EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2008
Paula M. T. Ferreira
Abstract Several N -acyl-,-hydroxyamino acids were prepared and treated with di- tert -butyl dicarbonate in the presence of 4-(dimethylamino)pyridine, followed by treatment with N,N,N,,N, -tetramethylguanidine to give the corresponding N -acyldehydroamino acids in good to high yields. These were then treated with I2/K2CO3 followed by 1,8-diazabicyclo[5.4.0]undec-7-ene. The methyl esters of N -acyldehydroaminobutyric acid gave the corresponding substituted oxazoles in good to high yields. The N -acyldehydrophenylalanines gave 5-phenyloxazole derivatives in low to moderate yields together with ,-iododehydrophenylalanines. Under the same conditions, N -acyldehydroalanines failed to give the corresponding oxazoles. However, when the reaction was carried out in the absence of DBU, it was possible to isolate the ,,,-diiododehydroalanine derivatives. Although the reason for the different reactivities of the N -acyldehydroamino acids is not completely clear to us, cyclic voltammetry studies showed that the less-reactive derivatives have higher reduction potentials. This suggests that the double bonds in dehydroaminobutyric acid derivatives are more susceptible to electrophilic attack by iodine.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Lipid analysis of the sex pheromone gland of the moth Heliothis virescens

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2005
S.P. Foster
Abstract The sex pheromone gland of female Heliothis virescens was analyzed for fatty acid and lipid content. Base methanolysis of the gland showed a large amount of methyl (Z)-11-hexadecenoate (Z11-16:Acyl), the fatty acyl analog of the major pheromone component, (Z)-11-hexadecenal, as well as a small amount of methyl (Z)-11-octadecenoate. Methyl esters of various common fatty acids were also observed. HPTLC analysis of the glandular lipids revealed large quantities of triacylglycerols (TGs), and lesser amounts of 1,2-diacylglycerols (1,2-DGs), 2- monoacylglycerols (2-MGs), phosphatidyl ethanolamines, and phosphatidyl cholines. The greatest amount of Z11-16:Acyl in these lipids was in the TGs, with lesser amounts in the two phospholipid classes and only trace amounts in the other neutral lipids. The glands of females at various ages and photoperiodic times were extracted, fractionated into neutral and polar fractions by silica SPE, and fatty acid titers in these fractions determined. All fatty acids, but notably Z11-16:Acyl, showed significant total and neutral lipid fraction peaks at mid scotophase for 2-day-old females; a less dramatic, but significant, Z11-16:Acyl peak in the polar fraction was also observed. However, only a relatively small proportion (<50%) of this acid was recovered from the silica at all times. This "non-recoverable" Z11-16:Acyl showed a dramatic and significant peak at mid scotophase for 2-day females, corresponding roughly with maximal pheromone titer. All other acids in the gland were recovered in high proportions, and their respective "non-recoverable" titers were not different at any of the times analyzed. Based on previous work, this non-recoverable Z11-16:Acyl is likely the CoA ester. Therefore, it appears that the pheromone gland of H. virescens maintains pools of Z11-16:Acyl in both CoA ester and TG forms, which are available for biosynthesis of pheromone. These pools are greatest during maximal pheromone production when the biosynthetic enzymes, possibly the fatty acid reductase, are unable to utilize rapidly enough the quantities of Z11-16:Acyl biosynthesized. Arch. Insect Biochem. Physiol. 59:80,90, 2005. © 2005 Wiley-Liss, Inc. [source]

ChemInform Abstract: Studies in Acyl C,H Activation via Aryl and Alkyl to Acyl "Through Space" Migration of Palladium.

CHEMINFORM, Issue 45 2009
Tanay Kesharwani
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Substitution of Acyl for Acetyl with N-Acylbenzotriazoles Catalyzed by Samarium Triiodide.

CHEMINFORM, Issue 44 2007
Xuefei Zou
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Transformation of 1-(Acyl)(2-haloethyl)amino-9,10-anthraquinones into 1-(2-Acyloxyethylamino)-9,10-anthraquinones.

CHEMINFORM, Issue 12 2007
L. M. Gornostaev
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Benzamidines in Cyclocondensation with Hexafluoroacetone and Methyl Trifluoropyruvate Acyl- and Ethoxycarbonylimines.

