Synthesis of polysubstituted cyclopenta[b] indoles via relay gold(I)/Bronsted acid catalysis

An efficient relay catalytic process involving Au(I)/ Bronsted acid to access various polysubstituted cyclopentannulated indoles from easily accessible 1-(2-aminophenyl) prop-2-ynols and readily available 1,3-dicarbonyls has been developed. In an unprecedented event, the intermediate 2-indolylmethyl cations undergo the cation-Ene reaction with various 1,3-dicarbonyls followed by an intramolecular FriedelCrafts- type reaction generating functionalized cyclopenta[b] indoles.