Synthesis and antimicrobial activity of 2-alkenylchroman-4-ones, 2-alkenylthiochroman-4-ones and 2-alkenylquinol-4-ones

2-Alkenylchroman-4-ones, 2-alkenylthiochroman-4-ones, and 2-alkenylquinol-4-ones were prepared with very good regioselectivity by Me3SiOTf-mediated conjugate addition of alkenylmagnesium bromides and alkenyllithium compounds to chromones thiochromones, and quinol-4-ones. A number of products exhibit a considerable antimicrobial activity. The best activity, with respect to the spectrum of antimicrobial activity, was observed for 2-vinylchroman-4-ones containing an unsubstituted vinyl group and a chloride group located at the chromanone moiety.     

New C-nucleoside analogs by dehydration of 1-benzyl-4,5,6,7-tetrahydro-6,6-dimethyl-2-(d-galacto-pentitol-1-yl)-indol-4-one

The reaction between 2-(benzylamino)-2-deoxy-d-glycero-l-gluco-heptose and 5,5-dimethyl-1,3-cyclohexanedione yields 1-benzyl-4,5,6,7-tetrahydro-6,6-dimethyl-2-(d-galacto-pentitol-1-yl)-indol-4-one (2). Acid-catalyzed, intramolecular dehydration of 2 under kinetically controlled conditions gives 1-benzyl-4,5,6,7-tetrahydro-2-α-d-lyxofuranosyl-6,6-dimethylindol-4-one; the anomeric configuration of this compound is only suggested. When the dehydration reaction is conducted under thermodynamically controlled conditions, it produces a 1:1 mixture of the α- and β-d-lyxopyranosyl compounds. The structures of the new compounds were elucidated by chemical and physical methods.     

Preparation of optically active 4-allylazetidin-2-ones. An access to carbacephams

Transesterification of 4-allyl-1-hydroxymethylazetidin-2-ones using vinyl acetate in the presence of the lipase from Pseudomonas cepacia led to the corresponding (R)-acetates and the remaining (S)-alcohols in high yields and excellent ee's (E: 32–71). Subsequent reaction with BF₃-Et₂O can lead to the carbacepham framework.     

2,3-diarylpyran-4-ones: a new series of selective cyclooxygenase-2 inhibitors

A new series of cyclooxygenase-2 (COX-2) inhibitors with gamma-pyrone as central scaffold unit has been synthesized and their biological activities were evaluated against cyclooxygenase inhibitory activity. The changes of physical properties of the molecules were performed according to the medicinal chemistry principles and moderate oral anti-inflammatory activity was obtained with this series of inhibitors.     

Stereoselective intramolecular cyclization to 4-(hydroxymethyl)-3-(1H-indolyl)oxazolidin-2-ones

A simple high-yield three-steps route to optically active 4-hydroxymethyl-3-(1H-indolyl)oxazolidin-2-ones from (S)-glycidol is described. The key intermediates (R)-oxiran-2-ylmethyl 1H-indol-4/-5-ylcarbamates are obtained in high yields from (S)-glycidol. These are readily transformed to oxazolidin-2-ones, very interesting building blocks in drug synthesis.     

Inhibition of human chymase by 2-amino-3,1-benzoxazin-4-ones

A series of 2-sec.amino-4H-3,1-benzoxazin-4-ones was evaluated as acyl-enzyme inhibitors of human recombinant chymase. The compounds were also assayed for inhibition of human cathepsin G, bovine chymotrypsin, and human leukocyte elastase. Introduction of an aromatic moiety into the 2-substituent resulted in strong inhibition of chymase, cathepsin G, and chymotrypsin. Extension of the N(Me)CH2Ph substituent by one methylene unit was unfavourable to inhibit these proteases. Towards chymase, 2-(N-benzyl-N-methylamino)-4H-3,1-benzoxazin-4-one (32) and 2-(N-benzyl-N-methylamino)-6-methyl-4H-3,1-benzoxazin-4-one (33) were found to exhibit Ki values of 11 and 17 nM, respectively, and form stable acyl-enzymes with half-lives of 53 and 25 min, respectively. Benzoxazinone 33 also inhibited the human chymase-catalyzed formation of angiotensin 11 from angiotensin I.     

Analgesic activity of new synthetic thiazolidine-4-ones derivatives

Ten new synthetic thiazolidine-4-ones derivatives (5 chlorothiazolidine-4-ones, 3 methoxythiazolidine-4-ones and 2 hydoxythiazolidine-4-ones) having different substituents at R1, R2 and R3 were evaluated for their analgesic activity using different animal models and their structure activity relationship was also elucidated. Chlorothiazolidine-4-ones and methoxythiazolidine-4-ones exhibited analgesic activity in tail flick test, tail immersion test and acetic acid writhing test. C-III (chloride substituents at R1 and R2) produced higher latencies than any other compounds in tail flick test and C-I (no substituents at R1 and R2) was not effective in acetic acid writhing test. Hydroxythiazolidine-4-ones did not show analgesic activity in any of the animal models used. In conclusion, the character of substituents at R3 of thiazolidine moiety position may have an effect on the analgesic activity of thiazolidine-4-ones and either chloride or methoxy substitution may be necessary to produce analgesic activity. Two chloride substituents in a compound may increase the central analgesic activity of the compound.     

