ISSN:
0018-019X
Schlagwort(e):
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Spectra and chemical transformations allow to establish the gross structure 6,7-epoxy-4,7-dimethyl-l-oxa-spiro[4.4]non-3-en-2-one for adriadysiolide (1), the first monoterpenoid isolated from a marine sponge, a Dysidea sp. of the Adriatic Sea. Its configuration 5R*, 6S*, 7S* as given in 1a is derived from diastereoselective total syntheses of both 1a and its diastereoisomer 1b via stereochemically predictable peracid epoxidations of olefinic precursors. Thus, OH assistance in allylic alcohol 8 leads to oxirane 13 which is subjected to methyl cuprate conjugate addition to give epiadriadysiolide (1b), whilst electronic deactivation by a neighboring heterocyclic O-atom in intermediate 5, derived from 8 mainly leads to adriadysiolide (1a). Comparative 1H-NMR shift-reagent effects with 1a and 1b, evaluated with the aid of molecular-mechanics calculations, support these conclusions.
Zusätzliches Material:
1 Tab.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/hlca.19870700806
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