Nucleotides. Part XXVII Bis[2-(p-nitrophenyl)ethyl] Phosphorochloridate,a New Versatile Phosphorylating Agent in Nucleotide Chemistry

A new, versatile phosphorylating agent, bis[2-(p-nitrophenyl)ethyl] phosphorochloridate ( 3 ), has been prepared and is used for 3′- and/or 5′-phosphorylations of nucleosides. The resulting bis[2-(p-nitrophenyl)ethyl] phosphotriesters are versatile synthons in oligonucleotide synthesis leading finally to 3′- and/or 5′-terminated monophosphates in excellent yields.     

TRANSESTERIFICATION OF TRIS(p-NITROPHENYL) PHOSPHATE WITH SODIUM ALKOXIDES: BIS(p-NITROPHENYL) METHYL PHOSPHATE,BIS(p-NITROPHENYL) BENZYL PHOSPHATE,BIS(p-NITROPHENYL) n-BUTYL PHOSPHATE

Abstract

Transesterification of tris(p-nitrophenyl) phosphate by sodium alkoxides, in dichloromethane at 0°, provides a convenient synthetic route to diaryl alkyl phosphates which are produced in a high state of purity and in moderate to high yields. The procedure is used to prepare bis(p-nitrophenyl) methyl phosphate, bis(p-nitrophenyl) benzyl phosphate and bis(p-nitrophenyl) n-butyl phosphate.     

New substituted mono-and bis(imidazolyl)pyridines and their application in nitroaldolisation reaction

New chiral nitrogen ligands based on the substituted mono-and bis(imidazolyl)pyridines have been prepared and characterised. Their complexes with cupric acetate were used as catalysts in the nitroaldolisation reaction. In the case of optically pure complexes of mono(imidazolyl)pyridine, the isolated products were 2-nitro-1-(2-nitrophenyl)ethanols or 2-nitro-1-(4-nitrophenyl)ethanols in overall yields of 49–93 % and with the maximum enantiomeric excess of 15.6 %. The complexes of bis(imidazolyl)pyridine also catalyse the nitroaldol reaction, the yields being 64–90 %, but with zero enantioselective excess. Presented at the 57th Congress of Chemical Societies, Tatranské Matliare, 4–8 September 2005.     

Synthesis of aromatic polyamides by 1-hydroxybenzotriazole-catalyzed polycondensation of active aromatic diesters with aromatic diamines

Catalytic actions of various additives were studied in the polycondensation of di(4-nitrophenyl) isophthalate with bis(4-aminophenyl) ether in N-methyl-2-pyrrolidone, and 1-hydroxybenzotriazole (HOBt) was found to be a highly effective catalyst that yielded high-molecular-weight polyamide. In addition to the polycondensation of the 4-nitrophenyl ester, the polymerization of negatively substituted phenyl esters like di(2,4,5-trichlorophenyl) isophthalate was also accelerated by HOBt. For the HOBt-catalyzed aminolysis of esters a bifunctional concerted mechanism that involves an eight-membered transition state was proposed.     

Azoles and Azines: CXIX. Alkylation of 5,5'-(4-Nitrobenzylidene)bis(2-thiobarbituric) Acid and 5-(4-Nitrophenyl)-2,8-dithioxo-5,7,8,9-tetrahydro-2H-pyrano[2,3-d:6,5-d']dipyrimidine-4,6(1H,3H)-dione with Haloacetic Acids and Their Esters

5,5'-(4-Nitrobenzylidene)bis(2-thiobarbituric) acid and 5-(4-nitrophenyl)-2,8-dithioxo-5,7,8,9-tetrahydro-2H-pyrano[2,3-d:6,5-d']dipyrimidine-4,6(1H,3H)-dione, similar to unsubstituted 2-thiobarbituric acid, readily react with haloacetic acids and their esters to form regioselectively the S-alkylation products. The alternative routes fo 5,5'-(4-nitrobenzylidene)bis[(4-hydroxy-6-oxo-1,6-dihydropyrimidine-5,2-diyl)sulfanyl]diacetic acids, based on condensation of 4,6-dihydroxypyrimidin-2-ylthioacetic acid with carbonyl compounds followed by cyclodehydration to [(5-(4-nitrophenyl)-4,6-dioxo-3,5,6,7-tetrahydro-4H-pyrano[2,3-d:6,5-d']dipyrimidine-2,8-diyl)di(sulfanyl)]diacetic acid derivatives, are less efficient. Alkylation of 2-thiobarbituric acid with ethyl bromoacetate in ethanol in the presence of alkali yields 5-(2-oxo-2,5-dihydro-1,3-thiazol-4-yl)-2-thiobarbituric acid.     