CHEMINFORM, Issue 8 2006
V. B. Sokolov
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF. [source]

Catalytic Cross-Coupling Reaction of Esters with Organoboron Compounds and Decarbonylative Reduction of Esters with HCOONH4: A New Route to Acyl Transition Metal Complexes Through the Cleavage of Acyl,-Oxygen Bonds in Esters.

CHEMINFORM, Issue 51 2004
Hiroto Tatamidani
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Regioselective Cycloaddition of Cyclic Ketones to Acyl(imidoyl)ketenes.

CHEMINFORM, Issue 37 2003
N. Yu.
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Cyclodimerization of Acyl-(3-oxo-2-quinoxalinyl)ketenes.

CHEMINFORM, Issue 2 2003
A. N. Maslivets
No abstract is available for this article. [source]

ChemInform Abstract: Selective Reduction of the Acyl Group in Cyclic ,-Acyl-,-dicarbonyl Compounds with Sodium Cyanoborohydride.

CHEMINFORM, Issue 49 2001
-Alkyl-, -dicarbonyl Compounds., Efficient Synthesis of Cyclic
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Thermal Cross Fries Acyl and Benzoyl Migrations from Aromatic Diesters to Phenols.

CHEMINFORM, Issue 19 2001
P. C. Thapliyal
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Dehydrogenation of Hydridoirida-,-diketones in Methanol: The Selective Formation of Mono- and Dinuclear Acyl Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2010
Roberto Ciganda
Abstract The hydridoirida-,-diketone [IrH{(PPh2(o -C6H4CO))2H}Cl] (1) reacts with diimines (NN) or with pyridine (py) in refluxing methanol to undergo dehydrogenation. The reactions afford selectively the cis -acyl, trans -phosphane isomers of the cationic [Ir(PPh2(o -C6H4CO))2(NN)]+ {NN = 2,2,-bipyridine (2); R,N=C(CH3),C(CH3)=N,R, [R = R, = NH2 (3); R = R, = OH (4); R = OH, R, = NH2 (5)]} or neutral [IrCl(PPh2(o -C6H4CO))2(py)] (6) derivatives. The reactions are faster for ligands containing amino substituents. Refluxing 1 in MeOH affords the formation of an equimolar mixture of dimercationic species [Ir2(,-Cl)(,-PPh2(o -C6H4CO))2(PPh2(o -C6H4CO))2]+ (7a and 7b) containing two acyls and a chloride as bridging groups. The isomers could be separated by fractional precipitation. Compound [3]Cl, containing amino substituents in the imino functionalities, catalyses the hydrogen transfer from 2-propanol to cyclohexanone to afford cyclohexanol. All the complexes were fully characterised spectroscopically. Single crystal X-ray diffraction analysis was performed on complexes 6 and [7b]ClO4. [source]

Synthesis of Substituted Oxazoles from N -Acyl-,-hydroxyamino Acid Derivatives

A Temporary Stereocentre Approach for the Stereodivergent Synthesis of Either Enantiomer of ,-Methyloctanal

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 33 2007
D. Gangani Niyadurupola
Abstract The aldol reaction of a chiral N -(acyl)oxazolidin-2-one with 2-methyleneoctanal or (E)-2-methyloct-2-enal affords chiral aldol products whose alkene functionalities were hydrogenated using Brown's or Wilkinson's catalyst to afford syn - or anti -selective products with excellent levels of diastereocontrol. Subsequent retro -aldol cleavage of these syn - or anti -adducts resulted in the formation of either (R)- or (S)-enantiomer of ,-methyloctanal with no racemisation occurring, which could be derivatised in-situ to afford chiral dithiane, alcohol or ,,,-unsaturated ester products in enantiopure form.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

6-Deoxy-,- L -talopyranosides from Streptomyces sp.,

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2006
Jens Bitzer
Abstract Streptomyces sp. strain GöM1 was found to produce seven novel glycosides (2,8) containing the rare deoxysugar 6-deoxy-,- L -talose. The aglycones are small phenols, isovaleric acid or aromatic carboxylic acids. By precursor-directed biosynthesis, the yields of the compounds could be increased significantly. Feeding of 4-hydroxybenzoic acid led to the production of both acyl and aryl glycosides, and of compound 9 with both structural elements. Pyrrol-2-ylcarbonyl 6-deoxy-,- L -talopyranoside (6) shows remarkable growth inhibition of some parasites. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Catalytic Hydrogenation of Cyanohydrin Esters as a Novel Approach to N -Acylated ,-Amino Alcohols , Reaction Optimisation by a Design of Experiment Approach

