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Paper | Special issue | Vol 101, No. 2, 2020, pp.580-592
Published online, 7th October, 2019
DOI: 10.3987/COM-19-S(F)48
Trialkylsulfonium and Tetraalkylammonium Salts as Hydrogen-Bonding Catalysts in an Aza-Diels-Alder Reaction: Experimental and Computational Studies

Masahiro Yamanaka,* Ayaka Mochizuki, Takumi Nakamura, Keiji Maruoka, and Seiji Shirakawa*

*Department of Chemistry, Faculty of Science, Rikkyo University, 3-34-1 Nishiikebukuro, Toshima-ku, Tokyo 171-8501, Japan

Abstract

Hydrogen-bonding catalysis by cyclic trialkylsulfonium and tetraalkylammonium salts in an aza-Diels-Alder reaction was investigated. Among the examined onium salt catalysts, cyclic trialkylsulfonium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate possessing a non-coordinating counter anion was the most effective. Details of the activation modes of cyclic trialkylsulfonium and tetraalkylammonium salts were discussed on the basis of DFT calculation.