catalyst ligation state and solvent polarity or coordinating ability. However, in many cases, further systematic studies will be necessary to deconvolute the influences of metal identity, ligand, solvent, additives, nucleophilic coupling partner, and other factors on chemoselectivity.
Regiodivergent Synthesis of Spirocyclic Compounds through Pd‐Catalyzed Regio‐ and Enantioselective [3+2] Spiroannulation
MRVrev iew
A Pd0‐catalyzed highly regio‐ and enantioselective [3+2] spiroannulation reaction has been developed for rapid assembly of [5,5] spirocyclic carbo‐ and heterocycles. The regioselectivity could be dominated by fine‐tuning the Pd‐π‐allyl intermediate. An array of coupling partners could be well‐tolerated with excellent regio‐, and enantioselectivities. Potential application of the reaction was exemplified by several further transformations.
Abstract
A novel Pd0‐catalyzed highly regio‐ and enantioselective [3+2] spiroannulation reaction has been developed for rapid assembly of a new class of [5,5] spirocyclic carbo‐ and heterocycles. Notably, the regioselectivity could be dominated by fine‐tuning of the Pd‐π‐allyl intermediate. An array of coupling partners could be well‐tolerated with excellent regio‐, and enantioselectivities. Moreover, the potential application of this reaction was exemplified by several further transformations.