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1. Reductive Alkylation of 2-Bromoazoles via Photoinduced Electron Transfer: A Versatile Strategy to C sp ² –C sp ³ Coupled Products

   https://doi.org/10.1021/acs.orglett.5b01711  

   Arora, Amandeep; Teegardin, Kip A.; Weaver, Jimmie D. (July 2015, Organic Letters)

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2. Cobalt−NHC Catalyzed C(sp ² )−C(sp ³ ) and C(sp ² )−C(sp ² ) Kumada Cross‐Coupling of Aryl Tosylates with Alkyl and Aryl Grignard Reagents

   https://doi.org/10.1002/cctc.202001347  

   Piontek, Aleksandra; Ochędzan‐Siodłak, Wioletta; Bisz, Elwira; Szostak, Michal (November 2020, ChemCatChem)

   Abstract The first cobalt‐catalyzed cross‐coupling of aryl tosylates with alkyl and aryl Grignard reagents is reported. The catalytic system uses CoF₃and NHCs (NHC=N‐heterocyclic carbene) as ancillary ligands. The reaction proceeds via highly selective C−O bond functionalization, leading to the corresponding products in up to 98 % yield. The employment of alkyl Grignard reagents allows to achieve a rare C(sp²)−C(sp³) cross‐coupling of C−O electrophiles, circumventing isomerization and β‐hydride elimination problems. The use of aryl Grignards leads to the formation of biaryls. The C−O cross‐coupling sets the stage for a sequential cross‐coupling by exploiting the orthogonal selectivity of the catalytic system. 

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3. Nickel‐Catalyzed C( sp ² )−C( sp ³ ) Kumada Cross‐Coupling of Aryl Tosylates with Alkyl Grignard Reagents

   https://doi.org/10.1002/adsc.201801586  

   Piontek, Aleksandra; Ochędzan‐Siodłak, Wioletta; Bisz, Elwira; Szostak, Michal (April 2019, Advanced Synthesis & Catalysis)

   Abstract Aryl tosylates are an attractive class of electrophiles for cross‐coupling reactions due to ease of synthesis, low price, and the employment of C−O electrophiles, however, the reactivity of aryl tosylates is low. Herein, we report the Ni‐catalyzed C(sp²)−C(sp³) Kumada cross‐coupling of aryl tosylates with primary and secondary alkyl Grignard reagents. The method delivers valuable alkyl arenes by cross‐coupling with challenging alkyl organometallics possessing β‐hydrogens that are prone to β‐hydride elimination and homo‐coupling. The reaction is catalyzed by an air‐ and moisture stable‐Ni(II) precatalyst. A broad range of electronically‐varied aryl tosylates, including bis‐tosylates, underwent this transformation, and many examples are suitable at mild room temperature conditions. The combination of Ar−X cross‐coupling with the facile Ar−OH activation/cross‐coupling strategy permits for orthogonal cross‐coupling with challenging alkyl organometallics. Furthermore, we demonstrate that the method operates with TON reaching 2000, which is one of the highest turnovers observed to date in Ni‐catalyzed cross‐couplings. magnified image 

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4. Non- C ₂ -Symmetric Chiral-at-Ruthenium Catalyst for Highly Efficient Enantioselective Intramolecular C(sp ³ )–H Amidation

   https://doi.org/10.1021/jacs.9b09301  

   Zhou, Zijun; Chen, Shuming; Hong, Yubiao; Winterling, Erik; Tan, Yuqi; Hemming, Marcel; Harms, Klaus; Houk, K. N.; Meggers, Eric (December 2019, Journal of the American Chemical Society)
5. Nickel(IV) Intermediates in Aminoquinoline-Directed C(sp ² )–C(sp ³ ) Coupling

   https://doi.org/10.1021/jacs.2c10778  

   Milbauer, Michael W.; Kampf, Jeff W.; Sanford, Melanie S. (November 2022, Journal of the American Chemical Society)