Anion recognition by N,N′-diarylalkanediamides

The preparation of N,N′-diarylalkanediamides from the respective aliphatic dicarboxylic acids and 4-nitroaniline via microwave-prompted reactions is presented. The most positive effect of microwave irradiation was observed for N,N′-bis(4-nitrophenyl)butanediamide. Anion binding studies on the obtained diamides were carried out in DMSO and acetonitrile using UV-vis and ¹H NMR spectroscopy. A mechanism for selective fluoride recognition by N,N′-bis(4-nitrophenyl)butanediamide in DMSO is proposed.     

Novel synthesis of aromatic polysulfides from S,S′-bis(trimethylsilyl)-substituted aromatic dithiols and activated aromatic dihalides

A new method for the synthesis of aromatic polysulfides has been developed by the polycondensation of S,S′-bis(trimethylsilyl)-substituted aromatic dithiols with activated aromatic dihalides. The solution polycondensation of three S-silylated aromatic dithiols with bis(4-chloro-3-nitrophenyl) sulfone afforded readily aromatic polysulfides having inherent viscosities of 0.7 dL/g, and the polymerization with bis(4-fluorophenyl) sulfone gave the polymers with viscosity values of 0.3 dL/g. The silylation method was compared advantageously with a conventional route using parent dithiols and activated aromatic dihalides.     

Efficient promotion of phosphate diester cleavage by a face-to-face cyclodextrin dimer without metal

An organic face-to-face cyclodextrin dimer promotes the cleavage of bis(4-nitrophenyl) phosphate efficiently in neutral pH without the addition of metal. Both of the phosphate diester bonds can be cleaved.     

Synthesis of Amides by Nucleophilic Substitution of Hydrogen in 3-Nitropyridine

3-Nitropyridine reacted with nitrogen-centered carboxylic acid amide anions in anhydrous DMSO in the presence of K₃Fe(CN)₆ via oxidative nucleophilic substitution of hydrogen to give previously unknown N-(5-nitropyridin-2-yl) carboxamides. The reaction of nitrobenzene with urea anion in DMSO enabled one-pot synthesis of bis(4-nitrophenyl)amine.     

Evaluation of aryl oxalates for chemiluminescence detection in high-performance liquid chromatography

The chemiluminescence reaction between an aryl oxalate, hydrogen peroxide and a fluorescent compound is well known for use in h.p.l.c. post-column reactors. Here, several aryl oxalates are evaluated for this purpose in terms of intensity, rate of chemiluminescence decay, solubility in different solvents, and stability in the presence of hydrogen peroxide. Five oxalates are selected for different pH ranges of column eluates: bis(pentafluorophenyl) oxalate for pH < 2, bis(2,4-dinitrophenyl) oxalate for pH 2–4, bis(2-nitrophenyl) oxalate for pH 4–6, bis(2,4,6-trichlorophenyl) oxalate for pH 6–8, and bis(2,4,5-trichlorophenyl-6-pentyloxycarbonyl) oxalate for pH > 8.     

氢键型聚芳醚酮共聚物的合成与表征

氢键型聚芳醚酮共聚物的合成与表征王忠刚，陈天禄，徐纪平（中国科学院长春应用化学研究所长春１３００２２０）关键词氢键，聚芳醚酮，合成，表征高分子链之间的氢键相互作用可以有效地提高聚合物的性能［１，２］．本工作通过共聚反应，在酚酞型聚芳醚酮ＰＥＫ－Ｃ分子...     

Poly(4-nitrophenyl)quinoxalines

Via the reaction of 4,4-bis(4-nitrophenylglyoxalyl)diphenyl ether with different bis(o-phenylenediamine)s, new poly(4-nitrophenyl)quinoxalines were synthesized, which are of interest as precursors for polymers containing protogenic groups. Some properties of the obtained polymers were studied. It was shown that the solubility of poly(4-nitrophenyl)quinoxalines in organic solvents and their viscosity characteristics are comparable with the parameters of polyphenylquinoxalines that do not bear nitro groups. A study of the thermal properties of the polymers showed that the introduction of nitro groups into polyphenylquinoxalines is accompanied by some increase in the glass transition temperature and a decrease in the onset temperature of runaway thermal degradation.     

