Identification and Synthesis of New γ-Lactones from Tuberose Absolute (Polianthes tuberosa)

Six unsaturated γ-lactones, (Z)-5-octen-4-olide ( 1 ), (Z)-5-decen-4-olide ( 2 ).(Z)-6-nonen-4-olide ( 3 ), (Z)-6-dodecen-4-olide ( 4 ), (Z, Z)-6,9-dodecadien-4-olide ( 5 ), and tuberolide ( 6 ) have been identified for the first time in tuberose absolute (from Polianthes tuberosa L.). All structures were corroborated by synthesis and all, except 3 and 4 , are new.

1 The name ‘tuberolactone’ has been suggested for (Z, Z)-2,7-decadien-5-olide [1]. We propose the name ‘tuberolide’ for the bicyclic lactone 6 . (IUPAC name (1R*,5S*,Z)-6-(2′-pentenyl)-2-oxabicyclo[3.3.0]octan-3-one).

An improved method for the stereoselective synthesis of (±)-cis-bicyclo [4.3.0]-non-3-en-7-one ( 23 ) by an AlCl₃-catalyzed Diels-Alder reaction is reported.     

Thermodynamics of a Fluid of Hard D-dimensional Spheres: Percus-Yevick and Carnahan-Starling-like Results for D = 4 and 5

Abstract

The equations of state (EOS) of four and five dimensional hyperspheres have been calculated using Leutheusser's ansatz. In five dimensions these, and the correlation functions, are compared with the results obtained from the analytic solution of the Percus—Yevick (PY) approximation. It is shown that the ansatz reproduces extremely well the PY results. However, in both approximations neither the virial, Z_v , nor the compressibility, Z_c , EOS reproduce well the available molecular dynamics (MD) results. Yet a linear combination of Z_v and Z_c , following the Carnahan—Starling EOS for hard spheres, are in excellent agreement with the MD results in four and five dimensions.     

Synthesis of the Heaviest Chemical Elements—Results and Perspectives

All 17 artificially produced elements heavier than uranium were discovered by nuclear-chemical synthesis. The three heaviest ones–elements 107, 108 and 109–were synthesized at the heavy-ion accelerator UNILAC in Darmstadt by nuclear fusion from the heaviest stable nuclei, lead-208 and bismuth-209, and the most neutron-rich stable isotopes of chromium and iron: element 107 from bismuth-209 (atomic number Z = 83) and chromium-54 (Z = 24), element 108 from lead-208 (Z = 82) and iron-58 (Z = 26), and element 109 from bismuth-209 and iron-58. The first isotopes detected were those with mass numbers 262 (Z = 107), 265 (Z = 108) and 266 (Z = 109); these nuclei are short-lived α-emitters with half-lives of 8.2 ms, 1.8 ms and 3.4 ms, respectively. The yields of these reactions are extremely small; only three atoms of element 109 have ever been observed. Experiments to synthesize element 110 have given ambiguous results. All attempts to detect the “superheavy” elements with proton numbers near Z = 114 and neutron numbers near N = 184 have thus far failed. These elements have been predicted theoretically, and many attempts to synthesize them have been made, e.g. at UNILAC by fusion of calcium-48 (Z = 20) with curium-248 (Z = 96), or by transference of protons in the collision of two very heavy nuclei such as uranium-238 (Z = 92). Surprisingly, the heaviest known nuclei are far more stable toward spontaneous fission into two fragments than was expected, but their synthesis is strongly hindered–much more than initially anticipated. It is this hindrance rather than the decreasing nuclear stability which seems to presently limit the extent of the periodic table: even heavier elements should be able to exist, but no way has yet been found to produce them.     

