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101.
An efficient one-pot synthesis of highly functionalized bicyclic pyrrole derivatives by a three-component domino reaction of heterocyclic ketene aminals (HKAs), arylglyoxal monohydrate, and indoles in ethanol medium catalyzed by acetic acid is described. In this procedure, three sigma bonds were formed simultaneously. The present synthesis features excellent regio-selectivity, easy purification as well as simple starting materials. 相似文献
102.
A straightforward procedure for the preparation of nucleoside analogue 1 and its regioisomer 2 containing a dihydro-1,4-dithiin as sugar moiety has been accomplished in four steps by our readily available heterocyclic system 5. Nucleobase insertion was carried out by direct addition of N4-acetylcytosine to sulfoxide derivatives via Pummerer-type glycosidation reaction. 相似文献
103.
高效液相色谱法测定大气颗粒物中的杂环胺 总被引:2,自引:0,他引:2
建立了大气颗粒物中杂环胺的高效液相色谱检测方法.采用ODS C18色谱柱(250 mm×4.6 mm, 5 μm),乙腈-0.01 mol/L三乙胺缓冲溶液(pH 4.0 )为流动相,非线性梯度洗脱,流速1.0 mL/min,柱温30 ℃,紫外检测波长263 nm,并优化荧光激发和发射波长条件,实现了6种杂环胺的基线分离和4种杂环胺的高灵敏度荧光检测.本方法中荧光和紫外检测器的检出限分别为0.0018~0.0084 mg/L和0.093~0.609 mg/L(S/N=3),相关系数在0.9920~0.9999之间,RSD小于5.9%,平均回收率为75.3%~111.6%,回收率相对标准偏差为1.7%~2.3%,具有较高的精确度和准确度. 相似文献
104.
105.
Andrea C. Bruttomesso Javier Eiras Javier A. Ramírez Lydia R. Galagovsky 《Tetrahedron letters》2009,50(28):4022-4024
In this Letter we report that the Ugi reaction/cyclization sequence on a steroidal 17-carboxaldehyde leads to novel steroidal 2,5-diketopiperazines with a noteworthy stereoselectivity. A wide variety in the substitution pattern in the heterocyclic moiety was easily achieved by changing the components in the Ugi reaction. 相似文献
106.
Heinrich Hahn Wolfgang Meindl Kurt Utvary 《Monatshefte für Chemie / Chemical Monthly》1985,116(2):157-166
Photochemical chlorination of (CH3NPF3)2 yields ClCH2(NPF3)2CH3(I) and ClCH2(NPF3)2CH2Cl (II). By reaction with organometallics unsymmetric N-substituted hexafluorodiazadiphosphetidines are synthesized. Depending on the nucleophilic strength of the used organometallic the chlorine atom of the N-CH2Cl group can be selectively substituted versus an organic substituent without side-reaction at the phosphorus atom. 相似文献
107.
Reaction of (CH3NPF3)2 with lithiummethylat yields the 2,4-dimethoxysubstituted diazadiphosphetidine which shows a good insecticide effect as proven by screening tests. In order to investigate the influence of the substituent of the nitrogen atom, a number of different 2,4-dimethoxy-substituted diazadiphosphetidines were synthesized. 相似文献
108.
The methacrylate monomers bearing mesogenic group and heterocyclicazo dye have been synthesized. The monomeric dye was copolymerized with the mesogenicmonomer using a free radical initiator to produce polymers useful for nonlinear optics. Themonomers and polymers were characterized by IR, ~1H-NMR, and UV-Vis spectra. Theaverage molecular weight (M_w and M_n) of the polymers were determined by gel permeationchromatography. The thermal properties of the polymers such as thermal stability andphase transition behavior were studied by thermogravimetric analysis, differential thermalanalysis, polarizing optical microscope and X-ray diffractometer. The results demonstratethat the synthesized polymers are crystalline polymers at room temperature and no liquidcrystalline phases were observed for all of them. 相似文献
109.
Ramazan Erenler 《Tetrahedron letters》2005,46(34):5683-5685
The conversion of 4-pyridyl propargylic alcohols 1 to the (E)-propenones 3 and propynones 2 occurs under mild reaction conditions, pyridinium chloride in methanol at room temperature. (Z)-4-Pyridyl propenones 11 are detected as initial products when large substituents such as trimethylsilyl, tert-butyl and phenyl are attached at C-3 of the propynols and these (Z)-enones 11 are isomerised to the (E)-isomers 3 under the reaction conditions. In the presence of deuterated solvent, both hydrogens at the double bond of enone 3d are deuterated. An allenol is proposed as intermediate whose preferential protonation occurs at the less hindered side giving the (Z)-enone. The propargylic alcohols, pyridin-2-yl 12 and quinolin-4-yl 5, are converted to (E)-enones 13 and 7, respectively. 相似文献
110.
LinCheng Xi-gaoJian 《高分子科学》2004,(4):389-393
The direct polymerization of an unsymmetrical kink non-coplanar heterocyclic diamine (1) with various aromatic bis(trimellitimide)s (2a-e) using triphenyl phosphite and pyridine as condensing agents could generate a series of new aromatic poly(amide imide)s (3a-e) containing the kink non-coplanar phthalazinone heterocyclic units in the polymer main chains with inherent viscosities of 0.58-0.66 dL/g. The polymers are readily soluble in a variety of solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidinone, pyridine and m-cresol and can be cast to form flexible and tough films. The glass transition temperatures of polymers (T8) are in the range of 301-327℃, and the temperatures for 5% weight loss in nitrogen are in the range of 498-521℃. 相似文献