Reactivity of Amphiphilic Calix[4]resorcinolarenes and Phenols in the Reverse Micellar System Sodium Bis(2-ethylhexyl) Sulfosuccinate-Decane-Water

The mechanism of reaction of calix[4]resorcinolarene, aminomethylated calix[4]resorcinolarene, and 2-(dimethylaminomethyl)-4-isononylphenol with ethyl 4-nitrophenyl (chloromethyl)phosphonate in the reverse micellar system anionic surfactant-sodium bis(2-ethylhexyl) sulfosuccinate-decane-water changes compared with direct micellar systems and aqueous-organic solutions. It was shown that the calix[4]resorcinolarenes and phenol studied increase the percolation threshold of the system.     

Synthesis of meso-substituted porphyrins carrying carboranes and oligo(ethylene glycol) units for potential applications in boron neutron capture therapy

Selective delivery of 10B to tumours is one of the major remaining problems in boron neutron capture therapy (BNCT) of cancer. Porphyrins are selectively accumulated in tumours. Thus two series of carborane-carrying porphyrins were constructed, with additional functionality for attachment of uncharged potentially water-solubilising polyethers. 3-(1,2-Dicarbaclosododecaboran(12)-1-ylmethoxy)benzaldehyde was prepared by protection of the aldehyde of 3-(prop-2-ynyloxy)benzaldehyde as a dithioacetal, treatment with decaborane(14) and deprotection. Condensation with a 3-nitrophenyldipyrromethane gave a separable mixture of meso-(3-nitrophenyl)-meso-(3-carboranylmethoxyphenyl)porphyrins, resulting from extensive scrambling at the porphyrinogen stage. Similarly, condensation of 3-(1,2-dicarbaclosododecaboran(12)-1-yl)benzaldehyde with this dipyrromethane gave an analogous mixture of meso-(3-nitrophenyl)-meso-(3-carboranylphenyl)porphyrins. In this second series, the two regioisomeric bis(nitrophenyl)bis(carboranylphenyl)porphyrins could only be distinguished by X-ray crystallography, their NMR spectra being identical. The nitro groups of the mono(nitrophenyl)porphyrins and the bis(nitrophenyl)-porphyrins were reduced to the corresponding amines with tin(II) chloride and the monoamines were coupled with a omega-methoxy poly(ethylene glycol) chloroformate of mean MW 600 to give the MeOPEGylated tricarboranyl porphyrins.     

The role of nonbonded sulfur-oxygen interaction in the dissociative electron transfer to nitro-substituted arenesulfenyl chlorides

The electrochemical reduction of p-nitrophenyl sulfenyl chloride, o-nitrophenyl sulfenyl chloride as well as bis(4-nitrophenyl) disulfide and bis(2-dinitrophenyl) disulfide was investigated in acetonitrile at an inert electrode. Reduction standard potentials as well standard heterogeneous electron-transfer rate constants have been determined using convolution analysis. An unexpected big difference in the thermodynamics and kinetics of the initial electron-transfer process as well as a striking change in the reductive cleavage mechanism of the S-Cl bond as a function of the nitro group position on the aryl ring of the aryl sulfenyl chloride is observed. A computational study at the B3LYP level shows that this difference in behavior is due to the through-space nonbonded S...O interaction in the o-nitrophenyl sulfenyl chloride.     

Sulfur-substituted tetrahedranes

The stable sulfur-substituted tetrahedrane derivatives 2-4 were synthesized by the reaction of tris(trimethylsilyl)tetrahedranyllithium 1 with diphenyl disulfide, bis(4-nitrophenyl) disulfide, and bis(2,4-dinitrophenyl) disulfide, respectively, and characterized by both NMR spectroscopy and X-ray crystallography. Phenylsulfonyltetrahedrane 5 was prepared by the reaction of 2 and m-chloroperbenzoic acid. The UV-vis absorption spectra of 2-4 suggested an interaction of the σ orbital of the tetrahedrane core and the lone-pair electrons on the sulfur atom, whereas no interaction for 5 was found. Thermal reactions of 2 and 5 are also reported; 2 underwent fragmentation into two acetylene molecules, whereas 5 gave the corresponding cyclobutadiene.     

