Novel cembranolides (Coralloidolide D and E) and a 3,7‐Cyclized cembranolide (Coralloidolide C) from the mediterranean coral Alcyonium coralloides
1989; Wiley; Volume: 72; Issue: 7 Linguagem: Inglês
10.1002/hlca.19890720719
ISSN1522-2675
AutoresMichele D’Ambrosio, Antonio Guerriero, Francesco Pietra,
Tópico(s)Microbial Natural Products and Biosynthesis
ResumoAbstract The Mediterranean alcyonacean Alcyonium (= Parerytkropodium ) coralhides (PALLAS, 1766) is shown to contain three novel diterpenes which are of biogenetic significance: the 3,7‐cyclized cembranoid Coralloidolide C ( = (+)‐(6 R *, 7 R *, 11 S *, 12a S * 3a E )‐7,8‐epoxy‐3,5,6,7,8,9,10,11,12,12a‐decahydro‐12a‐hydroxy‐11‐isopropenyl‐1,4‐dimethyl‐3‐oxocyciopentacydoundecene‐8,6‐carbolactone; (−)‐ 3 ), the O‐bridged diketonic cembranolide Coralloidolide D (= (+)‐(1 R *, 2 S *, 3 R *, 5 R *, 12 S *, 8 Z )‐2,5‐epoxy‐1‐hydroxy‐12‐isopropenyl‐5,9‐dimethyl‐7,10‐dioxocyclotetradeca‐8‐ene‐1,3‐carbolactone; (+)‐ 4 ), and the diketonic epoxycembranolide coralloidolide E (=(+)‐(1 R *, 2 R *, 3 R *, 12 S *, 5 Z , 8 Z )‐1,2‐epoxy‐12‐isopropenyl‐5,9‐dimethyl‐7,10‐dioxocyclotetra‐deca‐5,8‐diene‐1,3‐carbolactone; (+)‐ 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 ID and 2D NMR and MS spectral data. Either corailoidolide A ((−)‐ 1 ) or the hypothetic unsaturated 1,4‐diketone 9 can be envisaged as the precursors of all coralloidolides.
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