Revisiting 3-azidoindoles: overcoming the trade-off challenges between stability and reactivity of in situ-generated azidoindoles

A concise protocol based on the E2 reaction of indoline hemiaminals for accessing 3-azidoindoles is reported. In contrast to previous methods that require in situ generation by hypervalent iodine reagents, our protocol allows for the isolation of a variety of 3-azidoindoles upon a mild reaction for a short reaction time at room temperature. The obtained 3-azidoindoles are reasonably reactive, bench-stable and easy to handle. These findings could be used as a starting point for various reactions, including Huisgen reaction, [3+2] cycloaddition, phosphoramidation, and cine-substitution with the release of N₂.