14 results match your criteria time o-acylation

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Catalyst-Controlled Regioselective Acylation of β-Ketoesters with α-Diazo Ketones Induced by Visible Light.

Org Lett 2018 11 2;20(22):7278-7282. Epub 2018 Nov 2.

Hubei International Scientific and Technological Cooperation Base of Pesticide and Green Synthesis, Key Laboratory of Pesticide & Chemical Biology, Ministry of Education , College of Chemistry, Central China Normal University , 152 Luoyu Road , Wuhan , Hubei 430079 , P. R. China.

A catalyst-controlled acylation reaction of β-ketoesters was developed for the first time by combining visible-light photoactivation with Lewis acid or base catalysis. By employing a NiCl·glyme complex with a bis(oxazoline) ligand as the Lewis acid catalyst, C-acylation products are exclusively achieved, while utilizing pyridine or DABCO as the Lewis base catalyst affords O-acylation products with complete regioselectivity. A range of β-ketoesters with satisfactory structural diversity were suitable for this transformation, demonstrating the functional group compatibility of the method, which was attributed to the mild reaction conditions. Read More

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November 2018

Identification and Characterization of a New Series of Ghrelin O-Acyl Transferase Inhibitors.

SLAS Discov 2018 02 28;23(2):154-163. Epub 2017 Aug 28.

1 Takeda Pharmaceutical Company Limited, Fujisawa, Kanagawa, Japan.

Ghrelin O-acyl transferase (GOAT; MBOAT4) catalyzes O-acylation at serine-3 of des-acyl ghrelin. Acyl ghrelin is secreted by stomach X/A-like cells and plays a role in appetite and metabolism. Therefore, GOAT has been expected to be a novel antiobesity target because it is responsible for acyl ghrelin production. Read More

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February 2018

Model studies on iTRAQ modification of peptides: sequence-dependent reaction specificity.

J Proteome Res 2012 Mar 15;11(3):1512-20. Epub 2012 Feb 15.

Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch , Galveston, Texas 77555, United States.

A multiplexed peptide quantification strategy using the iTRAQ reagent has been described for relative measurements of peptides in digested protein mixtures. To validate the chemical specificity of the iTRAQ reaction, we have performed a detailed study of iTRAQ reactivity with two sets of synthetic peptides. The first set of peptides had sequences of Tyr-Xaa-Ser-Glu-Gly-Leu-Ser-Lys and Tyr-Xaa-Ser-Glu-Tyr-Leu-Ser-Lys where Xaa = Ala, Pro, Trp, Tyr, or Glu and was designed to study the extent of O-acylation by iTRAQ, especially hydroxyl-containing residues in different positions. Read More

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2,2-Bis(ethoxycarbonyl)vinyl (BECV) as a versatile amine protecting group for selective functional-group transformations.

Chemistry 2010 Mar;16(9):2938-43

School of Chemistry, Bharathidasan University, Palkalaiperur, Tiruchirappalli-620 024, Tamil Nadu, India.

A 2,2-Bis(ethoxycarbonyl) vinyl- (BECV) group was used for the selective protection of amines at room temperature in the presence of potentially interfering functional groups such as OH, SH, COOH as well as other NH(2) groups. Several functional group transformations such as esterification, O-alkylation, O-acylation, N-alkylation, N-acylation, S-alkylation can selectively be carried out in the presence of the BECV group. The selective deprotection of the BECV group was achieved in a short time using ethylenediamine at room temperature while several other functional groups such as benzoate, aliphatic esters, amides and ethers remain intact. Read More

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Expedient synthesis of substituted (S)-N-(alpha-methylbenzyl)aziridines.

Chem Commun (Camb) 2006 Sep 11(33):3513-5. Epub 2006 Jul 11.

School of Chemical Sciences & Pharmacy, University of East Anglia, Norwich, Norfolk, UK.

We report for the first time that after O-acylation the conjugate addition products of (S)-N-(alpha-methylbenzyl)hydroxylamine undergo an efficient diastereoselective 3-exo-tet ring-closure reaction affording 2- and 2,3-disubstituted-N-alkylaziridines in good to excellent yields. Read More

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September 2006

Enhancement of amino acid detection and quantification by electrospray ionization mass spectrometry.

Anal Chem 2006 Jul;78(13):4702-8

Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.

A new strategy for amino acid analysis is reported involving derivatization with an N-hydroxysuccinimide ester of N-alkylnicotinic acid (Cn-NA-NHS) followed by reversed-phase chromatography and electrospray ionization mass spectrometry (RPC-MS). Detection sensitivity increased as the N-alkyl chain length of the nicotinic acid derivatizing agent was increased from 1 to 4. N-Acylation of amino acids with the Cn-NA-NHS reagents in water produced a stable product in roughly 1 min using a 4-fold molar excess of derivatizing agent in 0. Read More

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A novel type of highly negatively charged lipooligosaccharide from Pseudomonas stutzeri OX1 possessing two 4,6-O-(1-carboxy)-ethylidene residues in the outer core region.

Eur J Biochem 2004 Jul;271(13):2691-704

Dipartimento di Chimica Organica e Biochimica, Universita degli Studi di Napoli Federico II, Napoli, Italy.

