Synthesis of new indolyl crown ethers catalyzed with ferric hydrogensulfate

Efficient reaction of bis-indolyl podand with different aldehydes using Fe(HSO4)3 as catalyst to afford the corresponding new indolyl crown ethers is described. The structures of three distinct isomers have been optimized using HyperChem geometry optimizations. Also percentage of each isomer was obtained with 1H NMR spectroscopy.