- Synthesis and mass spectra of rearrangement bio-signature metabolites of anaerobic alkane degradation via fumarate addition
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Metabolite profiling in anaerobic alkane biodegradation plays an important role in revealing activation mechanisms. Apart from alkylsuccinates, which are considered to be the usual biomarkers via fumarate addition, the downstream metabolites of C-skeleton rearrangement can also be regarded as biomarkers. However, it is difficult to detect intermediate metabolites in both environmental samples and enrichment cultures, resulting in lacking direct evidence to prove the occurrence of fumarate addition pathway. In this work, a synthetic method of rearrangement metabolites was established. Four compounds, namely, propylmalonic acid, 2-(2-methylbutyl)malonic acid, 2-(2-methylpentyl)malonic acid and 2-(2-methyloctyl)malonic acid, were synthesized and determined by four derivatization approaches. Besides, their mass spectra were obtained. Four characteristic ions were observed at m/z 133 + 14n, 160 + 28n, 173 + 28n and [M - (45 + 14n)]+ (n = 0 and 2 for ethyl and n-butyl esters, respectively). For methyl esterification, mass spectral features were m/z 132, 145 and [M - 31]+, while for silylation, fragments were m/z 73, 147, 217, 248, 261 and [M - 15]+. These data provide basis on identification of potential rearrangement metabolites in anaerobic alkane biodegradation via fumarate addition.
- Chen, Jing,Zhou, Lei,Liu, Yi-Fan,Hou, Zhao-Wei,Li, Wei,Mbadinga, Serge Maurice,Zhou, Jing,Yang, Tao,Liu, Jin-Feng,Yang, Shi-Zhong,Wu, Xiao-Lin,Gu, Ji-Dong,Mu, Bo-Zhong
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- New syntheses of 1,7-dimethylnonyl propanoate, the western corn rootworm pheromone, in four different ways via cross metathesis, alkylation and coupling reactionsss
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A mixture of the four stereoisomers of 1,7-dimethylnonyl propanoate, the female sex pheromone of the western corn rootworm (Diabrotica virgifera virgifera LeConte), was synthesized in four different ways by employing one of the following four reactions as the key step: (i) cross metathesis using the Grubbs I catalyst, (ii) cross metathesis using the Grubbs II catalyst, (iii) alkylation of an alkynide anion, and (iv) Grignard coupling in the presence of dilithium tetrachlorocuprate. Although the cross metathesis approaches enabled two short syntheses (4 or 6 steps) of the pheromone to be achieved, the cheapest and most efficient synthesis was possible via Grignard coupling to give the desired pheromone in a 40% overall yield based on 2-methyl-1-butanol (8 steps).
- Mori, Kenji
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experimental part
p. 595 - 600
(2011/04/23)
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- Photochromic glassy liquid crystals comprising mesogenic pendants to dithienylethene cores
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Photochromic glassy liquid crystals were synthesized using dithienylethenes as the volume-excluding cores to which liquid crystalline mesogens were chemically bonded through alkyl spacers. Nematic, smectic, and cholesteric glassy liquid crystals were demonstrated with glass transition temperatures above 90 °C and clearing points up to 220 °C without traces of crystallization on cooling or crystalline melting on heating. A monodomain cholesteric glassy liquid crystalline film containing an enantiomeric 2-methylpropylene chiral spacer was characterized as a left-handed helical stack, exhibiting a selective reflection band centered at 686 nm, an orientational order parameter of 0.65 for the quasi-nematic layers, and a combination of reflective coloration with photoswitchable absorptive coloration.
- Kim, Chunki,Marshall, Kenneth L.,Wallace, Jason U.,Chen, Shaw H.
