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951.
Alessandro Fumagalli Maria Carlotta Malatesta Michele Vallario Gianfranco Ciani Massimo Moret Angelo Sironi 《Journal of Cluster Science》2001,12(1):187-200
The reaction of Ru3(CO)12 and [Ir(CO)4]- (as [PPh4]+ or [N(PPh3)2]+ salts) yields the anion [Ru3Ir2(CO)14]2- (1) which has been found to derive from the intermediate [Ru3Ir(CO)13]- anion. Treatment of (1) with acids gives the conjugated hydrido species [Ru3Ir2(CO)14H]- (2). The two anions were characterized by single-crystal X-ray diffraction of their [PPh4]+ salts. [PPh4]2[Ru3Ir2(CO)14]: space group C2/c, Z=4, a=22.121(5) Å, b=10.546(5) Å, c=25.931(5) Å, =103.870(5)°, R=0.052 and Rw=0.130 for 3128 independent reflections with I>2(I ). [PPh4][Ru3Ir2(CO)14H]: space group P21/c, Z=8, a=22.833(5) Å, b=13.893(5) Å, c=25.810(5) Å, =92.650(5)°, R=0.070 and Rw=0.150 for 12141 independent reflections with I>2(I). Both anions 1 and 2 have a trigonal bipyramidal metal frame. There are two independent anions in the asymmetric unit of 2 differing in their ligand stereochemistry. 相似文献
952.
Badioli M Ballini R Bartolacci M Bosica G Torregiani E Marcantoni E 《The Journal of organic chemistry》2002,67(25):8938-8942
Readily preparable morpholine amides hitch in good yields with organocerium reagents to produce ketones. Even in the presence of substrates and reagents with high steric hindrance, the organometallic compounds prepared from dry cerium(III) chloride and organomagnesium or organolithium compounds at -78 degrees C add cleanly to morpholine amides. The low cost of starting materials makes this new scheme of synthesis very interesting for the preparation of biologically important pheromones. 相似文献
953.
The Mediterranean stolonifer Sarcodictyon roseum (= Rolandia rosea) (Cnidaria, Anthozoa, Alcyonaria, Stolonifera, Clavulariidae) is shown to contain two novel diterpenoidic alcohols esterified by (E)-N(1)-methyl-urocanic acid (= E)-3-(l-methyl-lH-imidazol-4-yl)acrylic acid). They are sarcodictyin A ( = (?)-(4R,4a,R, 7R,10S,11S,12aR,lZ,5E,8Z)-7,10-epoxy-3,4,4a,7,10,11,12,12a-octahydro-7-hydroxy-6-(methoxycarbonyl)-1,10-dimethyl-4-(1-methylethyl)benzocyclodecen-11-yl (E)-3-(1-methyl-lH-imidazol-4-yl)acrylate; (?)- 1 ) and sarco-dictyin B (the 6-(ethoxycarbonyl analogue; (?)- 2 ). The assignment of the structures is mainly based on 1D- and 2D-NMR data, as well as on chemical transformations of (?)- 1 , such as transesterification with MeONa/MeOH giving methyl (E)-N(1)-methylurocanate ( 3 ) and the free alcohol (+)- 4 and reduction with LiAlH4 followed by benzoylation giving dibenzoate 7. Absolute configurations are based on Horeau's method of esterification of (+)- 4 . 相似文献
954.
Renato Capasso Antonio Evidente Carla Visca Liloana Gianfreda Michele Maremonti Guido Greco 《Applied biochemistry and biotechnology》1997,61(3):365-377
Pure-grade oleuropein, a bitter, hypotensive, phenolic glucoside, was obtained from organic extracts of olive plant leaves
by two Chromatographic steps. The purified compound was characterized by spectroscopic NMR and FAB-MS methods. The glucoside
underwent chemical and enzymatic hydrolysis. Aglycone was characterized by spectroscopic methods (1H-NMR and FAB-MS). Glucose was measured by enzymatic methods. The enzymatic hydrolysis of oleuropein was carried out by a
soluble β-glucosidase. The reaction was characterized in terms of kinetic parameters, optimal pH value, activation energy,
inhibition constant by glucose, and thermal stability. Preliminary experiments were also performed in a continuousflow ultrafiltration
membrane reactor. The cut-off of the membrane was lower than the molecular-weight of the enzyme, thus determining β-glucosidase
confinement within the reactor. Under these conditions, β-glucosidase had a good long-term stability. This is an encouraging
result in view of possible industrial applications. 相似文献
955.
