title: Synthesis of 5-chloro-8-hydroxy-6-methoxy-3-pentylisocoumarin.
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).
authors.affiliation: Department of Chemistry, Quaid-I-Azam University, Islamabad, Pakistan. aamersaeed@yahoo.com
authors.forename: Aamer
authors.initials: A
authors.lastname: Saeed
mesh_terms: D007887:Fabaceae / Q000737:chemistry*; D006843:Hydrocarbons, Chlorinated / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D049934:Isocoumarins / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: C560685:5-chloro-8-hydroxy-6-methoxy-3-pentylisocoumarin; D006843:Hydrocarbons, Chlorinated; D049934:Isocoumarins