Abstract
An efficient, facile, and environmentally friendly electrophilic substitution reaction of indoles with various aldehydes and ketones proceeded smoothly in water using the hexamethylenetetramine–bromine complex to afford the corresponding bis(indolyl)methanes in excellent yields. This method provides several advantages such as being environmentally friendly, giving high yields, and having simple workup procedure. Water was chosen as a cheap, nontoxic, green solvent.