On water-promoted direct coupling of indoles with 1,4-benzoquinones without catalyst

A highly efficient direct coupling of indole compounds with 1,4-benzoquinones was developed on water in the absence of any catalyst, organic co-solvent, or additives. The on-water conditions provided the best yields of the corresponding products and the only system to produce bis(coupling) products. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006.