Iodine in aqueous micellar environment: a mild effective ecofriendly catalytic system for expedient synthesis of bis(indolyl)methanes and 3-substituted indolyl ketones

The three-component condensation reaction of indoles with carbonyl compounds to yield bis(indolyl)methanes has been accomplished with a catalytic amount of iodine (2 mol%) in the presence of sodium dodecylsulfate (SDS) in aqueous solution above its critical micellar concentration (cmc). The surfactant-aided water-compatible Lewis acid catalyst has been found to be efficient for a wide range of carbonyl compounds including aromatic aldehydes bearing electron-releasing and electron-withdrawing groups, alpha,beta-unsaturated aldehydes, heterocyclic aldehydes, cyclic and aromatic ketones with respect to yield, and reaction time. The protocol has been extended to Michael addition of indoles with alpha,beta-unsaturated ketones exclusively yielding 3-substituted indolyl ketones in excellent yields.