Diastereoselective Additive Trifluoromethylation/Halogenation of Isoxazole Triflones: Synthesis of All‐Carbon‐Functionalized Trifluoromethyl Isoxazoline Triflones.

Highly functionalized 5-trifluoromethyl-2-isoxazoline derivatives featuring a triflyl (SO2CF3) group at the 4-position were successfully synthesized via diastereoselective trifluoromethylation and halogenation of isoxazole triflones using the Ruppert– Prakash reagent. The trifluoromethylation is quite general in terms of the substrates including 3,5-diaryl isoxazole triflones and 3-aryl-5-styrylisoxazole triflones to provide products in high yields with excellent diastereoselectivities. The highly functionalized 5-trifluoromethyl-2-isoxazoline derivatives are expected to be a new class of antiparasiticides. Thus the triflyl group both activates isoxazoles and the 4-postion of CF3 adducts, and has a potential biological function.