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1.
Bohumil Proksa Richard Hercek Tibor Liptaj Nada Prónayová 《Monatshefte für Chemie / Chemical Monthly》2009,140(5):485-487
Abstract A new compound was isolated from the reaction mixture after O-demethylation of 6-O-acetyl-10α-acetoxycodeine with boron tribromide. The structure of this compound, 10α-hydroxy-β-isomorphine, was elucidated by spectral data, and its spatial arrangement was deduced from an NOE experiment. Capillary zone
electrophoresis was used for separation of morphine and its 10-hydroxy analogues.
Graphical abstract
相似文献
2.
The Diels–Alder reactions of three β-chloro-α,β-unsaturated carbonyl compounds 1–3 with different dienes were carried out to afford highly functionalized cyclohexenes 4–9, bearing quaternary centers, in good yields. These cycloadducts (CAs) undergo dehydrochlorination with subsequent aromatization in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene DBU to produce new substituted benzenes 11–14. Compound 10 is the product of lactonization and removal of an HCl molecule from compound 7. All products were characterized by NMR, IR, elementary analysis and some of them by MS. Structure assignments of isomers were carried out on the basis of NMR chemical shifts and coupling constants using 1D, 2D and heteronOe NMR techniques. 相似文献
3.
Flávio José L. dos Santos Antônio Flávio de C. Alcântara Dalton L. Ferreira-Alves Dorila Piló-Veloso 《Structural chemistry》2008,19(4):625-631
This work describes the synthesis of new derivatives of 6α,7β-dihydroxyvouacapan-17β-oic acid (1) employing the Swern method for the oxidation of C-6 and C-7 of methyl 6α,7β-di-hydroxyvouacapan-17β-oate (2) and the formation of methyl 6,7-dioxovouacapan-17β-oate (3). NMR structural studies associated with theoretical calculations of reaction intermediates and products are also reported.
The mixture of methyl 7β-hydroxy-6-oxovouacapan-17β-oate (4; 21%) and methyl 6α-hydroxy-7-oxovouacapan-17β-oate (5; 79%) was the product from the first step of the oxidation of 2. The lower energy of 5, calculated by HF/6-31G* and DFT/BLYP/6-31G* methods, reinforces the thermodynamic control proposed for the reaction. After
further Swern oxidation of the mixture of 4 and 5, the isomeric form methyl 6-hydroxy-7-oxovouacap-5-en-17β-oate (6) was obtained. Theoretical calculations indicate a lower energy for the mono-enol 6 than the 1,2-diketo 3 and the other mono-enol methyl 7-hydroxy-6-oxovouacap-7-en-17β-oate (7). 相似文献
4.
β-Methoxycarbonyl-γ-butyrolactones bearing a γ-aromatic substituent were prepared via copper-catalyzed reductive aldol addition/lactonization domino reactions of ketones with α,β-unsaturated dicarboxylate esters and a silane under ambient temperature. The reaction has advantage of using readily available reagents, mild conditions and high efficiency. 相似文献
5.
O. A. Luk’yanov G. A. Smirnov P. B. Gordeev 《Russian Journal of Organic Chemistry》2007,43(8):1228-1231
A preparation method was developed for previously unknown tetrazole derivatives containing in the 1, 2, and/or 5 positions of the tetrazole ring N-methyldiazene-N-oxide-N′-oxymethyl groups. 相似文献
6.
7.
Yasunori Matsui Minoru Shigemori Toshiyuki Endo Takuya Ogaki Eisuke Ohta Kazuhiko Mizuno Hiroyoshi Naito Hiroshi Ikeda 《Research on Chemical Intermediates》2018,44(8):4765-4774
The semiconductor properties of the earliest known stable radical, α,γ-bisdiphenylene-β-phenylallyl radical (Koelsch radical, 1?) were assessed using spectroscopic and electrical techniques. This radical undergoes reversible redox processes, and it has low redox potentials. In addition, 1? possesses long wavelength absorption bands, owing to the existence of a singly-occupied molecular orbital whose energy level lies between those of the HOMO and LUMO. A spin-coated thin-film of 1? displays photocurrent and an electron mobility of 6.3 × 10?7 cm2 V?1 s?1 on a trially-fabricated organic field effect transistor. 相似文献
8.
