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31.
尽管已报道了多种结构类型的手性单或双噁唑啉, 但手性多噁唑啉的合成及其应用的文献报道比较少. 本工作以多元羧酸为原料, 与手性2-氨基-1-丁醇经一步反应合成了8个手性多噁唑啉, 产率为89%~98%, 其结构经1 H NMR谱、IR谱、MS谱和元素分析确证. 相似文献
32.
Sarah C. Hubbard 《Tetrahedron》2005,61(31):7425-7430
The preparation and investigation of triplet photosensitizers designed to be preferentially soluble in room-temperature ionic liquids are reported. Photosensitizers prepared by covalent attachment of 1-methylimidazole to aryl ketones are soluble in ionic liquids and remain in the ionic liquid layer when the solution is extracted with an organic solvent. The photosensitized isomerization of trans-β-ionol to cis-β-ionol was efficiently carried out in ionic liquid solution with the product ionol being extracted and the sensitizer/ionic liquid mixture being re-used in additional photosensitization reactions. The scope and utility of the sensitizers in sensitizing other reactions are discussed. 相似文献
33.
Jungyeob Ham 《Tetrahedron letters》2005,46(39):6683-6686
A new synthesis of an agonist for the peroxisome proliferator-activated receptor δ (PPARδ) GW501516 as a potential antiobesity drug is described. The synthetic route involves the in situ protection of the phenol group with a Grignard reagent and a regio-controlled one-pot reaction for the formation of a sulfide bond as the key step. Starting from commercially available 4-iodo-2-methylphenol, this approach affords GW501516 with an overall yield of 87%. 相似文献
34.
S. I. Oshevski 《Russian Chemical Bulletin》2002,51(7):1171-1176
The possibility of specific cleavage of a single-stranded DNA fragment due to cooperative action of two oligonucleotide derivatives bearing chemical groups (at the 3"-phosphate and 5"-thiophosphate ends, respectively) located close to each other in a complementary complex is demonstrated. 相似文献
35.
18-冠-6与Eu(fod)3+在CCl4中的化学平衡及其配合物的结构 总被引:1,自引:0,他引:1
在室温下测定了CCl_4溶液中,18-冠-6的亚甲基、Eu(fod)的t—丁基质子的PMR化学位移与溶液组成的相互关系。提出了生成配合物RS,R_2S,R_2,R_3(S为18-冠-6,R为Eu(fod)_3)的模式。求得了平衡常数值(升/摩):K_1=[RS]/([R][S])=2.O×10~5,K_2=[R_2S]/([R][RS])=1.0×10~3,Q_1=[R_2]/[R]~2=4.2×10~2,Q_2=[R_3]/([R_2][R])=4.0×10~1。并测得在配合物RS,R_2S中18-冠-6质子的平均化学位移分别为4.90,10.84(ppm,相对于纯18-冠-6); 在配合物R,R_2,R_3,RS,R_2中t-丁基质子平均化学位移分别为1.53,2.33,0.54,1.02,2.42(ppm,相对于TMS)。 根据配合物的化学位移值,并考虑分子及分子轨道的对称性、位阻等因素提出了配合物R_2,RS,R_2S的可能的结构模型。 相似文献
36.
As part of a programme to synthesize thione derivatives with pentacyclo[5.4.0.02,6.03,10.05,9]undecane moieties it was decided to sulfurize the monoacetal 6 of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione 2. Unexpectedly the diol 9 was isolated as the product. 相似文献
37.
Alkylation of cyclohexenyl monoacetate 1 with R2Cu(CN)(MgCl)2 or RMgBr/CuCN (cat.) in Et2O produced trans 1,2-isomers 4, while arylation and alkenylation of 1 was accomplished with lithium borates 5 and a nickel cat. to afford trans 1,4-isomers 3 selectively. Furthermore, several transformations of the products were carried out to demonstrate synthetic advantages of the present reactions. 相似文献
38.
An enantioselective high-performance liquid chromatographic method, with precolumn derivatization with Marfey’s chiral reagent,
sodium 2,4-dinitro-5-fluorophenyl-l-alanine amide, has been developed for resolution of the enantiomers of a new antiepileptic drug, pregabalin, in the bulk
drug. The diastereomers of the pregabalin enantiomers were resolved to baseline on a reversed-phase ODS column with a 60:40
(v/v) mixture of aqueous 0.2% triethylamine (pH adjusted to 3.5 with dilute orthophosphoric acid) and acetonitrile as mobile phase.
Resolution between the diastereomers was not less than five. The method was extensively validated and proved to be robust.
The calibration plot was indicative of an excellent linear relationship between response and concentration over the range
750 (LOQ) to 7,500 ng L−1 for the R enantiomer. The limits of detection and quantification of the R enantiomer were 250 and 750 ng L−1, respectively, for an injection volume of 10 μL. Recovery of the R enantiomer from bulk drug samples of pregabalin ranged from 97.5 to 101.76%. Solutions of pregabalin in water and in the
mobile phase were found to be stable for at least 48 h. The method was found to be suitable and accurate for quantitative
determination of the R enantiomer in the bulk drug. It can be also used to test the stability of samples of pregabalin. 相似文献
39.
The properties of porphyrinogen as a new chromogenic reagent were examined. 5,10,15,20-Tetrahydro-tetraphenylporphyrinogen (TPPN) is changed to 5,10,15,20-tetraphenylporphine (TPP) by the oxidative reaction involving six electrons, and its formation of the porphine ring significantly increased the absorbance in the Soret band.The horseradish peroxidase (HRP) accelerated the oxidative reaction as a catalyst and the increment of absorbance depended upon the increase in the concentration of HRP. The reaction proceeded in the presence of dissolved oxygen and in the neighborhood of pH 7. Based on these findings, a chemical analysis by catalytic action using HRP was developed.In the procedure for this determination, the difference in absorbance at 419 nm (ΔA419=As−Ab, where As and Ab are the absorbances of the sample solution containing HRP and the blank solution without HRP after 30 min, respectively), was measured. The determination range of HRP, which was obtained from the ΔA419—HRP concentration curve, was 0.05-1.0 mg/l. The relative standard deviation in the median of the calibration curve was 3.19% (seven determinations), and the detection limit (S/N=3) was 29 ng/l. Furthermore, when the proposed method was applied to the enzyme immunoassay, bisphenol A (BPA) was selectively and sensitivity determined. 相似文献
40.
Synthesis of new diheteroarylcarbazoles: a facile and simple route of 3,6-di(pyrazol-4-yl)carbazoles
Ramu Meesala 《Tetrahedron letters》2006,47(43):7557-7561
A short and facile route to the synthesis of new 3,6-di(pyrazol-4-yl)carbazoles is reported. Dipyrazolylcarbazoles were synthesized in two steps from 3,6-diacetylcarbazoles through a Vilsmeier reaction which led to the formation of carbazolyl-β-chlorovinyl aldehydes, followed by cyclization with hydrazine hydrate. The reaction of the Vilsmeier reagent with hydrazones of diacetylcarbazoles yielded the corresponding pyrazole dicarbaldehydes in good yields. 相似文献