Synthesis of 3H-thieno[3,2-c]-1,2-dithiole-3-thione and its reaction with n-butylamine

A convenient synthesis of 3H-thieno[3,2-c]-1,2-dithiole-3-thione (7) is proposed. The reaction of 7 with n-butylamine afforded the N-butylthieno[3,2-c]isothiazole-3(2H)-thione (7a) in dynamically equilibrium [1] with its 3H-thieno[3,2-c]-1,2-dithiole-N-butyl-3-imino isomer 7b. Characterizations and antimicrobial activities of the synthesized products are reported.     

Reaction of ketenes with N,N-disubstituted à-aminomethyleneketones. IX. Synthesis of 2H,5H-pyrano[3,2-c][1]benzopyran derivatives

Cycloaddition of dichloroketene to N,N-disubstituted 3-aminomethylene-4-chromanones gave in good yield N,N-disubstituted 4-amino-3,3-dichloro-3,4-dihydro-5H-pyrano[3,2-c][1]benzopyran-2-ones only in the case of aromatic N-substitution. Dehydrochlorination with triethylamine of these adducts afforded N,N-disubstituted 4-amino-3-chloro-5H-pyrano[3,2-c][1]benzopyran-2-ones in good to moderate yield. The cycloaddition to 3-dimethylaminomethylene-4-chromanone led directly to 3-chloro-4-dimethylamino-5H-pyrano[3,2-c][1]benzopyran-2-one.     

Tensile properties,thermal and morphological analysis of thermoplastic polyurethane films reinforced with multiwalled carbon nanotubes

The paper reports on thermal, tensile and morphological properties of thermoplastic polyurethane (TPU) based films obtained by melt-compounding and chill-roll extrusion. Composite films containing up to 1 wt% of multiwalled carbon nanotubes (MWNTs) are characterized in terms of thermal properties, tensile behavior and morphological issues taking the neat TPU film as the reference material.     

Ex vivo evaluation of the effects of a white grape juice extract on lymphocytic mitochondrial functions

Abstract

The physio-pathological role of mitochondria in aging and age-related diseases has stimulated the search for compounds able to promote mitochondrial functionality. Our study was designed to evaluate the effect of a white grape juice extract (WGJe) on mitochondrial activity, in an ex vivo experimental model consisting of activated lymphocytes obtained from a younger age group and an older age group of subjects. WGJe steadily decreased the lymphocytic mitochondrial mass in the older subjects, without a relevant effect in their younger counterpart, and significantly enhanced Δψm in both groups investigated. Finally, WGJe reduced the endogenous mitochondrial production of H₂O₂ in all subjects. The results support the potential use of WGJe to improve mitochondrial functionality, thus maintaining human health and slowing down aging.     

High-efficiency volume reflection of an ultrarelativistic proton beam with a bent silicon crystal

The volume reflection phenomenon was detected while investigating 400 GeV proton interactions with bent silicon crystals in the external beam H8 of the CERN Super Proton Synchrotron. Such a process was observed for a wide interval of crystal orientations relative to the beam axis, and its efficiency exceeds 95%, thereby surpassing any previously observed value. These observations suggest new perspectives for the manipulation of high-energy beams, e.g., for collimation and extraction in new-generation hadron colliders, such as the CERN Large Hadron Collider.     

Determination of 17beta-estradiol in bovine plasma: development of a highly sensitive technique by ion trap gas chromatography-tandem mass spectrometry using negative chemical ionization

A novel approach to the determination of 17beta-estradiol in bovine plasma is presented. The observed enhanced sensitivity is gained by the application of tandem mass spectrometry (MS) fragmentation to a stable, well characterized negative ion produced by chemical ionization (methane as reagent gas). A specific derivatizing reactant is employed (pentafluorobenzyl bromide), combined with bis-trimethylsilyltrifluoroacetamide, to favor the formation of a diagnostic precursor negative ion. Plasma samples are purified through a C18 solid phase extraction column and derivatized before gas chromatography-MS analysis. The accuracy and the precision of the method, tested over a set of spiked samples, were satisfactory. The limit of detection was found to be 5 pg ml(-1) and the limit of quantification was fixed at 20 pg ml(-1). The fragmentation pattern is fully explained and the method is applicable for the official analysis of bovine plasma for the detection of 17beta-estradiol according to the European criteria 256/93 and to the draft SANCO/1805/2000 rev. 3. The quantification of incurred positive samples was performed according to the proposed procedure and compared with the results obtained by standardized radio immuno assay; the estimated concentrations were significantly similar.     

Ion chemistry of phthalamic acids. 2—mass spectral retrosynthesis of phthalanilic acids and structure analysis of [C8H6NO2]+ ions from N-cyclohexylphthalamic acid and [MH]+ of N-cyclohexylphthalimide

Under electron impact o-phthalanilic acids show the retrosynthetic reaction previously described for other phthalamic acids. As primary amine derivatives they undergo thermal and electron impact induced water loss. Like the molecular ions of the related phthalimides, their [M? H₂O]^+˙ do not give [C₈H₆NO₂]⁺ fragments, which are obtained from the N-cyclohexyl derivative. The structure of such fragments is investigated by collisionally activated mass analysed ion kinetic energy spectra, and compared with the [MH]⁺ of phthalimide, obtained by chemical ionization with CH₄ or NH₃ and assumed to be possible models.     

Stereoselective hydroazidation of amino enones: synthesis of the ritonavir/lopinavir core

[reaction: see text] The base-catalyzed hydroazidation of alpha'-amino alpha,beta-unsaturated ketones with in situ generated hydrazoic acid was found to proceed with high stereoselectivity in favor of the syn product. The stereoselectivity is controlled by the configuration of the enone and syn/anti ratios up to 7:1 were obtained with secondary and tertiary amines at low temperature. By this route the diamino alcohol core of HIV-PR inhibitors ritonavir and lopinavir was synthesized in 37% yield from phenylalanine.     

Probing Long‐Range Anisotropic Interactions: a General and Sign‐Sensitive Strategy to Measure 1H–1H Residual Dipolar Couplings as a Key Advance for Organic Structure Determination

Residual dipolar couplings (RDCs) are amongst the most powerful NMR parameters for organic structure elucidation. In order to maximize their effectiveness in increasingly complex cases such as flexible compounds, a maximum of RDCs between nuclei sampling a large distribution of orientations is needed, including sign information. For this, the easily accessible one‐bond ¹H–¹³C RDCs alone often fall short. Long‐range ¹H–¹H RDCs are both abundant and typically sample highly complementary orientations, but accessing them in a sign‐sensitive way has been severely obstructed due to the overflow of ¹H–¹H couplings. Here, we present a generally applicable strategy that allows the measurement of a large number of ¹H–¹H RDCs, including their signs, which is based on a combination of an improved PSYCHEDELIC method and a new selective constant‐time β‐COSY experiment. The potential of ¹H–¹H RDCs to better determine molecular alignment and to discriminate between enantiomers and diastereomers is demonstrated.