- 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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- Radical Heterocyclization and Heterocyclization Cascades Triggered by Electron Transfer to Amide-Type Carbonyl Compounds
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Radical heterocyclizations triggered by electron transfer to amide-type carbonyls, using SmI2-H2O, provide straightforward access to bicyclic heterocyclic scaffolds containing bridgehead nitrogen centers. Furthermore, the first radical heterocyclization cascade triggered by reduction of amide-type carbonyls delivers novel, complex tetracyclic architectures containing five contiguous stereocenters with excellent diastereocontrol.
- Huang, Huan-Ming,Procter, David J.
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supporting information
p. 14262 - 14266
(2017/10/20)
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- A practical chemoenzymatic synthesis of (R)-isovaline based on the asymmetric hydrolysis of 2-ethyl-2-methyl-malonamide
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(R)-Isovaline has potential applications in drug development, and therefore the development of an efficient method for the production of (R)-isovaline is desired. Herein we have investigated the asymmetric hydrolysis of 2-ethyl-2-methyl-malonamide into (S)-2-ethyl-2-methyl-malonamic acid, a useful synthetic intermediate in the production of (R)-isovaline, using CsAM, which is a recombinant amidase originally derived from Cupriavidus sp. KNK-J915. The produced (S)-2-ethyl-2-methyl-malonamic acid (98.6% ee) could be easily converted into (R)-isovaline by the Hofmann rearrangement. Starting from diethyl 2-methylmalonate, we obtained (R)-isovaline (99.1% ee) in 58.6% yield over eight steps, including the CsAM-catalyzed asymmetric hydrolysis of 2-ethyl-2-methyl-malonamide.
- Nojiri, Masutoshi,Yoshida, Fumi,Hirai, Yoshinori,Nishiyama, Akira,Yasohara, Yoshihiko
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- Synthesis and evaluation of α,α -disubstituted-3-mercaptopropanoic acids as inhibitors for carboxypeptidase A and implications with respect to enzyme inhibitor design
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2-Ethyl-2-methyl-3-mercaptopropanoic acid (6) and 2-benzyl-2-methyl-3-mercaptopropanoic acid (7) were synthesized and evaluated as inhibitors for carboxypeptidase A (CPA), a prototypical zinc protease with the expectation that the binding affinities of these inhibitors would be augmented over those of 2-ethyl-3-methylsuccinic acid (2) and 2-benzyl-3-methylsuccinic acid (3), respectively, in light of the fact that the sulfhydryl group is a better zinc coordinating moiety than the carboxylate group. Contrary to the expectation, however, the inhibitory potency of 6 was not improved and that of 7 was rather attenuated by the replacement. A probable explanation for the unexpected results is offered.
- Lee, Hyun Soo,Kim, Dong H.
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p. 4685 - 4691
(2007/10/03)
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- Effect of supramolecular inclusion on the 1,2-rearrangement of free radicals
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The free radicals 3-ethoxy-2-(ethoxycarbonyl)-3-oxopropyl (1′) and 3-ethoxy-2-(ethoxycarbonyl)-2-methyl-3-oxopropyl (2′) were generated by photolysis of perester precursors in i) hexane solution, ii) in the presence of β-cyclodextrin, and iii) in NaY zeolite. While free radicals in solution are reluctant to rearrange, they do so when encapsulated in β-cyclodextrin or NaY zeolite. The coenzyme-B12-dependent enzymic rearrangement of methylmalonyl-CoA to succinyl-CoA could be mimicked by photochemical generation of an analogue of the putative intermediate radical in a molecular container.
- Chen, Ying,Kervio, Eric,Retey, Janos
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p. 552 - 558
(2007/10/03)
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- 2,2-disubstituted glycerol and glycerol-like compounds, compositions and methods of use
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Novel 2,2-disubstituted glycerol-like compounds are disclosed for use as anti-allergic and anti-inflammatory compounds. The compounds are antagonists of platelet activating factor ("PAF"). Also disclosed are methods of synthesizing and using the compounds of the invention as well as pharmaceutical compositions thereof. The compounds have the formula STR1 wherein R1, R2, R3, and R4 are as defined in the specification.
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- 2,2-Disubstituted glycerol and glycerol-like compounds, compositions and methods of use
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Novel 2,2-disubstituted glycerol compounds are disclosed for use as anti-allergic and anti-inflammatory compounds. The compounds are antagonists of platelet activating factor ("PAF). Also disclosed are methods of synthesizing and using the compounds of the invention as well as pharmaceutical compositions thereof. The compounds have the formula wherein R1, R2, R3, and R4 are as defined in the specification.
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- SELECTIVE MIXED COUPLING OF CARBOXYLIC ACIDS (II). -PHOTOLYSIS OF UNSYMMETRICAL DIACYLPEROXIDES WITH ALKENYL-, HALO-, KETO-, CARBOXYL-GROUPS AND A CHIRAL α-CARBON. COMPARISON WITH THE MIXED KOLBE ELECTROLYSIS.
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- Alkenoyl and functionalized alkanoyl dodecanoyl peroxides are prepared in 70 to 97 percent yield and photolyzed at -78 deg C.Thereby 4- to 10-alkenoyl and 4-alkynoyl peroxides afford good yields (56 - 68 percent) of unsymmetrical coupling products.Similarly α- to δ-haloalkanoyl, cholanoyl or 3- and 4-carboxyalkanoyl peroxides can be coupled (40 - 70 percent).The α-chiral diacyl peroxide 1s undergoes the photochemical coupling reaction with 80 percent retention of its configuration.The photolysis of diacyl peroxides at -78 deg C proves to be a favorable supplement of the Kolbe-electrolysis in cases, where the electrolysis fails or produces low yields.
- Feldhues, Michael,Schaefer, Hans J.
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p. 4213 - 4236
(2007/10/02)
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- Herbicidal isoxazolidine-3,5-diones
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2-Substituted isoxazolidine-3,5-diones and isoxazolidine-3-one-5-thiones exhibit herbicidal activity, controlling effectively the growth of a wide spectrum of grassy and broad-leaved plant species. The preparation and herbicidal activity of the compounds is exemplified.
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