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2006
Lars Veum
Abstract The catalytic hydrogenation of acylated cyanohydrins and subsequent intramolecular migration of the acyl group to yield pharmaceutically interesting N -acyl ,-amino alcohols is shown to be a successful one-pot preparation method. The combination of a multistep DoE approach and high-throughput methodology proved to be an effective strategy for the optimisation of the reaction. With the favoured catalyst/solvent combination of nickel on alumina in dioxane, both hydrogenation and acyl group migration proceeded smoothly, giving the N -acyl ,-amino alcohols in yields (determined by GC) of up to 90,% for aliphatic substrates and up to 50,% for benzylic ones, the latter being more prone to side reactions. No racemisation was found to occur at the chiral centre of an aliphatic molecule when an enantiopure cyanohydrin ester was used, though a minor decrease in ee was observed with a benzylic substrate. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Identification and characterization of a new gene from Variovorax paradoxus Iso1 encoding N -acyl- d -amino acid amidohydrolase responsible for d -amino acid production

FEBS JOURNAL, Issue 19 2002
Pei-Hsun Lin
An N -acyl- d -amino acid amidohydrolase (N -D-AAase) was identified in cell extracts of a strain, Iso1, isolated from an environment containing N -acetyl- d -methionine. The bacterium was classified as Variovorax paradoxus by phylogenetic analysis. The gene was cloned and sequenced. The gene consisted of a 1467-bp ORF encoding a polypeptide of 488 amino acids. The V. paradoxusN -D-AAase showed significant amino acid similarity to the N -acyl- d -amino acid amidohydrolases of the two eubacteria Alcaligenes xylosoxydans A-6 (44,56% identity), Alcaligenes facelis DA1 (54% identity) and the hyperthermophilic archaeon Pyrococcus abyssi (42% identity). After over-expression of the N -D-AAase protein in Escherichia coli, the enzyme was purified by multistep chromatography. The native molecular mass was 52.8 kDa, which agreed with the predicted molecular mass of 52 798 Da and the enzyme appeared to be a monomer protein by gel-filtration chromatography. A homogenous protein with a specific activity of 516 U·mg,1 was finally obtained. After peptide sequencing by LC/MS/MS, the results were in agreement with the deduced amino acid sequence of the N -D-AAase. The pI of the enzyme was 5.12 and it had an optimal pH and temperature of 7.5 and 50 °C, respectively. After 30 min heat treatment at 45 °C, between pH 6 and pH 8, 80% activity remained. The N -D-AAase had higher hydrolysing activity against N -acetyl- d -amino acid derivates containing d -methionine, d -leucine and d -alanine and against N -chloroacetyl- d -phenylalanine. Importantly, the enzyme does not act on the N -acetyl- l -amino acid derivatives. The enzyme was inhibited by chelating agents and certain metal ions, but was activated by 1 mm of Co2+ and Mg2+. Thus, the N -D-AAase from V. paradoxus can be considered a chiral specific and metal-dependent enzyme. [source]

Absence of Gup1p in Saccharomyces cerevisiae results in defective cell wall composition, assembly, stability and morphology

FEMS YEAST RESEARCH, Issue 7 2006
Célia Ferreira
Abstract Saccharomyces cerevisiae Gup1p and its homologue Gup2p, members of the superfamily of membrane-bound O -acyl transferases, were previously associated with glycerol-mediated salt-stress recovery and glycerol symporter activity. Several other phenotypes suggested Gup1p involvement in processes connected with cell structure organization and biogenesis. The gup1, mutant is also thermosensitive and exhibits an altered plasma membrane lipid composition. The present work shows that the thermosensitivity is independent of glycerol production and retention. Furthermore, the mutant grows poorly on salt, ethanol and weak carboxylic acids, suggestive of a malfunctioning membrane potential. Additionally, gup1, is sensitive to cell wall-perturbing agents, such as Calcofluor white, Zymolyase, lyticase and sodium dodecyl sulphate and exhibits a sedimentation/aggregation phenotype. Quantitative analysis of cell wall components yielded increased contents of chitin and ,-1,3-glucans and lower amounts of mannoproteins. Consistently, scanning electron microscopy showed a strikingly rough surface morphology of the mutant cells. These results suggest that the gup1, is affected in cell wall assembly and stability, although the Slt2p/MAP kinase from the PKC pathway was phosphorylated during hypo-osmotic shock to a normal extent. Results emphasize the pleiotropic nature of gup1,, and are consistent with a role of Gulp1p in connection with several pathways for cell maintenance and construction/remodelling. [source]

