Undecane Skeleton Research Articles

A diterpenoid from Portulaca pilosa

A new diterpenoid, pilosanone C, having a bicyclo[5.4.0]undecane skeleton, has been isolated from the aerial parts of Portulaca pilosa. Its structure was elucidated on the basis of spectral studies. Its biosynthesis and implication in chemosystematic evolution is discussed.

Isolepidozene, a diastereomer of bicyclogermacrene, in some liverworts

Isolepidozene, the diastereomer of the widespread sesquiterpene hydrocarbon, bicyclogermacrene, has been identified in several liverworts. This previously unknown sesquiterpene hydrocarbon is based on the rare trans-bicyclo[8.1.0]undecane skeleton.

ChemInform Abstract: A New Synthesis of a Functionalized Bicyclo(5.4.0)undecane Skeleton Based on a Sequence Involving (2 + 2) Photoaddition and Regioselective β‐Scission of Alkoxyl Radicals Generated from the Resulting Cyclobutanols.

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Minor Constituents of Lippia integrifolia

Three new sesquiterpenes (1-3) possessing the 2,6,6,9-tetramethyltricyclo[5.4.0.0 2,4 ]undecane (lippifoliane) skeleton were isolated as minor constituenrs of Lippia integrifolia. Their structures and stereochemistry were elucidated from nmr data including double resonance experiments, COSCV, and nOe, and by comparison of their 13 C-nmr spectra with those of lippifoli-1(6)-en-5-one

Total synthesis of the novel sesquiterpenes of Eremophila georgei Diels

The first stereoselective total synthesis of the natural sesquiterpenes 4 and 5, having the tricyclo[6.2.1.01,5]undecane skeleton with a bridgehead methyl group, is reported via the intermediate 9, which was obtained by the acid catalysed rearrangement of the alcohols 7 and 8.

Rearrangements of tricyclic ketones: [3.3.3]propellane formation via a γ-enolate revealed in an approach to the pentalenene skeleton through β-enolization

The known isomerization of the tricyclo[5.3.1.01,5]- to the [6.3.0.01,5]undecane skeleton by β-homoenolization led to examination of 2,9,9-trimethyl-6-methoxymethyltricyclo[5.3.1.01,5]undecanone (6) as a potential precursor for the synthesis of pentalenene, a naturally occurring sesquiterpenoid, utilizing a β-enolate rearrangement as a key step. While the anticipated rearrangement of 6 occurs, it is a minor process. The major rearrangement product arises by generation of a γ-enolate intermediate from a tricyclic enone formed by loss of methanol from 6. This constitutes a new route to [3.3.3]propellanes and provides a third example of γ-enolate rearrangement. Structures of the products were established primarily from their 1H and 13Cmr spectra.

A new synthesis of a functionalized bicyclo[5.4.0]undecane skeleton based on a sequence involving [2 + 2] photoaddition and regioselective β-scission of alkoxyl radicals generated from the resulting cyclobutanols

A new general synthesis of a functionalized bicyclo[5.4.0]undecane skeleton based on a regioselective β-scission of the alkoxyl radicals generated from 2-hydroxytricyclo[5.4.0.02,6]undecan-8-ones (prepared by [2 + 2] photoaddition of cyclic enones with the trimethylsilyl enol ethers of cyclic ketones) is described.

ChemInform Abstract: Enantioselective Synthesis of the Tricyclo(5.2.2.01,5)undecane Skeleton Using Aprotic Michael Additions: Formal Total Synthesis of (+)‐Isoeremolactone.

AbstractMichael addition of the ester (I) to the enone (II) affords the adduct (III) (space group P212121; Z=4).

Minor diterpenoids from Portulaca cv Jewel

A trans-clerodane and a diterpenoid with the bicyclo[5.4.0]undecane skeleton were isolated from the aerial part of Portulaca cv Jewel, and their structures were elucidated by spectroscopic methods, chemical correlation and X-ray diffraction analysis. The chemotaxonomical significance is discussed.

Enantioselective synthesis of the tricyclo[5.2.2.0]undecane skeleton using aprotic Michael-additions; formal total synthesis of (+)-lsoeremolactone

The (formal) total synthesis of the diterpene (+)-Isoeremolactone (2) is described starting from the tricyclic ester (15), which was formed by an aprotic Michael-addition (AMA) sequence. The structure of the ester (15) was confirmed by X-ray analysis. The key compound (4) for the synthesis of (2) was made from (15) in 8 steps (25% overall yield).

Structural studies in the cedrane series by 13C NMR

AbstractThe complete analysis of the 13C NMR spectra of 30 cedrane derivatives with various functionalities on the 2, 6, 6, 8‐tetramethyltricyclo[5.3.11,701,5]undecane skeleton is reported. The assignment of the signals to the appropriate carbons has been made using the various functionalities on the molecular framework and the chemical shift theory (α, β, γ effects). When necessary, off‐resonance decoupling, INEPT and DEPT experiments have been used, as well as specific deuterium labelling. The last ambiguities were resolved with the aid of lanthanide shift reagents and SFORD experiments. The assignments for the reference compounds neoisocedranol oxide, cedrol and cedrene were made using the carbon‐carbon connectivity 2D INADEQUATE pulse sequence. The examination of cedrane derivatives functionalized on C‐9 (carbonyl, hydroxyl, acetate) and C‐8 (methyl, axial or equatorial) showed that the 13C chemical shifts of C‐5, ‐6, ‐11 and ‐13 are sensitive probes for the conformation of the six‐membered ring (ring C), which is essentially a flattened chair, and for the stereochemistry of the C‐8 and C‐9 substituents. Comparison with 2‐methylbicyclo[3.2.1]octan‐3‐ones shows that the Anti Reflex effect is operative in cedrane derivatives.Cedrane oxides and their derivatives have also been examined and the corresponding 13C data are reported. Using all this information it was possible to carry out a complete analysis of lac acids, which have a functionalized tricyclo[5.31,7, 01,5]undecane framework like the cedrane derivatives. The 13C spectral analysis shows that, from the structural point of view, this tricyclic system behaves as a bicyclo[3.3.0] skeleton with an additional three‐carbon bridge between C‐1 and C‐7, rather than as a bicyclo[3.2.1]octane with an additional cyclopentane fused on C‐1 and C‐5; when additional strain is introduced into this system, the five‐membered ring A and the six‐membered ring C undergo conformational deformations more easily than ring B.

