Copper-Catalyzed Domino Synthesis of Indoles

Significance

A general route for the construction of N-arylated, -acylated and -unsubstituted indoles using a ligand-free intermolecular hydroamination/intramolecular N-amination methodology catalyzed by CuI is presented. The use of KOt-Bu as base was shown to be crucial for the success of this reaction; use of aryl chlorides rather than bromides afforded only poor yields of products. After a ligand screening study, the methodology was extended to the use of carbamates or amides as coupling partners instead of anilines. A one-pot procedure for the above-mentioned coupling and subsequent deprotection was realized using TFA. Whether this is a true one-pot process or whether there were work-up steps involved is not clear from the experimental conditions.