Total synthesis of (±)-streptonigrin: de novo construction of a pentasubstituted pyridine using ring-closing metathesis.

The synthesis of the potent antitumor agent (±)-streptonigrin has been achieved in 14 linear steps and 11% overall yield from ethyl glyoxalate. The synthesis features a challenging ring-closing metathesis reaction, followed by elimination and aromatization, to furnish a key pentasubstituted pyridine fragment.