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101.
I. V. Ukrainets N. L. Bereznyakova G. P. Petyunin I. A. Tugaibei V. B. Rybakov V. V. Chernyshev A. V. Turov 《Chemistry of Heterocyclic Compounds》2007,43(6):729-739
An improved method for the preparation and purification of ethyl 2-hydroxy-4-oxo-4H-pyrido[1,2-a]-pyrimidine-3-carboxylates
is proposed. According to 1H and 13C NMR spectroscopic data the synthesized compounds exist in DMSO solution in the 2-hydroxy-4-oxo form while in the crystal
(at least for the case of the unsubstituted derivative) X-ray analysis shows that it occurs in the bipolar 2,4-dioxo form.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 864–876, June, 2007. 相似文献
102.
R. Janciene Z. Stumbreviciute L. Pleckaitiene B. Puodziunaite 《Chemistry of Heterocyclic Compounds》2002,38(6):738-740
When 4-methyl-7-nitro-2,3,4,5-tetrahydro-1H-1,5-benzodiazepin-2-one were reacted with phosphorus pentasulfide, the corresponding benzodiazepine-2-thione and its thiol tautomer were formed, which via the 2-methylmercapto derivative were converted to 4-(2-acetylhydrazino)-2-methyl-8-nitro-2,3-dihydro-1H-1,5-benzodiazepine. 相似文献
103.
The addition of secondary and primary amines to ethyl (1-amino-9,10-anthraquinon-2-yl)propynoate affords an easily separable
mixture of the corresponding ethyl 3-dialkylaminoor 3-alkylamino-3-(1-amino-9,10-anthraquinon-2-yl)acrylate and 3-dialkylamino-
or 3-alkylaminonaphthol[2,3-h]quinoline-2(1H), 7,12-trione (in ∼4: 1 ratio). Intramolecular cyclization of the resulting substituted ethyl acrylates results in the formation
of 4-dialkylaminoor 4-alkylamino-2-chlorinated pyridine rings. Subsequent nucleophilic substitution of the chlorine atom gives
2-functionalized 4-dialkylamino- or 4-alkylaminonaphtho[2,3-h]quinoline-7,12-diones.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2327–2332, November, 1998. 相似文献
104.
Wolfgang Stadlbauer Rita Laschober Thomas Kappe 《Monatshefte für Chemie / Chemical Monthly》1991,122(10):853-861
Summary 4-Chloro-3-aryl-coumarins and quinolones2 a–e undergo thermolytic ring closure by reaction with sodium azide in refluxing dimethyl formamide to yield indolo[3,2-c]coumarins and indolo[3,2-c]quinolin-6(5H)-ones6 a–e. In the case of the coumarin2 a the azido coumarin5 can be isolated. The mono- and diazacoumestrol-dimethylethers6 a–c are converted into the coumestrol analogues7 a–c and their diacetyl derivatives8 a–c.
Potentielle nichtsteroidale Östrogene und Antiöstrogene, 4. Mitt.: Organische Azide in der Heterocyclensynthese, Teil 13: Synthese von Aza- und Diazacumöstrolen über Azidzwischenstufen
Zusammenfassung 4-Chlor-3-arylcumarine und-chinolone2 a–e reagieren thermolytisch mit Natriumazid in siedendem Dimethylfomamid unter Ringschluß zu Indolo[3,2-c]cumarinen und Indolo[3,2-c]chinolin-6(5H)-onen6 a–e. Nur aus dem Cumarinderivat2 a kann das zwischenzeitlich gebildete Azidocumarin5 isoliert werden. Die so erhaltenen Mono- und Diazacumöstroldimethylether6 a–c werden in die entsprechenden Cumöstrole7 a–c und ihre Diacetylderivate8 a–c umgewandelt.相似文献
105.
G. Bruno P. Capezzuto G. Cicala F. Cramarossa 《Plasma Chemistry and Plasma Processing》1986,6(2):109-125
Plasma-chemical reduction of SiCl4 in mixtures with H2 and Ar has been studied by optical emission spectroscopy (OES) and laser interferometry techniques. It has been found that the Ar:H2 ratio strongly affects the plasma composition as well as the deposition (r
D) and etch (r
E) rates of Si: H, Cl films and that the electron impact dissociation is the most important channel for the production of SiClx species, which are the precursors of the film growth. Chemisorption of SiClx and the reactive surface reaction SiClx+H–SiCl(x–1)0+HCl are important steps in the deposition process. The suggested deposition model givesr
D [SiClx][H], in agreement with the experimental data. Etching of Si: H, Cl films occurs at high Ar: H2 ratio when Cl atoms in the gas phase become appreciable and increases with increasing Cl concentration. The etch rate is controlled by the Cl atom chemisorption step. 相似文献
106.
