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Updated: Jun 1, 2026

Real-time Monitoring of Reactions Performed Using Continuous-flow Processing: The Preparation of 3-Acetylcoumarin as an Example
Published on: November 18, 2015
Synthesis of 5-chloro-8-hydroxy-6-methoxy-3-pentylisocoumarin
1Department of Chemistry, Quaid-I-Azam University, Islamabad, Pakistan. aamersaeed@yahoo.com
Abstract:
The synthesis of title isocoumarin, the 5-chloro analog of naturally occurring 7-chloro-8-hydroxy-6-methoxy-3-pentylisocoumarin, isolated from Tessmannia densiflora is described. Chlorination of ethyl 2-(2-ethoxy-2-oxoethyl)-4,6-dimethoxybenzoate (2) afforded 3-chloro ester (3) followed by hydrolysis to furnish the 2-(carboxymethyl)-3-chloro-4,6-dimethoxybenzoic acid (4) that was converted to corresponding anhydride (5). Condensation of the latter with hexanoyl chloride in the presence of tetramethylguanidine and triethyl amine afforded 5-chloro-6,8-dimethoxy-3-pentylisocoumarin (6) which upon regioselective demethylation yielded the title isocoumarin (1).
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