Synthesis of organosoluble polyamides with bulky triaryl imidazole pendent group

New unsymmetrical diamine monomer containing triaryl imidazole pendent group,4-[4-(4,5-diphenyl-1H-imidazol-2-yl)phenoxy] -1,3-benzenediamine,was synthesized via aromatic substitution reaction of 1-chloro-2,4-dinitrobenzene with 4-(4,5- diphenyl-1H-imidazol-2-yl)phenol,followed by palladium-catalyzed hydrazine reduction.This new monomer was further confirmed by FT-IR,~1H NMR and ~(13)C NMR.Novel polyamides having pendant triaryl imidazole group were prepared by the phosphorylation polycondensation of fou...     

Spectroscopic study of 2-, 4- and 5-substituents on pKa values of imidazole heterocycles prone to intramolecular proton-electrons transfer

New 2-(1H-imidazol-2-yl)phenols (L1Et–L8tBuPt) bearing a phenolic proton in the vicinity of the imidazole base were prepared and characterized. Experimental studies of the dependence of their protonation/deprotonation equilibrium on substituent identities and intramolecular hydrogen bonding tendencies were carried out using electronic absorption spectroscopy at varying pH values. In order to make comparison, 2-(anthracen-10-yl)-4,5-diphenyl-1H-imidazole (L9Anthr) bearing no phenolic proton and 4,5-diphenyl-2-(4,5-diphenyl-1H-imidazol-2-yl)-1H-imidazole (L10BisIm) bearing two symmetrical imidazole base fragments were also prepared and experimentally investigated. DFT calculations were carried out to study frontier orbitals of the investigated molecules. While electron-releasing substituents produced increase in protonation–deprotonation pK_as for the hydroxyl group, values for the imidazole base were mainly affected by polarization of the imidazole ring aromaticity across the 2-imidazole carbon and the 4,5-imidazole carbons axis of the imidazole ring. It was concluded that electron-releasing substituents on the phenol ring and/or electron-withdrawing substituents on 4,5-imidazole carbons negatively affects donor strengths/coordination chemistries of 2-(1H-imidazol-2-yl)phenols, and vice versa. Change of substituents on the phenol ring significantly altered the donor strength of the imidazole base. The understanding of pK_a variation on account of electronic effects of substituents in this work should aid the understanding of biochemical properties and substituent environments of imidazole-containing biomacromolecules.     

香豆素-咪唑类荧光染料的设计与研究

合成了不同给电子取代基(羟基、丁氧基、二乙基氨基等)的菲并[9,10-d]咪唑(CA1~CA6)或4,5-二苯基咪唑(CB1~CB6)修饰的香豆素衍生物,初步考察了它们的溶液发光和固体发光现象.研究表明,当香豆素取代基为氨基时,化合物在二氯甲烷中的荧光较强,而羟基取代、丁氧基取代或者无取代的衍生物在二氯甲烷中的荧光都很弱,而菲并[9,10-d]咪唑修饰的衍生物CA1~CA5的溶液荧光要比4,5-二苯基取代咪唑修饰的衍生物CB1~CB5的溶液强.另外,染料分子的分子内氢键强度及咪唑基-香豆素环间二面角大小都会对染料分子的发光性能产生影响.     

Phase transition behavior of novel pH-sensitive polyaspartamide derivatives grafted with 1-(3-aminopropyl)imidazole

