From Propargylamides to Oxazole Derivatives: NIS-Mediated Cyclization and Further Oxidation by Dioxygen

NIS-mediated iodocyclization of N-sulfonyl propargylamides for the synthesis of various oxazolidines and iodoalkylidenedihydrooxazoles via a 5-exo-dig process is developed. The resulting iodoalkylidene­dihydrooxazoles can be further transformed into the corresponding oxazoles in the presence of dioxygen.