An efficient method for the synthesis of xanthenediones and (arylmethylene) bis(naphthalene-2-yl-sulfane) derivatives using PVPP-p-TSA as a catalyst

Extensive biological activities associated with xanthenes, both synthetic and naturally occurring, ensure that the synthesis of these compounds remains a topic of current interest. In this research, an efficient methods for the synthesis of some bulky xanthenediones was developed by the reaction of dimedone or 1,3-cyclohexadione with aledydes or bisaldehydes in the presence of polyvinylpolypyrrolidone supported p-toluene sulfonic acid (PVPP-p-TSA) as a new polymeric catalyst in ethanol at room temperature. Forthermore, a convenient method for the synthesis of (arylmethylene)bis(naphthalene-2-yl-sulfane) derivatives by polyvinylpolypyrrolidone supported p-toluene sulfonic acid (PVPP-p-TSA) is described. The reaction proceeded via condensation of aldehydes with 2-thionaphthol in the presence of PVPP-p-TSA in ethanol at reflux conditions. All synthesized compounds were identified by FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. Polyvinylpolypyrrolidone supported p-toluene sulfonic acid (PVPP-p-TSA) was characterized via Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Clean methodologies, simple preparation of the catalyst, high yields, environment-friendly and reusable catalyst are some advantages of this work.