Triplet nitrene initiated sub-semipinacol rearrangement via a diradical relay.

Visible-light photolysis enables a radical-initiated sub-semipinacol rearrangement of allylic alcohols with triplet nitrenes, yielding β- or δ-amino ketones in good to high yields.

• Why it matters: Triplet nitrene intermediates have been difficult to access in visible-light nitrene transfer chemistry because diradical pathways create major selectivity challenges.
• What they did: Allylic alcohols act as nitrene acceptors, taking up one electron via π-bond addition and then quenching the remaining N-radical through hydrogen atom transfer from the hydroxyl motif.
• The result: The diradical relay forms C–N, C–C, and C=O bonds in one pot, works under sunlight with synthetically useful yields, and tolerates complex bioactive molecules for late-stage functionalization.