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Updated: Aug 11, 2026

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
Synthesis and antiallergic activities of 1,3-oxazolo[4,5-h]quinolines
Abstract:
A series of new 1,3-oxazolo[4,5-h]quinolines has been prepared. These compounds were tested as inhibitors of antigen-induced release of histamine (AIR) in vitro from rat peritoneal mast cells (RMC) and as inhibitors of IgE-mediated passive cutaneous anaphylaxis in the rat (PCA). After several modifications of the original lead, the most potent compound of the series was determined to be 5-chloro-1,3-oxazolo[4,5-h]quinoline-2-carboxylic acid methyl ester (4a). It has an IC50 of 0.3 microM in the RMC assay and an ED50 (intraperitoneal) of 0.1 mg/kg in the PCA test, which is 10 times and 60 times more potent than disodium cromoglycate (DSCG), respectively. Of greater importance, it is orally active (ED50 = 0.5 mg/kg) as an inhibitor of the PCA test.
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