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1.
Reaction of 3-methyl-4-nitro-5-alkylisoxazoles with hydroxylamine provides a practical means to interchange the N,O-heteroatoms on the isoxazole core thereby expanding the range of compounds obtainable from 3-methyl-4-nitro-5-styrylisoxazoles. 相似文献
2.
We have investigated the reactivity of 3-methyl-4-nitro-5-styrylisoxazoles with S-nucleophiles. This study revealed that the title compounds were optimal Michael acceptors toward thiols. A procedure was also established to prepare isoxazole-containing sulfides in one-pot and without the use of chromatography. Isoxazole-containing sulfides were converted into the corresponding sulfones in high yield. 相似文献
3.
Dengfeng Cheng Lan Zhang Mingwei Wang Gucai Li Yongxian Wang 《Journal of fluorine chemistry》2007,128(3):196-201
Vasoactive intestinal peptide (VIP) receptors are expressed on various tumor cells in much higher density than somatostatin receptors, which provides the basis for radiolabeling VIP as tumor diagnostic agent. However, fast proteolytic degradation of VIP in vivo limits its clinical application. With the aim to develop and evaluate new ligands for depicting the VIP receptors with positron emission tomography (PET), the structure modified [R8,15,21, L17]-VIP analog was radiolabeled with 18F using two different methods. With the first method, N-4-[18F]fluorobenzoyl-[R8,15,21, L17]-VIP ([18F]FB-[R8,15,21, L17]-VIP 7) was produced in a decay-corrected radiochemical yield (RCY) of 33.6 ± 3%, a specific radioactivity of 255 GBq/μmol (n = 5) within 100 min in four steps. Similarly, N-4-[18F](fluoromethyl)-benzoyl-[R8,15,21, L17]-VIP ([18F]FMB-[R8,15,21, L17]-VIP 8) was synthesized in a RCY of 34.85 ± 5%, a specific radioactivity of 180 GBq/μmol (n = 5) within 60 min in only one step. The two products 7 and 8 were both shown good stability in HSA. Moreover, the low bone uptakes of 7 and 8 in vivo of mice showed good defluorination stability. 相似文献
4.
We report the first synthetic route to prepare 3-methyl-4-nitro-5-(2-alkylethenyl)isoxazoles in high yields and exclusively as E-diastereoisomers. 相似文献
5.
An efficient synthesis of novel isoxazoloepoxides is described. The title compounds were obtained in high yields and without the use of chromatography. 相似文献
6.
S. G. Dzhavakhishvili A. V. Borisov V. M. Nikitchenko S. N. Kovalenko 《Chemistry of Heterocyclic Compounds》2007,43(1):98-105
The cyclization of unsymmetrical 2-mercaptoimidazoles with aliphatic and aromatic ketones has been studied. Using 1H NMR and X-ray analysis it has been shown that 4-R1-1H-2-mercaptoimidazoles undergo selective oxidative cyclization to the corresponding 3-R3-2-R2-6-R1-imidazo[2,1-b][1,3]thiazoles while 6-R4-1H-2-mercaptobenzo[d]imidazoles give a mixture of 6-R4-3-R2-2-R3-benzo[4,5]imidazo[2,1-b][1,3]thiazole and 7-R4-3-R2-2-R3-benzo[4,5]imidazo[2,1-b][1,3]thiazole in the ratio 1: 1.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 115–122, January, 2007. 相似文献
7.
This paper describes an efficient synthesis of fluorobenzyloxoimidazolidinone derivatives. The title compounds 1a, 1b and 1c could be prepared with high diasteromeric purity (>99%) and overall yields of 19%, 48% and 41% in a ten or six-step synthetic procedure, respectively. These compounds are used as precursors for isotopic 18F-labelling. 相似文献
8.
