Intramolecular Fischer Indole Synthesis for the Direct Synthesis of 3,4-Fused Tricyclic Indole and Application to the Total Synthesis of (-)-Aurantioclavine.

Aryl hydrazides with a ketone or aldehyde containing side chains linked to the meta-position of the aromatic ring undergo acid-promoted intramolecular Fischer indole synthesis to generate 3,4-fused tricyclic indoles. The preparative utility of this conceptually new synthetic approach, which does not require prefunctionalization of the indole ring, was demonstrated by its application to a concise total synthesis of (-)-aurantioclavine.