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A general, stereospecific, and straightforward method for the rapid preparation of functionalized (E)-monofluoroenamines is reported. Rather than transition metals (Rh, Ni, Pd, Cu, Ag, etc.), Et2O·BF3 was employed to promote the formation of α-diazoimine through the Dimroth equilibrium of common 1-sulfonyl-1,2,3-triazole for the first time. An overall migration of fluoride from boron to the diazo-linked carbon of α-diazoimine was achieved. Derivations and late-stage modification of bioactive molecule were conducted. A plausible mechanism was also proposed.

A tandem reaction of 4-(1-acetoxyallyl)-1-sulfonyl-1,2,3-triazole including formation of α-imino rhodium carbene, 1,2-migration of an acetoxy group and six electron electrocyclic ring closure was reported. The migration of the OAc group with excellent chemoselectivity was the crucial process, leading to the formation of 1,2-dihydropyridine specifically in up to 90% yield. Several transformations of the dihydropyridine product were also achieved illustrating the potential of the protocol in organic synthesis. Based on the observation of the intermediate, a plausible mechanism was proposed.

Sodium iodide is used for the first time as a nucleophile to trap an α-imino rhodium carbene, which triggers a tandem process involving intermolecular nucleophilic attack and intramolecular SN2 reaction. A series of 5-iodo-1,2,3,4-tetrahydropyridines are obtained in high yield, and the synthetic utility of the products is demonstrated in cross-coupling reactions and the construction of biorelated polycyclic compounds.