Pseudomonas stutzeri OXI is a Gram-negative microorganism able to grow in media containing aromatic hydrocarbons. A novel lipo-oligosaccharide from P. stutzeri OX1 was isolated and characterized. Read More

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The structure of lipid A of the lipopolysaccharide from Burkholderia caryophylli with a 4-amino-4-deoxy-L-arabinopyranose 1-phosphate residue exclusively in glycosidic linkage.

Chemistry 2003 Apr;9(7):1542-8

Dipartimento di Chimica Organica e Biochimica, Università degli studi di Napoli Federico II, Italy.

From the lipopolysaccharides (LPSs) of the plant-pathogenic bacterium Burkholderia caryophylli, the complete structure of lipid A has been characterized. For the first time, a 4-amino-4-deoxy-L-arabinopyranose 1-phosphate residue was proven to be exclusively linked to the reducing end of lipid A from a wild-type LPS. The LPSs of B. Read More

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Molecular cloning and heterologous expression of the C-13 phenylpropanoid side chain-CoA acyltransferase that functions in Taxol biosynthesis.

Proc Natl Acad Sci U S A 2002 Oct 13;99(20):12715-20. Epub 2002 Sep 13.

Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.

The structural pharmacophore of Taxol, responsible for binding the N terminus of the beta-subunit of tubulin to arrest cell proliferation, comprises, in part, the 13-O-(N-benzoyl-3-phenylisoserinoyl) side chain. To identify the side chain transferase of Taxol biosynthesis, a set of transacylases obtained from an enriched cDNA library (constructed from mRNA isolated from Taxus cuspidata cells induced with methyl jasmonate for Taxol production) was screened. A cDNA clone (designated TAX7) encoding a taxoid C-13 O-phenylpropanoyltransferase was isolated which yielded a recombinant enzyme that catalyzes the selective 13-O-acylation of baccatin III with beta-phenylalanoyl CoA as the acyl donor to form N-debenzoyl-2'-deoxytaxol. Read More

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October 2002

Lipopolysaccharides possessing two L-glycero-D-manno-heptopyranosyl-alpha -(1-->5)-3-deoxy-D-manno-oct-2-ulopyranosonic acid moieties in the core region. The structure of the core region of the lipopolysaccharides from Burkholderia caryophylli.

J Biol Chem 2002 Mar 14;277(12):10058-63. Epub 2002 Jan 14.

Dipartimento di Chimica Organica e Biochimica, Università degli studi di Napoli "Federico 11," I-80126 Napoli, Italy.

The carbohydrate backbone of the core-lipid A region was characterized from the lipopolysaccharides (LPSs) of the plant-pathogenic bacterium Burkholderia caryophylli. For the first time, the presence of two moieties of l-glycero-d-manno-heptopyranosyl-alpha-(1-->5)-3-deoxy-d-manno-oct-2-ulopyranosonic acid was identified in a core region, which is of particular interest with regard to the biosynthesis of this and of LPSs in general. The LPSs of B. Read More

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Metabolism of cottonseed microsomal N-acylphosphatidylethanolamine.

Arch Biochem Biophys 1995 Apr;318(2):401-7

Department of Biological Sciences, University of North Texas, Denton 76203, USA.

N-acylphosphatidylethanolamine (NAPE) was recently shown to be synthesized in vitro in cottonseed microsomes by the direct N-acylation of phosphatidylethanolamine (PE) with unesterfied fatty acids (K.D. Chapman and T. Read More

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The occurrence of O-acylation during biotinylation of gonadotropin-releasing hormone and analogs. Evidence for a reactive serine.

J Biol Chem 1992 Mar;267(8):5060-9

Department of Anatomy and Neurosciences, University of Texas Medical Branch, Galveston 77550.

Gonadotropin-releasing hormone (GnRH) and two of its analogs ([D-Lys6]GnRH and des-Gly10-[D-Trp6]-GnRH) were reacted with sulfonated N-hydroxysuccinimide esters of biotin that have been reported to react specifically with primary amino groups. Fractionation by reversed-phase high performance liquid chromatography demonstrated the occurrence of multiple biotinylated derivatives for each reacted peptide. These results were unexpected since GnRH and des-Gly10-[D-Trp6]GnRH contained no reactive amino groups and [D-Lys6]GnRH had only one. Read More

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Urdamycins, new angucycline antibiotics from Streptomyces fradiae. V. Derivatives of urdamycin A.

J Antibiot (Tokyo) 1989 Feb;42(2):299-311

Institut für Organische Chemie, Universität Göttingen, FRG.

Derivatives of the angucycline urdamycin A (1) were prepared in order to study structure-activity relationships in this group of antitumor antibiotics. Derivatives of 1 formed by methanolysis, O-acylation, hydrogenation and treatment with diazomethane were isolated and characterized by their spectroscopic data. Urdamycin G (20) was isolated from Streptomyces fradiae by shortening the fermentation time. Read More

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February 1989

The biosynthesis of gram-negative endotoxin. Formation of lipid A precursors from UDP-GlcNAc in extracts of Escherichia coli.

J Biol Chem 1985 Dec;260(29):15536-41

The Gram-negative bacterium Escherichia coli has previously been shown to utilize two unique glucosamine (GlcN)-derived phospholipids in the biosynthesis of lipid A disaccharides (Bulawa, C.E., and Raetz, C. Read More

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December 1985
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