Buchwald-Hartwig indole synthesis

The mechanism of the direct intramolecular Buchwald-Hartwig indole synthesis is that of a traditional palladium-catalyzed cross-coupling reaction and begins with loss of a ligand on palladium. Oxidative addition of an appropriately substituted Z-vinylhaloarene (1) generates intermediate 2. Deprotonation of 2 and displacement of a halide ligand sets up a reductive elimination on 3 to yield indole 4. 

The Buchwald-Hartwig indole synthesis has been used successfully to prepare complex natural products featuring functionalized indoles. One of the earliest examples was a transformation carried out by Hartwig and coworkers to prepare 18, an intermediate in the synthesis of damirone B, a topoisomerase II inhibitor. " ... 

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