efficient and green synthesis of bis (indolyl) methanes catalyzed by fe3o4@sio2-imid-pman magnetic nanocatalyst

highly efficient and eco-friendly protocol for the synthesis of bis(3-indolyl)methanes by the electrophilic substitution reaction of indole with aldehydes catalyzed by fe₃o₄@sio₂-imid-pmaⁿ was described. simple work-up procedure, shorter reaction times, excellent yields, avoiding hazardous organic solvents, and reusability of the catalyst are the most obvious advantages of this method. also, the catalyst can be easily recovered by a magnetic field and reused for six consecutive reaction cycles without significant loss of activity.