Ester hydrolysis by a cyclodextrin dimer catalyst with a metallophenanthroline linking group

A novel beta-cyclodextrin dimer, 1,10-phenanthroline-2,9-dimethyl-bridged-bis(6-monoammonio-beta-cyclodextrin) (phenBisCD, L), was synthesized. Its zinc complex (ZnL) has been prepared, characterized, and applied as a new catalyst for diester hydrolysis. The formation constant (logK(ML)=9.56+/-0.01) of the complex and deprotonation constant (pK(a)=8.18+/-0.04) of the coordinated water molecule were determined by a potentiometric pH titration at (298+/-0.1) K. Hydrolytic kinetics of carboxylic acid esters were performed with bis(4-nitrophenyl) carbonate (BNPC) and 4-nitrophenyl acetate (NA) as substrates. The obtained hydrolysis rate constants showed that ZnL has a very high rate of catalysis for BNPC hydrolysis, giving a 3.89x10(4)-fold rate enhancement over uncatalyzed hydrolysis at pH 7.01, relative to only a 42-fold rate enhancement for NA hydrolysis. Moreover, the hydrolysis second-order rate constants of both BNPC and NA greatly increases with pH. Hydrolytic kinetics of a phosphate diester catalyzed by ZnL was also investigated by using bis(4-nitrophenyl) phosphate (BNPP) as the substrate. The pH dependence of the BNPP cleavage in aqueous buffer shows a sigmoidal curve with an inflection point around pH 8.11, which was nearly identical to the pK(a) value from the potentiometric titration. The k(cat) of BNPP hydrolysis promoted by ZnL was found to be 9.9x10(-4) M(-1) s(-1), which is comparatively higher than most other reported Zn(II)-based systems. The possible intermediate for the hydrolysis of BNPP, BNPC, and NA catalyzed by ZnL is proposed on the basis of kinetic and thermodynamic analysis.     

Der zweistufige Carbanion-Mechanismus der Fragmentierung von 3-Aminopropylbenzoaten. Fragmentierungs-Reaktionen. 25. Mitteilung

The unsubstituted and p-substituted benzoates 2b – 2e of 3-dimethylamino-2,2bis(p-nitrophenyl)-propanol ( 2a ) undergo quantitative fragmentation in 80% ethanol yielding 1,1-bis(p-nitrophenyl)-ethylene ( 5 ) besides formaldehyde and dimethylamine, the hydrolysis products of the imonium ion 3 . The corresponding alcohol 2a , however, yields 2,2-bis(p-nitrophenyl)-ethanol ( 9 ) in addition to fragmentation products. Conversely, no fragmentation is observed with the benzoates 6b – 6e of 3-dimethylamino-2,2-diphenylpropanol ( 6a ) which lack electronwithdrawing substituents in the β-phenyl groups. These results are in agreement with a two-step carbanion mechanism (Scheme 2) involving the ionization of the aminoalkohol 2a and its esters 2b – 2e to the imonium ion 3 and the carbanions 4a – 4e . The latter undergo competitive cleavage, recombination and protonation to 5 , 2 and 9 , respectively, depending on the nucleofugal activity of –X. These conclusions are supported by the first-order rate constants for the benzoates 2b – 2e which differ merely by a factor of three. Since the p-substituents in the benzoate groups have only a minor effect on the reaction rate the bonds to the nucleofugal groups are not appreciably broken in the rate determining step.     

双[N,O]配体合镍催化剂/MAO催化MMA聚合的研究

合成了双[水杨醛(对硝基苯)亚胺]合镍催化剂A和双[水杨醛(对甲氧基苯)亚胺]合镍催化剂B.该两种双[N,O]配体合镍配合物/MAO催化体系能有效地催化极性单体甲基丙烯酸甲酯(MMA)聚合,催化活性可高达105gPMMA/(molNi.h).其中配体对位含有硝基吸电子(共轭)效应的催化剂A/MAO体系有相对较高的聚合反应热稳定性,温度达50℃时仍具有高催化活性.配体对位含有甲氧基推电子(共轭)效应的催化剂B/MAO则在30℃和Al/Ni摩尔比为600时表现出最高的催化活性.催化剂B/MAO体系催化得到PMMA的链序列结构以间规为主(含高达73.2%rr三元组),具有较高的玻璃化转变温度(Tg=106.4℃).     

Reverse micellar catalysis of phosphorylation of pyrimidinophanes

The reaction of pyrimidinophanes with 4-nitrophenyl bis(chloromethyl)phosphinate in reverse micellar solutions of cetyltrimethylammonium bromide, polyethylene glycol 600 monolaurate, and their mixture was studied by spectrophotometry in chloroform. The catalytic activity of the micelles was found to depend on the macrocycle size and concentration and relative content of surfactants in the solution.