@article {2493, title = {Total Synthesis and Stereochemical Assignment of Micrococcin P1}, journal = {Angewandte Chemie-International Edition}, volume = {48}, number = {23}, year = {2009}, note = {ISI Document Delivery No.: 452GHTimes Cited: 11Cited Reference Count: 41Lefranc, David Ciufolini, Marco A.}, pages = {4198-4201}, type = {Article}, keywords = {ACID, antibiotics, CHEMISTRY, DOMAIN, FRAGMENT A-C, GE2270-A, HETEROCYCLES, MICROCOCCIN P1, P-1, PROTEIN-SYNTHESIS, THIOPEPTIDE ANTIBIOTICS, thiopeptides, THIOSTREPTON}, isbn = {1433-7851}, url = {://000266527800024}, author = {Lefranc, D. and Ciufolini,Marco A.} } @article {1382, title = {Deposition ice nucleation on soot at temperatures relevant for the lower troposphere}, journal = {Journal of Geophysical Research-Atmospheres}, volume = {111}, number = {D4}, year = {2006}, note = {ISI Document Delivery No.: 021EPTimes Cited: 36Cited Reference Count: 43}, month = {Feb}, pages = {9}, type = {Article}, abstract = {The ice nucleating efficiency of many important atmospheric particles remains poorly understood. Here we investigate the ice nucleation properties of a range of soot types including soot that has been treated with atmospherically relevant amounts of ozone. We focus on deposition nucleation below water saturation and at temperatures ranging from 243 to 258 K. For our experimental conditions, ice nucleation never occurred at temperatures above 248 K and below water saturation. Below 248 K, ice occasionally formed in our experiments with no indication of the formation of water droplets prior to ice formation. However, even at these temperatures the relative humidity with respect to ice (RHi) was close to water saturation when ice nucleation was observed, suggesting water nucleation may have occurred first followed by ice nucleation during the condensation process. We also performed a complimentary set of experiments where we held soot particles at 248 K and RHi = 124 +/- 4\%, which is just below water saturation, for a period of 8 hours. From these measurements we calculated an upper limit of the heterogeneous ice nucleation rate coefficient of 0.1 cm(-2) s(-1). If the number of soot particles is 1.5 x 10(5) L-1 in the atmosphere ( which corresponds to urban-influenced rural areas), then the number of ice particles produced below water saturation at these conditions is at most 0.1 particles L-1 on the basis of our upper limit. We conclude from our studies that deposition nucleation of ice on most types of soot particles is not important in the Earth{\textquoteright}s troposphere above 243 K and below water saturation.}, keywords = {ACID, AEROSOL, CARBON, CLOUDS, crystallization, CRYSTALS, deliquescence, EXHAUST, PARTICLES, WATER}, isbn = {0148-0227}, url = {://000235966800008}, author = {Dymarska, M. and Murray, B. J. and Sun, L. M. and Eastwood, M. L. and Knopf, D. A. and Bertram, A. K.} } @article {1443, title = {Lanthanide(III) and group 13 metal ion complexes of tripodal amino phosphinate ligands}, journal = {Dalton Transactions}, number = {1}, year = {2006}, note = {ISI Document Delivery No.: 993PUTimes Cited: 2Cited Reference Count: 23}, pages = {31-38}, type = {Article}, abstract = {The tripodal amino-phosphinate ligands, tris(4-(phenylphosphinato)-3-benzyl-3-azabutyl) amine (H(3)ppba center dot 2HCl center dot H2O) and tris(4-(phenylphosphinato)-3-azabutyl) amine (H(3)ppa center dot HCl center dot H2O) were synthesized and reacted with Al3+, Ga3+, In3+ and the lanthanides (Ln(3+)). At 2 : 1 H(3)ppba to metal ratios, complexes of the type [M(H(3)ppba)(2)](3+) (M = Al3+, Ga3+, In3+, Ho3+-Lu3+) were isolated. The bicapped [Ga(H(3)ppba)(2)](NO3)(2)Cl center dot 3CH(3)OH was structurally characterized and was shown indirectly by various techniques to be isostructural with the other [M(H(3)ppba)(2)](3+) complexes. Also, at 2:1 H(3)ppba to metal ratios, complexes of the type [M(H(4)ppba)(2)](5+) (M = La3+-Tb3+) were characterized, and the X-ray structure of [Gd(H(4)ppba)(2)](NO3)(4)Cl center dot 3CH(3)OH was determined. At 1:1 H(3)ppba to metal ratios, complexes of the type [M(H(4)ppba)](4+) (M = La3+-Er3+) were isolated and characterized. Elemental analysis and spectroscopic evidence supported the formation of a 1:1 monocapped complex. Reaction of 1:1 ratios of H(3)ppa with Ln(3+) and In3+ yielded complexes of the type [M(H(3)ppa)](3+) (M = La3+-Yb3+) but with Ga3+, complex of the type [Ga(ppa)]center dot 3H(2)O was obtained. Reaction of 1:1 ratios of H(3)ppa with Ln(3+) and In3+ yielded complexes of the type [M(H(3)ppa)](3+) (M = La3+-Yb3+) but with Ga3+ a neutral complex [Ga(ppa)]center dot 3H(2)O was obtained. The formation of an encapsulated 1:1 complex is supported by elemental analysis and spectroscopic evidence.}, keywords = {ACID, BEARING, CIRCULARLY-POLARIZED LUMINESCENCE, CONTRAST AGENTS, MAGNETIC-RESONANCE, NMR, RELAXOMETRY}, isbn = {1477-9226}, url = {://000233968200004}, author = {Kovacs, M. S. and Monga, V. and Patrick, B. O. and Orvig, Chris} } @article {1443, title = {Lanthanide(III) and group 13 metal ion complexes of tripodal amino phosphinate ligands}, journal = {Dalton Transactions}, number = {1}, year = {2006}, note = {ISI Document Delivery No.: 993PUTimes Cited: 2Cited Reference Count: 23}, pages = {31-38}, type = {Article}, abstract = {The tripodal amino-phosphinate ligands, tris(4-(phenylphosphinato)-3-benzyl-3-azabutyl) amine (H(3)ppba center dot 2HCl center dot H2O) and tris(4-(phenylphosphinato)-3-azabutyl) amine (H(3)ppa center dot HCl center dot H2O) were synthesized and reacted with Al3+, Ga3+, In3+ and the lanthanides (Ln(3+)). At 2 : 1 H(3)ppba to metal ratios, complexes of the type [M(H(3)ppba)(2)](3+) (M = Al3+, Ga3+, In3+, Ho3+-Lu3+) were isolated. The bicapped [Ga(H(3)ppba)(2)](NO3)(2)Cl center dot 3CH(3)OH was structurally characterized and was shown indirectly by various techniques to be isostructural with the other [M(H(3)ppba)(2)](3+) complexes. Also, at 2:1 H(3)ppba to metal ratios, complexes of the type [M(H(4)ppba)(2)](5+) (M = La3+-Tb3+) were characterized, and the X-ray structure of [Gd(H(4)ppba)(2)](NO3)(4)Cl center dot 3CH(3)OH was determined. At 1:1 H(3)ppba to metal ratios, complexes of the type [M(H(4)ppba)](4+) (M = La3+-Er3+) were isolated and characterized. Elemental analysis and spectroscopic evidence supported the formation of a 1:1 monocapped complex. Reaction of 1:1 ratios of H(3)ppa with Ln(3+) and In3+ yielded complexes of the type [M(H(3)ppa)](3+) (M = La3+-Yb3+) but with Ga3+, complex of the type [Ga(ppa)]center dot 3H(2)O was obtained. Reaction of 1:1 ratios of H(3)ppa with Ln(3+) and In3+ yielded complexes of the type [M(H(3)ppa)](3+) (M = La3+-Yb3+) but with Ga3+ a neutral complex [Ga(ppa)]center dot 3H(2)O was obtained. The formation of an encapsulated 1:1 complex is supported by elemental analysis and spectroscopic evidence.