In this study, the determination of 4-Bromoaniline (4-BA) in green algae Chlamydomonas reinhardtii (C. reinhardtii) was investigated by applying continuous-flow microextraction (CFME) combined with high-performance liquid chromatography
(HPLC). Continuous-flow microextraction was conducted in a homemade glass chamber, i.e. the sample solution flowed through
a constant volume drop of solvent in the chamber at a constant flow rate. The effects of different factors on extraction efficiencies
were also investigated and these factors included the kind of extraction solvent, solvent drop volume, sample flow rate, extraction
time and addition amount of salt. Under the optimum extraction conditions (extraction solvent, carbon tetrachloride; solvent
drop volume, 3.5 μL; sample flow rate, 1.0 mL min−1; extraction time, 10 min; no addition of salt), the calibration plot was set up by plotting peak area against a series of
4-Bromoaniline concentrations (0.01–10 μg mL−1) in aqueous solution. The correlation coefficient (r) was 0.9990. The limit of detection (LOD) was 0.6 ng mL−1. The precision of this method was obtained by successive five time analyses of 100-ng mL−1 standard solution of 4-Bromoaniline, and the relative standard deviation (RSD) was 3.5%. The concentration factor was calculated
by the ratio of peak area of the analyte obtained after and before extraction and found to be 10.6. 4-Bromoaniline residues
in Chlamydomonas. reinhardtii cells and tap water samples were satisfactorily analyzed according to the method described above. 相似文献
107.
The reactions of Fe(CO)5, Fe(CO)4P(C6H5)3, M(CO)6 (M W, Mo, Cr), and (CH3C5H4Mn(CO)3 with KH and several boron and aluminium hydrides were investigated. Iron pentacarbonyl was converted quantitatively to K+Fe(CO)4-(CHO) by hydride transfer from KBH(OCH3)3 allowing isolation of [P(C6H5)3]2-Nn+Fe(CO)4(CHO)? in 50% yield. Lower yields were obtained with LiBH(C2H5)3, and other hydride sources gave little or no formyl product. The stability of Fe(CO)4(CHO)? in THP was found to depend on the cation, decreasing in the order [P(C6H5)3]2N+ > K+ > Na+ > Li+. No formyl complexes were isolated and no spectroscopic evidence for formyl formation was observed in the reactions of the other transition metal carbonyls with several hydride sources. Fe(CO)4-P(C6H5)3 gave K2Fe(CO)4 when treated with KHB(OCH3)3. When treated with LiBH(C2H5)3, W(CO)6 gave a mixture of HW2(CO)10?and (OC)5W(COC2H5)?; the latter was methylated to give the carbene complex (OC)5WC(OCH3)C2H5. 相似文献
108.
Apparent pK values of the wine pigment, 5-carboxypyranomalvidin-3-glucoside (vitisin A), were determined using UV-vis spectroscopy, viz. pKa1=0.98 (±0.10), pKH1=4.51 (±0.03) and pKH2=7.57 (±0.02). An additional ionisation constant at high pH (pKa4=8.84±0.06) was established by high-voltage paper electrophoresis. These data in conjunction with previously published pKa values determined by high-voltage electrophoresis suggest that in wine (pH 3.2-3.8), 5-carboxypyranomalvidin-3-glucoside exists as a complex mixture of hydrated and non-hydrated, partially ionised species with the predominant species being the quinonoidal base (λmax 498 nm). 相似文献
109.
Charles A. Micchelli 《Aequationes Mathematicae》1980,21(1):105-109
We show that, for the Chebyshev weight function (1–x
2)–1/2, the Cotes numbers for the quadrature rule with nodes at the zeros of the ultraspherical polynomialP
n
/()
are nonnegative if and only if –1/2<1. 相似文献
110.
H. Groemer 《Aequationes Mathematicae》1981,22(1):215-222
In the euclidean planeE
2 letS
1,S
2, ... be a sequence of strips of widthsw
1,w
2, .... It is shown thatE
2 can be covered by translates of the stripsS
i if w
1
3/2
= . Further results concern conditions in order that a compact convex domain inE
2 can be covered by translates ofS
1,S
2, ....This research was supported by National Science Foundation Research Grant MCS 76-06111. 相似文献