Efficient and green synthesis of bis(indolyl)methanes catalyzed by ABS in aqueous media under ultrasound irradiation.

Ultrasound-promoted synthesis of bis(indolyl)methanes catalyzed by ABS via the reaction of indole or N-methylindole with aromatic aldehyde was carried out in excellent yields in aqueous media at 23-25°C, providing a simple and efficient synthesis of these compounds.