Synlett, Table of Contents Synlett DOI: 10.1055/a-2720-9415 Letter Alkoxy Group-Boosted Internal Redox Reaction: Application to Benzylic Hydride Shift/Cyclization of Electron-Deficient Aromatic Rings Authors Author Affiliations Mizuki Katagiri 1 Graduate School of Engineering, Department of Applied Chemistry, Tokyo University of Agriculture and Technology, Tokyo, Japan Tomoko Kawasaki-Takasuka 1 Graduate School of Engineering, Department of Applied Chemistry, Tokyo University of Agriculture and Technology, Tokyo, Japan Keiji Mori 1 Graduate School of Engineering, Department of Applied Chemistry, Tokyo University of Agriculture and Technology, Tokyo, Japan Recommend Article Abstract Buy Article(opens in new window) All articles of this category(opens in new window) Abstract We report a C(sp3)–H bond functionalization at the benzylic position of electron-deficient aromatic rings, considered a challenging transformation in hydride shift–mediated C(sp3)–H bond functionalization chemistry. The key to achieving the reaction was the employment of substrates having a methoxy group at the benzylic position. The methoxy group was easily eliminated from the cyclized adducts by treating with a strong Brønsted acid, such as TfOH. A one-pot operation of two processes, C(sp3)–H bond functionalization and MeOH elimination, was also accomplished. Synthetic utility of the present method was well showcased by derivatization from the obtained dihydronaphthalenes. Keywords KeywordsC–H bond functionalization - Redox process - Tetralin - Hydride shift - Sequential reaction Full Text References References For recent reviews on C–H activation, see: 1a Godula K, Sames D. Science 2006; 312: 67 1b Bergman RG. Nature 2007; 446: 391 1c Alberico D, Scott ME, Lautens M. Chem Rev 2007; 107: 174 1d Davies HML, Manning JR. Nature 2008; 451: 417 1e Chen X, Engle KM, Wang D-H, Yu J-Q. Angew Chem Int Ed 2009; 48: 5094 1f Jazzar R, Hitce J, Renaudat A, Sofack-Kreutzer J, Baudoin O. 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Tetrahedron 1981; 37: 3899 11 Detailed examination of the reaction conditions from 2a was described in SI. 12 Simultaneous treatment of 1a with Sc(OTf)3 (0.5 mol%) and TfOH (5 mol%) in refluxing DCE for 21 h resulted in the formation of 3a in only 14%, accompanied by 2a (57%) and 6 (30). This result clearly indicates the importance of sequential operation. 13 Unpublished result. 14 Amano K, Kawasaki-Takasuka T, Mori K. Org Lett 2024; 36: 1824 Supplementary Material Supplementary Material Supplementary Material (PDF) (opens in new window)