Johannes Ermert Thomas Ludwig René Gail Heinz H. Coenen 《Journal of organometallic chemistry》2007,692(19):4084-4092
Based on the recent availability of no-carrier-added (n.c.a.) 1-bromo-4-[18F]fluorobenzene with high radiochemical yield, the 4-[18F]fluorophenyl compounds of lithium, sodium and magnesium can now also effectively be prepared. Thus, [18F]fluoroarene reagents with a nucleophilic reaction centre are available and suitable among others for the formation of [18F]fluorophenyl compounds with electron donating substituents in the radiosynthesis of 18F-labelled complex organic structures. For these arylation reactions, however, the presence of macroscopic amounts of a haloarene as co-reactant is necessary with all n.c.a. [18F]fluorophenyl metallics. The 18F-fluoroarylation was verified for examples of aryl-carbon, -silicon, -sulphur, and -nitrogen bond formation with radiochemical yields of 20-25% related to the starting radioactivity of [18F]fluoride. 相似文献
9.
《Analytical letters》2012,45(4):413-426
Abstract A radioiodination technique is described which consists of heating Testosterone (T) with Na125I and hydrogen peroxide in acetic acid in sealed vial. The binding capacity of labelled substances was measured after thin layer chromatography of the reaction mixture. One compound was selected for radioimmunoassay on the basis of its binding capacity for anti-T serum. Standard curves utilizing tritiated and radioiodinated T, under identical conditions, were superimposible. Serum hormone concentrations determined by the two tracers were comparable. Accuracy, precision and sensitivity were satisfactory. Mass spectroscopy and nuclear magnetic resonance of the unlabelled iodinated T indicated that iodine is in C-2. 相似文献
10.
V. A. Lopyrev L. I. Larina A. I. Albanov M. S. Sorokin G. V. Dolgushin 《Russian Chemical Bulletin》1996,45(12):2861-2862
Silylotropy in 4-substitutedN-trimethylsilypyrazoles is studied by dynamic1H,13C, and29Si NMR spectroscopy. The catalytic 1,2-migration of a trimethylsilyl group in 4-halo-N-trimethylsilylpyrazoles was detected. Silylotropy inN-trimethylsilylpyrazoles in the presence of halogens of trimethylhalosilanes is believed to proceed through formation ofN,N-bis(trimethylsilyl)pyrazolium salts, the barrier of silylotropy in pyrazoles being markedly reduced.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 3011–3013, December, 1996. 相似文献
11.
A multicomponent synthesis of cyclopropanes is described. The title compounds were obtained in high yields from commercially available materials. 相似文献
12.
Alan G. Osborne 《Monatshefte für Chemie / Chemical Monthly》1988,119(12):1385-1395
Assignments of13C chemical shifts and13C-1H coupling constants are presented for six bipyridine derivatives. Some earlier spectral assignments have been corrected. The spectral parameters of the bipyridines are generally very similar to those of the appropriate simple substituted pyridines. Long range interring coupling constants in these compounds have been discussed.
13C-NMR einiger Bipyridine
Zusammenfassung Es werden die Zuordnungen der13C-Verschiebungen und der13C-1H-Kopplungskonstanten für sechs Bipyridinderivate präsentiert. Dabei wurden einige früher getroffene Zuordnungen korrigiert. Das NMR-Verhalten der Bipyridine ist dem der analog substituierten Pyridine generell sehr ähnlich. Die Long-Range-Kopplungen zwischen den Ringen werden diskutiert.相似文献
13.
The major reaction center in the reaction of 4,4-dialkyl-5-methylene-2-phenyliminothiazolidines with acid chlorides or anhydrides and with arenesulfonyl chlorides is the nitrogen atom at position 3 of the ring.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 12, pp. 2968–2970, December, 1996. 相似文献
14.
Sirirat U. Kokpol Supot V. Hannongbua Jamras P. Limtrakul 《Monatshefte für Chemie / Chemical Monthly》1989,120(6-7):491-499
Summary The influence of Na+ on hydrogen bonds of the OH O and NH O type between an aliphatic amino acid (glycine zwitterion) and water is investigated byab initio calculations with minimal Gaussian basis sets. Distortion of the hydration shell caused by Na+, and interaction energies contributing to the over-all stabilization are discussed.
Der Einfluß von Na+ auf die benachbarten Wasserstoffbindungen in aliphatischen Aminosäuren
Zusammenfassung Der Einfluß von Na+ auf die Wasserstoffbindungen vom OH O- und NH O-Typ in aliphatischen Aminosäuren (Glycin-Zwitterion) und Wasser wurde mittelsab initio Berechnungen mit einem minimalen Gausschen Basissatz untersucht. Die durch Na+-Ionen hervorgerufenen Verzerrungen der Hydratationsschale und die zur Gesamtstabilisierung beitragenden Wechselwir-kungsenergien werden diskutiert.相似文献
15.
