Indium trifluoromethanesulfonate (In(OTf)3). A novel reusable catalyst for intramolecular Diels–Alder reactions

Indium trifluoromethanesulfonate (In(OTf)3) is found to be an effective catalyst for intramolecular Diels–Alder reactions of furans. This novel catalyst, soluble in both aqueous and organic media, is easily recovered from the aqueous layer after the reaction is completed.