Structure-dependent selective O- or C-trifluoroethylation of 1,3-dicarbonyls by mesityl(2,2,2-trifluoroethyl)iodonium triflate

Abstract

Reaction of [ArICH2CF3][OTf] with structurally diversified 1,3-dicarbonyls and an appropriate base at room temperature gave O-trifluoroethylated products, C-trifluoroethylated products, or a mixture of O- and C-trifluoroethylated products in good yields. The product type was dramatically dependent upon the structure of the starting 1,3-dicarbonyls in this reaction. The cyclic 1,3-diketones exclusively afforded the O-trifluoroethylated products, whereas the acyclic 1,3-diketones, β-keto esters, and malonates selectively or specifically formed the C-trifluoroethylated products. Li2CO3 facilitated the C-trifluoroethylation of acyclic 1,3-diketones and β-keto esters. The reaction proceeded under mild conditions, without pre-activation of 1,3-dicarbonyls and use of strong base, and demonstrated a catalyst-free structure-dependent regioselective trifluoroethylation of 1,3-dicarbonyls by mesityl(2,2,2-trifluoroethyl)iodonium triflate.