Disturbed hepatic carbohydrate management during high metabolic demand in medium-chain acyl,CoA dehydrogenase (MCAD),deficient mice,

HEPATOLOGY, Issue 6 2008
Hilde Herrema
Medium-chain acyl,coenzyme A (CoA) dehydrogenase (MCAD) catalyzes crucial steps in mitochondrial fatty acid oxidation, a process that is of key relevance for maintenance of energy homeostasis, especially during high metabolic demand. To gain insight into the metabolic consequences of MCAD deficiency under these conditions, we compared hepatic carbohydrate metabolism in vivo in wild-type and MCAD,/, mice during fasting and during a lipopolysaccharide (LPS)-induced acute phase response (APR). MCAD,/, mice did not become more hypoglycemic on fasting or during the APR than wild-type mice did. Nevertheless, microarray analyses revealed increased hepatic peroxisome proliferator-activated receptor gamma coactivator-1, (Pgc-1,) and decreased peroxisome proliferator-activated receptor alpha (Ppar ,) and pyruvate dehydrogenase kinase 4 (Pdk4) expression in MCAD,/, mice in both conditions, suggesting altered control of hepatic glucose metabolism. Quantitative flux measurements revealed that the de novo synthesis of glucose-6-phosphate (G6P) was not affected on fasting in MCAD,/, mice. During the APR, however, this flux was significantly decreased (,20%) in MCAD,/, mice compared with wild-type mice. Remarkably, newly formed G6P was preferentially directed toward glycogen in MCAD,/, mice under both conditions. Together with diminished de novo synthesis of G6P, this led to a decreased hepatic glucose output during the APR in MCAD,/, mice; de novo synthesis of G6P and hepatic glucose output were maintained in wild-type mice under both conditions. APR-associated hypoglycemia, which was observed in wild-type mice as well as MCAD,/, mice, was mainly due to enhanced peripheral glucose uptake. Conclusion: Our data demonstrate that MCAD deficiency in mice leads to specific changes in hepatic carbohydrate management on exposure to metabolic stress. This deficiency, however, does not lead to reduced de novo synthesis of G6P during fasting alone, which may be due to the existence of compensatory mechanisms or limited rate control of MCAD in murine mitochondrial fatty acid oxidation. (HEPATOLOGY 2008.) [source]

Synthesis of the new adducts of imines and enamines with PH acids and their derivatives,

HETEROATOM CHEMISTRY, Issue 2 2009
Andrey A. Prishchenko
Nucleophilic or radical addition of esters of trivalent organophosphorus acids with PH fragments to various imines and enamines is proposed as convenient methods for the synthesis of new substituted aminomethyl organophosphorus compounds with three-, four-, and five-coordinated phosphorus. Also the new functionalized derivatives of these compounds with acyl and methanesulfonyl moieties are synthesized, and some properties of the obtained compounds are presented. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:70,80, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20513 [source]

Copper-Catalyzed N -Arylation/Hydroamin(d)ation Domino Synthesis of Indoles and its Application to the Preparation of a Chek1/KDR Kinase Inhibitor Pharmacophore

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2009
Lutz Ackermann
Abstract Inexpensive copper catalysts allow for efficient syntheses of N -aryl-, N -acyl-, or N -H-(aza)indoles starting from ortho -alkynylbromoarenes. The broad scope of this domino N -arylation/hydroamin(d)ation process is highlighted by the synthesis of highly functionalized indoles, as well as of a Chek1/KDR inhibitor pharmacophore. [source]

Preparative Enzymatic Synthesis of the Acylglucuronide of Mycophenolic Acid

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6-7 2003
Matthias Kittelmann
Abstract The acylglucuronide (3) of mycophenolic acid (1) was enzymatically synthesised on a preparative scale (450,mg substrate) under optimised reaction conditions with 51% conversion. By screening 9 liver homogenates from 8 vertebrate species, it was shown that only with liver homogenate from horse as the catalyst were the acyl- (3) and the O -glucuronide (2) were formed in a ca. 1,:,1 ratio. With homogenates from other sources, the O -glucuronide (2) was produced in high excess. By optimising the concentration of the co-substrate UDP-glucuronic acid and the reaction temperature, the conversion to the acylglucuronide (3) was increased from initially 34 to 55% and the ratio of acyl- (3) to O -glucuronide (2) from 1.5,:,1 to 3.9,:,1. The reaction was also performed continuously in an enzyme membrane reactor, however, with lower conversion yield and therefore, higher specific UDP-glucuronic acid consumption. [source]

