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Stereoselective Synthesis of (3 R )‐3,4‐Dihydro‐6,8‐dimethoxy‐3‐undecyl‐ 1 H ‐[2]benzopyran‐1‐one and Derivatives, Metabolites from Ononis natrix
Author(s) -
Saeed Aamer
Publication year - 2003
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200390038
Subject(s) - chemistry , stereoselectivity , stereocenter , stereochemistry , enantioselective synthesis , enantiomer , demethylation , organic chemistry , biochemistry , gene expression , dna methylation , gene , catalysis
A short stereoselective synthesis of (3 R )‐3,4‐dihydro‐6,8‐dimethoxy‐3‐undecyl‐1 H ‐[2]benzopyran‐1‐one and derivatives isolated from Ononis natrix has been described. Condensation of dodecanoyl chloride with 3,5‐dimethoxyhomophthalic acid afforded 6,8‐dimethoxy‐3‐undecylisocoumarin 3 , which, on sequential saponification and esterification, yielded the keto ester 5 . Enantioselective reduction of 5 with TarB‐NO 2 /LiBH 4 directly furnished the title dihydroisocoumarin 1a in 80% ee (82% yield). Partial as well as complete demethylation of the latter provided the dihydroisocoumarins 1b and 1c , respectively. Diastereotopy of the CH 2 H‐atoms on either side of the stereogenic center (C(3)) and the mass‐fragmentation pattern of the dihydroisocoumarins have also been described. All of the compounds synthesized were examined in vitro for antifungal activity.