title: Copper-Mediated Domino Cyclization/Trifluoromethylation/Deprotection with TMSCF3: Synthesis of 4-(Trifluoromethyl)pyrazoles.
abstract: A copper-mediated synthesis of 4-(trifluoromethyl)pyrazoles is described. In one step from readily accessible α,β-alkynic tosylhydrazones, a remarkable domino sequence of cyclization, trifluoromethylation, and detosylation takes place to furnish the 4-CF3N-H pyrazole cores with good functional group compatibility. The reaction conditions are mild and convenient, at room temperature in air, using the commercially available trifluoromethyltrimethylsilane (TMSCF3) as the CF3source. The method can be applied to the synthesis of a 4-CF3analogue of the anti-inflammatory drug celecoxib.
authors.affiliation: Department of Chemistry, The Chinese University of Hong Kong , Shatin, New Territories, Hong Kong, China.
authors.forename: Quande
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Chemistry, The Chinese University of Hong Kong , Shatin, New Territories, Hong Kong, China.
authors.forename: Lisi
authors.initials: L
authors.lastname: He
authors.affiliation: Department of Chemistry, The Chinese University of Hong Kong , Shatin, New Territories, Hong Kong, China.
authors.forename: Kin Keung
authors.initials: KK
authors.lastname: Li
authors.affiliation: Department of Chemistry, The Chinese University of Hong Kong , Shatin, New Territories, Hong Kong, China.
authors.forename: Gavin Chit
authors.identifier: 0000-0003-4824-8745
authors.initials: GC
authors.lastname: Tsui