New pH-sensitive polyaspartamide derivatives were synthesized by grafting 1-(3-aminopropyl)imidazole and/or O-(2-aminoethyl)-O'-methylpoly(ethylene glycol) 5000 on polysuccinimide for application in intracellular drug delivery systems. The DS of 1-(3-aminopropyl)imidazole was adjusted by the feed molar ratio, and the structure of the prepared polymer was confirmed using FT-IR and 1H NMR spectroscopy. Their pH-sensitive properties were characterized by light transmittance measurements, and the particle size and its distribution were investigated by dynamic light scattering measurements at varying pH values. The pH-sensitive phase transition was clearly observed in polymer solutions with a high substitution of 1-(3-aminopropyl)imidazole. The prepared polymers showed a high buffering capacity between pH 5 and 7, and this increased with the DS of 1-(3-aminopropyl)imidazole. The pH dependence of the aggregation and de-aggregation behavior was examined using a fluorescence spectrometer. For MPEG/imidazole-g-polyaspartamides with a DS of 1-(3-aminopropyl)imidazole over 82%, self aggregates associated with the hydrophobic interactions of the unprotonated imidazole groups were observed at pH values above 7, and their mean size was over 200 nm, while the aggregates of polymers were dissociated at pH values below 7 by the protonation of imidazole groups. These pH-sensitive polyaspartamide derivatives are potential basic candidates for intracellular drug delivery carriers triggered by small pH changes.     

Thiazolo[4,5-d]pyrimidines. Part I. synthesis and anti-human cytomegalovirus (HCMV) activity in vitro of certain alkyl derivatives

Alkyl derivatives of the thiazolo[4,5-d]pyrimidine congeners of guanine and uracil were prepared and assessed for in vitro activity against human cytomegalovirus (HCMV). The finding that the 3-pentyl 1b and 3-hexyl 1c derivatives of 5-aminothiazolo[4,5-d]pyrimidine-2,7(3H,6H)-dione (1e) had potent in vitro anti-HCMV activity prompted a broader study of alkyl derivatives in this ring system. A series of 3-alkyl derivatives of 1e , viz. 1f-w , were prepared by direct alkylation of the sodium salt of 1e and by subsequent modifications, 2a-d. For comparison with 1c , 5-amino-2-hexylaminothiazolo[4,5-d]pyrimidin-7(6H)-one (4) was prepared and studied. The 3-(2-alkenyl) derivatives of 1e were found to be the more active antiviral agents with the Z isomer of 5-amino-3-(2-penten-1-yl)thiazolo[4,5-d]pyrimidine-2,7(3H,6H)-dione (1f) having the better therapeutic index. Analogous 4-(2-alkenyl) derivatives of 2-aminothiazolo[4,5-d]pyrimidine-5,7(4H,6H)-dione 6a and 6b were also prepared but were found to have poor therapeutic indices. Single crystal X-ray diffraction analysis was used to unequivocally establish the structure of 1f.     

Thermal condensation of imidazole with trifluoroacetaldehyde

The title condensation occurred readily at reflux (100°C) with the methyl hemiacetal of trifluoroacetaldehyde and provided 37.3% of 4(5)-(1′-hydroxy-2′,2′,2′-trifluoroethyl)imidazole as the major product, together with 8.8% of 2-(1′-hydroxy-2′,2′,2′-trifluoroethyl)imidazole, 7.2% of 2,4(5)-bis-(1′-hydroxy-2′,2′,2′-trifluoroethyl)imidazole and 0.4% of the 4,5-bis-product. (Trifluoroacetyl)imidazoles were prepared by oxidation of these condensation products. Nitration and bromination of the condensation products gave the corresponding nitro- and bromoimidazoles, respectively.     

Acyclic analogues of purine and imidazole nucleosides

Hydroxyl-protected derivatives of 1- and 3-(2-hydroxyethoxymethyl)imidazoles ( 4,5,7-10 ) have been prepared from 5-amino-4-carbamoylimidazoles ( 2 ). The protected derivatives were converted to acyclic analogues of imidazole nucleosides ( 6 ) or subjected to various cyclisation reactions leading to 9-(2-hydroxy-ethoxymethyl)-substituted 2-methyl-, 2-phenyl- and 2-azahypoxanthines ( 18,13 and 20 , respectively) and 1-methylguanine ( 28 ). For assignment of structures to isomeric imidazole and purine derivatives, ¹³C chemical shifts have been used.     

