One step synthesis of indigoids from indoles in a self-assembled capsule

Indigoids, which are derivatives of indigo and indirubin, have been synthetized from indoles in the presence of H 2 O 2 and a supramolecular capsule formed from 2,8,14,20-tetra-undecyl-resorcin[4]arene and water, with the latter acting as an organocatalyst. The dimerization reaction of the oxides formed takes place within the confined space provided by the capsule. This one-pot synthesis is carried out under mild conditions, 8 hours at 40°C, with a "green" oxidant, and requires no metal. The method yielded nine dyes, including indigo, indirubin, and two novel derivatives of these molecules: 6,6'-dibenzyloxyindigo and 6,6'-dibenzyloxyindirubin. • Supramolecular assistance in the formation of indigoid derivatives through the reaction of indoles with H 2 O 2 . • Formation of nine distinct indigoid derivatives, including the two new indigoids, 6,6′-dibenzyloxyindigo and 6,6′-dibenzyloxyindirubin. • Utilization of a self-assembled capsule composed of 2,8,14,20-tetra-undecyl-resorcin[4]arene and water.