9.
A. A. Shamitov I. K. Garkushin A. V. Kolyado E. P. Petrov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(2):300-303
The n-decane–n-hexadecane–cyclododecane, n-decane–cyclododecane, and n-hexadecane–cyclododecane systems are studied by means of low-temperature differential thermal analysis using a differential scanning heat flow calorimeter. It is noted that all studied systems belong to the eutectic type. It is concluded that in the n-decane–n-hexadecane–cyclododecane system, the eutectic composition contains 85.0 wt % n-С10Н22, 4.0 wt % n-С16Н34, and 11.0 wt % С12Н24. It has a melting point of ?35.0°C. 相似文献
10.
S. N. Gridchin 《Russian Journal of General Chemistry》2016,86(5):1069-1072
Stability constants and heat effects of the formation reactions of magnesium and calcium trimethylenediaminetetraacetates at 298.15 K and ionic strength of 0.1, 0.5, and 1.0 (mol/L KNO3) have been determined by means of potentiometry and calorimetry. Standard thermodynamic parameters (log K0, ΔrG0, ΔrH0, and ΔrS0) of the studied equilibriums have been determined. 相似文献
11.
Yttrium and lanthanum amido-complexes with bis(pyrazol-1-yl)acetates in their coordination spheres were studied as the catalysts in ε-caprolactone and lactide ring-opening polymerisation. A high molecular mass poly(ε-caprolactone) (PCL) was obtained in almost quantitative yield under mild conditions. rac-Lactide polymerisations were less efficient and required quite harsh experimental conditions to obtain atactic PLA samples with moderate yields. The average chain-length of PCL was dependent upon the choice of the metal centre and the presence of substituents on the pyrazole rings of the ancillary ligand. The ground-state geometries of the complexes and the first stages of ε-caprolactone polymerisation were computationally modelled by means of DFT calculations. 相似文献
12.
N. V. Kovganko S. N. Sokolov Yu. G. Chernov Zh. N. Kashkan V. L. Survilo 《Chemistry of Natural Compounds》2010,46(5):750-755
New derivatives of steroidal 6-ketoximes containing α-chloropyridine neonicotinoid groups characteristic of bioactive compounds were synthesized by formation of oximes of cholestane
and stigmastane 3β,5-dihydroxy-6-ketosteroids with O-(2-chloropyridin-5-ylmethyl)hydroxylamine in the presence of zinc or tin(IV) chloride. 相似文献
13.
Background
Since chitin is a highly abundant natural biopolymer, many attempts have been made to convert this insoluble polysaccharide into commercially valuable products using chitinases and β-N-acetylglucosaminidases (GlcNAcases). We have previously reported the structure and function of chitinase A from Vibrio harveyi 650. This study t reports the identification of two GlcNAcases from the same organism and their detailed functional characterization. 相似文献14.
The sodium salt of N-(6-chloronicotinoyl)-γ-aminobutyric acid, a structural analog of the known nootropic and vasidilating drug picamilon, was synthesized via Schotten–Baumann
acylation of γ-aminobutyric acid with 6-chloronicotinoyl chloride and subsequent neutralization of the N-(6-chloronicotinoyl)-γ-aminobutyric acid that was obtained in >60% yield. 相似文献
15.
