Progress in the Synthesis of Indole Alkaloid Uleine and Its Derivatives

Uleine and its derivatives belong to the monoterpenoid indole alkaloids based on their structures. The characteristic of their structures is only one carbon atom which separates the indole nucleus and the basic nitrogen atom, as opposed to the normal two-carbon bridge of tryptamine and most monoterpenoid indole alkaloids. Their natural contents are extremely low, and their synthetic work has attracted generations of chemists. The synthetic methods of uleine and its derivatives are reviewed according to the types of structure building methodology. The indole and pyridine derivatives were used as the starting material in most tetracyclic synthesis. Several simple and convenient routes are succeeded.