Structure of pilosanones A and B: novel diterpenoids with a bicyclo[5.4.0.]undecane skeleton from Portulaca pilosa L.

Pilosanones A (1) and B (2), the major diterpenoid constituents of Portulaca pilosa l., have been assigned structures with a novel bicyclo[5.4.0.]undecane skeleton on the basis of detailed spectroscopic analyses, and their significance in the biosynthesis and the chemosystematics of Portulaca plants is suggested.

A short and efficient synthesis of capnellene

A short synthesis of the marine triquinane sesquiterpene capnell-9(12)-ene based on titanium-induced oxo ester cyclization as the key step for construction of the cis-transoid-cis-tricyclo[6.3.0.02,6]undecane skeleton is described.

Novel Diterpenes with Bicyclo[5.4.0]undecane Skeleton from Portulaca grandiflora Hook, Possible Linking Intermediates in the Biosynthesis of Portulal

Abstract Three new diterpenes with bicyclo[5.4.0]undecane skeleton were isolated from Portulaca grandiflora Hook and their structures have been elucidated by spectroscopic methods involving an extensive application of NMR technigues. The significance of these compounds in the consideration of biosynthesis of portulal is suggested.

A highly efficient synthesis of bicyclo[n.3.1] ring systems by allene intramolecular cycloaddition: Tandem intramolecular [2+2] cycloaddition-[3,3]-sigmatropic rearrangement

A novel one-step construction of bicyclo[5.3.1]undecane skeleton via intramolecular cycloaddition of allenyl ethers is described.

Subergorgic acid, a novel tricyclopentanoid cardiotoxin from the pacific gorgonian coral [formula omitted

The structure of subergorgic acid ( 1), a cardiotoxic sesquiterpene with a new tricyclo[6.3.0.0 1,5]undecane (angular triquinane) skeleton, has been determined by combined spectral, chemical and x-ray crystallographic methods.

The acetylation of cedrene in the presence of titanium tetrachloride

The acetylation of α-cedrene with acetic anhydride in the presence of titanium tetrachloride affords two new products in addition to acetylcedrene. These materials have been characterised as a hydroxyketone having a tricyclo[5.2.2.01,5]undecane skeleton and a vinyl ether derived from it.

ChemInform Abstract: STUDIES WITH BICYCLO(2.2.2)OCTENES. VIII. SYNTHESIS OF THE TRICYCLO(5.2.2.01,5)UNDECANE SKELETON RELATED TO EREMOLACTONE

Chemischer InformationsdienstVolume 9, Issue 51 Isocyclic Compounds ChemInform Abstract: STUDIES WITH BICYCLO(2.2.2)OCTENES. VIII. SYNTHESIS OF THE TRICYCLO(5.2.2.01,5)UNDECANE SKELETON RELATED TO EREMOLACTONE G. I. FEUTRILL, G. I. FEUTRILLSearch for more papers by this authorR. N. MIRRINGTON, R. N. MIRRINGTONSearch for more papers by this author G. I. FEUTRILL, G. I. FEUTRILLSearch for more papers by this authorR. N. MIRRINGTON, R. N. MIRRINGTONSearch for more papers by this author First published: December 19, 1978 https://doi.org/10.1002/chin.197851150Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume9, Issue51December 19, 1978 RelatedInformation

Marine natural products: dactylol, a new sesquiterpene alcohol from a sea hare

A new sesquiterpene alcohol, dactylol, having an uncommon bicyclo [6.3.0] undecane skeleton has been isolated from the sea hare Aplysia dactylomela. Chemical degradation and NMR studies using a shift reagent established the structure and relative stereochemistry. The absolute configuration was derived from ORD/CD data of a substituted cyclopentanone degradation product.

ChemInform Abstract: SYNTHESIS OF THE TRICYCLO(5.2.2.01,5)UNDECANE SKELETON RELATED TO ISOEREMOLACTONE

Chemischer InformationsdienstVolume 7, Issue 47 Isocyclic Compounds ChemInform Abstract: SYNTHESIS OF THE TRICYCLO(5.2.2.01,5)UNDECANE SKELETON RELATED TO ISOEREMOLACTONE G. I. FEUTRILL, G. I. FEUTRILLSearch for more papers by this authorR. N. MIRRINGTON, R. N. MIRRINGTONSearch for more papers by this author G. I. FEUTRILL, G. I. FEUTRILLSearch for more papers by this authorR. N. MIRRINGTON, R. N. MIRRINGTONSearch for more papers by this author First published: November 23, 1976 https://doi.org/10.1002/chin.197647217AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume7, Issue47November 23, 1976 RelatedInformation