Synthesis of novel acyclonucleosides. Reactions of 1-(1-bromo or 3-bromo-2-oxopropyl)pyridazin-6-ones

Reaction of 1-(3-bromo-2-oxopropyl)pyridazin-6-ones 1 and 2 with sodium azide at room temperature gave the corresponding 1-(3-azido-2-oxopropyl)pyridazin-6-ones 3 and 4 , whereas reaction of 1-(1-bromo-2-oxo-propyl)pyridazin-6-ones 5 and 6 with excess sodium azide afforded 4-azido-5-chloropyridazin-6-one 7 and 4,5-diazido-3-nitropyridazin-6-one 8 by dealkylation. Some 1-(2-hydroxypropyl)pyridazin-6-ones 9, 10, 11 were synthesized from the corresponding 1-(2-oxopropyl) derivatives 1, 2, 3 . 4,5-Dichloro-1-(2,3-dihydroxypropyl)-pyridazin-6-one 13 was also prepared from compound 9 via the corresponding 2,3-epoxypropyl derivative 12 . Treatment of compound 5 with thiourea gave 4,5-dichloro-1-(2-amino-4-methylthiazol-5-yl)pyridazin-6-one 14 . Reaction of compounds 1 and 2 with thiourea at 20° afforded the corresponding 3-formamidinylthio-2-oxo-propyl derivatives 15 and 16 , whereas treatment of compound 1 with thiourea at 45° gave 4,5-dichloro-1-[(2-aminothiazol-5-yl)methyl]pyridazin-6-one 17 . Compound 17 was also prepared from compound 15 by refluxing in ethanol.     

2-Trifluoromethylimidazole, 2,4,5-tris (trifluoromethyl)imidazole and related compounds

2-Trifluoromethylimidazole, prepared by the reaction of imidazole-2-carboxylic acid with sulphur tetrafluoride, afforded a silver salt which reacted with organohalides (bromomethane, ethyl bromoacetate, N,N-dimethyl-2-chloroethylamine, and chloroacetonitrile) to give the corresponding N-alkylated derivatives. 2-Trifluoromethylimidazole-4,5-dicarboxylic acid was obtained by oxidation of 2-trifluoromethylbenzimidazole, and on decarboxylation gave only traces of 2-trifluoromethylimidazole; the major product was 2-trifluoromethylimidazole- 4-carboxylic acid. The di-acid and sulphur tetrafluoride gave 2,4,5-tris (trifluoromethyl) imidazole.     

DC Electrical Conductivity of Three-Branched Dendritic and Linear Metal Complexes of N-Substituted Imidazole Phenanthroline Derivatives

N-substituted imidazole phenanthroline dendritic metal complexes of 2-(4-(4,5-diphenyl-2,5-1H-imidazol-2-yl)phenyl)-1H-imidazo[4,5-f][1,10]-phenanthroline, N-phenyl substituted phenylene imidazole derivative (TIPIP) and N,N-dimethyl phenylene imidazole derivative (MIPIP), were synthesized and characterized. DC electrical conductivity behavior vs. temperature in the range 300–500 K of the prepared three-branched metal (II) complexes of Co, Ni, Cu, Zn, Cd, and Hg was studied. Of the entire dendritic metal complexes, Cu(II) complexes showed the best electrical conductivity in the range 10^?7–10^?12 Scm^?1; a semiconductor behavior. For comparison, the linear Cu(II) complexes of TIPIP and MIPIP were synthesized and their electrical conductivity behavior was studied. Linear and dendritic Cu(II) complexes showed consistent DC electrical conductivity behavior. N,N-dimethyl substituted phenylene imidazole (MIPIP) Cu(II) dendritic and linear complexes showed the highest electrical conductivity values which reached 10^?7 Scm^?1 at high temperatures. The synthesized materials were characterized using CHN analyses, FTIR, UV-visible, ¹H-NMR, and thermal analyses (TGA, DTA).     

