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1.
The total synthesis of (±)-8,13-diaza-3-thia-A-norgona-1,5(10)-dien-17-one (XII) was achieved starting from 2-(2-thienyl) ethylamine (VII) and 3-succinimidopropionyl chloride (IX) as the A and D ring precursors respectively. 相似文献
2.
Kojima N Suga Y Hayashi H Yamori T Yoshimitsu T Tanaka T 《Bioorganic & medicinal chemistry letters》2011,21(19):5745-5749
The convergent synthesis of C35-fluorinated analogues of solamin, a mono-THF Annonaceous acetogenin, has been achieved by the Sonogashira coupling of the THF ring fragment and the fluorinated γ-lactone fragment. It was revealed that the number of fluorine atoms on the γ-lactone moiety affects the growth inhibitory activities against human cancer cell lines. 相似文献
3.
A novel cyclic hexamer of acetylated beta-glycosamino acid was synthesized and its conformation and molecular assembly formation was investigated. Variable temperature NMR study indicated that the cyclic hexapeptide took a C(3) symmetric conformation at room temperature, but at elevated temperatures a C(6) symmetric one, which was not due to averaging of the C(3) symmetric conformation, appeared. Computational geometry optimization showed that the C(6) symmetric conformation was a highly planar structure with amide groups orienting perpendicular to the ring plane. The cyclic hexa-beta-peptide formed rod-shaped crystals from an N,N-dimethyl formamide solution at elevated temperature. The optical microscopy observation with a sensitive tint plate under cross-nicol configuration and electron diffraction analysis of the crystals revealed that the cyclic hexa-beta-peptides were stacked one after the other to form a regular nanotube structure. 相似文献
4.
Elaine O’Reilly Lara Pes Yannick Ortin Helge Müller-Bunz Francesca Paradisi 《Amino acids》2013,44(2):511-518
Conformationally restricted amino acids are important components in peptidomimetics and drug design. Herein, we describe the synthesis of a novel, non-proteinogenic constrained delta amino acid containing a cyclobutane ring, cis-3(aminomethyl)cyclobutane carboxylic acid (ACCA). The synthesis of the target amino acid was achieved in seven steps, with the key reaction being a base induced intramolecular nucleophilic substitution. A small library of dipeptides was prepared through the coupling of ACCA with proteinogenic amino acids. 相似文献
5.
Six amphiphilic model conetworks of a new structure, that of cross-linked "in-out" star copolymers, were synthesized by the group transfer polymerization (GTP) of the hydrophobic monomer benzyl methacrylate (BzMA) and the ionizable hydrophilic monomer 2-(dimethylamino)ethyl methacrylate (DMAEMA) in a one-pot preparation. The synthesis took place in tetrahydrofuran (THF) using tetrabutylammonium bibenzoate (TBABB) as the catalyst, 1-methoxy-1-(trimethylsiloxy)-2-methyl-propene (MTS) as the initiator, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. Three heteroarm star-, two star block-, one statistical copolymer star-, and one homopolymer star-based networks were prepared. The synthesis of these star-based networks involved four to six steps, including the preparation of the linear (co)polymers, the "arm-first" and the "in-out" star copolymers, and finally the network. The precursors and the extractables were characterized using gel permeation chromatography (GPC) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The degrees of swelling (DSs) of all the networks were measured in THF, while the aqueous DSs were measured as a function of pH. The DSs at low pH were higher than those at neutral or high pH because of the protonation of the DMAEMA units and were found to be dependent on the structure of the network. The DSs in THF were higher than those in neutral water and were independent of the structure. Finally, DNA adsorption studies onto the networks indicated that the DNA binding was governed by electrostatics. 相似文献
6.
A total synthesis of the 12-membered ring natural macrolide, sporiolide B, was achieved from D-glucal in 17 steps with 4.8% overall yield. The required stereochemical configuration at C-3 and C-5 in sporiolide B was easily introduced by applying a Mitsunobu reaction on the chiral template D-glucal. Yamaguchi esterification and ring closing metathesis greatly improved the access to the target compound. 相似文献
7.
