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1. Forging C−S Bonds Through Decarbonylation: New Perspectives for the Synthesis of Privileged Aryl Sulfides

   https://doi.org/10.1002/cctc.202101206  

   Liu, Chengwei; Szostak, Michal (October 2021, ChemCatChem)

   Abstract Aryl thioethers are tremendously important motifs in various facets of chemical science. Traditional technologies for the precise assembly of aryl thioethers rely on transition‐metal‐catalyzed cross‐coupling of aryl halides; however, despite the continuous advances, the scope of these methods remains limited. Recently a series of reports has advanced an alternative manifold in which thio(esters) are subject to transition‐metal‐catalyzed decarbonylation, which (1) permits to exploit ubiquitous carboxylic acids as highly desirable and orthogonal precursors to aryl halides; (2) overcomes the issues of high concentration of thiolate anion leading to catalyst poisoning; (3) enables for novel disconnections not easily available from aryl halides; and (4) introduces new concepts in catalysis. 

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2. Fe-Catalyzed dicarbofunctionalization of electron-rich alkenes with Grignard reagents and (fluoro)alkyl halides

   https://doi.org/10.1039/D1CC04619E  

   Rotella, Madeline E.; Sar, Dinabandhu; Liu, Lei; Gutierrez, Osvaldo (November 2021, Chemical Communications)

   An iron-catalyzed regioselective dicarbofunctionalization of electron-rich alkenes is described. In particular, aryl- and alkyl vinyl ethers are used as effective linchpins to couple alkyl or (fluoro)alkyl halides and sp 2 -hybridized Grignard nucleophiles. Preliminary results demonstrate the ability to engage thioethers as linchpins and control enantioselectivity in these transformations, an area which is largely unexplored in iron-catalyzed three-component cross-coupling reactions. 

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3. Decarbonylative cross-coupling of amides

   https://doi.org/10.1039/c8ob01832d  

   Liu, Chengwei; Szostak, Michal (November 2018, Organic & Biomolecular Chemistry)

   Cross-coupling reactions are among the most powerful C–C and C–X bond forming tools in organic chemistry. Traditionally, cross-coupling methods rely on the use of aryl halides or pseudohalides as electrophiles. In the past three years, decarbonylative cross-couplings of amides have emerged as an attractive method for the construction of a wide variety of carbon–carbon and carbon–heteroatom bonds, allowing for the synthetically-valuable functional group inter-conversion of the amide bond. These previously elusive reactions hinge upon selective activation of the N–C(O) acyl amide bond, followed by CO extrusion, in a formal double N–C/C–C bond activation, to generate a versatile aryl–metal intermediate as an attractive alternative to traditional cross-couplings of aryl halides and pseudohalides. In this perspective review, we present recent advances and key developments in the field of decarbonylative cross-coupling reactions of amides as well as discuss future challenges and potential applications for this exciting field. 

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4. Chemoselective, Scalable Nickel‐Electrocatalytic O ‐Arylation of Alcohols

   https://doi.org/10.1002/anie.202107820  

   Zhang, Hai‐Jun; Chen, Longrui; Oderinde, Martins S.; Edwards, Jacob T.; Kawamata, Yu; Baran, Phil S. (August 2021, Angewandte Chemie International Edition)

   Abstract The formation of aryl‐alkyl ether bonds through cross coupling of alcohols with aryl halides represents a useful strategic departure from classical S_N2 methods. Numerous tactics relying on Pd‐, Cu‐, and Ni‐based catalytic systems have emerged over the past several years. Herein we disclose a Ni‐catalyzed electrochemically driven protocol to achieve this useful transformation with a broad substrate scope in an operationally simple way. This electrochemical method does not require strong base, exogenous expensive transition metal catalysts (e.g., Ir, Ru), and can easily be scaled up in either a batch or flow setting. Interestingly, e‐etherification exhibits an enhanced substrate scope over the mechanistically related photochemical variant as it tolerates tertiary amine functional groups in the alcohol nucleophile. 

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5. Nickel-Palladium nanoparticles supported on multi-walled carbon nanotubes as an effective catalyst for Sonogashira cross-coupling reactions

   Ali R. Siamaki, Katherine Coker (October 2022, Abstracts of papers American Chemical Society)

   Sonogashira cross coupling reactions have a wide range of applications in pharmaceutical industry for drug discovery and organic synthesis of natural products and pharmaceutical compounds. These reactions typically involve the coupling of aryl halides with terminal alkynes in the presence of palladium catalyst under appropriate reaction conditions. Most Sonogashira reactions have been carried out with homogeneous Pd catalysis, in which the catalyst is soluble in the reaction mixture. There are many disadvantages to this method including the difficulty to remove the catalyst from the sample and recyclability. Heterogeneous catalysis is an alternative approach to address the issues associated with homogeneous system mainly due to facile and clean removal of the catalyst and minimum metal residual contamination. Herein, we report the preparation of nickel-palladium nanoparticles supported on multi-walled carbon nanotubes (Ni-Pd/MWCNTs) as an effective heterogeneous catalyst for Sonogashira coupling reactions. The catalyst was prepared by mixing the appropriate ratio of nickel-palladium salts with multi-walled carbon nanotubes using a mechanical power of a ball mill. The nanoparticles prepared by this method were successfully used to catalyze Sonogashira coupling reactions of various substituted aryl halides and terminal alkynes using an equal amount of water and ethanol as an environmentally benign solvent system. This project provides a facile and effective method for largescale preparation of Ni-Pd/MWCNTs to catalyze Sonogashira cross-coupling reactions. The recyclability of the catalyst makes this an affordable and clean option for pharmaceutical and industrial applications. 

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