An organocatalytic method for the synthesis of some novel xanthene derivatives by the intramolecular Friedel-Crafts reaction

Abstract

An efficient organocatalytic method for the synthesis of new substituted 9-arylxanthenes (2a-2u) starting from diarylcarbinol compounds with an arenoxy group (1a-1u) has been developed using the intramolecular FriedelCrafts reaction. The substrates were prepared in two steps by Ullmann-type coupling and then Grignard reaction. Some organic Bronsted acids were studied as catalysts (3a-3g) in the intramolecular Friedel-Crafts alkylation reaction for the first time. N-triflylphosphoramide (3g) provided the synthesis of some novel substituted 9-arylxanthenes with excellent yields at room temperature within 15 minutes.