A convenient synthesis of coumarin-3-carboxylic acids via Knoevenagel condensation of Meldrum's acid with ortho-hydroxyaryl aldehydes or ketones

A Song, X Wang, KS Lam

Index: Song, Aimin; Wang, Xiaobing; Lam, Kit S. Tetrahedron Letters, 2003 , vol. 44, # 9 p. 1755 - 1758

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Citation Number: 155

Abstract

Coumarin-3-carboxylic acids were obtained in high yields with excellent purity from ortho- hydroxybenzaldehydes and Meldrum's acid after a 2 h reflux in ethanol. The less reactive ketones were first reacted with alcoholic ammonia to form ketimines, which were then condensed with Meldrum's acid to generate 4-alkylcoumarin-3-carboxylic acids in moderate yields.