Gold-Catalyzed Photoredox C(sp(2)) Cyclization: Formal Synthesis of (±)-Triptolide.

Photoexcitation of a dimeric gold complex showed the activation of a C(sp(2))-Br bond to generate a vinyl radical in a mild photoredox catalysis process. Use of [Au2(dppm)2]Cl2 with 365 nm LEDs in a photoredox catalysis process to produce polycyclic scaffolds using vinyl radicals is reported. This method achieved the synthesis of a small library of butenolide polycyclic compounds and naphthol polycyclic compounds. The efficacy of this photoredox process was further demonstrated by accomplishing the concise formal synthesis of (±)-triptolide.