Synthesis of bis(indolyl)methanes under dry grinding conditions, promoted by a Lewis acid–surfactant–SiO2-combined nanocatalyst

An in situ developed Lewis acid–surfactant–SiO2-combined (LASSC) nanocatalyst was used, for the first time, as a green and effective promoting medium for the electrophilic activation of aldehydes under solvent-free and dry grinding conditions. The advantages of using the LASSC nanocatalyst include avoiding the generation of wastewater containing sodium dodecyl sulfate and the use of toxic reagents, excellent reusability of the catalyst, and obtaining a high yield of bis(indolyl)methanes.