The uncoupling of respiratory-chain phosphorylation by 4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazole

1. 30mmum-4,5,6,7-Tetrachloro-2-trifluoromethylbenzimidazole (TTFB) uncouples respiratory-chain phosphorylation. The respiration rate of uncoupled mitochondria is significantly greater than the state 3 rate. Neither added orthophosphate nor ATP is required to sustain this rate. The oligomycin- and octylguanidine-induced inhibitions of respiration are relieved by uncoupling concentrations of TTFB. 2. Uncoupling concentrations of TTFB elicit a high adenosinetriphosphatase activity and inhibit the ATP-dependent succinate-linked reduction of NAD catalysed by submitochondrial particles from ox-heart mitochondria. 3. The action of TTFB is similar to that of 2,4-dinitrophenol. Evidence is presented which shows that it is the anionic forms of benzimidazoles and imidazoles, having the negative charge localized on the ring nitrogen atom, which are the effective uncoupling agents.     

Synthesis of isochroman-4-ones and 2H-pyran-3(6H)-ones by gold-catalyzed oxidative cycloalkoxylation of alkynes

Gold catalysis is a convenient tool to oxidatively functionalize alkyne into a range of valuable compounds. In this article, we report a new access to isochroman-4-one and 2H-pyran-3(6H)-one derivatives that involves a gold-catalyzed oxidative cycloalkoxylation of an alkyne in the presence of a pyridine N-oxide. The reaction proceeds under mild conditions, is relatively efficient and exhibits a high functional group compatibility.     

Derivatives of imidazotriazine and pyrrolotriazine C-nucleosides as potential new anti-HCV agents

Previous investigations identified 2′-C-Me-branched ribo-C-nucleoside adenosine analogues, 1, which contains a pyrrolo[2,1-f][1,2,4]triazin-4-amine heterocyclic base, and 2, which contains an imidazo[2,1-f][1,2,4]triazin-4-amine heterocyclic base as two compounds with promising anti-HCV in vitro activity. This Letter describes the synthesis and evaluation of a series of novel analogues of these compounds substituted at the 2-, 7-, and 8-positions of the heterocyclic bases. A number of active new HCV inhibitors were identified but most compounds also demonstrated unacceptable cytotoxicity. However, the 7-fluoro analogue of 1 displayed good potency with a promising cytotherapeutic margin.     

Polysubstituted 2H-pyran-2-ones: A new class of hepatoprotective agents

The synthesis and hepatoprotective activity of 6-aryl-3-substituted-4-methylthio-2H-pyran-2-ones (3, 5, 7) and the corresponding 2-thiones (6), 6-aryl-4-methylthio-2H-pyran-2-ones (4) and 6-aryl-3-carbethoxy-5-cyano-4-methylthio-2H-pyran-2-ones are described.     

Modification of valinomycin-mediated bilayer membrane conductance by 4,5,6,7-tetrachloro-2-methylbenzimidazole

Summary The compound, 4,5,6,7-tetrachloro-2-methylbenzimidazole (TMB), has been found to markedly modify the steady-state valinomycin-mediated conductance of potassium (K⁺) ions through lipid bilayer membranes. TMB alone does not contribute significantly to membrane conductance, being electrically neutral in solution. In one of two classes of experiments (I), valinomycin is first added to the aqueous phases then changes of membrane conductance accompanying stepwise addition of TMB to the water are measured. In a second class of experiments (II), valinomycin is added to the membrane-forming solution, follwed by TMB additions to the surrounding water. In both cases membrane conductance shows an initial increase with increasing TMB concentration which is more pronounced at lower K⁺ ion concentration. At TMB concentrations in excess of 10^–5 m, membrane conductance becomes independent of K⁺ ion concentration, in contrast to the linear dependence observed at TMB concentrations below 10^–7 m. This transition is accompanied by a change of high field current-voltage characteristics from superlinear (or weakly sublinear) to a strongly sublinear form. All of these observations may be correlated by the kinetic model for carriermedicated transport proposed by Läuger and Stark (Biochim. Biophys. Acta 211:458, 1970) from which it may be concluded that valinomycin-mediated ion transport is limited by back diffusion of the uncomplexed carrier at high TMB concentrations. Experiments of class I reveal a sharp drop of conductance at high (>10^–5 m) TMB concentration, not seen in class II experiments, which is attributed to blocked entry of uncomplexed carrier from the aqueous phases. Valinomycin initially in the membrane is removed by lateral diffusion to the surrounding torus. The time dependence of this removal has been studied in a separate series of experiments, leading to a measured coefficient of lateral diffusion for valinomycin of 5×10^–6 cm²/sec at 25°C. This value is about two orders of magnitude larger than the corresponding coefficient for transmembrane carrier diffusion, and provides further evidence for localization of valinomycin in the membrane/solution interfaces.     

