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1.
A simple route for the synthesis of Boc-protected tetrazole analogs of amino acids starting from N α-Boc amino acids has been described. The [2 + 3] cycloaddition of Boc-α-amino nitrile and sodium azide in the presence of a catalytic amount of zinc bromide yielded the desired tetrazoles in good yields and purity. All the compounds obtained have been characterized by 1H and 13C-NMR and mass spectral studies. 相似文献
2.
The aqueous solubilities of glycine, dl-α-alanine (2-aminopropanoic acid), dl-α-aminobutyric acid (2-aminobutanoic acid), dl-α-norvaline (2-aminopentanoic acid), dl-α-norleucine (2-aminohexanoic acid), β-alanine (3-aminopropanoic acid), γ-aminobutyric acid (4-aminobutanoic acid), 5-aminovaleric acid (5-aminopentanoic acid), and 6-aminocaproic acid (6-aminohexanoic acid) were determined from 293.15 to 323.15 K at intervals of 5.00 K using the gravimetric method. The temperature dependence of the solubility of α-amino acids and α,ω-amino acids in water is well described by the van’t Hoff equation. Linear van’t Hoff plots were used to determine the differential enthalpy of solution. The results obtained are compared with reported values in literature and are discussed in terms of the position of the ionic groups in the hydrocarbon chain. 相似文献
3.
Zhi Hua MA Cong LIU Yong Hua ZHAO Wei LI Jian Bo WANG* Key Laboratory of Bioorganic Chemistry Molecular Engineering of Ministry of Education Department of Chemical Biology College of Chemistry Peking University Beijing 《中国化学快报》2002,13(8)
b-Amino acids and their derivatives have attracted considerable attention in recent years due to their occurrence in biologically active natural products, such as dolastatins 11, cyclohexylnorstatine 22 and taxol 33. bAmino acids also find application in the synthesis of blactams4, piperidines5, indolizidines6. Moreover, the peptides consisting of bamino acids, the so called bpeptides, have been extensively studied recently7. Consequently, considerable efforts have been directed to the synt… 相似文献
4.
Michal Achmatowicz Agnieszka Szczepańska Daniel T. Gryko Piotr Salański Janusz Jurczak 《Supramolecular chemistry》2013,25(1):93-95
Abstract Bisamidation of oxaloyl chloride using L-amino acid methyl ester hydrochlorides afforded chiral diesters. The following reactions of diesters with 2,2-(ethylene-dioxy)diethylamine, afforded tetramides possessing C2 symmetry. Coupling of N-hydroxysuccinimide ester of N-benzyloxycarbonyl-L-alanine with 1,5-diamino-3-oxapentane, followed by cleavage of protecting groups, afforded an optically active diamine, which was transformed consequently into tetramide via the reaction with diglycolic acid dimethyl ester under high pressure conditions. 相似文献
5.
Chiral dehydropiperidinones were synthesized in enantiopure form from α-amino acids and alkynes via azetidin-3-ones. 相似文献
6.
Regioselective reaction of lithium diene-and triene-diolates 1 and 2 with O-diphenylphosphinyl hydroxylamine affords unsaturated α-amino acids 3 and 4. Addition to DEAD leads selectively to γ-hydrazino unsaturated acids 5 and 6. 相似文献
7.
Nitrones 2a , 2b obtained from the aldehydes 1a , 1b , are used for the syntheses of the N-ethoxy iminium salts 4a and 4b . In the following procedure 4a and 4b react to several esters of phosphinic acids 6a - 6d . 相似文献
8.
Abstract We have previously reported (1,) the synthesis of a range of α-aminophosphonous acids and found them to be mimics of the naturally occurring amino acids. They inhibit the protein synthesis of E.Coli B (2) and other synthetases (3). We have now found that such compounds can be conveniently resolved via their N-acyl derivatives by enzymatic methods. Using penicillin-G-amidase from E.Coli (EC 3.5.1.11) the R-enantiomer is cleanly hydrolysed leaving the S-enantiomer intact. 相似文献
9.
