Cyclopentadithiophene (CPDT) dimer dication: bipolaron model for quaterthiophenes

[structure: see text] Cyclopentadithiophene (CPDT) dimers in which both 3,3' and 4' ',3' " positions were bridged with 1,3-dioxalane, carbonyl, or dicyanovinylidene were prepared. These compounds have small HOMO-LUMO gaps (1.03-2.25 eV). The electrochemical oxidation of a dicyanovinylidene-bridged CPDT dimer gave a dication that had a quinoid-like structure.     

Quinovic acid glycosides from Mitragyna stipulosa--first examples of natural inhibitors of snake venom phosphodiesterase I

Phytochemical investigations on the non-alkaloidal extracts of Mitragyna stipulosa bark has led to the isolation of a series of triterpenoids mainly consisting of quinovic acid ([structure: see text]) and its glycoside derivatives [structure: see text] and [structure: see text]. The other constituents isolated include alpha-amyrin, 3beta-acetyl ursolic acid and a mixture of oleanolic and ursolic acid and beta-sitosterol glucopyranoside. Their structures were identified by spectral and chemical studies and compounds [structure: see text] and [structure: see text] were, respectively, identified as quinovic acid 3-O-[beta-D-glucopyranoside] (quinovin glycoside C) and quinovic acid 3-O-[beta-D-quinovopyranoside]-27-O-[beta-D-glucopyranosyl] ester. Compounds [structure: see text] and [structure: see text] showed significant inhibitory activity against snake venom phosphodiesterase I.     

Influence of macro elements and nitrogen source on adventitious root growth and withanolide-A production in Withania somnifera (L.) Dunal

Withania somnifera (L.) Dunal. (Indian ginseng) is an important medicinal plant which yields pharmaceutically active compounds, namely withanolides. This study deals with the optimisation of the adventitious root suspension culture of W. somnifera for the production of biomass and withanolide-A. We investigated the effects of macro elements (NH(4)NO(3), KNO(3), CaCl(2), MgSO(4) and KH(2)PO(4)) and nitrogen source [[Formula: see text]] of Murashige and Skoog (MS) medium on the accumulation of biomass and withanolide-A content. The highest accumulation of fresh and dry biomass (127.52 and 12.45?g?L(-1)) was recorded in the medium with 0.5× concentration of NH(4)NO(3) and the highest production of withanolide-A was recorded in the medium with 2.0× KNO(3) (14.00?mg?g(-1) DW). The adventitious root growth was greater when the [Formula: see text] concentration was higher than that of [Formula: see text] and the withanolide-A production was highest in the absence of [Formula: see text]. Maximum biomass growth was achieved at [Formula: see text] ratio of 14.38?:?37.60, while withanolide-A production was greatest (11.76?mg?g(-1) DW) when the [Formula: see text] ratio was 0.00?:?18.80?mM. The results of this study are useful for scale-up processes.     

Synthesis, structural characterization, gas sorption and guest-exchange studies of the lightweight, porous metal-organic framework alpha-[Mg3(O2CH)6

Unsolvated magnesium formate crystallizes upon reaction of the metal nitrate with formic acid in DMF at elevated temperatures. Single-crystal XRD studies reveal the formation of [Mg3(O2CH)6 [symbol: see text] DMF], 1, a metal-organic framework with DMF molecules filling the channels of an extended diamondoid lattice. The DMF molecules in 1 can be entirely removed without disruption to the framework, giving the guest-free material alpha-[Mg3(O2CH)6], 2. Compound 2 has been characterized by both powder and single-crystal XRD studies. Thermogravimetric analyses of 1 show guest loss from 120 to 190 degrees C, with decomposition of the sample at approximately 417 degrees C. Gas sorption studies using both N2 and H2 indicate that the framework displays permanent porosity. The porosity of the framework is further demonstrated by the ability of 2 to uptake a variety of small molecules upon soaking. Single-crystal XRD studies have been completed on the six inclusion compounds [Mg3(O2CH)6 [symbol: see text] THF], 3; [Mg3(O2CH)6 [symbol: see text] Et2O], 4; [Mg3(O2CH)6 [symbol: see text] Me2CO], 5; [Mg3(O2CH)6 [symbol: see text] C6H6], 6; [Mg3(O2CH)6 [symbol: see text] EtOH], 7; and [Mg3(O2CH)(6) [symbol: see text] MeOH], 8. Analyses of the metrical parameters of 1-8 indicate that the framework has the ability to contract or expand depending on the nature of the guest present.     

Microbial transformation of (+)-androsta-1 ,4-diene-3,17-dione by Cephalosporium aphidicola

Fermentation of (+)-androsta-1,4-diene-3,17-dione ([structure: see text]) with Cephalosporium aphidicola for 8 days yielded oxidative and reductive metabolites, androst-4-ene-3,17-dione ([structure: see text]), 17beta-hydroxyandrosta-1,4-diene-3-one ([structure: see text]), 11alpha-hydroxyandrosta-1,4-diene-3,17-dione ([structure: see text]), 11alpha-hydroxyandrost-4-ene-3,17-dione ([structure: see text]), 11alpha,17beta-dihydroxyandrost-4-ene-3-one ([structure: see text]) and 11alpha,17beta-dihydroxyandrosta-1,4-diene-3-one ([structure: see text]). The fermentation of [structure: see text] with Fusarium lini also yielded metabolites [structure: see text]. The structures of these metabolites were elucidated on the basis of spectroscopic techniques.     

