排序方式: 共有15条查询结果,搜索用时 260 毫秒
1.
Nicolas Bogliotti Anne Ritter Séverine Hebbe Andrea Vasella 《Helvetica chimica acta》2008,91(11):2181-2202
The A*[s]U(*) dinucleosides 1 and 2 form thermoreversible gels in organic solvents. The basis of the gelation is the formation of linear aggregates by base pairing following desolvation of the nucleobases. This is evidenced by the absence of gel formation by the C(6)‐deaminated analogue 3 of 1 , the correlation of gelation with the anti‐conformation, as preferred for 1 , and the temperature‐, concentration‐, and time‐dependent CD spectra. The gels were also characterized by the minimum gelation concentration, the gel–sol transition (melting) temperature, and rheological properties. 相似文献
2.
A practical and efficient three-step sequence for the deamination of α-aminoesters is reported. This method is based on the NaBH4-mediated selective reduction of α-diazoesters to α-hydrazonoesters and has been successfully applied to the deamination of several representative α-aminoesters including some l-cysteine ethyl ester derivatives, key intermediates in the synthesis of a series of CysLT1 antagonists. 相似文献
3.
DNA中的胞嘧啶在化学致变剂作用下会发生脱氨反应,被认为是导致基因损伤的重要原因之一,本文采用毛细管电泳测定胞嘧啶和尿嘧啶,并将此种新方法用于过氧化氢存在下胞嘧啶脱氨反应的动力学研究,结果显示该反应对过氧化氢和胞嘧啶均为一级反应,反应活化能为70.35kJ.mol^-1,明显低于自发脱氨反应,表明过氧化氢可以加速胞嘧啶脱氨反应。 相似文献
4.
《Journal of Coordination Chemistry》2012,65(16):2948-2956
Two cadmium complexes, {[Cd(a-ptt)(ptt)]·H2O} n (1) and [Cd(a-Hmtt)2(SO4)H2O]·CH3OH (2), have been prepared based on 4-amino-3-(4-pyridine)-5-mercapto-1,2,4-triazole (a-Hptt) and 4-amino-3-methyl-5-mercapto-1,2,4-triazole (a-Hmtt), respectively. In 1, amino-triazole ligand a-Hptt can partly be deaminated and transformed into 3-(4-pyridine)-5-mercapto-triazole (Hptt) under hydrothermal conditions. X-ray diffraction analysis reveals that 1 exhibits an unusual 2-D lampshade-type layer structure in which the amino ligand a-ptt and the deamination ligand ptt display exo-tridentate bridging and bidentate bridging, respectively. Complex 2 is mononuclear and further assembled into a 3-D supramolecular architecture via non-covalent interactions. Complexes 1 and 2 were characterized by elemental analyses, IR, and thermogravimetric analyses. Furthermore, solid-state luminescent properties of 1 and 2 have also been investigated. 相似文献
5.
Xin-Meng Fan Xian-Tao Yang Yu-Jia Guo Ren-Min Wu De-Lin Pan Zhu Guan Xiao-Mei Ling Li-He Zhang Zhen-Jun Yang 《中国化学快报》2016,27(12):1759-1762
Deamination is a crucial step in the transformation of 6-cyclopropylamino guanosine prodrug to its active form. A convenient method using capillary electrophoresis (CE) without sample labeling was developed to analyze the deamination of a series of D-/L-6-cyclopropylamino guanosine analogs by mouse liver homogenate, mouse liver microsome, and adenosine deaminase (ADA). A two-step process involving a 6-amino guanosine intermediate formed by oxidative N-dealkylation was demonstrated in the metabolism of 6-cyclopropylamino guanosine to 6-hydroxy guanosine. The results indicated that the transformation rates of different prodrugs to the active form varied greatly, which were closely correlated with the configuration of nucleosides and the structure of glycosyl groups. Most importantly, D-form analogs were metabolized much faster than their L-counterparts, thus clearly pointed out that compared to guanine, modification of glycosyl part might be a better choice for the development of L-guanosine analogs for the treatment of HIV. 相似文献
6.