The total synthesis of (+)-macrosphelide A (1) (18.5% overall yield in 11 steps), (+)-macrosphelide C (2) (25% overall yield in 9 steps), (+)-macrosphelide E (3) (23.9% overall yield in 11 steps), (+)-macrosphelide F (4) (20% overall yield in 9 steps), and (+)-macrosphelide G (5) (22% overall yield in 9 steps) was achieved from a chemoenzymatic reaction product (4R,5S)-4-benzyloxy-5-hydroxy-2(E)-hexenoate 10. 相似文献
8.
Illán-Cabeza NA García-García AR Moreno-Carretero MN Martínez-Martos JM Ramírez-Expósito MJ 《Journal of inorganic biochemistry》2005,99(8):1637-1645
New complexes of rhenium(I) with some 5-nitrosopyrimidines with general formula [ReCl(CO)3L] have been prepared and characterized by elemental analysis, conductivity measurements, IR and 1H, 13C and 15N NMR spectroscopic methods. The complexes appear to be monomeric and the pyrimidine ligands act in a neutral form. The structure of [ReCl(CO)3(DANU)].CH3CN has been solved by X-ray diffraction. The coordination environment around the Re(I) may be described as a distorted octahedron in which the ligand behaves in a bidentate fashion through N5 and O4 atoms, making a five-membered chelate ring. The coordination sphere is completed with three carbonyl groups in fac-arrangement and one chlorine atom. The evaluation of the antiproliferative behavior against five human tumor cell lines (human breast cancer MCF-7 and EVSA-T, human neuroblastoma NB69, human glioma H4 and human bladder carcinoma cell line ECV) suggested a modulator behavior of cell growth at low concentrations due to their estrogenic-like characteristics. 相似文献
9.
Osaki T Obika S Harada Y Mitsuoka Y Sugaya K Sekiguchi M Roongjang S Imanishi T 《Nucleosides, nucleotides & nucleic acids》2007,26(8-9):1079-1082
We newly designed and synthesized a 2'-deoxy type trans-3',4'-bridged nucleic acid (trans-3',4'-BNA) analogues bearing a 4,7-dioxabicyclo[4.3.0]nonane structure. The synthesis of the trans-3',4'-BNA was carried out successfully from thymidine over 21 steps. The structure of trans-3',4'-BNA was confirmed by x-ray crystallographic analysis, indicating that the furanose ring has a typical S-type conformation with C(3')-exo puckering. 相似文献
10.
13C nuclear magnetic resonance detection of interactions of serine hydroxymethyltransferase with C1-tetrahydrofolate synthase and glycine decarboxylase complex activities in Arabidopsis. 总被引:3,自引:1,他引:2
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In C3 plants, serine synthesis is associated with photorespiratory glycine metabolism involving the tetrahydrofolate (THF)-dependent activities of the glycine decarboxylase complex (GDC) and serine hydroxymethyl transferase (SHMT). Alternatively, THF-dependent serine synthesis can occur via the C1-THF synthase/SHMT pathway. We used 13C nuclear magnetic resonance to examine serine biosynthesis by these two pathways in Arabidopsis thaliana (L.) Heynh. Columbia wild type. We confirmed the tight coupling of the GDC/ SHMT system and observed directly in a higher plant the flux of formate through the C1-THF synthase/SHMT system. The accumulation of 13C-enriched serine over 24 h from the GDC/SHMT activities was 4-fold greater than that from C1-THF synthase/SHMT activities. Our experiments strongly suggest that the two pathways operate independently in Arabidopsis. Plants exposed to methotrexate and sulfanilamide, powerful inhibitors of THF biosynthesis, reduced serine synthesis by both pathways. The results suggest that continuous supply of THF is essential to maintain high rates of serine metabolism. Nuclear magnetic resonance is a powerful tool for the examination of THF-mediated metabolism in its natural cellular environment. 相似文献
11.
A total synthesis of four flavans with a furan ring in different positions (1–4) was achieved successfully. The flavan was synthesized from flavanone by reduction and followed by deoxygenation steps. The synthesized compound 2 was confirmed as the naturally occurring moracinflavan E based on the comparison of their NMR spectral data. 相似文献
12.
A highly efficient synthetic method for the trans-tetrahydrofuran (THF) ring building block was established and the title compound was synthesized in 19 steps from trans-1,4-dichloro-2-butene via a convergent route with a Wittig reaction as the key step. 相似文献
13.