}, keywords = {ACID, BEARING, CIRCULARLY-POLARIZED LUMINESCENCE, CONTRAST AGENTS, MAGNETIC-RESONANCE, NMR, RELAXOMETRY}, isbn = {1477-9226}, url = {://000233968200004}, author = {Kovacs, M. S. and Monga, V. and Patrick, B. O. and Orvig, Chris} } @article {1413, title = {Mass spectrometric characterization of lipid-modified peptides for the analysis of acylated proteins}, journal = {Journal of Mass Spectrometry}, volume = {41}, number = {2}, year = {2006}, note = {ISI Document Delivery No.: 016BVTimes Cited: 13Cited Reference Count: 45}, month = {Feb}, pages = {229-241}, type = {Article}, abstract = {The analysis of acylated proteins by mass spectrometry (MS) has largely been overshadowed in proteomics by the analysis of glycosylated and phosphorylated proteins; however, lipid modifications on proteins are proving to be of increasing importance in biomedical research. In order to identify the marker ions and/or neutral loss fragments that are produced upon collision-induced dissociation, providing a means to identify the common lipid modifications on proteins, peptides containing an N-terminally myristoylated glycine, a palmitoylated cysteine and a farnesylated cysteine were chemically synthesized. Matrix-assisted laser desorption/ionization time-of-flight time-of-flight (MALDI-TOF-TOF), electrospray ionization quadrupole time-of-flight (ESI Q-TOF), and electrospray ionization hybrid triple-quadrupole/linear ion trap (ESI QqQ(LIT)) mass spectrometers were used for the analysis. The peptide containing the N-terminally myristoylated glycine, upon CID, produced the characteristic fragments a(1) (240.4 Th) and b(1) (268.4 Th) ions as well as a low-intensity neutral loss of 210 Da (C14H26O). The peptides containing a farnesylated cysteine residue fragmented to produce a marker ion at a m/z of 205 Th (C15H25) as well as other intense farnesyl fragment ions, and a neutral loss of 204 Da (C15H24). The peptides containing a palmitoylated cysteine moiety generated neutral losses of 238 Da (C16H30O) and 272 Da (C16H32OS); however, no marker ions were produced. The neutral losses were more prominent in the MALDI-TOF-TOF spectra, whereas the marker ions were more abundant in the ESI QqQ(LIT) and Q-TOF mass spectra. Copyright (c) 2006 John Wiley \& Sons, Ltd.}, keywords = {ACID, ELECTROSPRAY-IONIZATION, farnesylation, IMMUNODEFICIENCY-VIRUS TYPE-1, marker ion, MATRIX PROTEIN, MEMBRANE ASSOCIATION, myristoylation, N-MYRISTOYLATION, neutral loss, palmitoylation, PHOSPHORYLATION, POSTTRANSLATIONAL MODIFICATIONS, PRENYLATED, PROTEINS}, isbn = {1076-5174}, url = {://000235596500011}, author = {Hoffman, M. D. and Kast, J.} } @article {1213, title = {Dismutase activity of ADP-L-glycero-D-manno-heptose 6-epimerase: Evidence for a direct oxidation/reduction mechanism}, journal = {Biochemistry}, volume = {44}, number = {15}, year = {2005}, note = {ISI Document Delivery No.: 916ZNTimes Cited: 11Cited Reference Count: 33}, month = {Apr}, pages = {5907-5915}, type = {Article}, abstract = {The first positive evidence for the utilization of a direct C-6" oxidation/reduction mechanism by ADP-L-glycero-D-manno-heptose 6-epimerase is reported here. The epimerase (HldD or AGME, formerly RfaD) operates in the biosynthetic pathway Of L-glycero-D-manno-heptose, which is a conserved sugar in the core region of lipopolysaccharide (LPS) of Gram-negative bacteria. The stereochemical inversion catalyzed by the epimerase is interesting as it occurs at an "unactivated" stereocenter that lacks an acidic C-H bond, and therefore, a direct deprotonation/reprotonation mechanism cannot be employed. Instead, the epimerase employs a transient oxidation strategy involving a tightly bound NADP(+) cofactor. A recent study ruled out mechanisms involving transient oxidation at C-4 {\textquoteright}{\textquoteright} and C-7 {\textquoteright}{\textquoteright} and supported a mechanism that involves an initial oxidation directly at the C-6 {\textquoteright}{\textquoteright} position to generate a 6"-keto intermediate (Read, J. A., Ahmed, R. A., Morrison, J. P., Coleman, W. G., Jr., Tanner, M. E. (2004) J. Am. Chem. Soc. 126, 8878-8879). A subsequent nonstereospecific reduction of the ketone intermediate can generate either epimer of the ADP-heptose. In this work, an intermediate analogue containing an aldehyde functionality at C-6 {\textquoteright}{\textquoteright}, ADP-beta-D-manno-hexodialdose, is prepared in order to probe the ability of the enzyme to catalyze redox chemistry at this position. It is found that incubation of the aldehyde with a catalytic amount of the epimerase leads to a dismutation process in which one-half of the material is oxidized to ADP-beta-D-mannuronic acid and the other half is reduced to ADP-beta-D-mannose. Transient reduction of the enzyme-bound NADP(+) was monitored by UV spectroscopy and implicates the cofactor{\textquoteright}s involvement during catalysis.}, keywords = {ACID, ALCOHOL-DEHYDROGENASE, ALDEHYDE DEHYDROGENASE, D-MANNOHEPTOSE 6-EPIMERASE, DROSOPHILA-MELANOGASTER, EPIMERIZATION, ESCHERICHIA-COLI, GLUCOSE DEHYDROGENASE, LIVER, SITE RESIDUES, UDP-GALACTOSE 4-EPIMERASE}, isbn = {0006-2960}, url = {://000228425600037}, author = {Morrison, J. P. and Read, J. A. and Coleman, W. G. and Tanner, M. E.} } @article {1265, title = {A glucosamine dipicolylamine conjugate of Tc-99m(I) and Re-186(I) for use in imaging and therapy}, journal = {Dalton Transactions}, number = {4}, year = {2005}, note = {ISI Document Delivery No.: 895EYTimes Cited: 32Cited Reference Count: 16}, pages = {654-655}, type = {Article}, abstract = {The synthesis and metal complexation of a glucosamine-appended 2,2{\textquoteright}-dipicolylamine ligand to the tricarbonyls of Tc-99m and Re-186 is described; the ligand was found to bind in a tridentate fashion with the glucosamine function remaining pendant, and the Tc-99m complex was found to exhibit exceptional stability towards in vitro ligand exchange experiments.}, keywords = {ACID, BIOMOLECULES, COMPLEXES, RADIOPHARMACEUTICALS, RE}, isbn = {1477-9226}, url = {://000226844900003}, author = {Storr, T. and Fisher, C. L. and Mikata, Y. and Yano, S. and Adam,Michael J. and Orvig, Chris} } @article {1265, title = {A glucosamine dipicolylamine conjugate of Tc-99m(I) and Re-186(I) for use in imaging and therapy}, journal = {Dalton Transactions}, number = {4}, year = {2005}, note = {ISI Document Delivery No.: 895EYTimes Cited: 32Cited Reference Count: 16}, pages = {654-655}, type = {Article}, abstract = {The synthesis and metal complexation of a glucosamine-appended 2,2{\textquoteright}-dipicolylamine ligand to the tricarbonyls of Tc-99m and Re-186 is described; the ligand was found to bind in a tridentate fashion with the glucosamine function remaining pendant, and the Tc-99m complex was found to exhibit exceptional stability towards in vitro ligand exchange experiments.}, keywords = {ACID, BIOMOLECULES, COMPLEXES, RADIOPHARMACEUTICALS, RE}, isbn = {1477-9226}, url = {://000226844900003}, author = {Storr, T. and Fisher, C. L. and Mikata, Y. and Yano, S. and Adam,Michael J. and Orvig, Chris} } @article {1208, title = {Group 13 and lanthanide complexes with mixed O,S anionic ligands derived from maltol}, journal = {Inorganic Chemistry}, volume = {44}, number = {8}, year = {2005}, note = {ISI Document Delivery No.: 916GWTimes Cited: 23Cited Reference Count: 61}, month = {Apr}, pages = {2666-2677}, type = {Article}, abstract = {Four mixed O,S binding ligand precursors derived from maltol (3-hydroxy-2-methyl-4-pyrone) have been chelated to gallium(III), indium(III), and lanthanide(III) ions to yield a series of metal complexes. The four ligand precursors include two pyranthiones, 3-hydroxy-2-methyl-4-pyranthione, commonly known as thiomaltol (Htma), and 2-ethyl-3-hydroxy-4-pyranthione, commonly known as ethylthiornaltol (Hetma), and two pyridinethiones, 3-hydroxy-2-methyl-4(H)-pyridinethione (Hmppt) and 3-hydroxy-1,2-dimethyl-4-pyridinethione (Hdppt). Dimeric forms of the pyridinethiones, Hmppt dimer and Hdppt dimer, were also isolated and characterized. Complete characterization of the monomeric organic compounds is reported including acidity constants and crystal structures of Htma, Hetma, and Hdppt dimer. Reacting the four monomeric ligand precursors with Ga3+ and In3+ ions yielded new tris(bidentate ligand) complexes. X-ray-quality crystals of the fac isomer of Ga(tma)(3) were also obtained. New complexes with a range of anthanicles (Ln(3+)) were also synthesized with the two pyranthiones, Htma and Hetma. The synthesis reactions yielded complexes of the type LnL(3)center dot xH(2)O and LnL(2)(OH)center dot xH(2)O, as indicated by elemental analysis and spectroscopic evidence such as mass spectral data and IR and NMR spectra.