Jason T Manka 《Journal of fluorine chemistry》2003,124(1):39-43
Three pentahaloanilines were prepared by stepwise halogenation of 3,5-difluoroaniline and were deaminated to form pentahalobenzenes. Alternatively, two pentahalobenzenes were obtained by lithiation followed by iodination of 1,3-difluoro-4,6-dihalobenzenes. Alkylthiolation reactions of pentahaloanilines and benzenes in Me2SO were investigated. 相似文献
7.
《Tetrahedron》2013,69(19):3907-3912
A method for the regioselective synthesis of 3-unsubstituted 1-alkyl-1H-indazoles, starting with 2-halobenzonitriles and N-alkylhydrazines, is described. The two-step reaction pathway proceeds through the intermediacy of 1-alkyl-3-amino-1H-indazoles followed by reductive deamination. 相似文献
8.
Dr. Clément Ghiazza Lucas Wagner Dr. Sergio Fernández Dr. Markus Leutzsch Dr. Josep Cornella 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202212219
Among the tools available to chemists for drug design of bioactive compounds, the bioisosteric replacement of atoms or groups of atoms is the cornerstone of modern strategies. Despite the undeniable interest in amino-to-hydroxyl interchange, enzymatic deaminative hydroxylation remains unmatched. Herein, we report a user friendly and safe procedure to selectively convert aminoheterocycles to their hydroxylated analogues by means of a simple pyrylium tetrafluoroborate salt. The hydroxylation step relies on a Lossen-type rearrangement under mild conditions thus avoiding the use of strong hydroxide bases. In addition to biorelevant heterocycles, the deaminative hydroxylation of electron-deficient anilines was also demonstrated. Finally, mechanistic experiments allowed the identification of the key intermediates, thus unveiling a rather unusual mechanism for this formal aromatic substitution. 相似文献
9.
《Journal of Coordination Chemistry》2012,65(16):1455-1461
The crystal structure of a centrosymmetric dinuclear nickel(II) complex, formed from the reaction of bis(L-alaninato)nickel(II) with formaldehyde and methylamine, shows two bridging 2,4,8,10-tetramethyl-5-oxido-5′-carboxylato-2λ5,4,8,10-tetraazaspiro[5.5]undec-2-en(234-del)-ylium ligands, L, and two formato ligands; each nickel atom exists in a trans-N2O4 octahedral geometry with an average (μ-O)–Ni distance of 2.033(1)?Å and Ni···Nii distance of 2.894(1)?Å. Formation of L implicates an unprecedented deamination step involving activation of both the α-carbon and the α-methyl hydrogen atoms of the L-alaninato moiety. 相似文献
10.
Jussara Lopes de Miranda Jackeline da Silva Coelho Luiza Cristina de Moura Marcelo Hawrylak Herbst Bruno Araújo Cautiero Horta Ricardo Bicca de Alencastro Magaly Girão Albuquerque 《Polyhedron》2008
A deamination process was observed after copper(II) complexation reaction with guanidinoacetic (Gaa) and glutamic acids (Glu), forming the binuclear copper(II) complex K2Cu2C16H23N7O12 · 1/2H2O (1), which was characterized by elemental analysis (CHN), spectroscopy methods (IR and EPR), powder X-ray diffraction, thermogravimetric analysis (TGA), and mass spectrometry. A new ligand, namely biguanide-1,5-diethanoate (Bge) (C6H9N5O4), was formed during complexation, probably due to the reaction between two Gaa species and the consequent release of a significant amount of ammonia, thus, characterizing the deamination process. In complex 1, Bge behaved as a tetradentated ligand, using its oxygen and nitrogen atoms as coordinating sites to both Cu(II) ions. In addition, Glu has coordinated to Cu(II) through its α-N and O atoms. Theoretical calculations of the cis–cis, cis–trans, and trans–trans isomers of 1, considering three prototropic forms of the Bge ligand, were carried out using semi-empirical quantum mechanics (PM3/d). DFT (B3LYP and B3P86) calculations of complex 1, in which a hydrogen atom replaced the side chain of Glu, were also carried out using the 6-31G(d) basis set and the LanL2DZ effective core potential for the transition metal. Based on experimental and theoretical data, we concluded that the trans–trans isomer of the binuclear copper(II) complex 1 should be the most stable, although the occurrence of other isomers, even if in minor quantities, should not be disregarded. 相似文献