Total synthesis of carbazoquinocin C: application of the o-benzannulation of Fischer carbene complexes to carbazole-3,4-quinone alkaloids.

[reaction: see text] The photoinduced o-benzannulation of 3-(2-vinyl)indolylcarbene complexes provides a direct route to carbazole derivatives that are oxygenated in the 3- and 4-positions. This reaction is quite efficient and provides for a unique synthesis of the lipid peroxidation inhibitor carbazoquinocin C.