}, keywords = {ACID, aluminum, CHELATE COMPLEXES, CHEMISTRY, CRYSTAL-STRUCTURE, DIAGNOSTIC-TOOLS, gallium, indium, METAL-COMPLEXES, RADIOPHARMACEUTICALS}, isbn = {0020-1669}, url = {://000228374400017}, author = {Monga, V. and Patrick, B. O. and Orvig, Chris} } @article {1208, title = {Group 13 and lanthanide complexes with mixed O,S anionic ligands derived from maltol}, journal = {Inorganic Chemistry}, volume = {44}, number = {8}, year = {2005}, note = {ISI Document Delivery No.: 916GWTimes Cited: 23Cited Reference Count: 61}, month = {Apr}, pages = {2666-2677}, type = {Article}, abstract = {Four mixed O,S binding ligand precursors derived from maltol (3-hydroxy-2-methyl-4-pyrone) have been chelated to gallium(III), indium(III), and lanthanide(III) ions to yield a series of metal complexes. The four ligand precursors include two pyranthiones, 3-hydroxy-2-methyl-4-pyranthione, commonly known as thiomaltol (Htma), and 2-ethyl-3-hydroxy-4-pyranthione, commonly known as ethylthiornaltol (Hetma), and two pyridinethiones, 3-hydroxy-2-methyl-4(H)-pyridinethione (Hmppt) and 3-hydroxy-1,2-dimethyl-4-pyridinethione (Hdppt). Dimeric forms of the pyridinethiones, Hmppt dimer and Hdppt dimer, were also isolated and characterized. Complete characterization of the monomeric organic compounds is reported including acidity constants and crystal structures of Htma, Hetma, and Hdppt dimer. Reacting the four monomeric ligand precursors with Ga3+ and In3+ ions yielded new tris(bidentate ligand) complexes. X-ray-quality crystals of the fac isomer of Ga(tma)(3) were also obtained. New complexes with a range of anthanicles (Ln(3+)) were also synthesized with the two pyranthiones, Htma and Hetma. The synthesis reactions yielded complexes of the type LnL(3)center dot xH(2)O and LnL(2)(OH)center dot xH(2)O, as indicated by elemental analysis and spectroscopic evidence such as mass spectral data and IR and NMR spectra.}, keywords = {ACID, aluminum, CHELATE COMPLEXES, CHEMISTRY, CRYSTAL-STRUCTURE, DIAGNOSTIC-TOOLS, gallium, indium, METAL-COMPLEXES, RADIOPHARMACEUTICALS}, isbn = {0020-1669}, url = {://000228374400017}, author = {Monga, V. and Patrick, B. O. and Orvig, Chris} } @article {1126, title = {Surface composition of myrmecophilic plants: Cuticular wax and glandular trichomes on leaves of Macaranga tanarius}, journal = {Journal of Chemical Ecology}, volume = {31}, number = {10}, year = {2005}, note = {ISI Document Delivery No.: 969XKTimes Cited: 3Cited Reference Count: 30}, month = {Oct}, pages = {2323-2341}, type = {Article}, abstract = {Primary plant surfaces, covered with cuticles consisting of cutin and waxes, are important substrates for interaction with insects. The composition of leaf surfaces of the myrmecophilic plant Macaranga tanarius was studied. The prenylated flavanone nymphaeol-C was identified in surface extracts and was localized exclusively in glandular trichomes on the abaxial leaf side. The epidermal pavement cells surrounding these trichomes were covered with a smooth film of epicuticular wax from which few small wax crystals protruded. The epicuticular wax amounted to approximately 8 mu g cm(-2), corresponding to 85\% of the wax load on the adaxial as well as the abaxial leaf sides. The epicuticular wax mixtures from both leaf surfaces contained more than 70\% primary alcohols, 14\% fatty acids, 2\% aldehydes, and traces of alkyl acetates, with chain lengths ranging from C-20 to C-38. In contrast, the intracuticular wax layer was largely dominated by triterpenoid alcohols alpha-amyrin, beta-amyrin, and lupeol. Consequently, these characteristic compounds are not available for direct contact with insects on the plant surface.}, keywords = {ACID, ANT-PLANTS, BLOOMS, CHEMICAL-COMPOSITION, CREMATOGASTER, DIVERSITY, EPICUTICULAR WAX, EUPHORBIACEAE, flavanones, glandular, isoprenoids, leaf surface, Macaranga tanarius, nymphaeol-C, plant insect interactions, PRENYLFLAVANONES, trichomes}, isbn = {0098-0331}, url = {://000232269000006}, author = {Guhling, O. and Kinzler, C. and Dreyer, M. and Bringmann, G. and Jetter, R.} } @article {859, title = {Active site residues and mechanism of UDP-glucose dehydrogenase}, journal = {European Journal of Biochemistry}, volume = {271}, number = {1}, year = {2004}, note = {ISI Document Delivery No.: 756CXTimes Cited: 16Cited Reference Count: 33}, month = {Jan}, pages = {14-22}, type = {Article}, abstract = {UDP-glucose dehydrogenase catalyzes the NAD(+)-dependent twofold oxidation of UDP-glucose to give UDP-glucuronic acid. A sequestered aldehyde intermediate is produced in the first oxidation step and a covalently bound thioester is produced in the second oxidation step. This work demonstrates that the Streptococcus pyogenes enzyme incorporates a single solvent-derived oxygen atom during catalysis and probably does not generate an imine intermediate. The reaction of UDP-[6",6"-di-H-2]-D-glucose is not accompanied by a primary kinetic isotope effect, indicating that hydride transfer is not rate determining in this reaction. Studies with a mutant of the key active site nucleophile, Cys260Ala, show that it is capable of both reducing the aldehyde intermediate, and oxidizing the hydrated form of the aldehyde intermediate but is incapable of oxidizing UDP-glucose to UDP-glucuronic acid. In the latter case, a ternary Cys260Ala/aldehyde intermediate/NADH complex is presumably formed, but it does not proceed to product as both release and hydration of the bound aldehyde occur slowly. A washout experiment demonstrates that the NADH in this ternary complex is not exchangeable with external NADH, indicating that dissociation only occurs after the addition of a nucleophile to the aldehyde carbonyl. Studies on Thr118Ala show that the value of k(cat) is reduced 160-fold by this mutation, and that the reaction of UDP-D-[6",6"-di-H-2]-glucose is now accompanied by a primary kinetic isotope effect. This indicates that the barriers for the hydride transfer steps have been selectively increased and supports a mechanism in which an ordered water molecule (H-bonded to Thr118) serves as the catalytic base in these steps.}, keywords = {ACID, ALDEHYDE DEHYDROGENASE, CONSERVED CYSTEINE RESIDUES, DEHYDROGENASE, ENZYME, GDP-MANNOSE DEHYDROGENASE, GROUP-A STREPTOCOCCI, HISTIDINOL, MOLECULAR CHARACTERIZATION, PSEUDOMONAS-AERUGINOSA, URIDINE DIPHOSPHOGLUCOSE DEHYDROGENASE}, isbn = {0014-2956}, url = {://000187449200002}, author = {Ge, X. and Penney, L. C. and van de Rijn, I. and Tanner, M. E.