1731-1737A simple, highly rapid and efficient
electophilic substitution reaction of indole with various aromatic aldehydes
has been carried out using 5 wt% of monoammonium salt of 12-tungstophosphoric
acid [(NH4)H2PW12O40] as a solid acid catalyst in acetonitrile to afford the corresponding
bis(indolyl)methanes in excellent yields (84-95%) at room temperature. The
heteropolyacid-based catalyst has the advantages of simple workup procedure,
water insolubility with good activity and high yielding reaction for the
synthesis of bis(indolyl)methane derivatives