Bruno Benoliel Marcio José Poças-Fonseca Fernando Araripe Gonçalves Torres Lidia Maria Pepe de Moraes 《Applied biochemistry and biotechnology》2010,160(7):2036-2044
A β-glucosidase gene (bgl4) from Humicola grisea var thermoidea was successfully expressed in Saccharomyces cerevisiae. The recombinant protein (BGL4
Sc
) was initially detected associated with yeast cells and later in the culture medium. BGL4
Sc
showed optimal pH and temperature of 6.0 and 40 °C, respectively, and an apparent molecular mass of 57 kDa. The enzyme showed
activity against cellobiose and synthetic substrates, and was inhibited more than 80% by Fe2+, Cu2+, Zn2+, and Al3+. Using p-nitrophenyl-β-d-glucopyranoside (pNPG) as substrate, BGL4
Sc
presented a V
max of 6.72 μmol min−1 mg total protein−1 and a K
m of 0.16 mM under optimal conditions. Most important, BGL4
Sc
is resistant to inhibition by glucose and the calculated K
i value for this sugar is 70 mM. This feature prompts BLG4
Sc
as an ideal enzyme to be used in the saccharification process of lignocellulosic materials for ethanol production. 相似文献
16.
G. N. Khitrich I. I. Seifullin N. V. Khitrich 《Russian Journal of General Chemistry》2011,81(5):840-844
The CoLX2 complexes were obtained by the reaction of N,N-dimethyl-N′,N′-dimethylthio-carbamoylsulfenamide (L) with CoX2 (X = Cl, Br, I, NCS). The complexes were investigated by elemental and X-ray analysis, IR, 1H NMR, and electron spectroscopy, conductometry, magnetochemistry, thermogravimetry. It is found that these compounds are
high-spin complexes of pseudotetraedral structure with bidentate coordination of L through the thione sulfur atom and sulfenamide
nitrogen atom. 相似文献
17.
The synthesis and characterization of azo dyes containing o,o′-dihydroxy groups and their azo-metal(II) [Cu, Co, Ni, Zn] chelates by 1H N.M.R., IR, AAS, UV–VIS, magnetic susceptibility and thin-layer chromatography techniques are reported. The stochiometry
of the azo-metal chelates was determined by the spectroscopic titration method to be 1:2 (ML2). The synthesized azo dyes and azo-metal chelate dyes were applied on wool fabric. Fastness to light and washing were measured. 相似文献
18.
O. B. Kazakova E. F. Khusnutdinova A. N. Lobov N. I. Medvedeva L. V. Spirikhin 《Chemistry of Natural Compounds》2011,47(4):579-582
Allylic oxidation of 19β,28-epoxy-A-neo-5β-methyl-25-nor-18α-olean-9-ene by ozone produced 19β,28-epoxy-A-neo-5β-methyl-25-nor-18α-olean-9-en-1-one. 相似文献
19.
I. A. Tolmacheva A. V. Nazarov O. A. Maiorova V. V. Grishko 《Chemistry of Natural Compounds》2008,44(5):606-611
The α-hydroxyoximes of methyl betulonate and allobetulone were synthesized. Beckmann fragmentation of them produced the lupane
and 19β,28-epoxy-18α-oleanane 2,3-seco-derivatives.
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 491–494, September-October, 2008. Original article submitted July
4, 2008. 相似文献
20.
Waqas Jamil Darshana Kumari Muhammad Taha Muhammad Naseem Khan Mohd Syukri Baharudin Muhammad Ali M. Kanwal Muhammad Saleem Lashari Khalid Muhammad Khan 《Journal of the Iranian Chemical Society》2018,15(11):2441-2454
A series of 1,2,4-triazole hydrazones 1–25 has been synthesized and characterized using different spectroscopic techniques including FT-IR, 1H-NMR, and ESI MS spectrometry. The synthetic derivatives were evaluated for their β-glucuronidase enzyme inhibition properties. Among them, 17 compounds demonstrated potential inhibitory activity towards β-glucuronidase with IC50 values ranging between 2.50 and 53.70 µM. Compounds 1 having IC50?=?2.50?±?0.01 µM was found to be the most active compound of the series and showed remarkable activity and found to be far more potent than the standard d-saccharic acid 1,4-lactone (IC50?=?48.4?±?1.25 µM). Furthermore, the possible binding interaction of active compounds was explored by in silico studies. These compounds can be used for anti-diabetic drug development process. 相似文献