Issue 26, 2012

Tandem one-pot synthesis of flavans by recyclable silica–HClO4 catalyzed Knoevenagel condensation and [4 + 2]-Diels–Alder cycloaddition

Abstract

An efficient one-pot multi-component synthesis of flavans using perchloric acid supported on silica as a recyclable heterogeneous catalyst has been described. This is the first report of direct one-step construction of a flavan skeleton from a phenolic precursor. The method involves a Knoevenagel-type condensation leading to in situ formation of transient O-quinone methide which further undergoes [4 + 2]-Diels–Alder cycloaddition with styrene to yield a flavan skeleton. The method provides easy access to a wide range of bio-active natural products viz. flavonoids, anthocyanins and catechins.

Graphical abstract: Tandem one-pot synthesis of flavans by recyclable silica–HClO4 catalyzed Knoevenagel condensation and [4 + 2]-Diels–Alder cycloaddition

Supplementary files

Article information

Article type
Paper
Submitted
21 Feb 2012
Accepted
10 May 2012
First published
10 May 2012

Org. Biomol. Chem., 2012,10, 5143-5150

Tandem one-pot synthesis of flavans by recyclable silica–HClO4 catalyzed Knoevenagel condensation and [4 + 2]-Diels–Alder cycloaddition

S. B. Bharate, R. Mudududdla, J. B. Bharate, N. Battini, S. Battula, R. R. Yadav, B. Singh and R. A. Vishwakarma, Org. Biomol. Chem., 2012, 10, 5143 DOI: 10.1039/C2OB25376C

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