A-Chamigrene

Bromo-a-chamigrene, a compound isolated from marine algae, is... 

A recent X-ray crystallographic study has resulted in a revised structure (98) for nidifocene, a minor metabolite of the Hawaiian marine alga Laurencia nidifica. In the previous structure (Vol. 7, p. 69) the positions of chlorine and bromine were reversed. An extension of previous work on the non-enzymic biogenetic cyclization of geranyl and farnesyl diphenylphosphates has shown that (Z)-monocyclo-farnesyl diethylphosphate (99) can be converted into ( )-a-chamigrene (100) in... 

Syntheses have been reported for several other natural products related structurally to carotenoids, viz. dihydroactinidiolide (123) and tetrahydroactinidiolide (124), trans- and cis-a-damascone (125), dihydroedulans I and II, (51) and (52), bicyclodamascenones A and B, (53) and (54), the diastereoisomeric caparrapi oxides (126), ( )-a-chamigrene (127), and the novel passion-fruit ionone derivatives (47) and (48). ... 

Guella G, Chiasera G, Pietra F (1992) Conformational Studies of Marine Polyhalogenated a-Chamigrenes Using Temperature-Dependent NMR Spectra. Inverted Chair and Twist-Boat Cyclohexane Moieties in the Presence of an Axial Halogen Atom at C(8). Helv Chim Acta 75 2026... 

Perforatone (46) and perforenones A (47 R = OH) and B (47 R = Cl) have been discovered in the marine alga Laurencia perforata.78 It is suggested that (46) and (47) are formed from a chamigrene cation (48), and this hypothesis provides a full rationale for the biosynthesis of the wide variety of sesquiterpenoids that have been isolated from Laurencia species. 

Spiroannelatwn of phenolic a-diazoketones (8, 118-119). The Cu(I) decomposition of the phenolic a-diazo ketone 1 has been used for a synthesis of a-chamigrene (3). ... 

Bromo-a-chamigrene, a compound isolated from marine algae, is thought to be biosynthesized from y-bisabolene by the following route ... 

Full details of an earlier synthesis of chamigrene (161) have been published.95 Further work on the components of the red alga Laurencia nipponica Yamada has resulted in the isolation and structural elucidation (by Y-ray analysis) of the diol (162)96 and spironippol (164).97 The biogenesis of the latter compound can be viewed in terms of an intramolecular cyclization of the diol (163) derivable from the naturally occurring epoxide of 10-bromo-a-chamigrene. 

Further investigation of the seaweed species Laurencia perforata has revealed the presence of two new metabolites, perforenone (185) and perforenone-C (183) (c/. Vol. 6, p. 65 Vol. 7, p. 70). These compounds are further examples of a comparatively new structural type of sesquiterpenoid whose carbon skeleton is presumably derived by rearrangement of a chamigrene precursor (c/. Vol. 6, p. 65 Vol. 7 p. 70). Structures (183) and (185) were established by chemical correlation with perforatone (182), a previously reported constituent of L. perforata, and by the synthetic sequence outlined in Scheme 16. 

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