} } @article {828, title = {A one-pot synthesis and X-ray crystallographic and computational analyses of methyl-2,4-dimethoxysalicylate - a potential anti-tumour agent}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {82}, number = {7}, year = {2004}, note = {ISI Document Delivery No.: 861XBTimes Cited: 5Cited Reference Count: 34}, month = {Jul}, pages = {1179-1185}, type = {Article}, abstract = {The thermal decarboxylation of 2-methoxycarbonyl-5-(4{\textquoteright}-nitrophen-oxy)tetrazole (1a) with the electron-rich, aromatic compounds (anisole, N,N-dimethylaniline, 1,4-dimethoxybenzene, and 1,3,5-trimethoxybenzene), neat or in polar solvents (DMSO, DMF, and CH3CN), is investigated. The solid phase thermal decomposition of a mixture of 1a, 1,3,5-trimethoxybenzene, and a Lewis acid (AlCl3) produces methyl-2,4-dimethoxysalicylate (8) in good yield, instead of the expected 2,4,6-trimethoxybenzoic acid. The X-ray structure of 8 shows intramolecular hydrogen bonds between the carbonyl oxygen and hydrogens of Me and OH groups. A measured pK(a) value of 6.8 compares well with a value of 6.4 estimated using the [C=O...H...O] hydrogen bond distances.}, keywords = {2{\textquoteright}, 6{\textquoteright}-DIMETHOXYFLAVONE, ACID, anti-tumor, computational analysis, hydrogen bonds, HYDROGEN-BOND DATA, novel synthesis, PK(A), TETRAZOLES, X-ray structure}, isbn = {0008-4042}, url = {://000224450800007}, author = {Dabbagh, H. A. and Noroozi-Pesyan, N. and Patrick, B. O. and James, Brian R.} } @article {664, title = {Demethylation of methylarsenic species by Mycobacterium neoaurum}, journal = {Applied Organometallic Chemistry}, volume = {17}, number = {11}, year = {2003}, note = {ISI Document Delivery No.: 737CBTimes Cited: 6Cited Reference Count: 26}, month = {Nov}, pages = {831-834}, type = {Article}, abstract = {Mycobacterium neoaurum demethylates both methylarsonic acid and methylarsonous acid to mixtures of arsenate and arsenite. After 28 days of incubation, the yields of inorganic arsenic were 27\% from arsenate and 43\% from arsenite. A time study of the demethylation of methylarsonic acid by M. neoaurum showed that demethylation occurs rapidly during the growth and stationary phases of the bacterium, and indicates that MMA(V) is reductively demethylated to arsenite. Copyright (C) 2003 John Wiley Sons, Ltd.}, keywords = {ACID, arsenic, ARSENICALS, ARSINE, CANDIDA-HUMICOLA, DEGRADATION, demethylation, METABOLITES, methylarsonic acid, methylarsonous acid, MICROORGANISMS, Mycobacterium neoaurum, RATS, REDUCTION, SOIL}, isbn = {0268-2605}, url = {://000186209800002}, author = {Lehr, C. R. and Polishchuk, E. and Radoja, U. and Cullen, W. R.} } @article {408, title = {Bisphosphine ligands containing two o-N,N-dimethylanilinyl substituents at each phosphorus atom}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {80}, number = {11}, year = {2002}, note = {ISI Document Delivery No.: 623LDTimes Cited: 11Cited Reference Count: 35}, month = {Nov}, pages = {1600-1606}, type = {Article}, abstract = {The synthesis and complete characterization of the family of tetra(amine)bisphosphine ligands (o-NMe2C6H4)(2)P-(X)-P(o-NMe2C6H4)(2), where X = CH2 (dmapm), (CH2)(2) (dmape), and CH(CH2)(3)CH (dmapcp), are described. Crystal structure data are compared with known, analogous bisphosphines containing o-pyridyl or phenyl substituents in place of the o-dimethylanilinyl groups. Several short, intramolecular C-H...N distances in the anilinyl derivatives may represent the presence of weak hydrogen bonds.}, keywords = {ACID, amine, AMPHIPHILIC DIPHOSPHINES, CATALYTIC-HYDROGENATION, CHEMISTRY, DERIVATIVES, HYDROFORMYLATION, hydrogen-bonding to N atoms, phosphine, polydentate, RESOLUTION, RHODIUM COMPLEXES, RUTHENIUM(II), WATER-SOLUBLE PHOSPHINES}, isbn = {0008-4042}, url = {://000179703800030}, author = {Jones, N. D. and Meessen, P. and Smith, M. B. and Losehand, U. and Rettig, S. J. and Patrick, B. O. and James, Brian R.} } @article {454, title = {Dehydroalanine-based inhibition of a peptide epimerase from spider venom}, journal = {Journal of Organic Chemistry}, volume = {67}, number = {24}, year = {2002}, note = {ISI Document Delivery No.: 620AATimes Cited: 17Cited Reference Count: 42}, month = {Nov}, pages = {8389-8394}, type = {Article}, abstract = {Ribosomally produced peptides that contain D-amino acids have been isolated from a number of vertebrate and invertebrate sources. In each case, the D-amino acids are introduced by a posttranslational modification of a parent peptide containing only amino acids of the L-configuration. The only known enzyme to catalyze such a reaction is the peptide epimerase (also known as peptide isomerase) from the venom of the funnel web spider, Agelenopsis aperta. This enzyme interconverts two 48-amino-acid-long peptide toxins that differ only by the stereochemistry at a single serine residue. In this paper we report the synthesis and testing of two pentapeptide analogues that contain modified amino acids at the site normally occupied by the substrate serine residue. When the L-chloroalanine-containing peptide 3 was incubated with the epimerase it was converted into the dehydroalanine-containing peptide 4 via an elimination of HCl. The dehydroalanine peptide 4 was independently synthesized and found to act as a potent inhibitor of the epimerase (IC50 = 0.5 muM). These results support a direct deprotonation/reprotonation mechanism in which a carbanionic intermediate is formed. The observed inhibition by 4 can be attributed to the sp(2)-hybridization of the a-carbon in the dehydroalanine unit that mimics the planar geometry of the anionic intermediate.}, keywords = {ACID, ACTIVE-SITE, ENZYME, GLUTAMATE RACEMASE, GRAMICIDIN-S SYNTHETASE, INFLUENZAE DIAMINOPIMELATE EPIMERASE, INITIATION MODULE PHEATE, MECHANISM, PROLINE RACEMASE, RESIDUES}, isbn = {0022-3263}, url = {://000179509400011}, author = {Murkin, A. S. and Tanner, M. E.} } @inbook {423, title = {Pre-steady-state kinetics of enzymatic reactions studied by electrospray mass spectrometry with on-line rapid-mixing techniques}, booktitle = {Enzyme Kinetics and Mechanism, Pt F: Detection and Characterization of Enzyme Reaction Intermediates}, series = {Methods in Enzymology}, volume = {354}, year = {2002}, note = {ISI Document Delivery No.: BV53FTimes Cited: 8Cited Reference Count: 42Review525 B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 USA}, pages = {50-64}, publisher = {Academic Press Inc}, organization = {Academic Press Inc}, address = {San Diego}, keywords = {ACID, BETA-LACTAMASE, CATALYSIS, COMPLEXES, INTERMEDIATE, ION, IONIZATION, MECHANISM, REAL-TIME}, isbn = {0076-6879}, url = {://000179267700003}, author = {Konermann, L. and Douglas, D. J.} } @article {510, title = {Synthesis and solution studies of the complexes of trivalent lanthanides with the tetraazamacrocycle TETA-(PO)(2)}, journal = {Inorganic Chemistry}, volume = {41}, number = {4}, year = {2002}, note = {ISI Document Delivery No.: 524GATimes Cited: 9Cited Reference Count: 29}, month = {Feb}, pages = {685-692}, type = {Article}, abstract = {A new potentially multidentate hexaprotic ligand H-6[TETA-(PO)(2)] has been prepared by reaction of ethylenediamine-N,N{\textquoteright}-diacetic acid (EDDA), paraformaldehyde, and phosphinic acid; its coordination properties with three lanthanide ions (La3+, Gd3+, and Lu3+) have been explored. The structures of the complexes were studied in aqueous solution by potentiometric pH titrations and by P-31 NMR spectroscopy. Four acidity constants were determined potentiometrically in the range 2.5 < pH < 14. The four measured pK(a) values can be divided into two groups, and within each group the initial deprotonation was found to have little effect on the second. Variable temperature 31P and P-31{H-1} EXSY NMR spectra showed that, for [Lu(TETA-(PO)(2))](3-), the two phosphorus atoms exist in different chemical environments and undergo an exchange process which is very fast on the NMR time scale at room temperature. This result is consistent with one of the phosphinate residues coordinating the metal ion and exchanging with a free analogue. In the case of [La(TETA-(PO)(2))](3-), only one temperature invariant signal is observed in P-31 NMR spectra; it corresponds to both phosphinate residues remaining uncoordinated to La3+. The stability of [Ln-(TETA-(PO)(2))](3-) has an order of La3+ > Gd3+ > Lu3+. The coordination of one phosphinate residue to Lu3+ brings the metal ion closer to the plane of four nitrogens and farther from the four carboxylate arms, resulting in [Lu(TETA-(PO)(2))](3-) having a lower stability than the corresponding La3+ and Gd3+ complexes. A pM-pH distribution diagram showed that introducing two phosphinate groups into TETA renders [Gd(TETA-(PO)(2))](3-) more stable than [Gd(TETA)](-). The selectivity factor of the ligand for Gd3+ vs Ca2+, Zn2+, and Cu2+ has been calculated, and the hydration number for [Dy(TETA-(PO)(2))](3-) has been measured by O-17 NMR spectroscopy to be zero.