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supporting information; experimental part
p. 5592 - 5598
(2010/03/03)
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- Identification and assignment of the absolute configuration of biologically active methyl-branched ketones from limnephilid caddis flies
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Glands of the 4th and 5th abdominal stemite of the caddis flies Potamophylax latipennis, Potamophylax cingulatus, and Glyphotaelius pellucidus contain (S)-4-methyl-3-heptanone (4a), (4S,6S)-4,6-dimethyl-3-octanone (4b), and (4S,6S)-4,6-dimethyl-3-nonanone (4c). As shown by gas chromatography coupled with electrophysiological recordings, these ketones elicit a strong response in the insects' antennae. The structural assignment of the compounds was achieved on the basis of mass spectra, enantioselective synthesis, and gas chromatography on a chiral stationary phase.
- Bergmann, Jan,Loefstedt, Christer,Ivanov, Vladimir D.,Francke, Wittko
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p. 3175 - 3179
(2007/10/03)
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- Synthesis and biological activity of methyl 2,6,10-trimethyldodecanoate and methyl 2,6,10-trimethyltridecanoate: Male-produced sexual pheromones of stink bugs Euschistus heros and Piezodorus guildinii
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Methyl 2,6,10-trimethyltridecanoate (1) and methyl 2,6,10-trimethyldodecanoate (2) have been identified as male-produced sex pheromones of the Brazilian soybean stink bugs Euschistus heros (F.) and Piezodorus guildinii (Westwood). In order to establish a defined attractive blend for both species, compounds 1 and 2 were synthesized as mixtures of stereoisomers to be employed in behavior bioassays. (±)-Citronellol (3) was utilized as starting material, and the syntheses was carried out in six steps with good overall yield. When tested alone, synthetic compounds 1 and 2 proved to be active in a two-choice olfactometer; however, a 20: 1 mixture of 1 and 2 was much more attractive to E. heros females. A similar blend had been found among the headspace volatiles of males.
- Zarbin, Paulo H. G.,Reckziegel, Aurelia,Plass, Ernst,Borges, Miguel,Francke, Wittko
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p. 2737 - 2746
(2007/10/03)
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- Esterification of carboxylic acid salts
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Mono- or polycarboxylic acid esters are prepared by reacting a salt of such carboxylic acid with an organic halocompound, e.g., a (cyclo)alkyl, (cyclo)alkenyl, aryl or aralkyl halide, in an aqueous reaction medium, in the presence of a catalytically effective amount of a phase transfer catalyst, for example an onium salt.
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- Hair cosmetic composition
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A hair cosmetic composition comprising a branched fatty acids of the following formula (1), STR1 wherein R1 is a methyl or ethyl group, n is an integer of 4-16, and R2 is an amino, alkoxy, or glycerol group. The composition imparts excellent sensation to hair and prevents hairs from being damaged.
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- 5. Novel alkaloids from the poison glands of ants Leptothoracini
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Novel pyrrolidine alkaloids were isolated from the poison glands of ants Leptothoracini (Myrmicinae) and identified as a mixture of N-alkylated 3-methylpyrrolidines. The females of these species produce male-attracting pheromones in their poison glands. The basic compounds in the secretions were found to be active. The major alkaloid, 3-methyl-1-(3-methylbutyl)pyrrolidine (5), is present in only ng quantities per gland.
- Reder,Veith,Buschinger
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- Variation of the Alkyl Side Chain in Δ8-THC
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The synthesis of (2'RS)-2'-methyl-, (3'RS)-, (3'S)-3'-methyl-, and 4'-methyl-Δ8-THC has been carried out, and the pharmacology of all four compounds has been investigated. All four compounds showed typical cannabinoid activity both in vitro and in vivo. The 2'-methyl compound is somewhat more active than Δ8-THC, while the 4'-methyl isomer is less active. The 3'-methyl-Δ8-THC has approximately the same activity as the parent cannabinoid.
- Huffman, John W.,Lainton, Julia A. H.,Dai, Dong,Jordan, Robert D.,Duncan, Sammy G.
