Decatungstate-photocatalysed C(sp 3 )-H azidation.

C-H Azidation is an increasingly important tool for bioconjugation, materials chemistry, and the synthesis of nitrogen-containing natural products. While several approaches have been developed, these often require exotic and energetic reagents, expensive photocatalysts, or both. Here we report a simple and general C-H azidation reaction using earth-abundant tetra- n -butylammonium decatungstate as a photocatalyst and commercial p -acetamidobenzenesulfonyl azide ( p -ABSA) as the azide source. This system can azidate a variety of unactivated C(sp 3 )-H bonds in moderate to good yields and excellent turnover numbers. Preliminary mechanistic experiments implicate a radical mechanism proceeding VIA photo-hydrogen atom transfer (photo-HAT).