Abolghasem Shahbazi Yebo Li Michele R. Mims 《Applied biochemistry and biotechnology》2005,124(1-3):973-987
The FIRST (Feedstock Impregnation and Rapid Steam Treatment) approach was used in this study to isolate extractives, hemicellulose,
lignin, fibers, and cellulosic fines of softwood. With hydrolysis and fermentation of the hemicellulose and cellulosic fines
fractions, this approach produces four co-products: extractives, cellulose, lignin, and ethanol. The first unit operation
uses aqueous/alcohol to remove and recover the extractive rich fraction. The second unit operation uses steam treatment to
destructure the matrix and solubilize a large fraction of the hemicelluloses. The third unit operation uses alkaline delignification
to dissolve a lignin fraction. The fourth unit operation uses the refining process to separate fibers from cellulosic fines.
The fibers are bleached. The yields of lignin and bleached cellulose were about 20.0 kg and 38.3 kg out of 100 kg initial
dry pine, respectively. The recovered hemicelluloses were 23.3 kg (containing 16.1 kg hexoses and 5.0 kg pentoses) and the
cellulose fines derived hexoses amounted to 3.4 kg out of 100 kg initial dry pine. When the two liquors containing the hemicellulose
sugars and the cellulose fines-derived hexoses were fermented for ethanol production, an ethanol yield of 6.8 kg was obtained. 相似文献
956.
Improved functional group compatibility in the palladium-catalyzed synthesis of aryl amines 总被引:1,自引:0,他引:1
[reaction: see text] The use of Pd2dba3 with bulky, electron-rich ligands 1 or 2 and LiN(TMS)2 as the base for the coupling of amines with aryl halides containing hydroxyl, amide, or enolizable keto groups is described. This protocol expands the utility of palladium-catalyzed C-N bond formation by allowing for the use of aryl halides containing these functional groups, obviating the need for protecting group manipulations. 相似文献
957.
Maiara Maziero Marina Ortiz Lovatto Vinícius Victor Lorenzoni Greice Graziela Moraes Rafaela Castro Dornelles Michele Rorato Sagrillo 《Natural product research》2020,34(1):192-196
AbstractInga semialata (Vell.) C. Mart. belongs to the family Fabaceae. It is known for its therapeutic properties, highlighting its antimicrobial and antioxidant potential. The objective of the present work was to obtain crude extract leaves of Inga semialata, to identify and quantify active compounds, to evaluate the antioxidant potential of the crude extract in vitro, as well as to determine its antimicrobial activity. The crude extract was obtained by the maceration process. The identified and quantified of compounds present in the crude extract of Inga semialata was performed by high performance liquid chromatography. The evaluation of the antioxidant potential of the extract was realized by in vitro tests (DPPH, diacetate dichlorofluorescein test and nitric oxide test) and the evaluation of the antimicrobial activity was carried out using the minimum inhibitory concentration methodology. 相似文献
958.
Orsatti L Pallaoro M Steinküler C Orru' S Bonelli F 《Rapid communications in mass spectrometry : RCM》2002,16(20):1919-1927
The present work reports a mass spectrometric investigation of the NS2/3 protein, a protease from hepatitis C virus (HCV). During routine protein manipulation, in the presence of 100 mM beta-mercaptoethanol and under denatured conditions, the protein was unexpectedly modified at its cysteine residues, and the increased molecular weight corresponded to one molecule of beta-mercaptoethanol bound. The modified protein, once refolded, was found to be less active than the unmodified one. The aim of this work was to investigate whether the reactivity of cysteines with beta-mercaptoethanol involves one specific, highly reactive residue of the sequence, or if the modification is a random process. Liquid chromatography (LC) coupled on-line with an electrospray ion trap mass spectrometer was used to identify the modification sites. It was found that five cysteines out of nine had reacted with beta-mercaptoethanol, none of them showing a significantly higher reactivity than the others. 95% of sequence coverage was obtained. 相似文献
959.