New variants of polar glycopeptidolipids detected in Mycobacterium simiae, including ,habana' strains, as evidenced by electrospray ionization-ion trap-mass spectrometry

JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2008
L. Mederos
Abstract Aims:, To determine the composition of polar glycopeptidolipids (pGPLs) of Mycobacterium simiae and, particularly, those of ,habana' strains, in a search for specific markers given the immunogenic potential of ,habana' TMC 5135 in experimental tuberculosis. Methods and Results:, pGPLs were determined in free lipid extracts using electrospray ionization-ion trap-mass spectrometry (ESI-IT-MS), working in both negative- and positive-ion mode. In the case of TMC 5135, the presence of the previously characterized GPL-II (containing 2,4-di-O-CH3 glucuronic acid as distal sugar in the oligosaccharide antigenic moiety) and GPL-III (containing 4-O-CH3 glucuronic acid as distal sugar) was confirmed using MS/MS and MS/MS/MS approaches. Interestingly, some ,habana' strains presented variants of GPL-II, designated GPL-II,-A and GPL-II,-B. A di-O-CH3 -deoxy-hexose (tentatively, 2,3-di-O-CH3 -fucose) was identified as the penultimate sugar in the oligosaccharide moiety of GPL-II,-A, whereas in GPL-II,-B the penultimate sugar was fucose (tentative identification). On the contrary, the distal sugar of the oligosaccharide chain of pGPLs of Myco. simiae ATCC 25275T was identified as tri-O-CH3 -glucuronic acid (designated GPL-simT -I, with two variants: GPL-simT -I-A and GPL-simT -I-B), O-CH3 -glucuronic acid (designated GPL-simT -II) and di-O-CH3 -glucuronic acid (GPL-II,-A and GPL-II,-B). The penultimate sugar of the oligosaccharide chain of GPL-simT -I-A and GPL-simT -II was identified as di-O-CH3 -deoxy-hexose (tentatively, 2,3-di-O-CH3 fucose), and that of GPL-simT -I-B as deoxy-hexose (tentatively, fucose). In all strains studied, each [M-H], and [M+Na]+ ion was revealed as a mixture of homologous compounds varying in the number of ,O-CH3 groups present in the oligosaccharide moiety and in the length of the fatty acyl linked to the peptide. Conclusions:, The present work indicates that, within a similar general pattern of pGPLs, different strains of Myco. simiae present some variations, so that new compounds (GPL-II,-A, GPL-II,-B, GPL-simT -I-A, GPL-simT -I-B and GPL-simT -II) were defined. Noteworthy was the fact that the ,habana' strains clearly differed from the type strain of Myco. simiae. Significance and Impact of the Study:, The data obtained can be used in the delineation of the ,habana' group of Myco. simiae, including the quality control of the immunogenic strain ,habana' TMC 5135. [source]

Hepatic covalent adduct formation with zomepirac in the CD26-deficient mouse

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 1 2002
MIN WANG
Abstract Background and Aims: Zomepirac (ZP), a non-steroidal anti-inflammatory drug (NSAID), has been reported to cause immune-mediated liver injury. In vivo, ZP is metabolized to a chemically reactive acyl glucuronide conjugate (ZAG) which can undergo covalent adduct formation with proteins. Such acyl glucuronide-derived drug-protein adducts may be important in the development of immune and toxic responses caused by NSAID. We have shown using immunoabsorptions that the 110 kDa CD26 (dipeptidyl peptidase IV) is one of the hepatic target proteins for covalent modification by ZAG. In the present study, a CD26-deficient mouse strain was used to examine protein targets for covalent modification by ZP/metabolites in the liver. Methods and Results: The CD26-deficient phenotype was confirmed by immunohistochemistry, flow cytometry analysis, RT-PCR, enzyme assay and immunoblotting. Moreover, by using monoclonal antibody immunoblots, CD26 was not detected in the livers of ZP-treated CD26-deficient mice. Immunoblots using a polyclonal antiserum to ZP on liver from ZP-treated mice showed three major sizes of protein bands, in the 70, 110 and 140 kDa regions. Most, but not all, of the anti-ZP immunoreactivity in the 110 kDa region was absent from ZP-treated CD26-deficient mice. Conclusion: These data definitively showed that CD26 was a component of ZP-modified proteins in vivo. In addition, the data suggested that at least one other protein of approximately 110 kDa was modified by covalent adduct formation with ZAG. [source]

