Camphor sulfonic acid catalyzed facile and general method for the synthesis of 3,3'-(arylmethylene)bis(4-hydroxy-2H-chromen-2-ones), 3,3'-(arylmethylene)bis(2-hydroxynaphthalene-1,4-diones) and 3,3'-(2-oxoindoline-3,3-diyl)bis(2-hydroxynaphthalene-1,4-dione) derivatives at room temperature

Abstract

Camphor sulfonic acid catalyzed a straightforward, efficient, and general method has been developed for the synthesis of 3,3'-(arylmethylene)bis(4-hydroxy-2H-chromen-2-ones), 3,3'-(arylmethylene)bis(2-hydroxynaphthalene-1,4-diones) and 3,3'-(2-oxoindoline-3,3-diyl)bis(2-hydroxynaphthalene-1,4-dione) derivatives in aqueous ethanol at room temperature from the reactions of various aromatic aldehydes and 4-hydroxycoumarin or 2-hydroxynaphthalene-1,4-dione respectively. Mild reaction conditions, use of metal-free organocatalyst, good to excellent yields, high atom-economy, environmentally benign, easy isolation of products, and no column chromatographic separation are some of the major benefits of this developed protocol.

Graphical Abstract

Keywords:

• 3,3'-(arylmethylene)bis(4-hydroxy-2H-chromen-2-one)
• 3,3'-(arylmethylene)bis(2-hydroxynaphthalene-1,4-dione)
• 3,3'-(2-oxoindoline-3,3-diyl)bis(2-hydroxynaphthalene-1,4-dione)
• camphor sulfonic acid
• no column chromatography

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Acknowledgments

Dr. B. Banerjee is thankful to the Indus International University, Una, Himachal Pradesh, India and the Kartha Education Society, Mumbai, India for the support. Authors are grateful to AMRC, IIT Mandi, Himachal Pradesh, India for the spectral measurements such as FTIR.

Disclosure statement

No potential conflict of interest was reported by the author(s).