Effect of Solvents on the Spectra of Some β-Diketones

Acetoacetanilide, benzoylacetanilide and their derivatives have been examined in ultraviolet region in a series of solvents covering a broad polarity range e. e. from chloroform (Z, 63.2) to methanol (Z .83.6). Transition energies and oscillator strengths have been calculated and transition energy (E_T) has been plotted against Z-values, a new empirical measurement of solvent polarity. A linear relationship was observed between the transition energy and Z-values for π → π* and n → π* transitions. These transitions are identified as charge transfer (c-t) transitions and with the solvents having carbonyl oxygen and sulphur atom a c-t complex formation has been suggested. Strong electron-donating substituents on phenyl group of the nitrogen atom also showed a weak to moderate n → π* transitions. These substituents have no influence on the position of the λ_max in the same solvent. Stabilization energy of the excited state of these ligands and hence the dipole moments of the excited states have been calculated in comparison with pyridinium iodide. Solvent sensitivities of these ligands have also been calculated.     

(Z)-5-Tetradecen-14-olide,a New Macrocyclic Lactone,and Two Unsaturated Straight Chain Acetates from Ambrette Seed Absolute

(Z)-5-Tetradecen-14-olide ( 1 ), (Z)-5-dodecenyl acetate ( 2 ), and (Z)-5-tetradecenyl acetate ( 3 ) have been isolated from the absolute oil of Hibiscus abelmoschus L . The lactone 1 is a new macrocyclic musk compound, and the occurrence of the two acetates 2 and 3 in a plant is reported for the first time. Syntheses of the three compounds are described.     

Raspailynes,Novel Long-Chain Acetylenic Enol Ethers of Glycerol from the Marine Sponges Raspailia pumila and Raspailia ramosa

The sponges Raspailia pumila and ramosa (Demospongiae, Tetractinomorpha, Axinellida) from the North-East Atlantic are shown to contain a series of novel long-chain enol ethers of glycerol where the enol ether C?C bond is conjugated, in sequence, to both an acetylenic and an olefinic bond. Polar extracts give raspailynes hydroxylated at their (1Z5Z)-1,5-alkadien-3-ynyl chain, like raspailyne Al ( = (+)-(S)-3-[((1Z,5Z)-16-hydroxy-hexadeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; (+ 2 ) and isoraspailyne A ( = (+)-3-[((1Z,5Z)-17-hydroxyocta-deca-1,5-dien-3-ynyl)oxy]-1,2-[propanediol; (+)- 3 ). Less polar extracts give 3 different types of raspailynes not hydroxylated at the chain. Raspailynes of the first type have either the (1Z,5Z)-configuration in a linear chain such as raspailyne B2 (( = (?)-(s)-3-[((1Z,5Z)-trideca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; (?)-4), raspailyne Bl ( = (?)-3-[((1Z,5Z)-tetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol;(?)- 5 ), and raspailyne B ( = 3-[((1Z,5Z)-pentadeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 6 ) or the (1Z,5Z)-pentadeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 6 )or the (1Z,5Z)-configuration in a chain ending with an isopropyl group, like isoraspailyne Bl ( = 3-[((1Z,5Z)-12-methyltrideca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 7 ) and isoraspailyne B ( = 3-[((1Z,5Z)-13-methyltetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 8 ). Raspailynes of the second type have the (1Z,5E)-configuration, like isoraspailyne Bla ( =3-[((1Z,5E)-tetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 9 ) and isoraspailyne Ba ( = 3-[((1Z,5E)-13-methyltetradeca-1,5-dien-3-ynyl)oxy]-1,2-propanediol; 10 ). Raspailynes of the third type have the (1E,5Z)-configuration, like isoraspailyne Blb ( = 3-[((1E,5Z)-tetradeca-1,5-dien-3-ynyl)oxy]-1,2,-propanediol; 11 ). The (S)-configuration for (+)- 1 ,((+)- 2 , and (?)- 4 is derived from chemical correlations.     