}, keywords = {ACID, CRYSTAL-STRUCTURE, DERIVATIVES, DOTA, DYNAMICS, IONS, LIGANDS, luminescence, STABILITIES}, isbn = {0020-1669}, url = {://000174003700014}, author = {Song, B. and Storr, T. and Liu, S. and Orvig, Chris} } @article {5187, title = {Enantioselective photochemical synthesis of a beta-lactam via the solid state ionic chiral auxiliary method}, journal = {Synthesis-Stuttgart}, number = {8}, year = {2001}, note = {ISI Document Delivery No.: 448GETimes Cited: 12Cited Reference Count: 20Sp. Iss. SI}, pages = {1253-1257}, type = {Article}, abstract = {Photolysis of crystals of a carboxylic acid-containing N,N-dialkylarylglyoxylamide to which an optically pure ammonium ion (the ionic chiral auxiliary) has been attached through a salt bridge leads to a 91\% isolated yield of a beta -lactam in greater than 99\% enantiomeric excess. Suspension of the crystals in hexane allows the photoreaction to be carried out on a 500 mg scale, thus demonstrating the synthetic utility of the solid stare ionic chiral auxiliary approach to asymmetric synthesis.}, keywords = {ACHIRAL OXO AMIDE, ACID, asymmetric synthesis, beta-lactam, chiral auxiliaries, CRYSTALLINE STATE, HOST, INCLUSION COMPLEXES, PHOTOCHEMISTRY, PHOTOCYCLIZATION, solid state}, isbn = {0039-7881}, url = {://000169617900022}, author = {Scheffer, J. R. and Wang, K. Y.} } @article {5233, title = {Lanthanide chemistry with bis{[bis(carboxymethyl)amino]methyl}phosphinate: What does an extra phosphinate group do to EDTA?}, journal = {Inorganic Chemistry}, volume = {40}, number = {15}, year = {2001}, note = {ISI Document Delivery No.: 452MHTimes Cited: 9Cited Reference Count: 34}, month = {Jul}, pages = {3734-3738}, type = {Article}, abstract = {H5XT (bis{[bis(carboxymethyl)amino]methyl}phosphinic acid) is an EDTA(4-)-like ligand containing an extra phosphinate group. [Co-II(XT)](3-), [Co-III(XT)](2-), and a series of [Ln(XT)](2-) complexes have been prepared. The phosphinate group is not coordinated in the Co complexes but is bound in the lanthanide complexes. Solid state and solution behaviors of Ln-XT species are consistent: both monoprotonated and nonprotonated species have been found. Protonation of the metal complex does not lead to dissociation of a carboxylate; rather, the proton distributes around the molecular ion. The pM values of Ln-XT are comparable to those of Ln-EDTA but are higher than those of Ln-TMDTA. The inclusion of a phosphinate eases the selectivity of an EDTA-type ligand for late lanthanides.}, keywords = {ACID, AGENTS, AMINE PHENOL LIGANDS, ANTIBODY, COMPLEXES, CRYSTAL-STRUCTURES, DERIVATIVES, IONS}, isbn = {0020-1669}, url = {://000169861800011}, author = {Xu, L. and Rettig, S. J. and Orvig, Chris} } @article {5222, title = {Stereocontrolled construction of the A-ring of nitiol using a Pauson-Khand cycloaddition-ring fragmentation strategy}, journal = {Organic Letters}, volume = {3}, number = {13}, year = {2001}, note = {ISI Document Delivery No.: 445ZDTimes Cited: 5Cited Reference Count: 24}, month = {Jun}, pages = {2041-2044}, type = {Article}, abstract = {[GRAPHICS] A stereocontrolled construction of the A-ring of nitiol (1) is presented, Key features in this approach are a diastereoselective Pauson-Khand cycloaddition and a Norrish type 1 fragmentation reaction.}, keywords = {ACID, ACTIVE BICYCLO<3.3.0>OCTENONE DERIVATIVES, ALDER, ALKENE ALKYNE CYCLIZATIONS, ENZYME-CATALYZED-HYDROLYSIS, NATURAL-PRODUCTS}, isbn = {1523-7060}, url = {://000169487700020}, author = {Wilson, M. S. and Dake, G. R.} } @article {4043, title = {The characterization of arsenosugars in commercially available algal products including a Nostoc species of terrestrial origin}, journal = {Applied Organometallic Chemistry}, volume = {11}, number = {10-11}, year = {1997}, note = {ISI Document Delivery No.: YB269Times Cited: 77Cited Reference Count: 28}, month = {Oct-Nov}, pages = {797-803}, type = {Article}, abstract = {The arsenic species present in a range of commercially available dried-algal food products were characterized by HPLC-ICP-MS, The products of marine origin contain up to four dimethylarsinylribosides (1) in the 8-49 ppm range and some also contain dimethylarsinic acid (DMAA). These species are easily extracted and account for most of the arsenic burden. One sample of a freshwater alga Nostoc sp, was found to contain a lower concentration of arsenic, 3 ppm, and only 34\% of this was extractable, The extract representing 1 ppm of arsenic contained one of the arsenosugars 1 found in the marine samples (93\%), the rest being DMAA, This is the first report of the identification of an arsenosugar from an organism of terrestrial origin, The implications of this result in connection with the global arsenic cycle are discussed. (C) 1997 John Wiley \& Sons, Ltd.}, keywords = {(ICP-MS), ACID, ALGAE, arsenic, ARSENIC-CONTAINING RIBOFURANOSIDES, arsenobetaine, arsenosugar, ATOMIC-ABSORPTION SPECTROMETRY, chromatography (HPLC), high-performance liquid, IDENTIFICATION, inductively coupled plasma-mass spectrometry, SEAWEED, SPECIATION}, isbn = {0268-2605}, url = {://A1997YB26900005}, author = {Lai, V. W. M. and Cullen, W. R. and Harrington, C. F. and Reimer, K. J.} } @article {3927, title = {Tripodal aminophenolate ligand complexes of aluminum(III), gallium(III), and indium(III) in water}, journal = {Inorganic Chemistry}, volume = {36}, number = {2}, year = {1997}, note = {ISI Document Delivery No.: WC887Times Cited: 34Cited Reference Count: 53}, month = {Jan}, pages = {236-248}, type = {Article}, abstract = {Four water-soluble amine phenols have been prepared: tris(((2-hydroxy-5-sulfobenzyl)amino)ethyl)amine (H(6)TRNS), 1,1,1-tris(((2-hydroxy-5-sulfobenzyl)amino)methyl)ethane (H(6)TAMS), 1,2,3-tris((2-hydroxy-5-sulfobenzyl)amino)propane (H(6)TAPS), and cis,cis-1,3,5-tris((2-hydroxy-5-sulfobenzyl)amino)cyclohexane (H(6)TACS). Complex formation constants have been measured at 25 degrees C (mu = 0.16 M NaCl): log K [M(TRNS)](3-) ([M(HTRNS)](2-)) M = Ga 28.55 (36.90), In 29.3 (34.9); log K [M(TAMS)](3-) ([M(HTAMS)](2-)) M = Al 22.5 (29.3), Ga 31.53, In 28.49; log K [M(TAPS)](3-) ([M(HTAPS)](2-)) M = Al 22.8 (29.0), Ga 31.54 (35.15), In 27.56 (31.93). The order of stability is Ga(III) > In(III) > Al(III) for H(6)TAMS and H(6)TAPS, while far H(6)TRNS it is Ga(III) approximate to In(lII) > Al(III). The solution structures of the complexes have been probed by multinuclear NMR (H-1, C-13, Al-27, Ga-71, In-115) and UV spectroscopic studies, and these solution structures are compared with solid state structures for analogous complexes. The H-1 NMR spectrum in D2O establishes TAPS to be preorganized for metal ion binding. H(6)TACS exists in the wrong conformation for metal ion binding, and this results in slow complexation kinetics and relatively weaker binding.