Toxic acetylene-containing lipids from the red marine alga Liagorafarinosa lamouroux

Four new acetogenins, three of which contain acetylene functionalities, have been isolated from the red seaweed $\text{Liagora}$$\text{farinosa}$ from both the Pacific Ocean and the Caribbean Sea. Two of these compounds are lethal, at the 5–8 μg/ml range, to the reef-dwelling fish, $\text{Eupomacentrus}$$\text{leucostictus}$.     

A package compound of a metal atom with a hydrocarbon [4][4][4][4][3](1,2,3,4,5)ferrocenophane

Perbridged ferrocenes ($\text{9}$ and $\text{11}$: the title compound) have been synthesized and characterized by spectroscopies and X-ray diffraction, and an interesting rotational disorder has been found by the X-ray crystal analyses of both $\text{9}$ and $\text{11}$.     

Piscicidal constituents of pimelea species

Two fish toxins, linifolin a and linifolin b, which are both diterpene orthoesters, have been isolated from $\text{Pimelea}$$\text{linifolia}$.     

Palladium catalysed synthesis of N and S heterocyclic esters

Palladium catalysed alkoxycarbonylation of heterocyclic halides affords a simple and versatile synthesis of both $\text{N}$ and $\text{S}$ heterocyclic esters where a range of catalysts have been studied and a method to employ inexpensive inorganic bases has been found.     

Steroidal antifeedants from the dorid nudibranch Aldisasanguineacooperi

Two steroids, 3-oxo-chol-4-ene-24-oic acid ($\text{2}$) andi ts unsaturated analog $\text{4}$ have been isolated from the dorid nudibranch $\text{Aldisa}$$\text{sanguinea}$$\text{cooperi}$, and the acid $\text{2}$ has been shown to have antifeedant properties.     

Measurements of the electronic excitation in atomic collisions of potassium with the rare gases

Excitation cross sections for the potassium 4²P_{$\text{1}\text{2}$} and 4²P_{$\text{3}\text{3}$} states produced in collisions with rare gases are reported. They have been measured by the lightly yield as a function of the energy from 100 to 2500 eV. In addition to this, a spectral analysis from 3300 to 8600 Å of the light is given for some energies. This spectral analysis gives experimental evidence that the excited and ionized states of both potassium and the rare gases are involved in the collision process.     

Synthesis and 13C nmr characterization of some π-excessive heteropolyaromatic compounds

Several π-excessive heteropolyaromatic compounds, which contain furan and thiophen ring and are possible antifungal agents, have been synthesized in good yields according to two general methods. The first method has been used to prepare compounds possessing thiophens linked by their 2- and 5-positions, such as the ter-aryls $\text{2b}$, $\text{2d}$ and $\text{2a}$. Two precursors of these compounds have been obtained either by the Glaser reaction, or using a novel Pd-mediated reaction. The second method,which consists of the Ni-or Pd-catalyzed heteroarylation of heteroarene halides via cross-coupling with heteroaryl Grignard reagents or zinc halides,has been used to prepare the bi-aryls $\text{1a-e}$, which contain two heteroaromatic units, and the ter-aryl $\text{2c}$. Compound $\text{1e}$ has been also prepared starting from 2-(2-thienyl) furan ($\text{1c}$) by selective lithiation, followed by bromination.The ¹³C NMR signals of $\text{1a-e}$ and $\text{2a-d}$ have been assigned on the basis of the literature data and by relaxation measurements. Relaxation data have been also used to obtain qualitative informations on the conformational equilibria of the bi-aryls $\text{1a}$, $\text{1c}$ and the ter-aryls $\text{2a-d}$.     

A reinvestigation of the structures of acomonine,iliensine, 14-dehydroiliensine,and 14-benzoyliliensine

The novel structures assigned by Yunusov et al to the C₁₉-diterpenoid alkaloids, acomonine ($\text{1}$), iliensine ($\text{2}$), 14-dehydroiliensine ($\text{3}$), and 14-bensoyliliensine ($\text{4}$) have been found to be in error. We have demonstrated that these alkaloids are identical with the well-known alkaloids, delsoline ($\text{5}$), delcosine ($\text{6}$), 14-dehydrodeloosine ($\text{7}$), and 14-benzoyldelcosine ($\text{8}$), respectively.     

18-oxygenated polyfunctional steroids from the gorgonian isishippuris

Two new 18-oxygenated, polyfunctional steroids ($\text{2}$, $\text{3}$) related to hippurin-1 have been isolated from the gorgonian $\text{Isis}$$\text{hippuris}$ collected off Okinawa and their structures were determined.     