Effect of Solvents on the Spectra of Some N′-2-(Substituted Pyridyl)-N-Substituted-Thioureas

Some N′-2-(substituted pyridyl)-N-substituted thiourea (in all 12-substituted pyridyl thioureas) have been examined in ultraviolet region in a series of solvents covering a broad polarity range i. e. from benzene (Z, 54.0) to ethylene glycol (Z, 85.1). Transition energies and oscillator strengths have been calculated and transition energy (E_T) has been plotted against Z-values, a new-empirical measurement of solvent polarity. A linear relationship was observed between the transition energy and Z-value for pyridyl μ→μ* and thiocarbonyl μ→μ* transitions. The effect of substituent present in pyridyl group on λ_max of a compound in the same solvent has been studied. Solvent sensitivites of these ligands have also been calculated.     

Critical stability and quantum phase transition of screened two-electron system

The ground state energy and structural properties of a model two-electron system (Zee), bound via screened Coulomb interaction with nuclear charge Z, have been studied under the variational framework. Hylleraas type basis has been adopted for explicit incorporation of the electron–electron correlation. Critical nuclear charges (Z_c) of Zee system have been reported for different screening parameters (μ). Expectation values of different structural properties have been estimated to predict the internal structure of the Zee system. The variation of the structural properties with respect to Z for different μ reveals the signature of quantum phase transition (QPT) in the vicinity of Z_c. Moreover, the nature of variation of these properties with respect to Z in case of bare Coulomb or free system (μ = 0) is completely opposite to those of screened system (μ ≠ 0). Radial two-particle density (TPD) confirms the symmetry breaking of the electronic structure and therefore QPT in the vicinity of Z_c.     

Synthesis of (4Z)‐4‐(Arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones by the Reaction of Ethyl (2Z)‐3‐Aryl‐2‐isothiocyanatoprop‐2‐enoates with Organolithium Compounds

A convenient one‐pot method for the preparation of (4Z)‐4‐(arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones 2 and 3 from ethyl (2Z)‐3‐aryl‐2‐isothiocyanatoprop‐2‐enoates 1 , which can be easily prepared from ethyl 2‐azidoacetate and aromatic aldehydes, has been developed. Thus, these α‐isothiocyanato α,β‐unsaturated esters were treated with organolithium compounds, including lithium enolates of acetates, to provide 5‐substituted (4Z)‐4‐(arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones, 2 , and 2‐[(4Z)‐(4‐arylmethylidene)‐5‐ethoxy‐2‐thioxo‐1,3‐oxazolidin‐5‐yl]acetates, 3 .     

The Hartree–Fock ground state of atomic two-electron systems and the Wilson–Silverstone 1s orbital

For the Hartree–Fock ground state of atomic two-electron systems, the variational function of Wilson and Silverstone, ?(r) = (a + kr)^?1 exp(-kr) / (4π)^1/2, can be optimized in two complementary ways. For small values of the atomic number Z, all intergrals have been calculated numerically and optimization can be performed accurately. However, as Z increases, loss of significant figures is increasingly detrimental to the optimization process. For sufficiently large values of Z, the integrals may be replaced by asymptotic expansions in terms of (2a)^?. As a result of optimization, the parameters and expectation values can be given as expansions in terms of (32Z)^?1/2. Both methods yield good results for Z ≈ 25, so that the whole range of Z can be treated accurately. The results have been compared with those derived from other analytical two-parameter functions. It is found that ?(r) is indeed the outstanding two-parameter function, at least for small and intermediate values of Z.     

Atomic Thomas-Fermi theory and electron subshell filling

In previous work on electron subshell filling, the existence condition of the integrals involved has not been taken into proper account. As a result, part of the calculated subshell occupation numbers is meaningless. In Theis' theory [9] the average number of electrons in a subshell is calculated as the difference between two integrals. With each of these integrals an existence condition is associated. Because of this, the number of electrons with angular momentum quantum number l can only be calculated for atoms of which the Z value is (much) larger than the corresponding empirical first-appearance Z value. Thus, the range of Z for which such numbers can be calculated, is restricted considerably, especially for larger values of l. Results obtained from a normalized version of Mason's approximation [13] to the exact Thomas-Fermi function, have been compared with a least-squares fit of the empirical subshell occupation numbers, and these are found to be as good as one may expect from a statistical theory. A lower bound to each of the empirical first-appearance Z values has been calculated. The results agree well with those reported in other work.     

