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1. Indication of Pd–C or Cu–C Intermediates in Bimetallic Nanoclusters During Pd/Au-PVP- or Cu/Au-PVP-Catalyzed Oxidations of endo-4-Oxatricyclo[5.2.1.02,6]-8-decene and Tetrahydro-γ-carbolines

   https://doi.org/10.1055/a-2001-6888  

   Morita, Shunya ; Ren, Zhaoyang ; Gorla, Lingaraju ; Tong, Zongbo ; Edouarzin, Edruce ; Averkiev, Boris ; Day, Victor W. ; Hua, Duy H. ( March 2023 , Synthesis)

   Catalytic oxidation of tricyclic endo-norbornene-fused tetrahydrofuran with the bimetallic nanocluster Cu/Au-PVP in the presence of H2O2 or t-BuOOH as the oxidant leads to C–H bond oxidation adjacent to the ether function to give 4-oxa-tricyclo[5.2.1.0]-8,9-exo-epoxydecane, however, oxidation with Pd/Au-PVP takes place at the C=C double bond to give the same epoxide and the oxidative three-bond forming dimeric product, dodecahydro-1,4:6,9-dimethanodibenzofurano[2,3-b:7,8-b′]bisoxolane. Formation of the latter product suggests the involvement of a reactive Pd–C intermediate. Similarly, oxidative C–C bond-forming reactions are observed in cycloaddition reactions of N2-Boc-1,2,3,4-tetrahydro-γ-carbolines and 2,3-dihydroxybenzoic acid with Cu/Au-PVP (2–5 mol%) and H2O2 at 25 °C, providing two-bond-forming [4+2] cycloadducts. Under similar reaction conditions, Pd/Au-PVP did not produce the corresponding cycloadduct, indicating a need for complexation between Cu and the carboxylic acid group of 2,3-dihydroxybenzoic acid and the allylic amine function of the γ-carbolines during the cyclization reaction. The reported intermolecular coupling reactions using Pd/Au-PVP or Cu/Au-PVP nanocluster catalysts under oxidative conditions at 25 °C are unprecedented.

    

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2. Cycloadditions of Cyclopentadiene and Cycloheptatriene with Tropones: All Endo -[6+4] Cycloadditions Are Ambimodal

   https://doi.org/10.1021/jacs.0c13401  

   Jamieson, Cooper S. ; Sengupta, Arkajyoti ; Houk, K. N. ( March 2021 , Journal of the American Chemical Society)

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3. Endo Selectivity in the (4 + 3) Cycloaddition of Oxidopyridinium Ions

   https://doi.org/10.1021/acs.orglett.1c03028  

   Sungnoi, Wanna ; Keto, Angus B. ; Roseli, Ras Baizureen ; Liu, Jinchu ; Wang, Heather ; Fu, Chencheng ; Regalado, Erik L. ; Krenske, Elizabeth H. ; Harmata, Michael ( November 2021 , Organic Letters)
4. 5- Endo Cyclizations of NHC-Boraallyl Radicals Bearing Ester Substituents: Characterization of Derived 1,2-Oxaborole Radicals and Boralactones

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   Dai, Wen ; McFadden, Timothy R. ; Curran, Dennis P. ; Früchtl, Herbert A. ; Walton, John C. ( November 2018 , Journal of the American Chemical Society)
5. Universal deformation rings, endo-trivial modules, and semidihedral and generalized quaternion 2-groups

   https://doi.org/10.1016/j.jpaa.2018.08.006  

   Bleher, Frauke M. ; Chinburg, Ted ; Soto, Roberto C. ( May 2019 , Journal of Pure and Applied Algebra)

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