Synthesis of tetralin and chromane derivatives via In-catalyzed intramolecular hydroarylation

In(OTf)₃ was found to be an effective catalyst for the cyclization of ω-aryl-1-alkenes to form tetralin and chromane derivatives. Compared with the known Ru-catalyzed version, the In-catalyzed intramolecular cyclization was found to give higher yields and cleaner reactions in some cases. The use of cheaper indium salts instead of the expensive noble metal Ru can be advantageous when the reaction is run on a large scale.