}, keywords = {ACID, BINDING, EQUILIBRIUM-CONSTANTS, GA(III), HUMAN-SERUM TRANSFERRIN, IN(III), IN-VIVO, METAL-IONS, SCHIFF-BASE LIGANDS, STABILITIES}, isbn = {0020-1669}, url = {://A1997WC88700021}, author = {Caravan, P. and Orvig, Chris} } @article {3805, title = {Enzymatic formation and release of a stable glycal intermediate: The mechanism of the reaction catalyzed by UDP-N-acetylglucosamine 2-epimerase}, journal = {Journal of the American Chemical Society}, volume = {118}, number = {12}, year = {1996}, note = {ISI Document Delivery No.: UC380Times Cited: 19Cited Reference Count: 25}, month = {Mar}, pages = {3033-3034}, type = {Article}, keywords = {ACID, BACTERIOPHAGE-N4 ADSORPTION, biosynthesis, enterobacterial common antigen, ESCHERICHIA-COLI, MUTANTS, POSITIONAL ISOTOPE EXCHANGE, SEQUENCE}, isbn = {0002-7863}, url = {://A1996UC38000035}, author = {Sala, R. F. and Morgan, P. M. and Tanner, M. E.} } @article {3750, title = {Highly symmetric group 13 metal-phosphinato complexes: Multinuclear NMR (Al-27, P-31, Ga-71) determination of stability constants at low pH}, journal = {Journal of the American Chemical Society}, volume = {118}, number = {43}, year = {1996}, note = {ISI Document Delivery No.: VQ089Times Cited: 12Cited Reference Count: 56}, month = {Oct}, pages = {10446-10456}, type = {Article}, abstract = {{An N4O3 tripodal tren-based (aminomethylene)phosphinato ligand tris(4-(phenylphosphinato)-3-methyl-3-azabutyl)amine (H(3)ppma) has been synthesized, and its complexation properties with the group 13 metals Al, Ga. and In have been investigated. The molecular structure of the indium complex [In(H(3)ppma)(2)](NO3)(3) . 3H(2)O (C60H96InN11O24P6) has been solved by X-ray methods; the complex crystallizes in the trigonal space group R(3) over barc$, with a = 18.984(3) Angstrom}, keywords = {ACID, AL(III), aluminum, AMINE PHENOL LIGANDS, AQUEOUS-SOLUTION, COMPLEXES, gallium, IONS, LANTHANIDE(III), NUCLEAR-MAGNETIC-RESONANCE, PHOSPHONODIPEPTIDES}, isbn = {0002-7863}, url = {://A1996VQ08900015}, author = {Lowe, M. P. and Rettig, S. J. and Orvig, Chris} } @article {3855, title = {Selectivity of potentially hexadentate amine phenols for Ga3+ and In3+ in aqueous solution}, journal = {Inorganic Chemistry}, volume = {35}, number = {3}, year = {1996}, note = {ISI Document Delivery No.: TT717Times Cited: 29Cited Reference Count: 48}, month = {Jan}, pages = {715-724}, type = {Article}, abstract = {{A new series of linear N4O2 amine phenols (H(2)badd, H(2)Brbadd, and H(2)Clbadd) based on N,N{\textquoteright}-bis(3-aminopropyl)-ethylenediamine (tnentn) were prepared and characterized by spectroscopic techniques. Monocationic hexadentate metal complexes with the tnentn-based amine phenols were obtained from the reactions of Ga3+ and In3+ with the Linear amine phenol in the presence of a weak base (acetate). The molecular structure of [Ga(Brbadd)]ClO4 has been determined by X-ray crystallography; crystals of [Ga(Brbadd)][ClO4] (C22H30Br2ClGaN4O6) are orthorhombic: a = 12.462(1) Angstrom}, keywords = {ACID, aluminum, CHELATION, CRYSTAL, GA-68, gallium, IONS, LIGANDS, STABILITIES, TRIVALENT METAL-COMPLEXES}, isbn = {0020-1669}, url = {://A1996TT71700029}, author = {Wong, E. and Caravan, P. and Liu, S. and Rettig, S. J. and Orvig, Chris} } @article {3798, title = {Triplet-triplet energy transfer between organic molecules trapped in zeolites}, journal = {Chemical Communications}, number = {17}, year = {1996}, note = {ISI Document Delivery No.: VG303Times Cited: 7Cited Reference Count: 20}, month = {Sep}, pages = {2049-2050}, type = {Article}, abstract = {Double loading of a zeolite with a triplet energy donor and a triplet energy acceptor followed by selective irradiation into the donor absorption band leads to characteristic triplet state reactivity of the acceptor.}, keywords = {ACID, DIFFUSION, probes}, isbn = {1359-7345}, url = {://A1996VG30300026}, author = {Pitchumani, K. and Gamlin, J. N. and Ramamurthy, V. and Scheffer, J. R.} } @article {3148, title = {A CONVENIENT PROCEDURE FOR THE EFFICIENT PREPARATION OF ALKYL (Z)-3-IODO-2-ALKENOATES}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {72}, number = {8}, year = {1994}, note = {ISI Document Delivery No.: PE254Times Cited: 53Cited Reference Count: 29}, month = {Aug}, pages = {1816-1819}, type = {Article}, abstract = {Reaction of alkyl 2-alkynoates with sodium iodide (1.6-5.5 equiv.) in acetic acid (6.2-13 equiv.) at 115 degrees C provides good to excellent yields of the corresponding alkyl (Z)-3-iodo-2-alkenoates.}, keywords = {ACID, ALLYLIC ALCOHOLS, DERIVATIVES, PROPIOLIC, STEREOSPECIFIC HYDROHALOGENATION REACTION}, isbn = {0008-4042}, url = {://A1994PE25400009}, author = {Piers, E. and Wong, T. and Coish, P. D. and Rogers, C.} } @article {3060, title = {DESIGN AND SYNTHESIS OF ANALOGS OF IONOMYCIN}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {72}, number = {6}, year = {1994}, note = {ISI Document Delivery No.: NV309Times Cited: 7Cited Reference Count: 34}, month = {Jun}, pages = {1500-1511}, type = {Article}, abstract = {Based on the analysis of the crystal structure of the Ca2+ salt of ionomycin and the chemical and physical data on ionomycin, a number of ionomycin analogues have been synthesized to study the structural features affecting the Ca2+ binding and transport. Compounds 2, 3, and 4 were synthesized to study the effect of additional intramolecular oxygen coordination sites on Ca2+ transport. Compounds 5a-5d were prepared to study the effect of lipid solubility on Ca2+ binding and transport. Compounds 6a-6c were prepared to study the effect of the distance between the P-diketone and the carboxyl group on Ca2+ transport. A general synthetic route to these compounds has been developed. The key reactions in this route are the consecutive regioselective alkylations of the dianion of 2,4-pentanedione with the appropriate bromides.}, keywords = {ACID, HOST-GUEST COMPLEXATION, IONOPHORE, RESOLUTION}, isbn = {0008-4042}, url = {://A1994NV30900010}, author = {Hu, Thomas Q. and Weiler, L.} } @article {3068, title = {DETERMINATION OF THE SPECTROSCOPIC CONSTANTS OF A DARK VIBRATIONAL-STATE - FERMI AND CORIOLIS PERTURBATIONS IN THE NU-2 BAND OF FORMYL CHLORIDE}, journal = {Journal of Chemical Physics}, volume = {101}, number = {1}, year = {1994}, note = {ISI Document Delivery No.: NT521Times Cited: 20Cited Reference Count: 25}, month = {Jul}, pages = {31-38}, type = {Article}, abstract = {The nu(2) infrared fundamental of the transient molecule formyl chloride, HCOCl, has been recorded at high resolution. Detailed assignments of the rotational structure have been made for both HCO Cl-35 and (HCOCl)-Cl-37. The nu(2) band, whose origin is at 1784.1377 cm(-1) in (HCOCl)-Cl-35, is predominantly A type with a very weak B-type component. Numerous excited state perturbations occur throughout the band, caused mainly by Δ K-a\=2 Fermi resonance and Δ K-a\=1 Coriolis interactions with the 3(1)5(1) vibrational state. Even though no {\textquoteright}{\textquoteright}extra{\textquoteright}{\textquoteright} lines resulting from the perturbations could be assigned, a complete analysis of the perturbed rotational structure has been possible. Accurate molecular constants for both the {\textquoteright}{\textquoteright}bright{\textquoteright}{\textquoteright} perturbed 2(1) state and the {\textquoteright}{\textquoteright}dark{\textquoteright}{\textquoteright} 3(1)5(1) perturbing state have been obtained, using a Hamiltonian which includes both the Fermi and Coriolis interactions; only two interaction parameters are needed, one for each mechanism. Further perturbations at high K-a are assigned to Coriolis interactions with the 5(2)6(1) level.