Efficient electrophilic substitution reactions of indoles with various carbonyl compounds
proceed easily in solvent-free conditions using CeCl3·7H2O-NaI-SiO2 system promoter, to afford the corresponding bis(1H-indol-3-yl)alkanes in high yields. The synthetic value of the present procedure is
demonstrated by the synthesis of streptindole (9), human intestinal bacteria metabolite.
addition reactions - carbonyl complexes - indoles - lanthanides - Lewis acids - natural
products