O-Transfer-facilitated cyclizations of propargylamides with TMSN3: selective synthesis of tetrazoles and dihydroimidazoles†
An unprecedented formal [3+2] annulation of propargylamides with TMSN3 to deliver functionalized tetrazoles is developed. Oxygen-atom transfer (OAT) from the amide group to the CC bond was realized via a NIS-triggered-cyclization/ring-opening cascade pathway. The OAT process enables the amide to serve as a two-atom unit in the reactions. Notably, in situ umpolung of azide occurred when terminal propargylamides were employed in this reaction, providing an array of diiodomethylated dihydroimidazoles.