Nirmala Ramanujam Michele Follen Mitchell Anita Mahadevan-Jansen Sharon L. Thomson Gregg Staerkel Anais Malpica Thomas Wright Neely Atkinson Rebecca Richards-Kortum 《Photochemistry and photobiology》1996,64(4):720-735
Abstract— A portable fluorimeter was developed and utilized to acquire fluorescence spectra from 381 cervical sites in 95 patients at 337, 380 and 460 nm excitation immediately prior to colposcopy. A multivariate statistical algorithm was used to extract clinically useful information from tissue spectra acquired in vivo. Two full-parameter algorithms were developed using tissue fluorescence emission spectra at all three excitation wavelengths (161 excitation-emission wavelength pairs) for cervical precancer (squamous intraepithelial lesion [SIL]) detection: a screening algorithm that discriminates between SIL and non-SIL with a sensitivity of 82 ± 1.4% and specificity of 68 ± 0.0%, and a diagnostic algorithm that differentiates high-grade SIL from non-high-grade SIL with a sensitivity and specificity of 79 ± 2% and 78 ± 6%, respectively. Multivariate statistical analysis was also employed to reduce the number of fluorescence excitation-emission wavelength pairs needed to redevelop algorithms that demonstrate a minimum decrease in classification accuracy. Two reduced-parameter algorithms that employ fluorescence intensities at only 15 excitation-emission wavelength pairs were developed: the screening algorithm differentiates SIL from non-SIL with a sensitivity of 84 ± 1.5% and specificity of 65 ± 2% and the diagnostic algorithm discriminates high-grade SIL from non-high-grade SIL with a sensitivity and specificity of 78 ± 0.7% and 74 ± 2%, respectively. Both the full-parameter and reduced-parameter screening algorithms discriminate between SIL and non-SIL with a similar specificity (±5%) and a substantially improved sensitivity relative to Pap smear screening. A comparison of the full-parameter and reduced-parameter diagnostic algorithms to colposcopy in expert hands indicates that all three have a very similar sensitivity and specificity for differentiating high-grade SIL from non-high-grade SIL. 相似文献
960.
It is shown here that the stoloniferan coral Sarcodictyon roseum of east Pyrenean waters contains four novel diterpenoids, sarcodictyin C ((?) -3 ), D ((?) -4 ), E ((+)- 5 ), F ((+)- 6 ), which are related to sarcodictyin A ( = (?)-(4R,4aR,7R,10S,11S,12aR,1Z,5E,8Z-7,10-epoxy-3,4,4a,7,10,11,12,12a-octahydro-7-hydroxy-6-(methyoxycarbonyl)-1,10-dimethyl-4-(1-methylethyl)-benzocyclodecen-11-yl (E)-N1-methylyrocanate; ((?)? 1 ), previously isolated from the same coral. Sarcodictyin C ((?) -3 ) and D ((?) -4 ) and the 3α-hydroxy and 3α-acetoxy derivatives of (?) -1 ), sarcodictyin E ((+) -5 ) is the (Z)-urocanate isomer of (?) -3 ), and sarcodictyin F ((+) -6 ) is the 1α-hydroxy-2-ene isomer of (?) -3 . In all cases, the nine-membered ring is locked, and the molecule stabilized, by the urocanic appendage; when this is removed in MeOH/KOH, the C(11)–O? function is free to attack at C(5), and retro-condensations then lead to the ring-contracted butenolides 11 (from (?) -3 ) or 10 (from(?) -1 ) with extrusion of the hydroxyfuran nucleus (Scheme 3). Under the same conditions, with (?) -3 , the C(3)-O? group competitively attacks at C(5), the hydroxyfuran nucleus is expelled, and aldehyde 14 is formed. Peculiarly, in the reaction of (?) -3 with MeOD/KOD, the ring-contracted butenolide 17 contains D at the 4′-ax position. The sarcodictyins are unique in these chemical properties, not shared by the cladiellanes which have the same C-skeleton. 相似文献