}, keywords = {ACID, CL ATOM, FORMALDEHYDE, FTIR, INFRARED-SPECTRUM, MICROWAVE-SPECTRUM, OH, OXIDATION}, isbn = {0021-9606}, url = {://A1994NT52100005}, author = {Joo, D. L. and Clouthier, D. J. and Merer, A. J.} } @article {3145, title = {A NEW CYCLOPENTENONE ANNULATION METHOD}, journal = {Tetrahedron Letters}, volume = {35}, number = {46}, year = {1994}, note = {ISI Document Delivery No.: PT047Times Cited: 10Cited Reference Count: 24}, month = {Nov}, pages = {8573-8576}, type = {Article}, abstract = {Alkylation of the substrates 8-12 with (Z)-3-bromo-1-iodopropene (5), followed by n-Buli-mediated cyclization of the resultant products 15-19, provides the tertiary allylic alcohols 22-26, which, upon oxidation with a Cr(VI) reagent, afford the cyclopentenones 29-33. The alpha-methylcyclopentenones 34 and 35 are similarly derived from the kero esters 13 and 14.}, keywords = {ACID, ALCOHOLS}, isbn = {0040-4039}, url = {://A1994PT04700016}, author = {Piers, E. and Cook, K. L. and Rogers, C.} } @article {3107, title = {PREPARATION OF 2-SUBSTITUTED AND 4-SUBSTITUTED 3-HYDROXY-5-METHYLFURANS AND THE ALUMINUM AND GALLIUM COMPLEXES OF 3-HYDROXY-5-METHYL-2-(N-METHYLFORMAMIDO)FURAN}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {72}, number = {5}, year = {1994}, note = {ISI Document Delivery No.: NU280Times Cited: 3Cited Reference Count: 40}, month = {May}, pages = {1362-1369}, type = {Article}, abstract = {In model studies designed to study the synthesis of potentially hexadentate chelates based on the linkage of three furan rings to a triamine via amide linkages, new 2- and 1-substituted 3-hydroxy-5-methylfurans have been prepared. Particularly, 3-hydroxy-5-methyl-(N-methylformamido)fur (Hahm) and its Al and Ga complexes (M(ahm)(3)) have been prepared and thoroughly characterized by a variety of techniques, in the solid state and in solution. Solution equilibrium studies (mu = 0.6 M NaCl, 25 degrees C) uncovered a complicated set of equilibria in the Al3+/Hahm system; the solution potentiometric data were best explained by the presence of mixed ligand (HL = Hahm, L(-) = ahm(-)) hydroxo species [Al-3(OH)(4)L(3)](2+) and [AI(OH)(2)L(2)](-), in addition to the expected [AlL(n)]((3-n)+) (n = 1, 2, 3) species. Further solution studies at HL:M ratios of 3:1 (mu = 0.15 M NaCl, 25 degrees C) showed that Hahm is a relatively weak complexing agent for both Al and Ga, forming tris-ligand species with overall formation constants of 10(19.5) and 10(20.6), respectively.}, keywords = {0.6 M NA(CL), 3-HYDROXY-4-PYRIDINONES, ACID, AQUEOUS-SOLUTION, EQUILIBRIUM, HYDROLYSIS, indium, SILICON(IV)}, isbn = {0008-4042}, url = {://A1994NU28000020}, author = {Lutz, T. G. and Clevette, D. J. and Hoveyda, H. R. and Karunaratne, V. and Nordin, A. and Sjoberg, S. and Winter, M. and Orvig, Chris} } @article {3175, title = {THE SYNTHESIS AND STABILITY OF AZIRIDINO-GLUTAMATE, AN IRREVERSIBLE INHIBITOR OF GLUTAMATE RACEMASE}, journal = {Tetrahedron Letters}, volume = {35}, number = {24}, year = {1994}, note = {ISI Document Delivery No.: NR716Times Cited: 37Cited Reference Count: 17}, month = {Jun}, pages = {4073-4076}, type = {Article}, abstract = {Aziridino-glutamate (2-(2-carboxyethyl)aziridine-2-carboxylic acid, (+/-)4) was synthesized by heating alpha-fluoromethylglutamate in base. In neutral solution, 4 was shown to cyclize to the gamma-lactone 5 with a half life of 4 minutes. Aziridino-glutamate was shown to irreversibly inactivate glutamate racemase by alkylating an active site cysteine residue, Electrospray mass spectrometry was used to establish that a covalent bond had famed and that this bond protects one of the enzyme{\textquoteright}s two cysteine residues from reacting with iodoacetate under denaturing conditions.}, keywords = {ACID, EPIMERASE, ESCHERICHIA-COLI, MECHANISM, PEDIOCOCCUS-PENTOSACEUS}, isbn = {0040-4039}, url = {://A1994NR71600007}, author = {Tanner, M. E. and Miao, S. C.} } @article {3034, title = {THE SYNTHESIS OF ANTHRAPHOS, A CONFORMATIONALLY RIGID, C-2-SYMMETRICAL DIPHOSPHINE AND THE X-RAY CRYSTAL-STRUCTURE OF [RH(COD)(ANTHRAPHOS)]BF4}, journal = {Tetrahedron Letters}, volume = {35}, number = {41}, year = {1994}, note = {ISI Document Delivery No.: PL496Times Cited: 7Cited Reference Count: 18}, month = {Oct}, pages = {7593-7596}, type = {Article}, abstract = {Anthraphos (trans-9,10-dihydro-9,10-ethanoanthracene-11,12-bis(diphenylphosphine) (3), a conformationally rigid, C-2-symmetric diphosphine, has been prepared in three steps, the key step being the Diets-Alder reaction between anthracene and ethyndiylbis(diphenylphosphine oxide). Resolution of anthraphos followed by formation of the [Rh(COD)(anthraphos)]BF4 complex afforded an optically active hydrogenation catalyst precursor whose crystal and molecular structure and absolute configuration were determined by single crystal X-ray diffractometry. Use of the (R,R)-(-) form of the catalyst precursor to hydrogenate (Z)-alpha-acetamidocinnamic acid gave (S)-(+)-N-acetylphenylalanine in 90\% enantiomeric excess.}, keywords = {ACID, ASYMMETRIC-SYNTHESIS, COMPLEXES, HYDROGENATION, LIGANDS, NORPHOS}, isbn = {0040-4039}, url = {://A1994PL49600027}, author = {Fu, T. Y. and Liu, Z. Q. and Scheffer, J. R. and Trotter, J.} } @article {3034, title = {THE SYNTHESIS OF ANTHRAPHOS, A CONFORMATIONALLY RIGID, C-2-SYMMETRICAL DIPHOSPHINE AND THE X-RAY CRYSTAL-STRUCTURE OF [RH(COD)(ANTHRAPHOS)]BF4}, journal = {Tetrahedron Letters}, volume = {35}, number = {41}, year = {1994}, note = {ISI Document Delivery No.: PL496Times Cited: 7Cited Reference Count: 18}, month = {Oct}, pages = {7593-7596}, type = {Article}, abstract = {Anthraphos (trans-9,10-dihydro-9,10-ethanoanthracene-11,12-bis(diphenylphosphine) (3), a conformationally rigid, C-2-symmetric diphosphine, has been prepared in three steps, the key step being the Diets-Alder reaction between anthracene and ethyndiylbis(diphenylphosphine oxide). Resolution of anthraphos followed by formation of the [Rh(COD)(anthraphos)]BF4 complex afforded an optically active hydrogenation catalyst precursor whose crystal and molecular structure and absolute configuration were determined by single crystal X-ray diffractometry. Use of the (R,R)-(-) form of the catalyst precursor to hydrogenate (Z)-alpha-acetamidocinnamic acid gave (S)-(+)-N-acetylphenylalanine in 90\% enantiomeric excess.}, keywords = {ACID, ASYMMETRIC-SYNTHESIS, COMPLEXES, HYDROGENATION, LIGANDS, NORPHOS}, isbn = {0040-4039}, url = {://A1994PL49600027}, author = {Fu, T. Y. and Liu, Z. Q. and Scheffer, J. R. and Trotter, J.