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排序方式: 共有297条查询结果,搜索用时 10 毫秒
1.
R. B. King 《Russian Chemical Bulletin》1993,42(11):1772-1781
Reactions of disodium tetracarbonylferrate, Na2Fe(CO)4, with sterically hindered dialkylaminodichlorophosphines, R2NPCl2 (R2N=diisopropylamino, dicyclohexylamino, and 2,2, 6, 6-tetramethylpiperidino) in diethyl ether lead to the air-stable phosphorus-bridging carbonyl derivatives (R2NP)2COFe2(CO)6 as the major products. The phosphorus-bridging carbonyl group in (i-Pr2NP)2COFe2(CO)6 has been found to undergo the following types of reactions: 1)Reduction, 2)Acylation, 3)Extrusion of the carbonyl group. The mechanisms of the reactions have been considered.This work was presented at the Workshop «The Modern Problems of Heteroorganic Chemistry» held on the ship «Nikolai Bauman» during the period May 8–13, 1993.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1858–1867, November, 1993. 相似文献
2.
Dominik Rejman 《Tetrahedron》2007,63(5):1243-1253
The work deals with the synthesis of hydroxypyrrolidine analogs of nucleosides. Starting from the optically pure l- or d-tartaric acid, we improved the synthesis of enantiomeric trans-3,4-dihydroxypyrrolidines and elaborated a procedure for the synthesis of all possible diastereoisomers of 3-hydroxy-4-pyrrolidinyl derivatives of both purine and pyrimidine nucleobases. The prepared compounds were tested for cytostatic and antiviral properties but no significant activity was found. 相似文献
3.
W. Zielenkiewicz B. Golankiewicz G. L. Perlovich M. Koźbiał 《Journal of solution chemistry》1999,28(6):731-745
Solubilities of tricyclic analogs of acyclovir have been determined in water at 25, 35, and 45°C and in octanol, water-saturated octanol, and octanol-saturated water at 25°C. Octanol-water partition coefficients were determined at 25°C. Melting temperatures and molar enthalpies of fusion were measured. Activity coefficients in water, octanol, and in aqueous octanol solutions were determined and are discussed. The effect of hydrophilic and hydrophobic substituents in the tricyclic analogs on their thermodynamic properties are discussed. The standard Gibbs energy of transfer between the saturated phases were found to correlate with known values of the melting point of the solvents and the solubilities of the solute. For a number of the compounds examined, correlations between the minimum inhibitory concentration against the herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), varicella-zoster virus (VZV), thymidine kinase-deficient (TK–) strains of VZV and
were established. Detailed conclusions have been derived concerning the relationships between the structure and the thermodynamic parameters of the compounds examined. 相似文献
4.
Józef Oleksyszyn Ewa Gruszecka Paweł Kafarski Przemysław Mastalerz 《Monatshefte für Chemie / Chemical Monthly》1982,113(1):59-71
Preparation of the phosphonic analogs of -methylaspartic (4 a–d), glutamic (7 a–b) and -methylpyroglutamic (5 a–b) acids by aminoalkylation of trivalent phosphorus chlorides with ethyl esters of oxoalkyloacids and benzyl carbamate is described. The phosphonic analogs of pyroglutamic acid (8 a–b) was obtained by the cyclization of the corresponding esters (9 a–b). The stability of the phosphonic analogs of pyroglutamic acid in acidic and alkaline media was also studied.
Die Herstellung von neuen Phosphonanalogen der Asparagin- und Glutaminsäure in der Reaktion von trivalenten Phosphorchloriden mit Ethyl-acetyloacetat oder Ethyl-lävulinat bzw. Benzylcarbaminat
Zusammenfassung Es wurde die Darstellung der Phosphonanalogen der -Methylasparaginsäure (4 a–d), Glutamin- (7 a–b) und -Methylpyroglutaminsäure (5 a–b) in der Reaktion der trivalenten Phosphorchloride und der Oxoalkansäureethylester sowie des Benzylcarbaminats beschrieben. In der Ringschlußreaktion der Ester (9 a–b) erhält man Phosphonanaloge der Pyroglutaminsäure. Die Stabilität der Analogen der Pyroglutaminsäure wurde in sauren und alkalischen Medien geprüft.相似文献
5.
A one-step synthesis of 5-alkoxypyrrole-3-phosphonates is presented starting from suitable α-cyanomethyl-β-ketophosphonates. The key step in the synthesis involves a one-pot addition and heteroannulation sequence. The zinc perchlorate-catalyzed addition of alcohols to the nitrile carbon of α-cyanomethyl-β-ketophosphonates followed by annulation furnished 5-alkoxypyrrole-3-phosphonates. The addition-annulation process is carried out in the presence of water and 4,5-dihydro-5-oxo-1H-pyrrole-3-phosphonates (pyrrolinones) are obtained in good yields. 相似文献
6.