Molecular dynamics of (Z)-1-(2-hydroxy-5-methyl-3-nitrophenyl)ethanone oxime and (E)-2-hydroxy-5-methylacetophenone thiosemicarbazone in solution studied by NMR spectroscopy

The formation of hydrogen bonds and the molecular dynamics for molecules (Z)-1-(2-hydroxy-5-methyl-3-nitrophenyl)ethanone oxime and (E)-2-hydroxy-5-methylacetophenone thiosemicarbazone, (E)-4-bromoacetophenone thiosemicarbazone have been investigated in solution using NMR. The results confirm the formation of different O-H…O type intramolecular hydrogen bonds in the oxime molecule. The rotational barrier energy and energy of intramolecular hydrogen bonds have been determined.     

Synthesis,Isolation, and NMR-Spectroscopic Characterization of Fourteen (Z)-Isomers of Lycopene and of Some Acetylenic Didehydro- and Tetradehydrolycopenes

Eight (Z)-isomers of lycopene were prepared by stereocontrolled syntheses and fully characterized by ¹H-NMR, ¹³C-NMR, mass, and UV/VIS spectroscopy: (5Z)-, (7Z)-, (15Z)-, (5Z,5′Z)-, (7Z,7′Z)-, (7Z,9Z)-, (9Z,9′Z)-, and (7Z,9Z,7′Z,9′Z)-lycopene. Six additional (Z)-isomers, namely (9Z)-, (13Z)-, (5Z,9′Z)-, (9Z,13′Z)-, (5Z,9Z,5′Z)-, and (5Z,13Z,5′Z)-lycopene, were isolated in small quantities from isomer mixtures by semiprep. HPLC and were identified by ¹H-NMR spectroscopy.     

Reaction of 4-methylene-5(4H)-oxazolones with diazomethane

The reaction of diazomethane with some (E) and (Z)-2-substituted-4-methylene-5(4)-oxazolones ( 1a-c ) under two different conditions, has been studied. (E) and (Z)-1,2-disubstituted-7-oxo-6-oxa-4-azaspiro[2.4]-hept-4-enes ( 3a-c, 4a-c ) were mainly obtained, together with multiple addition compounds. The reaction showed to be stereoselective only when the substituents were aromatic. Acid hydrolysis of compounds 3a and 4a produced a mixture of (E) and (Z)-3,5-disubstituted-tetrahydrofuran-2-ones ( 8a, 9a ). Smooth methanolysis of the ring led to (E) and (Z)-1-benzamido-cyclopropanecarboxylic esters ( 10a-c, 11a-c ), which, on acid hydrolysis, gave (E) and (Z)-1-amino-2-phenylcyclopropanecarboxylic acids 12a and 13a . The pmr spectra have been analyzed by an iterative computer method, and the computed best values obtained have been used to deduce the stereochemistry of the spiroderivatives.     

