Filters
Results 1 - 10 of 3025
Results 1 - 10 of 3025.
Search took: 0.027 seconds
Sort by: date | relevance |
Microwave-assisted synthesis of arylperazine derivatives for neurotransmitter receptor imaging agent
Gwon, Hui Jeong; Park, Sang Hyun
Proceedings of international symposium on research reactor and neutron science2005
Proceedings of international symposium on research reactor and neutron science2005
AbstractAbstract
[en] An arylpiperazine, WAY100635, has been found as a highly selective ligand for imaging 5-HT1A receptor among other serotonergic receptors. We have established an efficient method for the synthesis of the arylpiperazine derivatives in which the acylation of 2-aminopyridine, the coupling reaction of the acyl compound with piperazines, and reduction of the arylpiperazines were performed under microwave irradiation (300 W) to afford the corresponding target compounds in quantitative yields. The synthesis time of the acylation, the coupling reaction and the reduction was remarkably reduced compared with that of the conventional method
Primary Subject
Source
The Korean Nuclear Society, Taejon (Korea, Republic of); Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); 922 p; 2005; p. 164-167; International symposium on research reactor and neutron science; Taejon (Korea, Republic of); 11-13 Apr 2005; Available from Korean Nuclear Society, Taejon (KR); 5 refs, 2 figs
Record Type
Miscellaneous
Literature Type
Conference
Country of publication
Reference NumberReference Number
Related RecordRelated Record
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] β-CD and CM-β-CD as chiral NMR shift agents were used to resolve the enantiomers of noradrenaline (NA). The stoichiometry of each complex formed between the CDs and the enantiomers of NA was found to be 1 : 1 through the continuous variation plots. The binding constants (K) of the complexes were determined from 1H NMR titration curves. This result indicated that both β-CD and CM-β-CD formed the complexes with the S (+)-NA more preferentially than its R(.)-enantiomer. The K values for the complexes with β-CD (KS(+) = 537 M-1 and KR(-) = 516 M-1) was larger than those with CM-β-CD (KS(+) = 435 M-1 and KR(-) = 313 M-1), however, enantioselectivity (α) of S(+)- and R(-)-NA to CM-β-CD (α = 1.38) was larger than that to β-CD (α = 1.04), indicating that CM-β-CD was the better chiral NMR solvating agents for the recognition of the enantiomers of NA. Two dimensional rotating frame nuclear Overhauser enhancement spectroscopy (ROESY) experiments were also performed to explain the binding properties in terms of spatial fitting of the NA molecule into the macrocyclic cavities
Primary Subject
Source
28 refs, 7 figs, 2 tabs
Record Type
Journal Article
Journal
Bulletin of the Korean Chemical Society; ISSN 0253-2964;
; v. 25(2); p. 216-220

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] In the preceding article, we have introduced a new chiral oxazolidin-2-one auxiliary (1) derived from a cheap Dmannitol, and demonstrated the chiral selectivity in alkylation, aldol reaction and β-lactam synthesis.1 The present work began with a search for useful chiral directing groups with which to control the chiral selectivity. Because the rigidity of cyclic structures contributes significantly to control of chirality,2 the 1,2:5,6-di-O-cyclohexylidene-Dmannitol (2) was used for the synthesis of oxazolidin-2-one chiral auxiliary (3) comparing the selectivity with the auxiliary (1) in alkylation and aldol reactions.
Primary Subject
Source
12 refs, 2 figs, 2 tabs
Record Type
Journal Article
Journal
Bulletin of the Korean Chemical Society; ISSN 0253-2964;
; v. 25(1); p. 143-146

