Three-component reaction between Indole with Arylglyoxals and amidines

Indole is among the most important chemical skeletons existing as the main core in the structure of diverse pharmaceutically important compounds. For example indole derivatives involve beneficial estron metabolism promoter [1], inhibitor for human prostate cancer cells and radical scavengers. The primary antitumor screening essay showed that some indole derivatives exhibited the inhibitory activities to some tumor cell growth at relatively high concentration [2, 3]. In this project we report a new and highly efficient method for synthesis of imidazolyl indole derivatives 4 by reaction between indole 1 with arylglyoxals 2 and amidine derivatives 3 in acetonitrile at room temperature in the presence of FeBr3 as a catalyst. The compound 4 can exist in equilibrium with compound 5.