Determination of regioselectivity in ring opening of tert -butylaziridinones by a combination of 15N labeling and electrospray ionization-ion trap mass spectrometry

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2002
E. R. Talaty
Abstract The ring opening of 1,3-di- tert -butylaziridinone by tert -butylamine and aniline was investigated by using electrospray ionization and collision-induced dissociation in an ion trap mass spectrometer in conjunction with 15N labeling of the two amine nucleophiles. Using the MSn capabilities of the ion trap instrument, we were able to monitor the retention of the 15N label through successive fragmentation steps. Both amines exhibited a remarkable degree of selectivity in that they both cleaved exclusively the 1,3-bond (the alkyl,nitrogen bond). This result is in contrast to that obtained previously with methylamine, which cleaved just the opposite bond, namely, the 1,2-bond (the acyl,nitrogen bond). These contrasting results could not have been predicted by previously published guidelines. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Selective ,1 -adrenoreceptor blocking activity of newly synthesized acyl amino-substituted aryloxypropanolamine derivatives, DPJ 955 and DPJ 890, in rats

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2005
K. Nandakumar
The in-vivo ,-adrenoreceptor antagonistic activity of test compounds DPJ 955 and DPJ 890 was assessed against ,-adrenoreceptor agonist (isoprenaline) induced tachycardia in anaesthetized rats. The selectivity to block isoprenaline responses on different ,-adrenoreceptor subtypes (,1, ,2 and ,3) of the test compounds was carried out on isolated rat right atria, isolated rat uterus and isolated rat colon preparations, respectively. Intravenous injection of isoprenaline alone in anaesthetized rats caused hypotension and tachycardia. DPJ 955 or DPJ 890 alone produced a fall in mean arterial pressure and bradycardia in a dose-dependent manner. Administration of isoprenaline to anaesthetized rats pre-treated with test compounds significantly blocked both the tachycardial and hypotensive responses induced by isoprenaline. The test compounds shifted the concentration response curves of isoprenaline towards the right for isolated rat right atrial preparations, rat uterus and rat colon, indicating ,1, ,2 and ,3 adrenoreceptor blockade, respectively. The selectivity ratio for ,1/,-adrenoreceptors to DPJ 955 and DPJ 890 was 64.6 and 83.2, respectively. DPJ 890 was more potent in blocking ,1 -adrenoreceptors and was more selective towards ,1 receptors than to other ,-adrenoreceptor subtypes. In conclusion, DPJ 955 and DPJ890 have ,-adrenoreceptor blocking activity with high selectivity for the ,1 -adrenoreceptor subtype. [source]

Alternating copolymerization of propylene oxide with carbon monoxide catalyzed by Co complex and Co/Ru complexes

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2002
Daisuke Takeuchi
Abstract Co2(CO)8 catalyzes the ring-opening copolymerization of propylene oxide with CO to afford the polyester in the presence of various amine cocatalysts. The 1H and 13C{1H} NMR spectra of the polyester, obtained by the Co2(CO)8,3-hydroxypyridine catalyst, show the following structure [CH2CH(CH3)OCO]n. The Co2(CO)8,phenol catalyst gives the polyester, which contains the partial structural unit formed through the ring-opening copolymerization of tetrahydrofuran with CO. The bidentate amines, such as bipyridine and N,N,N,,N,-tetramethylethylenediamine, enhance the Co complex-catalyzed copolymerization, which produces the polyester with a regulated structure. Acylcobalt complexes, (RCO)Co(CO)n (R = Me or CH2Ph), prepared in situ, do not catalyze the copolymerization even in the presence of pyridine. This suggests that the chain growth involves the intermolecular nucleophilic addition of the OH group of the intermediate complex to the acyl,cobalt bond, forming an ester bond rather than the insertion of propylene oxide into the acyl,cobalt bond. Co2(CO)8Ru3(CO)12 mixtures also bring about the copolymerization of propylene oxide with CO. The molar ratio of Ru to Co affects the yield, molecular weight, and structure of the produced copolymer. The catalysis is ascribed to the RuCo mixed-metal cluster formed in the reaction mixture. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4530,4537, 2002 [source]