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] Hydrogen bond is an important factor in the structures of carbohydrates. Because of great strength, short range, and strong angular dependence, hydrogen bonding is an important factor stabilizing the structure of carbohydrate. In this study, conformational properties and the hydrogen bonds in GlcNAc(β1,3)Gal(β)OMe in DMSO are investigated through NMR spectroscopy and molecular dynamics simulation. Lowest energy structure in the adiabatic energy map was utilized as an initial structure for the molecular dynamics simulations in DMSO. NOEs, temperature coefficients, SIMPLE NMR data, and molecular dynamics simulations proved that there is a strong intramolecular hydrogen bond between O7' and HO3' in GlcNAc(β1,3)Gal(β)OMe in DMSO. In aqueous solution, water molecule makes intermolecular hydrogen bonds with the disaccharides and there was no intramolecular hydrogen bonds in water. Since DMSO molecule is too big to be inserted deep into GlcNAc(β1,3)Gal(β)OMe, DMSO can not make strong intermolecular hydrogen bonding with carbohydrate and increases the ability of O7' in GlcNAc(β1,3)Gal(β)OMe to participate in intramolecular hydrogen bonding. Molecular dynamics simulation in conjunction with NMR experiments proves to be efficient way to investigate the intramolecular hydrogen bonding existed in carbohydrate
Primary Subject
Source
34 refs, 4 figs, 2 tabs
Record Type
Journal Article
Journal
Bulletin of the Korean Chemical Society; ISSN 0253-2964;
; v. 25(2); p. 198-202

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Pu, Y.; Ragauskas, A.J., E-mail: arthur.ragauskas@chemistry.gatech.edu2005
AbstractAbstract
[en] Lignin was isolated from aspen bleached chemithermomechanical pulp by employing a mild acid hydrolysis procedure, and the extracted material was acetylated with acetic anhydride. Nuclear magnetic resonance analyses indicated that the relative ease of acetylating lignin hydroxyl groups was phenolic >> γ-side chain > α-side chain. Non-acetylated and acetylated lignins were impregnated onto cellulosic test sheets, and the photo-behavior of the lignins was examined under irradiation with two light sources, a fluorescent lamp and a black lamp. Optical reflective studies indicated acetylation efficiently inhibited the photodiscoloration of aspen bleached chemithermomechanical pulp lignin under visible and near-UV light irradiation. The photostability of the lignin was correlated to the extent of lignin acetylation. The observed photo-stabilization of acetylated lignin during light irradiation was attributed to the acetylation of phenoxy and aliphatic hydroxyl groups in lignin. (author)
Primary Subject
Source
51 refs., 1 tab., 9 figs.
Record Type
Journal Article
Journal
Canadian Journal of Chemistry; ISSN 0008-4042;
; v. 83(12); p. 2132-2139

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] NMR spectra of large RNAs are difficult to assign because of extensive spectral overlap and unfavorable relaxation properties. Here we present a new approach to facilitate assignment of RNA spectra using a suite of four 2D-filtered/edited NOESY experiments in combination with base-type-specific isotopically labeled RNA. The filtering method was developed for use in 3D filtered NOESY experiments (Zwahlen et al., 1997), but the 2D versions are both more sensitive and easier to interpret for larger RNAs than their 3D counterparts. These experiments are also useful for identifying intermolecular NOEs in RNA-protein complexes. Applications to NOE assignment of larger RNAs and an RNA-protein complex are presented
Primary Subject
Source
Copyright (c) 2004 Kluwer Academic Publishers; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Journal of Biomolecular NMR; ISSN 0925-2738;
; v. 28(1); p. 59-67

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Guthrie, J.P.; Gallant, R.T.; Jennings, M.C., E-mail: peter.guthrie@uwo.ca2004
AbstractAbstract
[en] We have prepared and characterized new examples of 5-substituted-1-aza-4,6-dioxabicyclo[3.3.0]octanes (bicyclic amide acetals) and examples of the new heterocyclic system, 5-substituted-1-aza-4-oxa-6-thiabicyclo[3.3.0]octanes (bicyclic amide monothioacetals). Detailed analysis of NMR coupling constants and X-ray structure determination for an example of each class of compound established the stereochemistry and conformation of these ring systems. (author)
Primary Subject
Source
24 refs., 6 tabs., 4 figs.
Record Type
Journal Article
Journal
Canadian Journal of Chemistry; ISSN 0008-4042;
; v. 82(2); p. 268-278