P. A. Chugunov N. A. Troitskii K. S. Nosov M. P. Egorov O. M. Nefedov 《Russian Chemical Bulletin》2004,53(10):2327-2329
Element-centered mono- and dianions of alkyl- and arylstannanes were studied by NMR spectroscopy. The 13C and 119Sn NMR chemical shifts for the dianions R2SnLi2 (R = Ph, Et) were measured for the first time.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2229–2231, October, 2004. 相似文献
16.
Mono- and bis(trimethylsilyl) derivatives of N4-Boc-cytosine were synthesized and characterized by 1H NMR. Only the mono(trimethylsilyl)-N4-Boc-cytosine participates in the iodine-mediated nucleosidation of N-Fmoc-O-methylthiomethyl serine benzyl ester to produce the cytosine nucleoamino acid, while the bis(trimethylsilyl) derivative failed to give any product. A tentative mechanistic explanation is proposed. 相似文献
17.
Summary 16H-2,5,8,11,14-Pentaoxacyclopentadecano[2,3-a]phenoxazin-16-one, its 17-bromo analogue and 16-hydroxy-2,5,8,11,14-pentaoxacyclopentadecanophenoxazine were prepared by the reaction of 1,4-quinone of benzo[15]crown-5 or its dibromide with 2-aminophenol. Dehalogenation of the bromophenoxazinone was also investigated.
Synthese von Kronen-Phenoxazin-Derivaten (Kurze Mitt.)
Zusammenfassung 16H-2,5,8,11,14-Pentaoxacyclopentadecano[2,3-a]phenoxazin-16-on, sein Brom-Analog und 16-Hydroxy-pentaoxacyclopentadecanophenoxazin wurden mittels der Reaktion des 1,4-Chinons von Benzo[15]krone-5 oder dessen Dibromid mit 2-Aminophenol hergestellt. Die Dehalogenierung von Bromphenoxazinon wurde ebenfalls untersucht.相似文献
18.
The synthesis of 18-nor-Δ13(17)-androgens and the structurally related 13,17-epoxides is described. The synthetic route involves the cleavage of 17-ketosteroids by an abnormal Beckmann rearrangement, modification of the D-ring cleavage product to obtain an intermediate tricyclic diene and ring closing metathesis of the diene to the 18-nor-Δ13(17)-androgen. (3α,5α)-18-Norandrost-13(17)-en-3-ol and the derivative 13α,17α- and 13β,17β-epoxides were prepared by this route. 相似文献
19.
The one-pot reaction between 2-aminobenzo[d]isothiazol-3-one and alkyl propiolates in presence of triphenylphosphine leads to the corresponding alkyl 4-amino-5-oxobenzo[f][1,4]thiazepine-3-carboxylates. A plausible mechanism of the reaction is proposed and unambiguous evidence for the structures is obtained from a detailed magnetic resonance spectral analysis. 1D and 2D NMR spectra such as COSY, 1H-13C and 1H-15N HSQC and HMBC heteronuclear correlations and an INADEQUATE experiment are reported and discussed. 相似文献
20.
采用高温固相法合成了NaBaPOM4:Tb3+绿色荧光粉, 并研究了材料的发光性质. NaBaPOM4:Tb3+材料呈多峰发射, 发射峰位于437、490、543、587和624 nm, 分别对应Tb3+的5D3→7F4和5D4→7FJ=6, 5, 4, 3跃迁发射, 主峰为543 nm; 监测543 nm发射峰, 所得激发光谱由4f75d1宽带吸收(200-330 nm)和4f-4f 电子吸收(330-400 nm)组成, 主峰为380 nm. 研究了Tb3+掺杂浓度, 电荷补偿剂Li+、Na+、K+和Cl-, 及敏化剂Ce3+对NaBaPOM4:Tb3+材料发射强度的影响. 结果显示: 调节激活剂浓度、添加电荷补偿剂或敏化剂均可以在很大程度上提高材料的发射强度. 相似文献