Breaking the C3-symmetry of chiral tripodal oxazolines: enantio-discrimination of chiral organoammonium ions

[structure: see text] A phenylglycinol-derived tripodal oxazoline with C1-symmetry (C1-PhBTO) was synthesized, and its enantioselective recognition behavior toward alpha-chiral primary organoammonium ions was studied. The C1-PhBTO receptor showed higher selectivity with an opposite sense of enantio-discrimination compared to other C1-symmetric analogues examined but lower selectivity with the same sense of enantioselection compared to its C3-symmetric analogue. Binding studies indicated that the C1-symmetric receptors, particularly C1-PhBTO, interact with the guests in a 2:1 host-guest complex mode in stark contrast to its C3-symmetric analogues.     

Synthesis and an evaluation of the bioactivity of the C-glycoside of pseudopterosin A methyl ether

The Suzuki-Miyaura cross-coupling protocol was applied to the synthesis of 1a, the C-glycoside analogue of PsA methyl ether. This marks the first construction of a C-glycoside for this class of marine natural products, thereby offering an opportunity to compare its bioactivity to the natural substances. Its activity profile resembled that of PsA (1) and PsA O-methyl ether (1b) when assayed for its anti-inflammatory activity and its ability to inhibit phagocytosis. We conclude that the intact structure is present when a pseudopterosin expresses its anti-inflammatory and phagocytosis inhibitory properties and that they are, therefore, not likely to be prodrugs. Results show that 1a is an effective binding agent toward the A2A and A3 adenosine receptors, displaying IC50 values of 20 and 10 microM, respectively.     

Syntheses of di- and tetrahydropyrroles

Dehydration of 2,3,3-trimethyl-2-hydroxy-5-pyrrolidone and its 1-methyl and 1-phenyl derivatives gave 3,3-dimethyl-2-methylene-5-pyrrolidone and its 1-methyl and 1-phenyl analogs. Their alcoholysis and hydration were studied.     

Synthesis of 3,4-benzo-1-chloro-1-methyl-1-silacyclohexane and some of its derivatives

Conclusions 3,4-Benzo-1-chloro-1-methyl-1-silacyclohexane was synthesized by intramolecular cyclization of vinylbenzylmethylchlorosilane; its structure was demonstrated, and the properties of some of its derivatives were investigated.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2733–2737, December, 1969.     

Allosteric regulation of the conformational dynamics of a cavitand receptor

[reaction: see text] Inspired by allostery in nature, we synthesized cavitand 1 and investigated regulation of its conformational dynamics. Quantitative 1H NMR studies have revealed that the rate of the conformational isomerization of 1 can be modulated using the external addition of acid. As 1 maintains its vase-like conformation in an acidic environment, ample opportunities for controlling the kinetics of molecular recognition, and thus reactivity, in this and related receptors have arisen.     

Reactions of Bis(p-methoxyphenyl)trisulfane and Its Oxides with Dimethyldioxirane and (Trifluoromethyl)methyldioxirane

The reactions of dimethyldioxirane and (trifluoromethyl)methyldioxirane with bis(p-methoxyphenyl)trisulfane, its 1-oxide, its 2-oxide, and its 1,1-dioxide derivatives have been investigated. The reactions were followed by careful monitoring of the methoxy region of the (1)H NMR spectra and where possible by doping with authentic samples of the products. The decomposition of labile intermediates and products was investigated. A new mechanism for the rearrangement of a trisulfane 1,3-dioxide to a trisulfane 1,1-dioxide is proposed.     

Comparison of the Catalytic Activities of Three Isozymes of Carnitine Palmitoyltransferase 1 Expressed in COS7 Cells

The enzyme carnitine palmitoyltransferase 1 (CPT1) catalyzes the transfer of an acyl group from acyl-CoA to carnitine to form acylcarnitine, and three isozymes of it, 1a, 1b, and 1c, have been identified. Interestingly, the 1c isozyme was reported to show no enzymatic activity, but it was not clearly demonstrated whether this inactivity was due to its dysfunction or due to its poor expression. In the present study, we (a) expressed individual CPT1 isozymes in COS7 cells, (b) evaluated quantitatively their expression levels by Western blotting using the three bacterially expressed CPT1 isozymes as standards, and (c) evaluated their catalytic activities. With these experiments, we successfully demonstrated that the absence of the enzymatic activity of the 1c isozyme was due to its dysfunction. In addition, experiments on the preparation of standard CPT1 isozymes revealed that the 1c isozyme did not show the standard relationship between migration in an SDS–PAGE gel and molecular size. We further tried to determine why the 1c isozyme was inert by preparing chimeric CPT1 between 1a and 1c, but no clear conclusion could be drawn because one of the chimeric CPT1s was not sufficiently expressed.     