Ichthyotoxic sesterterpenoids from the neo guinean sponge carteriospongia foliascens

Six 20,24-dimethylscalarane derivatives ($\text{5}$, $\text{12}$, $\text{15}$, $\text{17}$, $\text{19}$, and $\text{21}$) have been isolated from the Neo Guinean sponge Carteriospongia foliascens. Compound $\text{12}$ is identical with a C₂₇ tetracyclic terpene previously isolated from an Australian specimen of the same sponge. The five other derivatives are new and their structures have been established on the basis of their spectral data. The structure of $\text{5}$ was confirmed by single-crystal X-ray diffraction and that of $\text{15}$ by chemical correlation with $\text{12}$. The configuration at C-4 for all these compounds has been determined through ¹³C NMR data. Evidence leading to reverse the configuration at this centre in previously reported C₂₇ tetracyclic terpenes is discussed. An ecological function is suggested for these molecules.     

Transition structures for the reaction of difluorocarbene with propene

Two $\text{ab}$$\text{initio}$ transition structures for the reaction of difluorocarbene with propene have been located with gradient techniques and the 3-21G basis set. The activation energy is 1.3 kcal/mol lower than for the reaction with ethylene. Two transition structures with the fluorines approaching $\text{syn}$ or $\text{anti}$ to the methyl group are identical in energy     

Synthesis,structure, and reactions of thiocarbonic acid derivatives new pentathiodipercarbonates, (RSS)2 CS, α,α,α-tris(disulfides), and the first α,α,α-tris(trisulfide)

Novel bis(perhaloalkyl) pentathiodipercarbonates $\text{5b-d}$ have been synthesized by reaction of sulfenyl chlorides with metal trithiocarbonates, and the heptathio analog $\text{21a}$ was prepared similarly. Lenthionine $\text{19}$ is the main product when diiodomethane is treated with sodium tetrathiopercarbonate. A rearrangement of bis(alkyldithio)chloromethanesulfenyl chlorides $\text{22}$ to alkyldithio) (alkyltrithio)dichloromethanes $\text{24}$ has been observed. Additions of sulfenyl chlorides and of thiosulfenyl chlorides to the thiocarbonyl compounds $\text{5}$ and $\text{21a}$ were achieved in acetonitrile. The structures of the first crystalline pentathiodipercarbonate $\text{5a}$ and α,α,α-tris(disulfide) $\text{29a}$, and of the first reported α,α,α-tris(trisulfide)$\text{31a}$ have been determined by X-ray crystallography.     

Synthesis and conformational behaviour of 1,9,17-triaza[2.2.2]metacyclophane-2, 10, 18-trione derivatives

The 1,9,17-triaza[2.2.2]metacyclophane-2, 10, 18-trione derivatives ($\text{1}$) – ($\text{3}$) have been synthesised. X-Ray crystallography shows that the 1,9,17-trimethyl derivative ($\text{3}$) adopts a Crown conformation ($\text{11}$) in the solid state. Dynamic n.m.r. spectroscopy indicates that both the 1,9-dimethyl-17-benzyl- ($\text{2}$) and 1,9,17-trimethyl- ($\text{3}$) derivatives exist as interconverting mixtures of Crown ($\text{11}$) and Saddle ($\text{12}$) conformations with the former predominating at equilibrium in solution.     

Effect of the form and the parameters of intermolecular interaction potential on calculated values. Henry constant for adsorption of noble gases on graphitized black and the specific surface area determined therefrom

The effect of the form and the parameters of the atom-atom potential of intermolecular interaction, as well as that of the approximations used in its summation over the atoms of a solid, on the values of the Henry constant $\text{K}$₁ for the adsorption of noble gases on the basal face of graphite has been examined. At fixed values of the depth and of the position of the atom-atom potential minimum, $\text{K}$₁ values are only slightly sensitive to the form of this potential, if its summation is performed taking into account the layer structure of graphite. Disregarding the laminated structure of the graphite lattice leads to highly underestimated values of $\text{K}$₁. The values of the parameter $\text{c}$₁ of the attractive forces of the potential (6, 8, exp) for the intermolecular interaction of the atoms of noble gases with the carbon atom of graphite have been determined, using experimental values of $\text{K}$₁ for the adsorption of these gases on graphitized thermal carbon blacks. The corresponding changes in internal energy, entropy and heat capacity have been calculated.The effect of the form and the parameters of the potential function φ of the intermolecular interaction of a monoatomic molecule with the basal face of graphite on the energy φ_o in the minimum of the potential curve φ($\text{z}$), and on the product $\text{sz}$_o of the specific surface area $\text{s}$, and the equilibrium distance between the molecule and the surface $\text{z}$_o, has been studied. φ_o and $\text{sz}$_o were determined from experimental values of the Henry adsorption constant $\text{K}$₁ measured at different temperatures. From the experimental values of $\text{K}$₁ for the adsorption of noble gases, the value of $\text{s}$ for graphitized thermal carbon black Sterling PT, 2700 (P-33), has been determined. This value of $\text{s}$ does not essentially depend on the adsorbate and lies within the limits of error of the $\text{s}$ value, determined for this carbon black by the BET method. When determining $\text{s}$ from $\text{K}$₁, it is necessary to take into account the structure of the solid so as to choose the form of potential φ correctly. Values of $\text{z}$_o should be determined from the atom-atom potential function of the adsorbate-adsorbent intermolecular interaction.     

