A simplified green chemistry approach for synthesis of bis-indolylmethanes using phenylphosphonic acid as an organocatalyst under grinding condition

A simple and efficient method for preparation of bis(indolyl)methanes (BIMs) is described from the electrophilic substitution reaction of indole with aromatic and aliphatic aldehydes in the presence of phenylphosphonic acid as organocatalyst under solvent-free conditions at room temperature by grinding method. This method provides several advantages such as operational simplicity, higher yield and environment friendly.