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We present herein a visible-light-induced 3 + 2 cycloaddition of a hypervalent iodine(III) reagent with α-ketoacids for the construction of 5-CF 3 -1,3,4-oxadiazoles that are of importance in medicinal chemistry. The reaction proceeds smoothly without a photocatalyst, metal, or additive under mild conditions. Different from the well-established trifluorodiazoethane (CF 3 CHN 2 ), the diazotrifluoroethyl radical CF 3 C(·)N 2 , a trifluoroethylcarbyne (CF 3 CĊ:) equivalent and an unusual CF 3 -containing building block, is involved in the present reaction system.
Zhao et al. (Sun,) studied this question.