Direct olefination at the C-4 position of tryptophan via C-H activation: application to biomimetic synthesis of clavicipitic acid.

The first Pd-catalyzed method for direct olefination at the C4 position of tryptophan derivatives has been developed via C-H activation to prepare 4-substituted tryptophans, which could be used for the synthesis of many hemiterpenoid indole alkaloids. This reaction proceeds under mild reaction conditions and with exceptional tolerance to a variety of functional groups. Furthermore, the efficiency of this method is demonstrated by the rapid and biomimetic synthesis of clavicipitic acid.