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排序方式: 共有93条查询结果,搜索用时 46 毫秒
1.
Casey Chun Zhou Eric J. Stoner Kent D. Stewart L. Steven Hollis Edmund D. Matayoshi Gregory M. Brill 《Tetrahedron》2004,60(47):10611-10618
Oritavancin is a semi-synthetic glycopeptide antibiotic which is structurally related to vancomycin. When oritavancin bisphosphate is dried in vacuo with heat, a new compound forms. This new compound is stable only in the solid state and reverts to oritavancin in solution. Highly enriched samples of this compound were obtained by preparative HPLC and the structure of this compound was elucidated by using one and two-dimensional (1H and 13C) NMR spectroscopy in conjunction with computer-assisted molecular modeling. It has been determined that oritavancin adopts a conformation similar to that of vancomycin in solution, while the new compound is the unnatural R-AB-biaryl atropisomer of oritavancin. This is the first observation and isolation of an AB-biaryl atropisomer in an intact member of the vancomycin family of glycopeptide antibiotics. 相似文献
2.
H. D. Hollis Showalter John M. Domagala Joseph P. Sanchez 《Journal of heterocyclic chemistry》1981,18(8):1609-1612
Starting from readily available 1,2-dihydro-6-methyl-2-oxo-3-pyridinecarbonitrile, 1, viable synthetic pathways to a number of C-6 functionalized 1,2-dihydro-2-oxo-3-pyridinecarbonitriles and corresponding acids are presented. Through the utilization of dianion chemistry, the C-6 methyl substituent is selectively functionalized to three different oxidation levels. 相似文献
3.
Back BB Baker MD Ballintijn M Barton DS Becker B Betts RR Bickley AA Bindel R Budzanowski A Busza W Carroll A Decowski MP García E Gburek T George N Gulbrandsen K Gushue S Halliwell C Hamblen J Harrington AS Henderson C Hofman DJ Hollis RS Hołyński R Holzman B Iordanova A Johnson E Kane JL Khan N Kulinich P Kuo CM Lee JW Lin WT Manly S Mignerey AC Noell A Nouicer R Olszewski A Pak R Park IC Pernegger H Reed C Remsberg LP Roland C Roland G Sagerer J Sarin P Sawicki P Sedykh I Skulski W Smith CE 《Physical review letters》2003,91(7):072302
We have measured transverse momentum distributions of charged hadrons produced in d+Au collisions at sqrt[s(NN)]=200 GeV. The spectra were obtained for transverse momenta 0.25
相似文献
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5.
M.J. Hollis 《Optics Communications》1978,25(3):395-398
Measurements are reported of the energy of electrons ejected by multiphoton ionization of N2 and Ar. Electrons with energy > 160 eV were found and the angular distribution using plane polarized light was anisotropic, at least for low electron energies. The data is interpreted in terms of multiphoton ionization followed by acceleration of free electrons by an EM field gradient force. 相似文献
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7.
Anthony D. Sercel Vladimir G. Beylin Mark E. Marlatt Boguslawa Leja H. D. Hollis Showalter Andr Michel 《Journal of heterocyclic chemistry》2006,43(6):1597-1604
Short, efficient pathways are described for the synthesis of racemic 2‐nitroimidazole radiation sensitizer RB‐6145 ( 2a ) and each of its corresponding (R)‐ and (S)‐enantiomers ( 2b and 2c , respectively). The synthesis of each enantiomer commences with the appropriate chiral epichlorohydrin and utilizes a novel application of 3‐trimethylsilyl‐2‐oxazolidinone ( 3b ) as a mild, safe surrogate for highly toxic aziridine. The synthesis of the (R)‐enantiomer ( 2b ) has been successfully scaled up to provide multi‐kilo quantities of material for early stage preclinical evaluation. 相似文献
8.
Nguyen HN Cee VJ Deak HL Du B Faber KP Gunaydin H Hodous BL Hollis SL Krolikowski PH Olivieri PR Patel VF Romero K Schenkel LB Geuns-Meyer SD 《The Journal of organic chemistry》2012,77(8):3887-3906
Herein we describe a general three-step synthesis of 4-substituted chlorophthalazines in good overall yields. In the key step, N,N-dimethylaminophthalimide (8a) directs the selective monoaddition of alkyl, aryl, and heteroaryl organometallic reagents to afford 3-substituted 3-hydroxyisoindolinones 9b, 9i-9am. Many of these hydroxyisoindolinones are converted to chlorophthalazines 1b-1v via reaction with hydrazine, followed by chlorination with POCl(3). We have also discovered two novel transformations of 3-vinyl- and 3-alkynyl-3-hydroxyisoindolinones. Addition of vinyl organometallic reagents to N,N-dimethylaminophthalimide (8a) provided dihydrobenzoazepinediones 15a-15c via the proposed ring expansion of 3-vinyl-3-hydroxyisoindolinone intermediates. 3-Alkynyl-3-hydroxyisoindolinones react with hydrazine and substituted hydrazines to afford 2-pyrazolyl benzoic acids 16a-16d and 2-pyrazolyl benzohydrazides 17a-17g rather than the expected alkynyl phthalazinones. 相似文献
9.
Computer simulations based on Discrete Element Method have been performed in order to investigate the influence of interparticle interactions on the kinetics of self-assembly and the mechanical strength of nanoparticle aggregates.Three different systems have been considered.In the first system the interaction between particles has been simulated using the JKR (Johnson,Kendall and Roberts) contact theory,while in the second and third systems the interaction between particles has been simulated using van der Waals and electrostatic forces respectively.In order to compare the mechanical behaviour of the three systems,the magnitude of the maximum attractive force between particles has been kept the same in all cases.However,the relationship between force and separation distance differs from case to case and thus,the range of the interparticle force.The results clearly indicate that as the range of the interparticle force increases,the self-assembly process is faster and the work required to produce the mechanical failure of the assemblies increases by more than one order of magnitude. 相似文献
10.