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p. 2021 - 2024
(2007/10/03)
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- Pheromones, 89.- Wittig Syntheses of Alkyl-Branched and Cyclic Analogs of (Z)-5-Decenyl Acetate, the Sex Pheromone of Agrotis segetum (Lepitoptera: Noctuidae)
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By means of (Z)-selective Wittig olefination alkyl-branched and cyclic analogs of (Z)-5-decenyl acetate, the sex pheromone of the turnip moth, Agrotis segetum (Lepidoptera: Noctuidae), have been synthesized. Key Words: Pheromones / (Z)-5-decenyl acetate / Wittig reactions / Agrotis segetum
- Albores, Martha,Bestmann, Hans Juergen,Doehla, Bodo,Hirsch, Hans-Ludwig,Roesel, Peter,Vostrowsky, Otto
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p. 231 - 236
(2007/10/02)
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- Synthesis and Properties of Optically Active (+)-p'-2-methyl-butoxyphenyl p-(p"-alkoxybenzoyloxy)-benzoates
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Ten compounds of the title series represented by (d)AmPABOB were synthesized and their mesomorphic properties evaluated by DSC and optical microscopy.All the compounds have liquid crystal phases and three out of ten have a smectic C* phase.Measurements of the molecular tilt angle and the pitch were presented.Investigation on textures of mesophases revealed some anomalous phenomena.
- Dong, C. C.,Sun, Z. M.,Li, G. Z.
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- Conformational Analysis and Stereodynamics of Primary Acyclic Alkyl Radicals by EPR Spectroscopy
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The EPR spectra of n-alkyl, 2-methylalkyl, 2,2-dimethylalkyl, 2,2,3-trimethylbutyl, and 2,2,3,3-tetramethylbutyl radicals indicate that at 90 K they exist in "rigid" conformations with respect to rotation about the Cβ-Cγ bonds.The preferred conformations about the Cα-Cβ and Cβ-Cγ bonds were deduced by analysis of the β- and γ-H hyperfine splittings (hfs). 2,2,3,3-Tetramethylbutyl radicals, the only radicals with a CH3 group approximately all-trans with respect to the semioccupied p-orbital, were also the only radicals to show resolved δ-hfs.The barriers to internal rotation of the methyl groups in n-propyl, isobutyl, neopentyl, 2,2-bis(trideuteriomethyl)butyl, and 2,2,3,3-tetramethylbutyl radicals were obtained by line shape analysis; the ethyl rotation barrier in 2,2-bis(trideuteriomethyl)butyl and the tert-butyl rotation barrier in 2,2,3,3-tetramethylbutyl radicals were estimated in a similar way.The experimental hfs of trans γ-hydrogens were shown to fit a relationship of the form aHγ = 0.1 +7.9 cos2 Φ, where Φ is the dihedral angle between the SOMO and the plane through Cα, Cβ, and Cγ.Trends in the internal rotation barriers of the alkyl groups were adequately accounted for in terms of steric effects.
- Ingold, K. U.,Nonhebel, D. C.,Walton, J. C.
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p. 2859 - 2869
(2007/10/02)
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- Silylaminyl Radicals. Part 2. Free Radical Chain Halogenation of Hydrocarbons using N-Halogenobis(trialkylsilyl)amines
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The liquid-phase halogenation of a number of hydrocarbons and of 1-chlorobutane by N-halogenobis(trialkylsilyl)amines has been studied using product analysis techniques.The reactions take place by free radical chain mechanisms which involve the propagation steps generalised in equations (A) and (B) (X=Br or Cl).At 353 K, the molar reactivities of toluene (benzylic C-H) and cyclohexane towards (R3Si)2N+RH(R3Si)2NH+R (A) R+(R3Si)2NXRX+(R3Si)2N (B) (Me3Si)2N are approximately equal and toluene is 5.2 times more reactive than perdeuteriotoluene.The relative rates of hydrogen abstraction by (Me3Si)2N and (ButMe2Si)2N from the primary, secondary, and tertiary C-H groups in 2-methylbutane show that the silylaminyl radicals are not only highly reactive but also sterically demanding.Thus, at 333 K the average primary C-H reactivity is 0.6 times that of the tertiary C-H towards attack by (Me3Si)2N, but 4.2 times that of the tertiary C-H towards attack by the more bulky (ButMe2Si)2N.Silylaminyl radicals are much more reactive in hydrogen abstraction than are analogous dialkylaminyl radicals and this difference is interpreted in terms of thermodynamic and polar effects which arise because of the ?-donor-?-acceptor nature of the trialkylsilyl substituent.