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Radu, L.; Gazdaru, D.; Constantinescu, B., E-mail: serbanradu@pcnet.ro2004
AbstractAbstract
[en] The effects produced by fast neutrons (0-100 Gy) on chromatin structure were analyzed by (i) [1H]-NMR spectroscopy, (ii) time resolved spectroscopy, and (iii) fluorescence resonance energy transfer (FRET). Two types of chromatin were tested: (i) a chromatin from a normal tissue (liver of Wistar rats) and (ii) a chromatin from a tumoral tissue (Guerin limphotrope epithelioma, a rat solid tumor). The fast-neutron action on chromatin determines greater values of the [1H]-NMR transverse relaxation time, indicating a more injured structure. Time-resolved fluorescence measurements show that the relative contribution of the excited state lifetime of bound ethidium bromide to chromatin DNA diminishes with increasing irradiation doses. This reflects the damage that occurs in DNA structure: production of single- and double-strand breaks due to sugar and base modifications. By the FRET method, the distance between dansyl chloride and acridine orange coupled at chromatin was determined. This distance increases upon fast-neutron action. The radiosensitivity of the tumor tissue chromatin seems higher than that of the normal tissue chromatin, probably because of its higher (loose) euchromatin/(compact) heterochromatin ratio. As the values of the physical parameters analyzed are specific for a determined dose, the establishment of these parameters may constitute a criterion for the microdosimetry of chromatin radiolesions produced by fast neutrons. (author)
Primary Subject
Source
17 refs., 5 figs.
Record Type
Journal Article
Journal
Canadian Journal of Physiology and Pharmacology; ISSN 0008-4212;
; v. 82(2); p. 79-83

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Silchenko, A.S.; Avilov, S.A.; Antonov, A.S.; Kalinovsky, A.I.; Dmitrenok, P.S.; Kalinin, V.I.; Woodward, C.; Collin, P.D., E-mail: kalininv@piboc.dvo.ru2005
AbstractAbstract
[en] Frondosides A2-4, A2-7, and A2-8 are new monosulfated triterpene glycosides isolated from the sea cucumber Cucumaria frondosa. Their structures have been elucidated on the basis of spectral data (2D NMR and MS). Frondosides A2-7 and A2-8 are isomers and differ from each other only by the position of a double bond in their non-holostane-type aglycones. (author)
Primary Subject
Source
7 refs., 4 tabs.
Record Type
Journal Article
Journal
Canadian Journal of Chemistry; ISSN 0008-4042;
; v. 83(12); p. 2120-2126

Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Kodess, M.I.; Ezhikova, M.A.; Levit, G.L.; Krasnov, V.P.; Olshevskaya, V.A.; Kalinin, V.N.; Charushin, V.N.; Chupakhin, O.N.
Eleventh international conference on boron chemistry. Programme and abstracts2002
Eleventh international conference on boron chemistry. Programme and abstracts2002
AbstractAbstract
No abstract available
Primary Subject
Source
Russian Academy of Sciences, Moscow (Russian Federation); RAS, Division of Chemistry and Material Sciences, Research Council on Organic and Organoelement Chemistry, Moscow (Russian Federation); RAS, A.N. Nesmeyanov Institute of Organoelement Compounds, Moscow (Russian Federation); RAS, N.D. Zelinsky Institute of Organic Chemistry, Moscow (Russian Federation); RAS, N.S. Kurnakov Institute of General and Inorganic Chemistry, Moscow (Russian Federation); RAS, Institute for Physical Chemistry of Ceramics, Moscow (Russian Federation); M.V. Lomonosov Moscow State University, Moscow (Russian Federation); State Scientific-Research Institute of Chemistry and Technology of Organoelement Compounds, Moscow (Russian Federation); VIAM State Research Center, Moscow (Russian Federation); 171 p; 2002; p. 113; 11. international conference on boron chemistry; Moscow (Russian Federation); 28 Jul - 2 Aug 2002
Record Type
Miscellaneous
Literature Type
Conference
Report Number
Country of publication
Reference NumberReference Number
Related RecordRelated Record
INIS VolumeINIS Volume
INIS IssueINIS Issue
1 | 2 | 3 | Next |