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S‐((Phenylsulfonyl)difluoromethyl)thiophenium Salts: Carbon‐Selective Electrophilic Difluoromethylation of β‐Ketoesters, β‐Diketones,and Dicyanoalkylidenes
Authors:Xin Wang  Guokai Liu  Dr. Xiu‐Hua Xu  Naoyuki Shibata  Etsuko Tokunaga  Prof. Dr. Norio Shibata
Affiliation:Department of Frontier Materials & Department of Nanopharmaceutical Science, Nagoya Institute of Technology, Gokiso, Showa‐ku, Nagoya 466‐8555 (Japan)
Abstract:S‐((Phenylsulfonyl)difluoromethyl)thiophenium salts were designed and prepared by a triflic acid catalyzed intramolecular cyclization of ortho‐ethynyl aryldifluoromethyl sulfanes. The thiophenium salts were found to be efficient as electrophilic difluoromehtylating reagents for introduction of a CF2H group to sp3‐hybridized carbon nucleophiles such as of β‐ketoesters and dicyanoalkylidenes. The (phenylsulfonyl)difluoromethyl group can be readily transformed into CF2H under mild reaction conditions. Enantioselective electrophilic difluoromethylation was also achieved in the presence of bis(cinchona) alkaloids.
Keywords:enantioselectivity  fluorine  regioselectivity  sulfur  synthetic methods
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