25346-33-2Relevant articles and documents
Synthesis and mass spectra of rearrangement bio-signature metabolites of anaerobic alkane degradation 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
, (2020/05/01)
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.
Identification and Synthesis of Branched Wax-type Esters, Novel Surface Lipids from the Spider Argyrodes?elevatus (Araneae: Theridiidae)
Chinta, Satya Prabhakar,Goller, Stephan,Uhl, Gabriele,Schulz, Stefan
, p. 1202 - 1220 (2016/10/03)
The analysis of cuticular extracts from the kleptoparasitic spider Argyrodes?elevatus revealed the presence of unusual esters, new for arthropods. These novel compounds proved to be methyl-branched long-chain fatty acid esters with methyl branches located either close or remote from the internally located ester group. The GC/MS analysis of the prosoma lipid blend from the male cuticle contained one major component, undecyl 2-methyltridecanoate (1). In contrast, four major wax-type esters, 2-methylundecyl 2,8-dimethylundecanoate (2), 2,8-dimethylundecyl 2,8-dimethylundecanoate (3), heptadecyl 4-methylheptanoate (4), and 14-methylheptadecyl 4-methylheptanoate (5), were identified in the lipid blend of female prosomata. Structure assignments were based on mass spectra, gas chromatographic retention indices, and microderivatization. Unambiguous proof of postulated structures was ensured by an independent synthesis of all five esters. Preferentially, odd-numbered carbon chains pointed to a distinct biosynthetic pathway, different from that of common fatty acids, because one or two C3 starter units are incorporated during the biosynthesis of all acid and alcohol building blocks present in the five esters. The striking sexual dimorphism together with the unique biosynthesis points to a function of the esters in chemical communication of the spiders, although no behavioral data are currently available to test this assumption.
Novel fatty acid methyl esters from the actinomycete Micromonospora aurantiaca
Dickschat, Jeroen S.,Bruns, Hilke,Riclea, Ramona
supporting information; experimental part, p. 1697 - 1712 (2012/02/04)
The volatiles released by Micromonospora aurantiaca were collected by means of a closed-loop stripping apparatus (CLSA) and analysed by GC-MS. The headspace extracts contained more than 90 compounds from different classes. Fatty acid methyl esters (FAMEs) comprised the major compound class including saturated unbranched, monomethyl and dimethyl branched FAMEs in diverse structural variants: Unbranched, α-branched, γ-branched, (ω-1)-branched, (ω-2)-branched, α-and (ω-1)-branched, γ-and (ω-1)-branched, γ-and (ω-2)-branched, and γ-and (ω-3)-branched FAMEs. FAMEs of the last three types have not been described from natural sources before. The structures for all FAMEs have been suggested based on their mass spectra and on a retention index increment system and verified by the synthesis of key reference compounds. In addition, the structures of two FAMEs, methyl 4,8-dimethyldodecanoate and the ethyl-branched compound methyl 8-ethyl-4-methyldodecanoate were deduced from their mass spectra. Feeding experiments with isotopically labelled [ 2H10]leucine, [2H10]isoleucine, [2H8]valine, [2H5]sodium propionate, and [methyl-2H3]methionine demonstrated that the responsible fatty acid synthase (FAS) can use different branched and unbranched starter units and is able to incorporate methylmalonyl-CoA elongation units for internal methyl branches in various chain positions, while the methyl ester function is derived from S-adenosyl methionine (SAM).
Selective dimerisation of α-olefins using tungsten-based initiators
Hanton, Martin J.,Daubney, Louisa,Lebl, Tomas,Polas, Stacey,Smith, David M.,Willemse, Alex
supporting information; experimental part, p. 7025 - 7037 (2010/09/17)
The selective dimerisation of the α-olefins 1-pentene through to 1-nonene is reported using an in situ-generated catalyst derived from tungsten hexachloride, aniline, triethylamine and alkylaluminium halide. The influence of reagent identity and reaction stoichiometry, along with activator, solvent and α-olefin substrate choice are probed. The catalyst is found to be highly selective towards dimerisation, minimising the formation of undesired heavier oligomers. Notably, the selectivity within the dimer fraction is found to favour the formation of products with methyl branches. The selectivity towards individual olefin isomers has been determined and the system is found to also produce trace levels of dienes and alkanes. A kinetic study of the system reveals a second order dependence on substrate. Comparison of the products observed, with those expected for metallacyclic and Cossee-type mechanisms, suggests that the latter is in operation, something confirmed by the results of a C2H4/C2D4 co-dimerisation experiment which showed full isotopic scrambling in the products. Thus a mechanistic proposal is made to account for the observed behaviour of the system, including the diene and alkane formation. The Royal Society of Chemistry 2010.