Molecular mechanism of AMD3100 antagonism in the CXCR4 receptor: transfer of binding site to the CXCR3 receptor 总被引:7,自引:0,他引:7
Rosenkilde MM Gerlach LO Jakobsen JS Skerlj RT Bridger GJ Schwartz TW 《The Journal of biological chemistry》2004,279(4):3033-3041
AMD3100 is a symmetric bicyclam, prototype non-peptide antagonist of the CXCR4 chemokine receptor. Mutational substitutions at 16 positions located in TM-III, -IV, -V, -VI, and -VII lining the main ligand-binding pocket of the CXCR4 receptor identified three acid residues: Asp(171) (AspIV:20), Asp(262) (AspVI:23), and Glu(288) (GluVII:06) as the main interaction points for AMD3100. Molecular modeling suggests that one cyclam ring of AMD3100 interacts with Asp(171) in TM-IV, whereas the other ring is sandwiched between the carboxylic acid groups of Asp(262) and Glu(288) from TM-VI and -VII, respectively. Metal ion binding in the cyclam rings of AMD3100 increased its dependence on Asp(262) and provided a tighter molecular map of the binding site, where borderline mutational hits became clear hits for the Zn(II)-loaded analog. The proposed binding site for AMD3100 was confirmed by a gradual build-up in the rather distinct CXCR3 receptor, for which the compound normally had no effect. Introduction of only a Glu at position VII:06 and the removal of a neutralizing Lys residue at position VII:02 resulted in a 1000-fold increase in affinity of AMD3100 to within 10-fold of its affinity in CXCR4. We conclude that AMD3100 binds through interactions with essentially only three acidic anchor-point residues, two of which are located at one end and the third at the opposite end of the main ligand-binding pocket of the CXCR4 receptor. We suggest that non-peptide antagonists with, for example, improved oral bioavailability can be designed to mimic this interaction and thereby efficiently and selectively block the CXCR4 receptor. 相似文献
14.
The asymmetric synthesis of an aryltetralin lignan, (-)-lintetralin, was achieved with an overall yield of 29% with seven steps. Key features of the synthesis are an asymmetric Strecker reaction, a diastereoselective Michael addition of the lithiated amino nitrile product to 5H-furan-2-one, and an intramolecular carbocationic cyclization to provide the desired ring skeleton with the correct configuration. 相似文献
15.
《Inorganica chimica acta》1986,125(3):159-166
This paper describes the synthesis of compounds of Ni(II) with uracil, uridine and the nucleotides 5′UMP, 5′CMP, 5′GMP and 5′IMP, and their characterization, carried out by elemental analysis, by studying the infrared spectra, diffuse reflectance and conductivity measurement.In the complexes of NiURA (and NiURD) with acetate, direct coordination of the metal ion to the C4O group of the pyrimidine ring is inferred from the changes observed on the infrared spectrum of the corresponding bands at vCO. The variations in frequency of the vCOO symmetric and asymmetric bands of the acetate group together with the conductivity and reflectance results seem to indicate the dimer structure of the compounds.In the compounds of NiURA (and NiURD) with ethylenediamine indirect bonding of Ni(II)to the pyrimidine ring is inferred, probably established through hydrogen bonds involving the C4O groups in the base or nucleoside and the −NH2 groups in the ethylenediamine.In the complexes of Ni-nucleotide, bonding seems to occur through the heterocyclic ring (C4O for 5′UMP, N(3) for 5′CMP, N(7) for 5′GMP and 5′IMP) together with additional interactions through the phosphate group. 相似文献
16.
Tsumoto K Yokota A Tanaka Y Ui M Tsumuraya T Fujii I Kumagai I Nagumo Y Oguri H Inoue M Hirama M 《The Journal of biological chemistry》2008,283(18):12259-12266
To address how proteins recognize polyether toxin compounds, we focused on the interaction between the ABC ring compound of ciguatoxin 3C and its specific antibody, 1C49. Surface plasmon resonance analyses indicated that Escherichia coli-expressed variable domain fragments (Fv) of 1C49 had the high affinity constants and slow dissociation constants typical of antigen-antibody interactions. Linear van't Hoff analyses suggested that the interaction is enthalpy-driven. We resolved the crystal structure of 1C49 Fv bound to ABC ring compound of ciguatoxin 3C at a resolution of 1.7A. The binding pocket of the antibody had many aromatic rings and bound the antigen by shape complementarity typical of hapten-antibody interactions. Three hydrogen bonds and many van der Waals interactions were present. We mutated several residues of the antibody to Ala, and we used surface plasmon resonance to analyze the interactions between the mutated antibodies and the antigen. This analysis identified Tyr-91 and Trp-96 in the light chain as hot spots for the interaction, and other residues made incremental contributions by conferring enthalpic advantages and reducing the dissociation rate constant. Systematic mutation of Tyr-91 indicated that CH-pi and pi-pi interactions between the aromatic ring at this site and the antigen made substantial contributions to the association, and van der Waals interactions inhibited dissociation, suggesting that aromaticity and bulkiness are critical for the specific recognition of polyether compounds by proteins. 相似文献
17.
