A highly active copper-based metal-organic framework catalyst for a friedel–crafts alkylation in the synthesis of bis(indolyl)methanes under ultrasound irradiation

Abstract

A robust copper-based metal-organic framework (MOF) catalyst, termed MOF-891, was successful applied to the synthesis of the family of bioactive compounds, bis(indolyl)methanes, through a Friedel–Crafts alkylation under ultrasound irradiation. The remarkable catalytic activity of MOF-891 was proven by the successful synthesis of bis(indolyl)methanes in high yield (up to 96%) and purity. In MOF-891, there exist two types of copper clusters, one discrete and one infinite rod, both are formed through water molecules triggering hydrogen bonds demonstrated the participation as catalytic active site for the Friedel–Crafts alkylation reaction. The well-defined construction of hydrogen bonds in MOF-891 along with Lewis copper sites attributed a stable catalysis activity and exhibited the heterogeneous nature with no significant loss of catalytic performance after six cycles.