Inhibition of polo-like kinase 1 by blocking polo-box domain-dependent protein-protein interactions

The serine/threonine kinase Polo-like kinase 1 (Plk1) is overexpressed in many types of human cancers, and has been implicated as an adverse prognostic marker for cancer patients. Plk1 localizes to its intracellular anchoring sites via its polo-box domain (PBD). Here we show that Plk1 can be inhibited by small molecules which interfere with its intracellular localization by inhibiting the function of the PBD. We report the natural product thymoquinone and, especially, the synthetic thymoquinone derivative Poloxin as inhibitors of the Plk1 PBD. Both compounds inhibit the function of the Plk1 PBD in vitro, and cause Plk1 mislocalization, chromosome congression defects, mitotic arrest, and apoptosis in HeLa cells. Our data validate the Plk1 PBD as an anticancer target and provide a rationale for developing thymoquinone derivatives as anticancer drugs.     

Catalytic hydrogenation of methyl esters of some 1h-pyrazoline-3-carboxylic acids

Hydrogenation over Raney nickel of the methyl ester of 1H-pyrazoline-3-carboxylic acid and also of its 4-phenyl and 5-methoxycarbonyl-substituted analogs, leads respectively to 3-aminopyrrolidin-2-one, its 4-phenyl- and 5-methoxycarbonyl derivatives, predominantly to the trans isomer. Under the same conditions 1-amino-4-methoxycarbonylpyrrolidin-2-one was obtained from 3,4-di(methoxycarbonyl)-1H-pyrazoline, but 3,4,5-tri(methoxycarbonyl)-1H-pyrazoline did not react.     

A redox-active tri-star molecule: merging of TTF and HAT chemistry

A planar pi-conjugated heteroaromatic molecule 1 has been synthesized and fully characterized; it combines two characteristics, a charge-transfer transition originating from its inherent donor-acceptor nature in its neutral state and an intervalence charge-transfer transition in its 1(2+) mixed-valence state.     

Fluorocarbon derivatives of nitrogen. Part IV [1]. Perfluoro-1-azacyclohex-1-ylcaesium

Caesium fluoride combined with perfluoro-1-azacyclohexene in acetonitrile to yield perfluoro-1-azacyclohex-1-ylcaesium (1), which was characterised by ¹⁹F n.m.r. spectroscopy and by treatment with iodomethane to give 2,2,3,3,4,4,5,5,6,6-decafluoro-1-methyl-1-azacyclohexane (2). Attempts to derivatize the caesium salt with chlorotrimethylsilane provided fluorotrimethylsilane, perfluoro-[1-(1-azacyclohex-1-en-2-yl)-1-azacyclohexane] (4), and 2-chloro-3,3,4,4,5,5,6,6-octafluoro-1-azacyclohexene (5); information on the course of this reaction was obtained through experiments in which perfluoro-1-azacyclohexene was shown to undergo conversion into its chloro-analogue (5) and its dimer (4) $\text{via}$ treatment with chlorotrimethylsilane and fluoride ion, respectively. Aluminium chloride also converts perfluoro-1-azacyclohexene into its chloro-analogue (5).     

Catalytic Properties of Dendrtic PAMAMSA-Zinc Complexes in the Oxidation of Cyclohexene

Denrdrimer has many special properties different from ordinary polymers [1]. In the last few years, much of the research work concerning this kind of compound focuses on its synthesis and physical properties. As to its catalytic properties, several of the reports have been published [2]. We report here a new 1method of using the well-known dendrimer PAMAM[3] (polyamidoamine, G=1～4) and its modified product as the ligands for the coordination of Zn2+ to obtain some dendritic complexes. When these complexes was employed as the catalysts for the oxidation of cyclohexene, the results afforded us some exciting information     

Synthesis of a calix[4]arene derivative for isolation of a stable cation radical salt for use as a colorimetric sensor of nitric oxide

We have designed and synthesized a modified calixarene derivative (1) that allows, for the first time, the isolation of a stable cation radical salt that binds a single molecule of nitric oxide deep within its cavity with remarkable efficiency (KNO >108 M-1), as demonstrated by isolation of a crystalline complex [1, NO]+ and its characterization by X-ray crystallography as well as by optical spectroscopy. Furthermore, the ready accessibility of the calixarene cation radical will allow the exploration of its use for developing efficient sensing devices for nitric oxide based on the accompanied color changes.     

