Diazotrifluoroethyl Radical: A CF-Containing Building Block in [3 + 2] Cycloaddition.

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-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 (CFCHN), the diazotrifluoroethyl radical [CFC(·)N], a trifluoroethylcarbyne (CFCĊ:) equivalent and an unusual CF-containing building block, is involved in the present reaction system.