Methylthiofurane: Herstellung und Reaktionen

Preparation and Reactions of Methylthiofurans By lithiation of 3,4-dimethoxyfuran, 2-methylfuran and furan, followed by reaction with dimethyldisulfide, the methylthiofurans 2, 8 , and 10 have been prepared. Reaction of 8 with maleic anhydride has yielded 6-methyl-3-(methylthio)phthalic anhydride ( 9 ), a yellow substance with a strong greenish fluorescence, obviously formed by elimination of H₂O from an unstable cycloadduct. An analgous reaction of 2 resulted in an unexpected mixture from which the following yellow compounds were isolated: 3-hydroxy-4,5-dimethoxy-6-(methylthio)phthalic anhydride ( 3 ), 4-hydroxy-5-methoxy-3,6-bis(methylthio)phthalic anhydride ( 4 ), and bis(S-methyl) (2Z,4E,6Z)-2,3,6,7-tetramethoxy-4,5-bis(methylthio)-2,4,6-octatrienethioate ( 5 ). Compound 5 is also formed on standing of 2 at RT. Mild acid hydrolysis of 2 results in ring-opening accompanied by an intramolecular oxido-reduction to yield S-methyl(3Z)-3-methoxy-4-(methylthio)-2-oxo-3-butenethioate ( 6a ). The structures of compounds 5 and 6a have been determined by X-ray analysis.     

Total synthesis of (3Z,9Z,6S,7R) and (3Z,9Z,6R,7S)-6,7-epoxy-3,9-octadecadienes

(3Z,9Z,6S,7R)-6,7-epoxy-3,9-octadecadiene (1) and (3Z,9Z,6R,7S)-6,7-epoxy-3,9-octadecadiene (2) have been stereoselectively synthesized in eight steps from 2-pentyn-1-ol with an overall yield of 8%. The key steps involved the Sharpless asymmetric dihydroxylation of (2E)-oct-2-en-5-yn-1-ol (6). The new synthetic method is suitable for multigram-scale preparation of 1 and 2 and might be used for producing sufficient quantities of the sex pheromone components for management of the pest of tea plantations.     

Synthesis of (E)‐ and (Z)‐5‐(Bromomethylene)furan‐2(5H)‐one by Bromodecarboxylation of (E)‐2‐(5‐Oxofuran‐2(5H)‐ylidene)acetic Acid

(E)‐ and (Z)‐5‐(bromomethylene)furan‐2(5H)‐one have been prepared starting from the commercially available adduct between furan and maleic anhydride. A bromodecarboxylation reaction is a key step in the synthesis. The reaction gives the (E)‐ or (Z)‐5‐(bromomethylene)furan‐2(5H)‐one as the major product, dependent on the method used in the bromodecarboxylation.     

The Photoisomerization Behavior of the (4-Hydroxycinnamoyl)-spermidines

The photoisomerization behavior of three mono[(E)-3-(4-hydroxyphenyl)prop-2-enoyl]spermidines, 1, 2 , and 3 , and three bis[(E)-3-(4-hydroxyphenyl)prop-2-enoyl]spermidines, 4, 5 , and 6 , are investigated. The synthetic product (E)- 1 could be almost quantitatively (> 96%) converted into its isomer (Z)- 1 under UV light irradiation. In the cases of (E)- 2 and (E)- 3 , a mixture of (E)/(Z) ca. 1:2 was obtained, when the same conditions were applied. The comparison of their UV spectra provides the possible explanation for these different behaviors. Furthermore, it was noticed that the (Z) → (E) isomerization of the C?C bond took place during the purification by reverse-phase high-performance liquid chromatography (RP-HPLC), and the (E)/(Z)-mixture is thus inseparable. The same feature could be observed during the isolation of the (Z,Z)-N,N′-bis[3-(4-hydroxyphenyl)prop-2-enoyl]-spermidines, (Z,Z)- 4 , (Z,Z)- 5 , and (Z,Z)- 6 . Nevertheless, the fractions of (Z,Z)- 5 and (Z,Z)- 6 were in almost pure state collected, and their ¹-NMR spectra are presented.     

