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Synfacts 2010(4): 0402-0402  
DOI: 10.1055/s-0029-1219497
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Thiophenium Salts: A Trifluoromethylation Reagent

Contributor(s): Victor Snieckus, Wei Gan
A. Matsnev, S. Noritake, Y. Nomura, E. Tokunaga, S. Nakamura, N. Shibata*
Nagoya Institute of Technology, Japan
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Publikationsdatum:
22. März 2010 (online)

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Significance

A triflic acid catalyzed intramolecular cyclization of ortho-ethynylaryltrifluoromethylsulfanes to S-(trifluoromethyl)thiophenium salts (Yagupolskii-Umemoto-type reagent) is reported. Simple catalysts, such as AuCl3 and CuCl2 for the cyclization of ortho-thiosubstituted aryl alkynes to benzothiophenes (I. Nakamura, T. Sato, Y. Yamamoto Angew. Chem. Int. Ed. 2006, 45, 4473), are not suitable in this reaction. Among the Brønsted acids tested, TfOH was found to be the only efficient acid in affording the desired products.