} } @article {2829, title = {COORDINATION CHEMISTRY OF 2-(2{\textquoteright}-HYDROXYPHENYL)-2-BENZOXAZOLE WITH GALLIUM(III) AND ALUMINUM(III) - 2 UNCOMMON GROUP-13 METAL ENVIRONMENTS STABILIZED BY A BIOLOGICALLY RELEVANT BINDING GROUP}, journal = {Inorganic Chemistry}, volume = {32}, number = {22}, year = {1993}, note = {ISI Document Delivery No.: ME779Times Cited: 28Cited Reference Count: 36}, month = {Oct}, pages = {4909-4913}, type = {Article}, abstract = {{The coordination chemistry of Ga(III) and Al(III) with 2-(2{\textquoteright}-hydroxyphenyl)-2-benzoxazole (Hhbo) was investigated both in the solid state (X-ray crystallography) and in solution (H-1, C-13, Al-27 N MR) These two group 13 metal ions exhibit different reactivities toward this bulky bidentate ligand leading with Ga(III) to the formation of Ga(hbo)3 (1) and [Ga(hbo)2(0,0{\textquoteright}-CH3CO2)] (2) complexes depending on the reaction conditions. With AI(III), the only complex formed is[Al(mu-OH)(hbo)2]2(3). The Ga bis(ligand) acetate complex 2 (C28H19GaN2O6) crystallizes in the monoclinic space group C2/c with a = 16.008(3) angstrom}, keywords = {ACID, AQUEOUS-SOLUTION, COMPLEXES, EQUILIBRIUM, HYDROLYSIS, PERSPECTIVE, PROTEINS, RIBONUCLEOTIDE REDUCTASE, SILICON(IV), SPECIATION}, isbn = {0020-1669}, url = {://A1993ME77900041}, author = {Hoveyda, H. R. and Rettig, S. J. and Orvig, Chris} } @article {7386, title = {INTERCALATION CHEMISTRY OF GRAPHITE FLUORIDES}, journal = {Journal of Fluorine Chemistry}, volume = {57}, number = {1-3}, year = {1992}, note = {ISI Document Delivery No.: JM833Times Cited: 1Cited Reference Count: 38}, month = {Apr-Jun}, pages = {53-63}, type = {Article}, abstract = {Graphite fluorides of the general composition CF(n), with n = 0.25-1.0, are found, according to X-ray diffraction and X-ray photoelectron studies, to contain graphitic zones which allow oxidative intercalation by bis(fluorosulfuryl)peroxide, S2O6F2, as well as intercalation by fluorosulfuric acid HSO3F and trifluoromethylsulfuric acid HSO3CF3. The reactions produce materials of the general composition CFn(SO3F)m or CFn(HSO3X)m, with X = F or CF3. While intercalation of S2O6F2 into the graphitic zones results in the formation of first-stage intercalation products in all instances, higher-stage materials form with HSO3F and to an increased degree with HSO3CF3, particularly when graphite fluorides with low fluorine contents are used. Interestingly, according to their X-ray photoelectron spectra, intercalation of all three reagents causes an increase in the polarity of the C-F bond; the oxidized graphitic zones appear to increase while the fluorine 1s binding energies suggest an increased ionic character.}, keywords = {ACID}, isbn = {0022-1139}, url = {://A1992JM83300007}, author = {Xia, J. and Aubke, F.} } @article {7322, title = {REACTIONS OF LIGNIN MODEL COMPOUNDS WITH PULP BLEACHING CHEMICALS - CANNIZZARO-TYPE REACTION OF TETRACHLORO-ORTHO-BENZOQUINONE WITH ALKALI}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {70}, number = {6}, year = {1992}, note = {ISI Document Delivery No.: JR097Times Cited: 1Cited Reference Count: 11}, month = {Jun}, pages = {1706-1710}, type = {Article}, abstract = {{Reaction of tetrachloro-o-benzoquinone 1 with aqueous sodium hydroxide resulted in a Cannizzaro-type disproportionation into tetrachloromuconic acid and tetrachlorocatechol. The tetrachloromuconic acid was isolated and identified by X-ray crystallography as the methyl ester of the cyclized lactone 3. Crystals of C7H3Cl3O4, 4, are orthorhombic}, keywords = {ACID, CATECHOL}, isbn = {0008-4042}, url = {://A1992JR09700021}, author = {McKague, A. B. and Reeve, D. W. and Rettig, S. J. and Trotter, J.} } @article {7313, title = {SYNTHESIS AND CHARACTERIZATION OF LANTHANIDE [LN(L)]2 COMPLEXES OF N4O3 AMINE PHENOL LIGANDS WITH PHENOLATE OXYGEN BRIDGES - EVIDENCE FOR VERY WEAK MAGNETIC EXCHANGE BETWEEN LANTHANIDE IONS}, journal = {Journal of the American Chemical Society}, volume = {114}, number = {15}, year = {1992}, note = {ISI Document Delivery No.: JE225Times Cited: 152Cited Reference Count: 37}, month = {Jul}, pages = {6081-6087}, type = {Article}, abstract = {{The synthesis and characterization of three potentially heptadentate (N4O3) amine phenols and of a series of their mononuclear and dinuclear lanthanide complexes are reported. The heptadentate ligands are KBH4 reduction products of the Schiff bases derived from the condensation reactions of tris(2-aminoethyl)amine with 3 equiv of one of salicylaldebyde (tris(((2-hydroxybenzyl)amino)ethyl)amine (H3L1)), 5-chlorosalicylaldehyde (tris(((2-hydroxy-5-chlorobenzyl)amino)ethyl)amine (H3L2)), and 5-bromosalicylaldehyde (tris(((2-hydroxy-5-bromobenzyl)amino)ethyl)amine (H3L3)). The reaction of an amine phenol with 1 equiv of a lanthanide (Ln) nitrate produces the mononuclear complex [Ln(H3L)(NO3)3]; homodinuclear complexes [Ln(L)]2 were obtained from the reaction of lanthanide salts with the respective ligand in the presence of a base (hydroxide or acetate). The X-ray structure of [Gd(L1)]2.2CHCl3 (H3L1 = tris(((2-hydroxybenzyl)amino)ethyl)amine) has been determined; it is the first structurally characterized example of an [Ln(L)]2 complex, a homodinuclear eight-coordinate lanthanide complex [Ln(L)]2 with heptadentate ligands only. The complex crystallizes as a chloroform solvate in the triclinic space group P1BAR with a = 12.002 (2) angstrom}, keywords = {ACID, CHEMISTRY, COORDINATION, CRYSTAL-STRUCTURES, MOLECULAR-STRUCTURE, SCHIFF-BASE LIGANDS, TETRAHYDRATE}, isbn = {0002-7863}, url = {://A1992JE22500028}, author = {Liu, S. and Gelmini, L. and Rettig, S. J. and Thompson, R. C. and Orvig, Chris} } @article {7313, title = {SYNTHESIS AND CHARACTERIZATION OF LANTHANIDE [LN(L)]2 COMPLEXES OF N4O3 AMINE PHENOL LIGANDS WITH PHENOLATE OXYGEN BRIDGES - EVIDENCE FOR VERY WEAK MAGNETIC EXCHANGE BETWEEN LANTHANIDE IONS}, journal = {Journal of the American Chemical Society}, volume = {114}, number = {15}, year = {1992}, note = {ISI Document Delivery No.: JE225Times Cited: 152Cited Reference Count: 37}, month = {Jul}, pages = {6081-6087}, type = {Article}, abstract = {{The synthesis and characterization of three potentially heptadentate (N4O3) amine phenols and of a series of their mononuclear and dinuclear lanthanide complexes are reported. The heptadentate ligands are KBH4 reduction products of the Schiff bases derived from the condensation reactions of tris(2-aminoethyl)amine with 3 equiv of one of salicylaldebyde (tris(((2-hydroxybenzyl)amino)ethyl)amine (H3L1)), 5-chlorosalicylaldehyde (tris(((2-hydroxy-5-chlorobenzyl)amino)ethyl)amine (H3L2)), and 5-bromosalicylaldehyde (tris(((2-hydroxy-5-bromobenzyl)amino)ethyl)amine (H3L3)). The reaction of an amine phenol with 1 equiv of a lanthanide (Ln) nitrate produces the mononuclear complex [Ln(H3L)(NO3)3]; homodinuclear complexes [Ln(L)]2 were obtained from the reaction of lanthanide salts with the respective ligand in the presence of a base (hydroxide or acetate). The X-ray structure of [Gd(L1)]2.2CHCl3 (H3L1 = tris(((2-hydroxybenzyl)amino)ethyl)amine) has been determined; it is the first structurally characterized example of an [Ln(L)]2 complex, a homodinuclear eight-coordinate lanthanide complex [Ln(L)]2 with heptadentate ligands only. The complex crystallizes as a chloroform solvate in the triclinic space group P1BAR with a = 12.002 (2) angstrom}, keywords = {ACID, CHEMISTRY, COORDINATION, CRYSTAL-STRUCTURES, MOLECULAR-STRUCTURE, SCHIFF-BASE LIGANDS, TETRAHYDRATE}, isbn = {0002-7863}, url = {://A1992JE22500028}, author = {Liu, S. and Gelmini, L. and Rettig, S. J. and Thompson, R. C. and Orvig, Chris} } @article {7064, title = {LASER-DESORPTION-IONIZATION FOURIER-TRANSFORM ION-CYCLOTRON-RESONANCE (LDI-FT-ICR) MASS-SPECTROMETRY (MS) OF BACTERIAL OLIGOSACCHARIDES}, journal = {Biochemical Society Transactions}, volume = {19}, number = {4}, year = {1991}, note = {ISI Document Delivery No.: GV019Times Cited: 2Cited Reference Count: 21639TH MEETING OF THE BIOCHEMICAL SOCJUL 16-19, 1991MANCHESTER, ENGLANDBIOCHEM SOC}, month = {Nov}, pages = {922-929}, type = {Proceedings Paper}, keywords = {ACID, CAPSULAR POLYSACCHARIDE}, isbn = {0300-5127}, url = {://A1991GV01900029}, author = {Lam, Z. and Beynon, L. and Comisarow, M. B. and Dutton, G. G. S. and Bjarnason, A.} }