Noncovalent self-assembly of bicyclo[4.2.2]diketopiperazines: influence of saturation in the bridging carbacyclic ring

[structure: see text] We have prepared 7,9-diazabicyclo[4.2.2]dec-3-ene-8,10-dione (3) and 7,9-diazabicyclo[4.2.2]decane-8,10-dione (4), which differ by virtue of the degree of unsaturation in the bridging carbacyclic tether on a 2,5-diketopiperazine. Remarkably different self-assembly patterns were observed in the solid state for the two compounds, attributed to subtle variations in the conformational constraints imposed by the tether.     

Design and synthesis of dual inhibitors of acetylcholinesterase and serotonin transporter targeting potential agents for Alzheimer's disease

Highly efficient acetylcholinesterase (AChE) and serotonin transporter (SERT) dual inhibitors, (S)-4 and (R)-13 were designed and synthesized on the basis of the hypothetical model of AChE active site. Both compounds showed potent inhibitory activities against AChE and SERT. [structure: see text]     

Synthesis of 1,10-dimethylbicyclo[8.8.8]hexacosane and 1,10-dihydroxybicyclo[8.8.8]hexacosane

[structure: see text] 1,10-Dimethylbicyclo[8.8.8]hexacosane (1) and 1,10-dihydroxybicyclo[8.8.8]hexacosane (2) were prepared in 4% yield over seven steps and in 18% yield over three steps, respectively, starting from 1,10-cyclooctadecanedione. The identities and out,out conformations of these compounds were established by single-crystal X-ray analysis.     

Alysinol--a new triterpene from Alysicarpus monolifer

A new triterpene named as alysinol 3alpha, 22beta-dihydroxyolean-12-ene [structure: see text] along with known compounds usnic acid, methyl 2,4-dihydroxy-3,6-dimethyl benzoate, 3-hydroxy benzoic acid, stigmasterol, poriferasterol and ursolic acid have been isolated from Alysicarpus monolifer. The structure of [structure: see text] has been established through spectroscopic techniques.     

A convenient route to diverse heterocycles through an addition of beta-amino carbonyl compounds to 3-halogeno-4-methoxybenzynes

[reaction: see text] 3-Halogeno-4-methoxybenzynes 5 generated from 5-(3-halogeno-4-methoxyphenyl)thianthrenium perchlorates 1 and LDA in THF at reflux reacted with various beta-amino carbonyl compounds and 2-aminophenyl benzenesulfonate etc. to give diverse heterocyclic compounds.     

Enantiomerisation of tetrahedral homochiral [M4L6] clusters: synchronised four Bailar twists and six atropenantiomerisation processes monitored by temperature-dependent dynamic 1H NMR spectroscopy

Temperature-dependent 1H NMR studies prove homochiral, racemic [([symbol: see text])/([symbol: see text])]-((NH4)4[symbol: see text] [Mg4(L1)6]) (1) to be kinetically stable on the NMR timescale. Due to steric reasons, rotation around the central C-C single bond in (L1)2- is blocked, which prevents 1 from enantiomerisation. Most interestingly, however, the 1H NMR spectrum of racemic 2a reveals dynamic temperature dependence. This phenomenon can be explained by simultaneous Bailar twists at the four octahedrally coordinated magnesium centres, synchronised with the sterically unhindered atropenantiomerisation processes around the C-C single bonds of the six ligands (L2)2-, leading to the unprecedented enantiomerisation ([symbol: see text])-2a [symbol: see text] ([symbol: see text])-2a. The profound nondissociative rearrangement occurs without the formation of diastereoisomers. Supplementary support for the interpretation of the temperature-dependent dynamic 1H NMR spectra of 2a is presented by additional studies of [([symbol: see text])/([symbol: see text])]-((EtNH3)4 [symbol: see text] [Mg4(L2)6]) (2b). In 2a and 2b, the ether methylene protons exhibit identical temperature dependence. However, with addition, the methylene protons of the ethyl ammonium groups of 2b display similar temperature dependence as the ligand ether methylene protons.     

Synthesis of [3]catenanes based on metal-directed self-assembly and pi-donor/pi-acceptor interactions

A metal-directed self-assembly of [3]catenanes in combination with pi-pi interactions was investigated. Ligands based on 4,4'-bipyridinium or 2,7-diazapyrenium were used in conjunction with dioxoaryl cyclophanes (4-6) and trans-PdCl2(CH3CN)2. The [3]catenanes show a dinuclear palladium 46-membered metallomacrocycle interlocked by two pi-complementary dioxoaryl macrocycles. [structure: see text].     

