The regioselective N-addition/substitution reaction between α-alkylidene pyrazolinones and propargyl sulfonium salts has been developed to construct functionalized allylthio-containing pyrazolones with moderate to excellent yields. α-Alkylidene pyrazolinones act as N-nucleophilic agents which are distinguished from reported C-nucleophilic reactions. Excellent regioselectivity, readily available starting materials, the broad range of substrates, gram-scale synthesis, and simple operation illustrate the synthetic advantages of this new reaction pathway.

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http://dx.doi.org/10.1021/acs.joc.9b02029DOI Listing

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