Fluorinated Isoxazoles as Potential Fungicides: Tf2O-Induced Electrophilic Cyclization of O-Methyl Oximes.

We report that a Tf2O-mediated strategy enables cycloisomerization of 2-alkynone O-methyl oximes with fluorinated sulfoxides. This metal-free approach provides modular access to SCF2H/D or SeCF3-functionalized isoxazoles from simple precursors and features a broad substrate scope, including late-stage modification of bioactive molecules. Furthermore, all target compounds displayed antifungal activity against the four tested fungal strains with remarkable inhibitory potency toward Rhizoctonia solani.