Ugi Four-Component Reaction with Tandem Deprotection, Cyclization and Pictet-Spengler Reaction: A Concise Route to N-Fused Polycyclic Indoledi­ketopiperazine Alkaloid Analogues

Abstract

Aza-fused polycyclic indolediketopiperazine alkaloids are of potential interest due to their broad range of biological activities. Traditionally, a number of methods have been used to generate N-fused polycyclic indolediketopiperazine skeletons, but the need to develop novel, concise methods with which to modify the substitution pattern continues. Herein, we describe the two-step formation of N-fused polycyclic indolediketopiperazine alkaloid analogues by the application of the Ugi four-component reaction with tandem deprotection, cyclization and Pictet–Spengler reaction.