S. A. Vasil'eva L. Kh. Kalimullina M. G. Safarov 《Chemistry of Heterocyclic Compounds》2003,39(2):174-178
4-Methyl-3,4-epithiotetrahydropyran was synthesized by the recyclization of 4-methyl-3,4-epoxytetrahydropyran by the action of thiourea. The product reacts with -amino acids in an alkaline medium with regioselective opening of the thiirane ring at the least substituted carbon atom. 相似文献
10.
《合成通讯》2013,43(9):1143-1150
Abstract The electrochemical synthesis of the 2‐arylpropionic acid group of nonsteroidal anti‐inflammatory agents such as ibuprofen, naproxen, indoprofen, biprofen, cicloprofen, and fenoprofen has been carried out in dimethylformamide (DMF) containing tetra‐n‐butylammonium perchlorate (nBu4NClO4) by electrochemical carboxylation of α‐methylbenzyl chlorides catalyzed by a schiff‐base complex [Co(salen)] in an undivided cell equipped with a platinum cathode and magnesium anode under constant current density of 10 mA/cm2 in good yields. Cyclic voltammetric studies have also been carried out to investigate the mechanism by which [Co(salen)] catalyzes the cathodic reaction of α‐methylbenzyl chlorides in presence of CO2 by taking α‐phenylethylchloride as the model compound. 相似文献
11.
A systematic study on the influence of Lewis acid, solvent, and temperature on the stereochemical course of the Ugi reaction was performed to find conditions in which the isocyanides derived from enantiopure α-amino acids do not racemize. After a series of experiments, dichloromethane was used as a solvent and BF3 · OEt2 as a Lewis acid catalyst. This combination allowed us to obtain a product in a model reaction with 99% diastereoisomeric ratio (dr), with the structure motif of a group of cathepsin K inhibitors. 相似文献
12.
Ivan I. Stoikov Nataly A. Fitseva Igor S. Antipin Alexander I. Konovalov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract Bghly selective biological transport of amino acids is usually mediated by carrier proteins. The application of such membrane systems for the analysis and separation of amino acids has long studied. This work is devoted to the transport of zwitterionic form of aromatic a-amino acids such as d,l-Phe, d,l-DOPA, d,l-His, d,l-Tyr, d,l-Trp, via supported liquid membrane (SLM). The lipophilic α-aminophosphonates (I). R1 amyl or 2-ethylhexyl; R2, R2-(CH2)4-(CH2)5-CH3 & (CH3), C4 H(CH9) & H; H & H; have been used as carrier in the membrane systems composed of a porous polymeric support (Millipore Type FA) impregnated with 10?1 M carrier in o-nitrophenyl n-octyl ether (amino acid concentration in source phase is 10?3 M). The cell for membrane extractions is presented on Fig I. 相似文献
13.
The review summarizes recent advances in the synthesis of cyclic -amino acids via intramolecular ring-closing metathesis of dienes and enynes. 相似文献
14.
F. Baffi 《International journal of environmental analytical chemistry》2013,93(3-4):173-176
Abstract A procedure for the quantitative determination of 17 amino acids in a marine matrix using HPLC is reported. Pre-column derivatization with o-phthalaldehyde, separation on C18-bonded silica with phosphate buffer (pH 7.2)-acetonitrile as eluent and fluorescence detection have been used. The good variation coefficient (average 2% with working curves in real matrix) and the low detection limit (1-5 fmoles) make the procedure suitable for the determination of total or free amino acids in matrix cultures. 相似文献
15.
Summary. The formation equilibria for the binary complexes of CoII, NiII, CuII, ZnII, CdII, MnII, PbII, ThIV, UO2II, and CeIII with tricine and for the ternary complexes involving some -amino acids (glycine, -alanine, proline, serine, asparagine, and aspartic acid) were investigated using pH-metric technique. The formation of binary and ternary complexes was inferred from the pH-metric titration curves. It was deduced that tricine acts as a primary ligand in the ternary complexes involving the monocarboxylic amino acids (glycine, -alanine, proline, serine, and asparagine), whereas it behaves as a secondary ligand in the ternary systems containing the dicarboxylic aspartic acid. The ternary complex formation was found to take place in a stepwise manner. The stability constants of the complexes formed in aqueous solutions were determined potentiometrically under the experimental conditions (t=25°C, I=0.1moldm–3 NaNO3). The order of stability of the ternary complexes in terms of the nature of the amino acids is investigated and discussed. The values of log K for the ternary complexes have been evaluated and discussed. Evaluation of the effects of ionic strength and temperature of the medium on the stability of the ternary system MII-tricine--alanine (MII=CoII, NiII, and CuII) has been studied. The thermodynamic parameters were calculated and discussed. 相似文献
16.
