Novel cembranolides (Coralloidolide D and E) and a 3,7-Cyclized cembranolide (Coralloidolide C) from the mediterranean coral Alcyonium coralloides

✍ Scribed by Michele D'Ambrosio; Antonio Guerriero; Francesco Pietra

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: German
• Weight: 464 KB
• Volume: 72
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19890720719

✦ Synopsis

= (+)-(6R *, 7R *, 8R *, 1 IS*, 12aS*,3aE)-7,8-epoxy-3,5,6,7,8,9,10,11,12,12a-decahydro-12a-hydroxy-11 -isopropenyl-l,4-dimethyl-3-oxocyclopentacycloundecene-8,6-carbolactone; (-)-3), the 0-bridged diketonic cembranolide coralloidolide D (=(+)-(1R*,2S*,3R*,5R*,12S*,8Z)-2,5-epoxy-l-hydroxy-12-isopropenyl-5,9dimethyl-7,lO-dioxocyclotetradeca-8-ene-1,3-carbolactone; (+)-4), and the diketonic epoxycembranolide coralloidolide E ( = (+)-( 1R*,2R*,3R*,12S*,5Z,8Z)-1,2-epoxy-12-isopropenyl-5,9-dimethyl-7,lO-dioxocyclotetradeca-5,8-diene-l,3-~arbolactone; (+)-5). The latter in pyridine at r.t. undergoes a double bond shift from C(4) = C(5) to C(4) = C(18) to give the isomer (-)-7. Structural assignments are mainly based on 1D and 2D N M R and MS spectral data. Either coralloidolide A ((-)-1) or the hypothetic unsaturated 1,4-diketone 9 can be envisaged as the precursors of all coralloidolides. ') We use the cembrene numbering for the structural formulae and spectroscopic data; IUPAC nomenclature and numbering are given in the Exper. Part.