- Cook, Malcolm D.,Roberts, Brian P.,Singh, Karamjit
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p. 635 - 644
(2007/10/02)
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- Reaction of Grignard Reagents with Benzaldehyde, 2,2-Dimethylpropanal and Cinnamates of Chiral Alcohols in Chiral Solvents
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The asymmetric induction in a Grignard reaction carried out in (-)-1-isopropyl-2-methoxy-4-methylcyclohexane was higher than in the reaction carried out in (+)-1-methoxy-2-methylbutane.The chirality of the solvent contributed more than that of the reagent stereodifferentiation in the reaction of (+)-2-methylbutylmagnesium bromide with benzaldehyde in (+)-1-methoxy-2-methylbutane.
- Jalander, Lars,Strandberg, Rolf
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- Isomerization of Alkane Molecular Ions
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The appearance energies of daughter ions for the major low-energy fragmentations, namely, losses of C2H6, CH4, and CH3*, of pentane and methylbutane radical cations have been measured.These reactions for ions of low internal energy content (rate constants in the range 1E5 - 1E7 s-1) have been studied by observations of metastable peak shapes.The behaviors of a variety of 13C- and 2H-labeled compounds were also examined.Hydrogen atoms do not extensively lose their positional identity in any of these fragmentations.For methylbutane, loss of C2H6 and CH3* yielded ionized propene and 2-butyl cations, respectively, at their calculated thermochemical thresholds.Loss of CH4 proceeded at an energy greater than that calculated for the production of ionized but-2-ene, methylpropene, but-1-ene, or methylcyclopropane.The labeling experiments permitted the separation of the complex Gaussian-type metastable peak for CH4 loss into high and low kinetic energy release components, each appropriately relating to the generation of different daughter ions via competing mechanistic pathways.Large isotope effects were observed, similar in magnitude to those observed for the loss of methane from the methylpropane radical cation.Ethane elimination is preceded partially (ca. 20-25percent) by a 1-2 methyl shift and a concominant 2-1 H shift; isotope effects associated with this reaction are discussed. for pentane, losses of CH3* and CH4 take place at the same energy, corresponding to the calculated threshold for production of the secondary cations; 13C labeling experiments showed that the penultimate C atoms are not lost but that C-3 is lost (46percent) in these reactions, with an ease similar to terminal C atom losses (54percent).As with methylbutane, 2H labeling permitted the separation of the metastable peak for methane loss into components having different kinetic energy releases and attributable to the production of different (+*) daughter ions.Although C2H6 loss was observed to take place at energies down to the calculated thermochemical threshold for generation of ionized propene, the appearance energy of the metastable peak was the same as that for CH3* and CH4 losses.Labeling experiments showed that the central C atom is not lost in this reaction.Detailed analysis of the observations leads to the conclusion that the CH3*, CH4, and C2H6 eliminations from pentane radical cations are preceded by an isomerization to energy-rich ionized methylbutane.
- Holmes, John L.,Burgers, Peter C.,Mollah, M. Yousuf A.,Wolkoff, Peder
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p. 2879 - 2884
(2007/10/02)
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- Liquid crystal compounds
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Novel liquid crystal compounds are disclosed, which are chiral esters based upon the phenol STR1 Typical examples are: STR2 and mixtures of these compounds have a helical pitch such that the mixtures reflect light of a specific wavelength when illuminated with ordinary light and the pitch is temperature sensitive so that the mixtures can be used in temperature indicating devices. Specific examples are given as are samples of mixtures that can be used in phase change electro-optic display devices.
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