Stereoselectivity and nonmigratory insertion mechanism of dimethylacetylene dicarboxylate into metallocene-hydride of Cp2M(L)H [Cp = η5-C5H5; M = Nb,V; L = CO,P (OMe)3]: A DFT study

The insertion of an alkyne into transition metal–hydrogen bonds is a key elementary step in catalytic polymerization and hydrogenation processes. It was found that a (Z)- or (E)-type alkyenyl complex can be formed through trans/cis stereospecific processes. In this work, the reaction mechanism of Cp₂M(L)H [Cp = η⁵-C₅H₅; M = Nb, V; L = CO, P (OMe)₃] with dimethylacetylene dicarboxylate (DMAD), and the factors influencing the stereoselectivity have been investigated based on density functional theory calculations. The calculated results show that all of the reactions are exothermic. For L = CO, the Z-isomer product forms first even at low temperatures because of the low Gibbs free energy barrier (ΔG^#). Then the Z-pro converts to E-pro , while for L = P (OMe)₃, the exclusive product is the E-isomer. For different metal centers, the reaction mechanisms of the Cp₂M(CO)H + DMAD (M = Nb and V) reaction are similar, while their products are different at room temperature. For M = Nb, because the energy barrier of the isomerization from Z-pro to E-pro is low and the relative free energies of Z-pro and E-pro are almost equal, both Z-pro and E-pro can be obtained. While for the Cp₂V(CO)H + DMAD reaction, only the Z-pro can be obtained under mild conditions, E-pro can be obtained only at high temperatures. For the Cp₂M(CO)H+DMAD(M=V and Nb) reactions, the formation of E-isomer products proceeds via two five-membered ring transition states. The calculated results provide an reasonable explanation for the experimental results and predict a new insertion reaction.     

Das Carotinoidspektrum der Hagebutten von Rosa pomifera: Nachweis von (5Z)-Neurosporin; Synthese von (3R, 15Z)-Rubixanthin

Carotenoids from Hips of Rosa pomifera: Discovery of (5Z)-Neurosporene; Synthesis of (3R, 15Z)-Rubixanthin Extensive chromatographic separations of the mixture of carotenoids from ripe hips of R. pomifera have led to the identification of 43 individual compounds, namely (Scheme 2): (15 Z)-phytoene (1) , (15 Z)-phytofluene (2) , all-(E)-phytofluene (2a) , ξ-carotene (3) , two mono-(Z)-ξ-carotenes ( 3a and 3b ), (6 R)-?, ψ-carotene (4) , a mono-(Z)-?, ψ-carotene (4a) , β, ψ-carotene (5) , a mono-(Z)-β, ψ-carotene (5a) , neurosporene (6) , (5 Z)-neurosporene (6a) , a mono-(Z)-neurosporene (6b) , lycopene (7) , five (Z)-lycopenes (7a–7e) , β, β-carotene (8) , two mono-(Z)-β, β-carotenes (probably (9 Z)-β, β-carotene (8a) and (13 Z)-β, β-carotene (8b) ), β-cryptoxanthin (9) , three (Z)-β-cryptoxanthins (9a–9c) , rubixanthin (10) , (5′ Z)-rubixanthin (=gazaniaxanthin; 10a ), (9′ Z)-rubixanthin (10b) , (13′ Z)- and (13 Z)-rubixanthin (10c and 10d , resp.), (5′ Z, 13′ Z)- or (5′ Z, 13 Z)-rubixanthin (10e) , lutein (11) , zeaxanthin (12) , (13 Z)-zeaxanthin (12b) , a mono-(Z)-zeaxanthin (probably (9 Z)-zeaxanthin (12a) ), (8 R)-mutatoxanthin (13) , (8 S)-mutatoxanthin (14) , neoxanthin (15) , (8′ R)-neochrome (16) , (8′ S)-neochrome (17) , a tetrahydroxycarotenoid (18?) , a tetrahydroxy-epoxy-carotenoid (19?) , and a trihydroxycarotenoid of unknown structure. Rubixanthin (10) and (5′ Z)-rubixanthin (10a) can easily be distinguished by HPLC. separation and CD. spectra at low temperature. The synthesis of (3 R, 15 Z)-rubixanthin (29) is described. The isolation of (5 Z)-neurosporene (6a) supports the hypothesis that the ?-end group arises by enzymatic cyclization of precursors having a (5 Z)- or (5′ Z)-configuration.