Eduardo A. Véliz 《Tetrahedron letters》2006,47(18):3153-3156
Herein, we report the use of triisopropyl phosphite (TIP) as an effective substitute for triphenylphosphine in the Mitsunobu reaction of nucleoside analogs. In addition, the use of triphenyl phosphite as an alternative reagent for the expensive hexamethylphosphorous triamide (HMPT) in the Véliz-Beal bromination protocol is reported. 相似文献
7.
T. I. Osipova A. V. Belyankin A. R. Khomutov Yu. N. Zhukov E. N. Khurs R. M. Khomutov 《Russian Chemical Bulletin》1996,45(11):2588-2591
The reaction of ketoximes with hypophosphorous acid resulted in previously unknown -substituted--aminophosphinic acids, which were oxidized into the corresponding -substituted--aminophosphonic acids.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2729–2732, November, 1996. 相似文献
8.
Monika Tarnowska Adam Liwo Mark D. Shenderovich Inta Liepiņa Alexander A. Golbraikh Zbigniew Grzonka Anna Tempczyk 《Journal of computer-aided molecular design》1993,7(6):699-719
Summary The effect of the substitution in position 1 on the low-energy conformations of the oxytocin/vasopressin 20-membered ring was investigated by means of molecular mechanics. Three representative substitutions were considered: -mercapto-,-dimethyl)propionic acid (Dmp), (-mercapto-,-cyclopentamethylene)propionic acid (Cpp), both forming strong antagonists, and (,-dimethyl--mercapto)propionic acid (-Dmp), forming analogs of strongly reduced biological activity, with the -mercaptopropionic (Mpa) residue taken as reference. Both ECEPP/2 (rigid valence geometry) and AMBER (flexible valence geometry) force fields were employed in the calculations. Three basic types of backbone conformations were taken into account which are distinguished by the type of -turn at residues 3 and 4: 1/III, II, and I/III, all types containing one or two intra-annular hydrogen bonds. The allowed (ring-closed) disulfide-bridge conformations were searched by an algorithm formulated in terms of scanning the disulfide-bridge torsional angle C-S-S-C. The ECEPP/2 and AMBER energies of the obtained conformations were found to be in reasonable agreement. Two of the low-energy conformers of the [Mpa1]-compound agreed very well with the cyclic part of the two conformers found in the crystal structure of [Mpa1]-oxytocin. An analysis of the effect of -substitution on relative energies showed that the conformations with the N-C-CH2-CH2 (1) and C-CH2-CH2-S (1) angles of the first residue around (–100°, 60°) and (100°, –60°) are not affected; this in most cases implies a left-handed disulfide bridge. In the case of -substitution the allowed values of 1 are close to ± 60°. This requirement, being in contradiction to the one concerning -substitution, could explain the very low biological activity of the -substituted analogs. The conformational preferences of substituted compounds can largely be explained by the analysis of local interactions within the first residue. Based on the selection of the conformations which are low in energy for both the reference and -substituted compounds, two distinct types of possible binding conformations were proposed, the first one being similar to the crystal conformer with a left-handed disulfide bridge, the second one having a right-handed bridge, but a geometry different from that of the crystal conformer with the right-handed bridge. The first type of disulfide-bridge arrangement is equally favorable for both I/III and II types of backbone structure, while the second one is allowed only for the II type of backbone. No conformation of the I/III type has a low enough energy to be considered as a possible binding conformation for all of the active compounds studied in this work. 相似文献
9.
Xue-qiang Yin 《Tetrahedron》2004,60(15):3451-3455
Prior to this work only two examples of carbanucleosides possessing a C-1′/C-6′ double bond had been reported and they were minor derivatized side products arising during other targeted syntheses. To develop this structural feature into a new class of potential antiviral agents, the 5′-nor derivative of aristeromycin with such an olefinic structure (6) represents the first example. In this regard, treatment of (1′S,2′S,3′S,4′R,5′S)-6-chloro-9-(2′,3′-isopropylidenedioxy-6′-oxabicyclo[3.1.0]hex-4′-yl)purine (7) with sodium methoxide yielded 6 via an E′2-like elimination pathway. A convenient way to the C-4′ epimer of 6 (that is, 17) also arose during these studies and is described. Antiviral analysis of 6 and 17 failed to produce any significant activity. 相似文献
10.
Asymmetric synthesis of 1,3-oxathiolan-5-one derivatives through dynamic covalent kinetic resolution
The asymmetric synthesis of 1,3-oxathiolan-5-one derivatives through an enzyme-catalyzed, dynamic covalent kinetic resolution strategy is presented. Dynamic hemithioacetal formation combined with intramolecular, lipase-catalyzed lactonization resulted in good conversions with moderate to good enantiomeric excess (ee) for the final products. The process was evaluated for different lipase preparations, solvents, bases, and reaction temperatures, where lipase B from Candida antarctica (CAL-B) proved most efficient. The substrate scope was furthermore explored for a range of aldehyde structures, together with the potential access to nucleoside analog inhibitor core structures. 相似文献