Barrenazine A and B; two new cytotoxic alkaloids from an unidentified tunicate

[structure: see text] Two novel compounds, barrenazine A (1) and B (2), were isolated from an unidentified tunicate collected at Barren Islands, Madagascar. The two new compounds are of an unprecedented heterocyclic skeleton, namely 1,3,4,6,8,9-hexahydrodipyridino[3,4-b:3',4'-e]pyrazine. The structures of the two alkaloids were elucidated by interpretation of MS, COSY, HMQC, HMBC, NOESY, and (15)N-HMBC data. Barrenazine A exhibits mild cytotoxicity against LOVO-DOX colon carcinoma (with a GI(50) value of 0.9 g/mL)     

Novel sulfur-containing rapamycin analogs prepared by precursor-directed biosynthesis

[reaction: see text] Two novel sulfur-containing analogs of the immunosuppressive natural product rapamycin (1) were obtained by feeding cultures of Streptomyces hygroscopicus with l-nipecotic acid (4) and either (S)-1,3-thiazane-4-carboxylic acid (5) or (S)-1,4-thiazane-3-carboxylic acid (6). The structures of the two new compounds, 20-thiarapamycin (2) and 15-deoxo-19-sulfoxylrapamycin (3), were determined by spectroscopic methods.     

Curvicollides A-C: new polyketide-derived lactones from a sclerotium-colonizing isolate of Podospora curvicolla (NRRL 25778)

Curvicollides A-C (1-3) have been obtained from cultures of an isolate of Podospora curvicolla (NRRL 25778) that colonized a sclerotium of Aspergillus flavus. The structures of these compounds were elucidated by analysis of one- and two-dimensional NMR data. The lead compound (1) showed antifungal activity against A. flavus and Fusarium verticillioides. [structure: see text]     

An enantioselective NMR shift reagent for cationic aromatics

[structure: see text] The water-soluble tetra l-prolinylmethyl derivative of a tetrasulfonated calix[4]resorcarene is an effective chiral NMR solvating agent for compounds with bicyclic aromatic or indole rings. Complexation of bicyclic substrates with the calix[4]resorcarene is likely promoted by hydrophobic effects. The bicyclic substrates have larger association constants with the calix[4]resorcarene than similar phenyl-containing compounds. Substantial enantiomeric discrimination is observed for several resonances in the (1)H NMR spectra of these substrates.     

Total syntheses of four stereoisomers of 4alpha-hydroxy-1beta,7beta-peroxy- 10betaH-guaia-5-ene

[reaction: see text]. The first total syntheses of four stereoisomers of 4alpha-hydroxy-1beta,7beta-peroxy-10betaH-guaia-5-ene are reported starting from the readily available (+)-dihydrocarvone. These compounds have been synthesized from dienes (-)-isoguaiene and (-)-10-epi-isoguaiene by tandem ene hydroperoxylation-[4 + 2] cycloaddition with O(2) followed by selective reduction. The structure of the natural 4alpha-hydroxy-1beta,7beta-peroxy-10betaH-guaia-5-ene isolated from Liabum floribundum has been confirmed.     

Raman scattering properties of a protonic titanate HxTi2-x/4[symbol: see text]x/4O4.H2O ([symbol: see text], vacancy; x=0.7) with lepidocrocite-type layered structure

Raman scattering spectroscopy is employed to characterize a layered titanate HxTi2-x/4[symbol: see text]x/4O4.H2O ([symbol: see text]: vacancy; x=0.7) with lepidocrocite (gamma-FeOOH)-type layered structure. Nine Raman lines corresponding to (3Ag+3B1g+3B3g) Raman-active modes expected from this orthorhombic structure (space group D2h25-Immm) are recorded at 183, 270, 387, 449, 558, 658, 704, 803, and 908 cm(-1), which are assigned to Ti-O lattice vibrations within the two-dimensional (2D) lepidocrocite-type TiO6 octahedral host layers. These intrinsic Raman bands present a clear signature that can be used for probing the protonic titanate HxTi2-x/4[symbol: see text]x/4O4.H2O and the 2D titanate nanosheets, as well as their corresponding derivates.     

On the stability of large [4n]annulenes

[reaction: see text] The stabilization energies (B3LYP/6-31G) of planar [4n]annulenes, evaluated by a new indene-isoindene isomerization method (see Abstract graphic), reveal that all 4n pi-electron rings larger than the energetically unfavorable cyclobutadiene are only slightly destabilized by the pi-electron interactions. Cyclooctatetraene prefers the "tub" conformation because of strain effects. Generally, the antiaromatic character of the larger systems with 4n pi-electrons is revealed best by their magnetic properties rather than by their energies.     

Synthesis of alpha-kainic acid from a 7-azabicyclo[2.2.1]heptadiene by tandem radical addition-homoallylic radical rearrangement

Reductive radical addition of 2-iodoethanol to N-Boc 2-tosyl-7-azabicyclo[2.2.1]heptadiene gives N-Boc syn-7-(2-hydroxyethyl)-4-tosyl-2-azabicyclo[2.2.1]hept-5-ene, which is converted into the neuroexcitants 3-(carboxymethyl)pyrrolidine-2,4-dicarboxylic acid and alpha-kainic acid. [structure: see text]