New aspects of reactions of methyl (thio)ureas with benzil

New pathways of reaction between 1-methylthiourea or 1-methylurea and benzil bring about new derivatives of (2S*,3aR*,6aS*)-perhydro-3aH-[1,3]dioxolo[4,5-d]imidazole and racemic (4S*,5R*)-4-alkoxy-5-hydroxy-1-methyl-4,5-diphenylimidazolidine-2-thiones. Some of the obtained urea-and thiourea derivatives were characterized by X-ray diffraction, which showed their supramolecular organization governed by the directionality of hydrogen bonds at the acceptor side C=O or C=S groups.     

Synthesis of 1- and 2-(2-quinolyl)azulenes by the friedländer reaction of acetylazulenes

1-Acetylazulene and 3-methyl-, 3-ethyl-, and 3-propyl-substituted 1-acetylazulenes were prepared by the reaction of 3-acetyl-2H-cyclohepta[b]furan-2-one with in situ generated enamines from aldehydes and amines. These four 1-acetylazulenes reacted with 2-aminobenzaldehyde and its 4,5-dimethoxy- and 4,5-methylenedioxy-substituted derivatives in the presence of sodium ethoxide to afford twelve 1-(2-quinolyl)azulenes. In a similar manner, three 2-(2-quinolyl)azulenes were also prepared from 2-acetylazulene.     

Imidazole derivatives as the organic precursor of ZnO nano particle

N₁-Hydroxy-2,4,5-trisubstituted imidazoles were synthesized starting from 1,2-diketones. The crystal structure of 4,5-dimethyl-2-(3-nitrophenyl)-1H-imidazol-1-ol has been determined. An unusual intermolecular hydrogen bonding through the association of water molecule has been reported. These imidazole derivatives can be thought of as the organic precursor for the synthesis of zinc oxide nano particles.     

Peroxide chemistry of triaryl-substituted imidazoles. Fenflumizole, a non-steroidal, anti-inflammatory agent.

Fenflumizole, [2-(2,4-difluorophenyl)4,5-bis(4-methoxyphenyl)imidazole] is a nonsteroidal, anti-inflammatory analgesic. It reacts quantitatively with 1O2 forming 2-(2,4-difluorophenyl)-4-hydroperoxy-4,5-bis(4-methoxyphenyl)imidazole in a reversible reaction. In ethanol solution at ambient temperatures, the peroxide regenerates parent fenflumizole and 1O2 together with minor quantities of other products. The structures of those products point to the intermediacy of a 1,3-endoperoxide and a dioxetane. These observations may be relevant to the biological activity of fenflumizole.     

咪唑并吡啶类化合物的合成及其应用*

咪唑并吡啶类化合物具有与吲哚、氮杂吲哚等类似的特殊结构和良好的生物活性,在医药和农药工业有着广泛的应用,成为有机化学家和药物化学家的研究热点。咪唑并吡啶类化合物主要有咪唑并[4,5-b]吡啶、咪唑并[4,5-c]吡啶、咪唑并[1,2-a]吡啶和咪唑并[1,5-a]吡啶等4个类型。本文阐述了近年来咪唑并吡啶类化合物的合成研究进展和应用情况,主要介绍了咪唑并[4,5-b]吡啶和咪唑并[4,5-c]吡啶这两类化合物的合成方法和在医药及农药领域的应用。     

Structure and synthesis of 6-(substituted-imidazol-1-yl)purines: versatile substrates for regiospecific alkylation and glycosylation at N9

