PTSA-Catalyzed Reaction of Indoles with 2-Oxoaldehydes: Synthesis of α,α-Bis(indol-3-yl) Ketones

Abstract

A convenient procedure for accessing a,a-bis(indol-3-yl) ketones from indoles and a-oxoaldehydes is described using an inexpensive and commercially available catalyst such as ptoluenesulfonic acid monohydrate. This protocol allows for the first time the synthesis of 2,2-bis(indolyl)-1-alkylethanones by employing aliphatic 2-oxoaldehydes, even as aqueous solutions. The high-yielded obtained ketones have been shown as useful starting materials for further synthetic transformations.