Preparation of a new, green and recyclable catalyst, silica-supported 1-(2-sulfooxy)ethyl)1H-pyridine-1-ium-chloride, and a solvent- and metal-free protocol for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthene derivatives

Abstract

A cost-effective and convenient procedure for the synthesis of silica-supported 1-(2-sulfooxy)ethyl)1H-pyridine-1-ium-chloride SiO2/[SEP]Cl as a recoverable heterogeneous and Brønsted acid catalyst is described, and was used for the one-pot synthesis of aryl-14H-dibenzo[a,j]xanthenes under solvent- and metal-free conditions at 110 °C in short reaction time with a yield of up to 95%. The present method offers several advantages such as simplicity in operation, ease of preparation and recycling of Brønsted acidic ionic liquid (BAIL), solvent-free reaction conditions, and no hazardous organic solvents are used in the entire procedure including workup and purification.