Preparation of 4??hydroxy??3??substituted, 2H??1??benzopyran??2??ones and 2H??1??benzothiopyran??2??ones from carboxylic esters and methyl salicylates or methyl …

SE Davis, AC Church, RC Tummons…

Index: Davis, Sharon E.; Church, A. Cameron; Tummons, Rebecca C.; Beam, Charles F. Journal of Heterocyclic Chemistry, 1997 , vol. 34, # 4 p. 1159 - 1162

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Citation Number: 9

Abstract

Abstract C (α)-Carboxylic acid esters were treated with excess lithium diisopropylamide, condensed with methyl salicylates or methyl thiosalicylate, followed by acid cyclization to either 4-hydroxy-3-substituted, 2H-1-benzopyran-2-ones (coumarins), or 2H-1- benzothiopyran-2-ones (thiocoumarins).