X-ray crystal structures of several 6-(azolyl)purine base and nucleoside derivatives show essentially coplanar conformations of the purine and appended 6-(azolyl) rings. However, the planes of the purine and imidazole rings are twisted approximately 57 degrees in a 2-chloro-6-(4,5-diphenylimidazol-1-yl)purine nucleoside, and a twist angle of approximately 61 degrees was measured between the planes of the purine and pyrrole rings in the structure of a 6-(2,5-dimethylpyrrol-1-yl)purine nucleoside derivative. Shielding "above" N7 of the purine ring by a proximal C-H on the 6-azolyl moiety is apparent with the coplanar compounds, but this effect is diminished in those without coplanarity. Syntheses of 6-(azolyl)purines from both base and nucleoside starting materials are described. Treatment of 2,6-dichloropurine with imidazole gave 2-chloro-6-(imidazol-1-yl)purine. Modified Appel reactions at C6 of trityl-protected hypoxanthine and guanine derivatives followed by detritylation gave 6-(imidazol-1-yl)- and 2-amino-6-(imidazol-1-yl)purines. Imidazole was introduced at C6 of 2',3',5'-tri-O-acetylinosine by a modified Appel reaction, and solvolysis of the glycosyl linkage gave 6-(imidazol-1-yl)purine. Guanosine triacetate was transformed into the protected 2,6-dichloropurine nucleoside, which was subjected to S(N)Ar displacement with imidazoles at C6 followed by glycosyl solvolysis to provide 2-chloro-6-(substituted-imidazol-1-yl)purines. Potential applications of these purine derivatives are outlined.     

2,4,5-三苯基咪唑Schiff碱的合成及其抑菌活性

以联苯甲酰、对硝基苯甲醛和乙酸铵为原料,经缩合和还原反应制得2-(4-氨基苯基)-4,5-二苯基咪唑(2);2再与芳香醛缩合制得三个新型的2,4,5-三苯基咪唑Schiff碱衍生物(3a～3c),其结构经1H NMR,IR和MS表征。初步抑菌活性测试结果表明,3a～3c对大肠杆菌,苏云金杆菌和枯草芽孢杆菌均有较好的抑菌活性。     

某些1-酰基苯并咪唑及1-酰基咪唑衍生物的合成

2-取代的苯氧甲基苯并咪唑、咪唑分别与酰氯在缚酸剂存在下反应,制备了24个新的1-酰基2-苯氧甲基苯并咪唑及1-苯氧乙酰咪唑衍生物.后者容易吸水,转变成相应的铵盐.所制得的化合物中某些经小麦垂直生长法测定表现出一定的促进或抑制生长活性.     

Synthesis and alkaline hydrolysis of (pentafluoroethyl)imidazoles

Photochemical ring substitution of the N-trifluoroacetyl derivatives of histamine and of L-histidine methyl ester by pentafluoroethyl radical provides the corresponding 2- and 4-pentafluoroethylated products in yields of 19% and 27%, respectively. Alkaline hydrolysis converts the 2-pentafluoroethyl group to trifluoroacetyl. The reaction mechanism, involving a diazafulvene intermediate, is analogous to that elucidated for (trifluoromethyl)imidazoles; however, the pentafluoroethyl group is markedly more reactive to hydrolysis than the trifluoromethyl group. For imidazole derivatives, the ratio of reactivities is 75 at C-2 and 40 at C-4. The hydrolysis of 4-(pentafluoroethyl)histamine affords the bicyclic product, 4-(trifluoromethyl)-6,7-dihydro-1H-imidazo[4,5-c]-pyridine in 65.4% yield.     

三芳基咪唑富勒烯吡咯烷衍生物的合成及在CdSe量子点敏化太阳能电池中的应用

本文合成了两个结构新颖的三芳基咪唑类化合物5(Im)和6(Bn-Im),然后通过1,3-偶极化反应合成了C60吡咯烷衍生物7(Im-C60)和8(Bn-Im-C60),用MS, NMR, IR 等对其结构进行了表征。初次组装了七个太阳能电池,结构分别为FTO/TiO2/CdSe/Pt, FTO/TiO2/C60/Pt,FTO/TiO2/Im-C60/Pt,FTO/TiO2/ Bn-Im-C60/Pt, FTO/TiO2/C60-CdSe/Pt,FTO/TiO2/Im-C60-CdSe/Pt和FTO/TiO2/Bn-Im-C60-CdSe /Pt,对其光电性能进行了表征,结果表明：与CdSe敏化太阳能电池相比,以Im-C60-CdSe和Bn-Im-C60-CdSe为敏化剂的电池效率分别增加了5.28%和40.08%。