Recent Advances in Total Synthesis of Prenylated Indole Alkaloids by Transition Metal-Catalyzed Reactions as the Key Step

The prenylated indole alkaloids are an intriguning and important class of natural products encompassing an indole ring, or derivatives thereof (that is, spirooxindole or pseudoindowoxyl), decorated by one or more prenyl groups or the vestige of a prenyl group. They comprise a large and structurally diverse family of natural products that display a diverse range of important biological properties. Nature employs dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP) as starting materials for the biosynthesis of numerous prenylated indole alkaloids. The indole core in these compounds is typically derived from L-tryptophan, or less commonly from indole-3-glycerol phosphate. Prenylation is a ubiquitous process common to almost all living organisms, and a key transformation in organic synthesis. In recent years, prenylated indole alkaloids have constantly received intensive research from synthetic chemical community and pharmacologists due to their intriguing structural motifs and diverse biological profiles. To date, the development of straightforward and efficient protocols to enable the synthesis of structurally diverse prenylated indole alkaloids is highly desirable and challenging. The recent advances in the total synthesis of prenylated indole alkaloids by transition metal-catalyzed reactions as the key step are summarized.