Intramolecular Larock indole synthesis for the preparation of tricyclic indoles and its application in the synthesis of tetrahydropyrroloquinoline and fargesine

A general and efficient strategy for fused tricyclic indoles from substituted 2-halogenanilines via the palladium-catalyzed intramolecular Larock indolization process has been developed. Using this strategy, a number of 3,4- and 3,5-fused indoles with a variety of ring sizes can been prepared. The utility of this method is demonstrated through the synthesis of the known tetrahydropyrrolo[4,3,2-de]quinoline 10 and the first total synthesis of fargesine.