α-Amino cyclobutyl-, cyclopentyl-and cyclohexylphosphonic acids (13) were efficiently prepared from the related unsubstituted cycloalkylphosphonates (5), in three steps including electrophilic azidation of the corresponding lithiated carbanions, catalytic hydrogenation of the intermediate α-azido cycloalkyl-phosphonates (10) and acidic hydrolysis of the resulting α-amino cycloalkyl-phosphonates (12). 相似文献
17.
Rui Zhang Chenghua Zhang Jiamu Tan Yifan He Dan Zhuo Jingxuan Zhang Zhenzhen Luo Qiaoqiao Li Jiaying Yao Changqiang Ke Chunping Tang Yang Ye Shijun He Xiang Sheng Cangsong Liao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(7):e202318550
Noncanonical amino acids (ncAAs) containing tertiary alcohols are valuable as precursors of natural products and active pharmaceutical ingredients. However, the assembly of such ncAA scaffolds from simple material by C−C bond formation remains a challenging task due to the presence of multiple stereocenters and large steric hindrance. In this study, we present a novel solution to this problem through highly selective enzymatic decarboxylative aldol addition. This method allows for the streamlined assembly of multifunctionalized ncAAs with γ-tertiary alcohols from readily available materials, such as L-aspartatic acid and isatins, vicinal diones and keto esters. The modularity of electrophiles furnished four classes of ncAAs with decent efficiency as well as excellent site and stereocontrol. Computational modeling was employed to gain detailed insight into the catalytic mechanism and to provide a rationale for the observed selectivities. The method offers a single-step approach to producing multifunctionalized ncAAs, which can be directly utilized in peptide synthesis and bioactivity assessment. 相似文献
18.
Yang Jiang Ru-Gang Zhong Bo Tan Yan-Mei Li Yu-Fen Zhao 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):831-837
The reactivity of N -phosphoryl f -alanine differs from N -phosphoryl g -alanine and N -phosphoryl n -amino butyric acid enormously. N -phospho- f -alanine could self-activate to yield N -phosphopeptides either in aqueous or nonaqueous media, but not g - or n -amino acid analogues. The mechanism of the reaction is discussed. 相似文献
19.
Rui Fu Soon Mog So Dr. Alan J. Lough Prof. Dr. Jik Chin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(11):4365-4369
l to d conversion of unactivated α-amino acids was achieved by solubility-induced diastereomer transformation (SIDT). Ternary complexes of an α-amino acid with 3,5-dichlorosalicylaldehyde and a chiral guanidine (derived from corresponding chiral vicinal diamine) were obtained in good yield as diastereomerically pure imino acid salt complexes and were hydrolysed to obtain enantiopure α-amino acids. A combination of DFT computation, NMR spectroscopy, and crystal structure provide detailed insight into how two types of strong hydrogen bonds assist in rapid epimerization of the complexes that is essential for SIDT. 相似文献
20.
A. J. Aishah M.A. Hartini S. Normala A.M. Norhuda H. H. N Hanis H.M. Razif T. Sugeng 《天然气化学杂志》2007,16(3):273-277
Carbon dioxide fixation technique was developed as an alternative dechlorination method of chlorobenzenes.Electrolysis of chlorobenzene was carried out in a one-compartment cell fitted with an alu- minium anode and a platinum cathode.Electrolysis in N,N-dimethylformamide(DMF)solution contain- ing 0.1 M of tetrapropylammonium bromide(TPAB)at 0℃,100 ml/min of CO_2 flow rate and 120 mA/cm~2 of current density was found to be the optimum conditions of this electrocarboxylation,which gave 72% yield of benzoic acid from chlorobenzene.These conditions were then applied to 1,2-dichlorobenzene and 1,3-dichlorobenzene in order to convert them to their corresponding benzoic acids. 相似文献