Histamine H3 and H4 receptor affinity of branched 3-(1H-imidazol-4-yl)propyl N-alkylcarbamates
?azewska, Dorota,Wiecek, Ma?gorzata,Ligneau, Xavier,Kottke, Tim,Weizel, Lilia,Seifert, Roland,Schunack, Walter,Stark, Holger,Kie?-Kononowicz, Katarzyna
scheme or table, p. 6682 - 6685 (2010/06/16)
A series of imidazole-containing (non-)chiral carbamates were tested at human histamine H3 receptor (H3R). All compounds displayed Ki values below 100 nM. A trend for a stereoselectivity at human H3R was observed for the chiral α-branched ligands. Selected compounds were also tested at human histamine H4 receptor and showed moderate to weak affinities (118-1460 nM).
Do enzymes recognise remotely located stereocentres? Highly enantioselective Candida rugosa lipase-catalysed esterification of the 2- to 8-methyldecanoic acids
Hedenstroem, Erik,Nguyen, Ba-Vu,Silks III, Louis A.
, p. 835 - 844 (2007/10/03)
Several racemic methyl decanoic acids have been synthesised and successfully resolved in esterification with 1-hexadecanol at aw=0.8 in cyclohexane using immobilised Candida rugosa lipase (CRL) as the catalyst. The enantiomeric ratios (E=2.8-68) obtained were surprisingly high even when the methyl group was as remotely located as in 8-methyldecanoic acid (E=25). Interestingly, the lipase shows enantiopreference for the S-enantiomer when the methyl group is located on even numbered carbons i.e. for the 2-,4-,6- and 8-methyldecanoic acids and to the R-enantiomer when the methyl group is located on uneven numbered carbons i.e. for the 3-,5- and 7-methyldecanoic acids.
Syntheses of female sex pheromone precursors of pine sawfly species and of some structurally related methyl-branched long-chain 2-alkanols.
Hedenstroem, Erik,Andersson, Fredrik
, p. 1237 - 1254 (2007/10/03)
3,7-Dimethyl-2-undecanol, 3,7,9-trimethyl-2-tridecanol, and 3,7, 11-trimethyl-2-tridecanol were synthesized as racemic mixtures in moderate yields. The alcohols are known precursors of the female sex pheromones of the pine sawfly species Diprion nipponica, Macrodiprion nemoralis, and Microdiprion pallipes, respectively. Stereoisomeric mixtures of 3,8,12-trimethyl-2-tridecanol, erythro-(2R,3R, 11R/S)-3,11-dimethyl-2-tetradecanol, 3,5-dimethyl-2-tetradecanol, and 5,7-dimethyl-2-tetradecanol, structurally related to sex pheromone alcohol precursors of pine sawfly species, were also synthesized in moderate yields. The key reaction in the syntheses was the ring opening of gamma-butyrolactones by using different alkyl lithiums as nucleophiles.
Identification and assignment of the absolute configuration of biologically active methyl-branched ketones from limnephilid caddis flies
Bergmann, Jan,Loefstedt, Christer,Ivanov, Vladimir D.,Francke, Wittko
, p. 3175 - 3179 (2007/10/03)
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.
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
Zarbin, Paulo H. G.,Reckziegel, Aurelia,Plass, Ernst,Borges, Miguel,Francke, Wittko
, p. 2737 - 2746 (2007/10/03)
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.
Development of chiral N-alkylcarbamates as new leads for potent and selective H3-receptor antagonists: Synthesis, capillary electrophoresis, and in vitro and oral in vivo activity
Sasse, Astrid,Kiec-Kononowicz, Katarzyna,Stark, Holger,Motyl, Malgorzata,Reidemeister, Sibylle,Ganellin, C. Robin,Ligneau, Xavier,Schwartz, Jean-Charles,Schunack, Walter
, p. 593 - 600 (2007/10/03)
Novel carbamates as derivatives of 3-(1H-imidazol-4-yl)propanol with an N-alkyl chain were prepared as histamine H3-receptor antagonists. Branching of the N-alkyl side chain with methyl groups led to chiral compounds which were synthesized stereospecifically by a Mitsunobu protocol adapted Gabriel synthesis. The optical purity of some of the chiral compounds was determined (ee > 95%) by capillary electrophoresis (CE). The investigated compounds showed pronounced to high antagonist activity (K(i) values of 4.1-316 nM) in a functional test for histamine H3 receptors on rat cerebral cortex synaptosomes. Similar H3-receptor antagonist activities were observed in a peripheral model on guinea pig ileum. No stereoselective discrimination for the H3 receptor for the chiral antagonists was found with the in vitro assays. All compounds were also screened for central H3-receptor antagonist activity in vivo in mice after po administration. Most compounds were potent agents of the H3-receptor-mediated enhancement of brain N(τ)- methylhistamine levels. The enantiomers of the N-2-heptylcarbamate showed a stereoselective differentiation in their pharmacological effect in vivo (ED50 of 0.39 mg/kg for the (S)-derivative vs 1.5 mg/kg for the (R)- derivative) most probably caused by differences in pharmacokinetic parameters. H1- and H2-receptor activities were determined for some of the novel carbamates, demonstrating that they have a highly selective action at the histamine H3 receptor.
