Recent Developments on the Synthesis of Biologically Significant bis/tris(indolyl)methanes under Various Reaction Conditions: A Review

Bis(indolyl)methane skeleton is the main building block of many naturally occurring bioactive compounds. Bis(indolyl)methanes are found to possess a wide range of pharmaceuitical efficacies. These important scaffolds are being used as anti-cancer, antioxidant, anti-bacterial, anti-inflammatory, and anti-proliferative agents. In this review, we summarized the latest developments on the synthesis of various bis/tris(indolyl)methane derivatives from the reactions of two equivalents of indoles and one equivalent of aldehydes or indole-3-carbaldehydes under various reaction conditions. More than hundred different catalysts were employed for these transformations which include various metal catalysts, ionic liquids, organocatalysts, surfactants, homogeneous, heterogeneous catalysts etc.