Violacene: A reassignment of structure

Engen, D. Van; Clardy, Jon; Kho-Wiseman, Ernest; Crews, Phillip; Higgs, M.D.; Faulkner, D. John

doi:10.1016/s0040-4039(01)88974-7

Cited by 25 publications

(9 citation statements)

References 7 publications

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“…This caused annoying problems; for example, the initial structure proposed for violacene22 ( 3 ), isolated from P. violaceum , was eventually corrected to 4 , based initially on our analysis of 13 C NMR shifts and definitively on the X-ray data collected of crystals we obtained 23…”

Section: The Early Days – Some Triumphs and Annoying Diversionsmentioning

confidence: 99%

A Selective Account of Effective Paradigms and Significant Outcomes in the Discovery of Inspirational Marine Natural Products

2009

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Marine natural products continue to be a source of significant molecular structures that serve as a stimulus to seed further significant research. This account reviews some of the major advances in the study of marine biomolecules made at UC Santa Cruz over more than three decades. The continuing challenge of discovery and characterization of what we term "inspirational molecular structures", will be presented in a comprehensive fashion. Examples of privileged molecular structures and their impact on biomedicinal research will be an important theme. The three major groups of organisms explored include: seaweeds, sponges, and marine derived fungi, and the study of their active principles has greatly benefited from synergistic collaborations with both academic and biopharmaceutical groups. The concluding sections of this chronicle will touch on prospects for future outcomes involving new sources and strategies.

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Section: The Early Days – Some Triumphs and Annoying Diversionsmentioning

confidence: 99%

A Selective Account of Effective Paradigms and Significant Outcomes in the Discovery of Inspirational Marine Natural Products

2009

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“…From specimens of P. cartilagineum collected from the Chilean coasts four new alicyclic monoterpenes (87-90) were isolated along with the known monoterpenes 91, mertensene (92) (Argandona et al, 2000) and violacene (93) ( Figure 11) Van Engen et al, 1978). The insecticidal and acaricidal activities of these polyhalogenated monoterpenes were investigated and violacene (93) showed the most potent anti-insect activity among the compounds tested, mainly against Macrosteles facifrons.…”

Section: Plocamium Cartilagineummentioning

confidence: 99%

Volatile halogenated metabolites from marine red algae

2004

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A significant number of halogenated low molecular weight metabolites have exhibited an impressive array of biological properties ranging from antimicrobial to insecticidal activities. Studies on the natural products chemistry of the red seaweeds were recently stimulated by the discovery of the acyclic monoterpene halomon, which exhibits selective antitumor activity in the National Cancer Institute's human tumor and disease oriented in vitro screen.The present review is a taxonomy based compilation of the available literature on the halogenated volatile metabolites (C 1 -C 10 ) produced by red seaweeds, with a short description of the reported ecological and pharmaceutical activities. The review begins with a presentation of simple halogenated hydrocarbons and phenols, showing their wide occurrence in rhodophyta, along with a description of simple halogenated lipids in some of the most frequently investigated red algae species and finally focuses on the chemical composition of individual red algae species.

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“…A separate investigation of P. violaceum resulted in the isolation of violacene-2 (Higgs et al, 1977) (also known as plocamene-C, 3) which was secured by a single crystal X-ray diffraction analysis but was found to have decomposed during acquisition . The first structural reassignment of a cyclic monoterpene was reported in 1978 for violacene (1) (Van Engen et al, 1978). A single-crystal X-ray diffraction study confirmed that the correct structure of violacene (1) is actually 4 and the revised structure is consistent with the reversed assignments at positions 5 and 10, for which the carbon chemical shift of the methylene chloride (CH 2 Cl) appears approximately 10 ppm further downfield compared with the carbon shift of the methylene bromide (CH 2 Br) (Van Engen et al, 1978).…”

Section: Introductionmentioning

confidence: 99%

“…The first structural reassignment of a cyclic monoterpene was reported in 1978 for violacene (1) (Van Engen et al, 1978). A single-crystal X-ray diffraction study confirmed that the correct structure of violacene (1) is actually 4 and the revised structure is consistent with the reversed assignments at positions 5 and 10, for which the carbon chemical shift of the methylene chloride (CH 2 Cl) appears approximately 10 ppm further downfield compared with the carbon shift of the methylene bromide (CH 2 Br) (Van Engen et al, 1978). In 1977 an additional five cyclic monoterpenes (5)(6)(7)(8)(9) were reported from P. cartilagineum, for which the stereochemical assignments were based on the absolute configuration previously reported for 3 (Higgs et al, 1977).…”

Section: Introductionmentioning

confidence: 99%

“…These included mertensene reported as 11 , 25 , 24 (Capon et al, 1984), 26 (Crews et al, 1984) and finally 27 (Coll et al, 1988). Alternative strategies reported include, 13 C (or 1 H) T 1 measurements, but ambiguities have been noted with this method, as well as lanthanide-induced shift methods (Van Engen et al, 1978;Crews et al, 1984). The approach adopted relied on substituent additivity parameters and model compound 13 C NMR shift data to predict halogen regiochemistry, resulting in plausible correlations between calculated and experimental values (Crews et al, 1984).…”

Section: Introductionmentioning

confidence: 99%

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