Benzenesulfonamide derivatives of 2-substituted 4H-3,1-benzoxazin-4-ones and benzthiazin-4-ones as inhibitors of complement C1r protease

A series of 2-sulfonyl-4H-3,1-benzoxazinones was prepared that inhibit C1r protease in vitro. Several compounds were found to be selective for C1r verses the related serine protease trypsin. Selected compounds demonstrated functional activity in a hemolysis assay.     

Preparation of various C-2 branched carbohydrates using intramolecular radical reactions

A new and efficient method for the facile synthesis of C-2 branched carbohydrates has been developed using an intramolecular radical cyclization fragmentation reaction. The desired C-2 branched glucopyranosides were isolated in 40-84% yield. Additionally, an unexpected furanoside was obtained from a tributyltin iodide-promoted rearrangement of the radical intermediate. The C-2 formyl glycal was also isolated in good yield using tris(trimethylsilyl)silane (TTMSS) as the reducing agent. This method was extended to synthesize a beta C-2 branched glucopyranoside, a C-2 branched galactoside and a C-2 cyano glucopyranoside.     

乳酸（酯）脱水制备丙烯酸（酯）研究进展

从植物淀粉发酵制备乳酸已经获得工业化生产,开发经济可行的生物质路线制备丙烯酸是生物资源利用的重要研究方向之一。因此,对近年来用乳酸脱水制备丙烯酸的研究工作进行了综述、分析和归纳,对应用前途可能性较大的几种新型的催化材料和方法进行了探索和讨论。     

Synthesis of 4-azasteroids by an intramolecular Ugi reaction

In this paper we report the use of an intramolecular Ugi reaction to synthesize new 4-azacholestanes diversely substituted both at N-4 and C-5. Both the scope and the stereochemical outcome of this approach were studied by varying the nature of the components necessary for this multicomponent reaction. In sight of our results we concluded that this methodology can be applied to obtain 4-azasteroids targeted to find new biologically active compounds.     

Preparation of 1-aryl-2-(benzylthio)-(1,2-dideoxy-d-glycero-β-l-gluco-heptofurano)[1,2-d]-2-imidazolines,and new,acyclic C-nucleosides of the imidazole

The reaction of 1-aryl-(1,2-dideoxy-d-glycero-β-l-gluco-heptofurano)[1,2-d]imidazolidine-2-thiones with benzyl chloride and an equivalent amount of sodium hydrogencarbonate yields 1-aryl-2-(benzylthio)-(1,2-dideoxy-d-glycero-β-l-gluco-heptofurano)[1,2-d]-2-imidazolines (2). If the reaction is carried out in the absence of sodium hydrogencarbonate, the 1-aryl-2-(benzylthio)-4-(d-galacto-pentitol-1-yl)imidazoles are obtained. These compounds are also obtained by acid-catalyzed isomerization of compounds 2.     

Synthesis of new bioactive venlafaxine analogs: novel thiazolidin-4-ones as antimicrobials

A one-pot, three-component, microwave irradiated and conventional solution-phase synthesis of bioactive venlafaxine analogs such as 2,3-disubstituted-1,3-thiazolidin-4-ones 3a-j under mild conditions and their characterization are reported. The novel thiazolidin-4-ones, 3-(2-(1-hydroxycyclohexyl)-2-(4-methoxyphenyl)ethyl)-2-phenyl-thiazolidin-4-one 3a, 2-(2,6-difluorophenyl)-3-(2-(1-hydroxycyclohexyl)-2-(4-methoxyphenyl)ethyl)thiazolidin-4-one 3c, and 2-(furan-2-yl)-3-(2-(1-hydroxycyclohexyl)-2-(4-methoxyphenyl)ethyl)thiazolidin-4-one 3i, were characterized by the single crystal X-ray diffraction method. The cyclohexane ring of all the three molecules is in chair conformation. All the synthesized compounds were screened for their efficacy as antimicrobials in vitro by the disk diffusion and microdilution method against pathogenic strains such as Bacillus subtilis, Escherichia coli, Pseudomonas fluorescens, Xanthomonas campestris pvs, Xanthomonas oryzae, Aspergillus niger, Aspergillus flavus, Fusarium oxysporum, Trichoderma species, and Fusarium monaliforme species. Among these compounds 3c, 3j, 3g, 3d, and 3e showed potent antimicrobial activity, when compared to standard drugs.     

N/C-4 substituted azetidin-2-ones: synthesis and preliminary evaluation as new class of antimicrobial agents

A series of 3-chloro-4-(3-methoxy-4-acetyloxyphenyl)-1-[3-oxo-3-(phenylamino)propanamido] azetidin-2-ones 3a-g and 3-chloro-4-[2-hydroxy-5-(nitro substituted phenylazo)phenyl]-1-phenylazetidin-2-ones 6a-h were synthesized using appropriate synthetic route. Structures of all the synthesized compounds were established on the basis of elemental analysis and spectroscopic data. The antimicrobial activity of the synthesized compounds was screened against several microbes. Several of these molecules showed potent antimicrobial activity against Bacillus anthracis, Staphylococcus aureus and Candida albicans and significant structure-activity relationship (SAR) trends.