Structural control of the photoluminescence of silole regioisomers and their utility as sensitive regiodiscriminating chemosensors and efficient electroluminescent materials

We synthesized a group of silole regioisomers 1(x,y), whose photoluminescence varied dramatically with its regiostructure. By internally hindering the intramolecular rotation, we succeeded in creating a novel silole (1(3,4)) that is strongly luminescent in solutions and whose fluorescence quantum yield in acetone is as high as 83%. We revealed that 1(3,4) was a sensitive chemosensor capable of optically discriminating nitroaromatic regioisomers of p-, o-, and m-nitroanilines. Against general belief, crystal formation of 1(2,4) blue-shifted its emission color and boosted its emission efficiency. The light-emitting diode based on the crystal of 1(2,4) emitted a strong blue light (464 nm) in a high current efficiency (5.86 cd/A).     

吲哚啉螺吡喃化合物光致变色性能的研究及在生物细胞成像中的应用

吲哚啉螺吡喃是一种重要的光致变色化合物,由于具有良好的变色回复性、抗疲劳性而得到广泛的关注.本文合成了1′-羟乙基-3′,3′-二甲基吲哚啉-6-硝基螺吡喃,研究了该化合物在紫外-可见光交替照射下紫外吸收强度的变化,并测试了光照前后化合物的荧光光谱.在开环态时,化合物具有优良的荧光性能,可以成功应用于细胞成像,在活细胞中可获得清晰的荧光成像图,同时也可以发挥螺吡喃光致变色可循环、耐疲劳等优势.     

Synthesis of cyclic prodrugs of Aggrastat and its analogue with a modified phenylpropionic acid linker

[structure: see text] The objective of this work was to synthesize cyclic prodrugs 1a and 1b from Aggrastat 2a and its analogue 2b, respectively, to improve their membrane permeation. Cyclic prodrugs 1a and 1b were formed using an ester bond between the -COOH group of Aggrastat or its analogue and the phenylpropionic acid linker 3 and an amide bond between the piperidinylamine and the -COOH group of the linker 3, respectively, as outlined in Scheme 4.     

Evaluation and Prediction of Joint Toxicity of Aniline and Its Derivatives to Photobacterium Phosphoreum

The single toxicity of aniline and its derivatives and the joint toxicity of the binary mixtures of aniline and each of its derivatives with the toxic unit ratios of 1:1, 1:4, 4:1 to photobacterium phosphoreum were determined, respectively. The toxic unit and the additive index were used to evaluate the joint toxicity. The result shows that the joint toxicity of each of the binary mixtures of aniline and each of its derivatives is mainly simple addition of the toxicities of the two compounds. On this basis, the QSAR equation that was built from the single toxicity of aniline was used to predict the toxicity of the derivatives of aniline in the mixtures. Good agreement between the predicted and experimental values was found with R^2=0. 921.     

Formation of para-substituted triphenylboroxines: a computational study

Density functional theory (B3LYP//6-311+G) calculations including Poisson-Boltzmann (PB) implicit solvent were applied to study the relative stability of triphenylboroxine (PhBO)(3) with respect to its phenylboronic acid monomers. In solution, formation of (PhBO)(3) is thermodynamically unfavorable; however, addition of an amine base results in the formation of stable 1:1 adducts of (PhBO)(3) and amine. Formation of 1:2 adducts is energetically unfavorable. We find that adduct formation is more exothermic than cleavage of the boroxine ring back to its monomers. pi-Electron-withdrawing groups in the para-position of the phenyl ring destabilize the boroxine ring with respect to its monomers. However, para-substituents that are net electron-withdrawing are found to stabilize formation of the 1:1 adduct.     

The synthesis of compounds with antithyroid activity

N-Acyl derivatives of imidazole-2-thione and its derivatives were obtained by the reaction of imidazole2-thione and its derivatives with aliphatic anhydrides and with benzoyl chloride in pyridine. The hydrochlorides of 1-methyl and 4 (5)-methyl-S benzoylimidazole-2-thione were obtained by the reaction of 1-methyl- and 4 (5)-methylimidazole-2-thione with benzoyl chloride in dry ethanol. The acylation of imidazole-2-thione and of some of its derivatives was investigated with the aid of their IR spectra, and the importance of the medium in the formation of N- and S -acyl derivatives was shown, as well as the possibility of the migration of substituants from the S — to the N atom under its influence.For part VI see [1].     

Enolization of Delta9,10-Octal-1-one: relative stabilities of s-trans exocyclic and s-cis endocyclic dienolates

Delta9,10-Octal-1-one (3,4,5,6,7,8-hexahydro-1(2H)-naphthalenone, 1) can be deprotonated at either of its two gamma positions to form the isomeric exocyclic (1-exo) and endocyclic (1-endo) dienolates. The rate of deuterium exchange for the gammaexo protons of 1 (1.6(+/-0.1)x10(-4) M-1 s-1) is 12-fold faster than that for those at the gammaendo position (1.38(+/-0.08)x10(-5) M-1 s-1). Assuming a Br?nsted coefficient of 0.5, these results indicate that the exocyclic dienolate is 3.0 kcal/mol more stable than its endocyclic counterpart.