Trichloroisocyanuric acid‐catalyzed reaction of indoles: An expeditious synthesis of bis‐indolyl, tris‐indolyl, di(bis‐indolyl), tri(bis‐indolyl), and tetra(bis‐indolyl)methane under solid‐state conditions

Trichloroisocyanuric acid is found to be an efficient catalyst for the electrophilic substitution reactionof indole with aldehydes/ketones to afford the corresponding bis-indolyl, tris-indolyl, di(bis-indolyl),tri(bis-indolyl), and tetra(bis-indolyl)methanes under solid-state conditions by pulverization-activationmethod at room temperature with excellent yields. The remarkable features of this new procedure arehigh conversions, shorter reaction times, cleaner reaction profiles, and simple experimental and work-upprocedures.