C-based nucleophiles, such as cyanide (48), indole (49), allyl (50), and enol ether (51), successfully coupled with the ATA reagent, producing functionalized azetidines with quaternary carbon centers. Overall, more than 20 classes of nucleophiles can be readily azetidinylated, providing a diverse library of functionalized azetidines. In addition, this simple protocol is also amenable to parallel synthesis, with either the ATA or the nucleophile used as the limiting reagent (see Figures S7-10 in Supporting Information for details).