Pheromone 51: synthese von ungesättigten pheromonketonen aus orgyia pseudotsugata (douglas fir tussock moth) und carposina niponensis (peach fruit moth) (lepidoptera)

The principal (9, 27) and minor (17, 28) sex pheromone components of both, the Douglas fir tussock moth ($\text{Orgyia pseudotsugata}$) and the peach fruit moth ($\text{Carposina}$$\text{niponensis}$), have been synthesized in four steps each, using the chain-lengtheningdifunctionalisation of Grignard reagents by reaction with ketenylidenetriphenylphosphorane as the key step.     

The infrared carbonyl band of ethyl haloacetates and rotational isomerism

The integrated intensities of the carbonyl band components of the following ethyl haloacetates, R-COOFt (R = CH₂Cl, CH₂Br, CHCl₂ and CHBr₂), have been measured at different temperatures. From these intensities, values of ΔH° for the equilibrium between the $\text{cis}$ and $\text{gauche}$ rotamers have been estimated. Ethyl haloacetates have been studied in both CCl₄ solution and in gas phase. The absolute values of ΔH° in solution are lower than in gas phase. Results obtained in gas phase indicate that the stability of the $\text{gauche}$ rotamer increases with the size of the halogen atom.     

Synthesis of novel macrobicyclic polyfunctional cryptands

A pathway yielding both $\text{syn}$ and $\text{anti}$-functionalized macrocycles derived from bis-tartaro-18-crown-6 (1) as well as a selective route to $\text{syn}$ compounds have been developed and applied to the synthesis of new macrobicyclic polyether cryptands (2) and (3), which may also be obtained by direct bridging of the dianhydride (4).     

Isolation of a crystalline thiete and its ‘open’ isomer; Photoproducts of xanthenethione and bis(tert-butylthio)ethyne

Irradiation of xanthenethione $\text{1}$ with bis(tert-butylthio)ethyne $\text{2}$ yielded both the expected α,β-unsaturated dithioester $\text{4b}$ and surprisingly its proposed intermediate thiete $\text{3b}$ as crystalline compounds. In solution an equilibrium between both compounds has been observed.     

The thiolate anion as a nucleophile Part XI. Effect of the size of the nucleophile

The nucleophilic substitution reactions of some simple fluorobenzenes, C₆H_6?xF_x with sodium methanethiolates Na⁺SR^?(R=Et, $\text{i}$-Pr, $\text{t}$-Bu) have been studied. Some fully substituted products, C₆H_6?x(SR)_x, could be obtained in DMF as solvent with R = Et and $\text{i}$-Pr, but not when R = $\text{t}$-Bu. All the new products isolated have been characterized by elemental analysis, and NMR (H-1 and F-19), infrared and mass spectroscopy.     

N-nitrosothialdine. Synthesis,X-ray crystallography,and N-N rotational barrier

Crystalline N-nitrosothialdine ($\text{2}$) has been prepared in 38% yield by treating thialdine ($\text{1}$) with $\text{n}$-butyl nitrite and acetic acid in hexane. X-Ray crystallography of $\text{2}$ revealed that its three methyl groups are a11 $\text{cis}$ and, rather surprisingly, all equatorial; this finding contrasts sharply with results for other nitrosamine heterocycles which have been investigated, whose bulky alpha substituents are forced into a primarily axial orientation by the large steric requirement of the N-N-0 system. The equatorial methyl group both displaces the nitroso group from the C-N-C plane and twists it somewhat about the N-N bond. N-Nitrosothialdine's unusually low barrier to rotation about the N-N bond (72 kJ/mole) is attributed to this steric crowding, combined with inductive electron withdrawal by the two sulfur atoms.