Stolz M Peters-Wendisch P Etterich H Gerharz T Faurie R Sahm H Fersterra H Eggeling L 《Applied and environmental microbiology》2007,73(3):750-755
The amino acid L-serine is required for pharmaceutical purposes, and the availability of a sugar-based microbial process for its production is desirable. However, a number of intracellular utilization routes prevent overproduction of L-serine, with the essential serine hydroxymethyltransferase (SHMT) (glyA) probably occupying a key position. We found that constructs of Corynebacterium glutamicum strains where chromosomal glyA expression is dependent on Ptac and lacIQ are unstable, acquiring mutations in lacIQ, for instance. To overcome the inconvenient glyA expression control, we instead considered controlling SHMT activity by the availability of 5,6,7,8-tetrahydrofolate (THF). The pabAB and pabC genes of THF synthesis were identified and deleted in C. glutamicum, and the resulting strains were shown to require folate or 4-aminobenzoate for growth. Whereas the C. glutamicum DeltasdaA strain (pserACB) accumulates only traces of L-serine, with the C. glutamicum DeltapabABCDeltasdaA strain (pserACB), L-serine accumulation and growth responded in a dose-dependent manner to an external folate supply. At 0.1 mM folate, 81 mM L-serine accumulated. In a 20-liter controlled fed-batch culture, a 345 mM L-serine accumulation was achieved. Thus, an efficient and highly competitive process for microbial l-serine production is available. 相似文献
18.
Sung Ryeol Park Ah Reum Han Yeon-Hee Ban Young Ji Yoo Eun Ji Kim Yeo Joon Yoon 《Applied microbiology and biotechnology》2010,85(5):1227-1239
Polyketides comprise one of the major families of natural products. They are found in a wide variety of bacteria, fungi, and
plants and include a large number of medically important compounds. Polyketides are biosynthesized by polyketide synthases
(PKSs). One of the major groups of polyketides are the macrolides, the activities of which are derived from the presence of
a macrolactone ring to which one or more 6-deoxysugars are attached. The core macrocyclic ring is biosynthesized from acyl-CoA
precursors by PKS. Genetic manipulation of PKS-encoding genes can result in predictable changes in the structure of the macrolactone
component, many of which are not easily achieved through standard chemical derivatization or total synthesis. Furthermore,
many of the changes, including post-PKS modifications such as glycosylation and oxidation, can be combined for further structural
diversification. This review highlights the current state of novel macrolide production with a focus on the genetic engineering
of PKS and post-PKS tailoring genes. Such engineering of the metabolic pathways for macrolide biosynthesis provides attractive
alternatives for the production of diverse non-natural compounds. Other issues of importance, including the engineering of
precursor pathways and heterologous expression of macrolide biosynthetic genes, are also considered. 相似文献
19.
The coordination of the ligands bis(pyrazol-1-yl)acetate (bpza) and bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza) to rhenium(VII) was investigated. The compounds [(bpza)ReO3] and [(bdmpza)ReO3] were synthesised by reaction of bpza and bdmpza with perrhenic acid with the loss of one water molecule. The new complex [(bdmpza)ReO3] was characterised by single-crystal X-ray analysis. It has a monomeric structure with a distorted octahedron for the [N,N,O]ReO3 central core. 相似文献
20.
ABSTRACTThe total synthesis of peramine, a natural product isolated from an endophytic fungi, has been achieved in four steps and 34% overall yield from known compounds. The key step was the one-pot construction of the pyrrolopyrazinone ring from pyrrole amide and propargyl bromide. The preparation of peramine-d4 as an internal standard for quantitative analysis by MS is also described. 相似文献