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Preparation of 4‐hydroxy‐3‐substituted, 2 H ‐1‐benzopyran‐2‐ones and 2 H ‐1‐benzothiopyran‐2‐ones from carboxylic esters and methyl salicylates or methyl thiosalicylate
Author(s) -
Davis Sharon E.,
Church A. Cameron,
Tummons Rebecca C.,
Beam Charles F.
Publication year - 1997
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570340411
Subject(s) - chemistry , lithium diisopropylamide , carboxylic acid , lithium (medication) , organic chemistry , benzopyran , medicinal chemistry , bicyclic molecule , methyl salicylate , ion , deprotonation , medicine , ecology , biology , endocrinology
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, 2 H ‐1‐benzopyran‐2‐ones (coumarins), or 2 H ‐1‐benzothiopyran‐2‐ones (thiocoumarins).