Efficient synthesis of bis (indolyl) methanes catalyzed by (PhCH2PPh3)+Br3− under solvent-free conditions

Benzyltriphenylphosphonium tribromide (BTPTB) has been applied as an efficient catalyst for the preparation of bis (indolyl) methanes (BIMs) via electrophilic substitution of indoles with aldehydes in the absence of solvent.