Efficient Synthesis of bis- and tris-Indolylalkanes Catalyzed by a Brønsted Acid–Surfactant Catalyst in Water

Abstract

A simple and efficient synthesis of bis- and tris-indolylalkanes from carbonyls (aldehydes/ketones) and indoles with excellent yields in the presence of dodecylsulphonic acid (DSA) in water at room temperature is described. The catalyst is also applicable for the synthesis of 3,3-di(3-indolyl)oxindoles. The dodecylsulphonic acid acts as both Brønsted acid and surface-active agent in the reaction mixture.

Keywords:

• bis-indolylalkane
• Brønsted acid–surfactant catalyst
• 3-substituted indoles
• water media

ACKNOWLEDGMENT

The authors acknowledge the director, Dr. P. G. Rao, and Dr. N. Borthakur, Head of the Division, Synthetic Organic Chemistry Division, the Analytical Division of Regional Research Laboratory, Jorhat, Assam, India, for their help. P. H. and S. D. S. thank Council of Scientific and Industrial Research, New Delhi, for research fellowships.

Notes

^a Isolated yield.

^b Stirring at room temperature.

^c The structure of the compound was determined using ¹H NMR, FTIR, and MS (m/z).

^d Sodium dodecyl sulfate.

^e No reaction.

^a Isolated yield.

^b Stirring at room temperature.

^c The structure of the compounds were determined by using ¹H NMR, FTIR, and MS (m/z), and known compounds were compared with authentic data.^[11,7c,7f]