Temperature and solvent dependent NMR studies on mangiferin and complete NMR spectral assignments of its acyl and methyl derivatives

MAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2006
Shaheen Faizi
Abstract By employing concerted 1 and 2D NMR techniques, exact NMR spectral assignments have been made of the acyl (2,7) and methyl (8 and 9) derivatives of mangiferin (1) isolated from the leaves of Bombax ceiba. Derivatives 2, 8 and 9 have been reported in literature, while 3,7 represent new compounds. The acetates 2 and 3 were found to be unstable and were converted into the same penta-acetate 4 at room temperature. Extensive NMR studies on mangiferin (1) and its derivatives showed that H-4 exchanges with deuterium of the solvent molecule more easily. This exchange under acidic conditions occurred at that position (C-4) where electrophilic substitution reactions can easily take place. This is the first report describing the exchange of C-4 proton of mangiferin (1), or any other xanthone, with deuterium of solvent molecules. Copyright © 2006 John Wiley & Sons, Ltd. [source]

EPR study of nitroxides formed from the reaction of nitric oxide with photolyzed amides

MAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2003
Fan Wang
Abstract Free radicals generated from UV irradiation of simple aliphatic amides in anaerobic and nitric oxide (NO)-saturated liquid mixtures or solutions gave EPR spectra of nitroxides. The application of isotopic effects to EPR spectra and the generation of radicals by transient radical attack on substrate molecules or by photolysing amine or acetoin were used to help identify photochemically produced radicals from the amides. The aliphatic amides used were formamide, acetamide and their N -methyl- or deuterium-substituted derivatives. Transient radicals used to attack the amides via hydrogen-atom abstraction were generated from the initiator AIBN or AAPH. The observation of various nitroxides indicates the reactivity of NO for trapping acyl, carbamoyl and other carbon-centered radicals. Possibly mechanistic pathways diagnosed with this trap are proposed. Copyright © 2003 John Wiley & Sons, Ltd. [source]

QSAR for Inhibition of Pseudomonas Species Lipase by 1-Acyloxy-3- N-n -octylcarbamyl-benzenes

MOLECULAR INFORMATICS, Issue 3 2009
Shyh-Ying Chiou
Abstract 1-Acyloxy-3- N-n -octylcarbamyl-benzenes (1,9) are synthesized to characterize the Quantitative Structure,Activity Relationship (QSAR) for the Third Acyl Group Binding Site (TACS) of Pseudomonas species lipase. Inhibitors 1,9 are characterized as pseudo or alternate substrate inhibitors of the enzyme. The inhibition constant (Ki) and carbamylation constant (k2) for the enzyme inhibitions by inhibitors 1,9 are determined. The carbamate carbons of the n -octylcarbamyl moieties of inhibitors 1,9 are nucleophilically attacked by the active site serine of the enzyme and the n -octylcarbamyl groups of inhibitors 1,9 are bound to the Acyl Group Binding Site (ACS) of the enzyme. Both pKi and log,k2 values are linearly corrected with the Hansch hydrophobicity , values of the substituents of the acyl moieties of inhibitors 1,7. The slopes for these corrections are 0.13 and 0.02, respectively. This result suggests that the enzyme inhibitions by inhibitors 1,7 have a common mechanism. Thus, all acyl moieties of inhibitors 1,7 should bind to the TACS of the enzyme since the acyl and carbamyl moieties of inhibitors 1,7 are meta to each other. This result also indicates that the major interaction between the acyl moiety of inhibitors 1,7 and the TACS of the enzyme is primarily the hydrophobic interaction. The more hydrophobic characters of inhibitors 1,7 are, the more tightly these inhibitors bind to the enzyme. In contrast, 1-triphenylacetoxy-3- N-n -octylcarbamyl-benzene (8) and 1-trimethylacetoxy-3- N-n -octylcarbamyl-benzene (9) do not bind to the TACS of the enzyme due to the fact that the inhibitions by both inhibitors are not linearly correlated with ,. It is possible that these two inhibitors are too bulky to fit into the TACS of the enzyme. [source]