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11.
Greice Tabarelli Marcelo Godoi Rômulo F. S. Canto José R. Mora Faruk Nome 《合成通讯》2014,44(23):3441-3449
We present herein a new catalyst-free and solvent-free approach for the synthesis of allylic thioethers directly from allylic alcohols and thiols. The methodology allows the synthesis of different allylic thioethers in good to excellent yields under microwave irradiation. Theoretical calculations for the allylic carbocation helped to explain the regioselectivity observed when nonsymmetric substrates are used in the reaction. 相似文献
12.
Kodanko JJ Hiebert S Peterson EA Sung L Overman LE de Moura Linck V Goerck GC Amador TA Leal MB Elisabetsky E 《The Journal of organic chemistry》2007,72(21):7909-7914
The previously unknown stereoisomers 3, 4, ent-1, and ent-4 of the tris(pyrrolidinoindoline) alkaloids hodgkinsine (1) and hodgkinsine B (2) were prepared by stereocontrolled total synthesis. In each synthesis, a catalyst-controlled intramolecular Heck reaction was the key step in appending a third cis-pyrrolidinoindoline ring to a hexacyclic chimonanthine precursor. Results of the preliminary evaluation of these hodgkinsine stereoisomers in the tail flick and capsaicin pain models are reported. 相似文献
13.
Ionic liquid: an efficient and reusable media for seleno- and thioester synthesis promoted by indium
Greice Tabarelli Anna M. Deobald Oscar E.D. Rodrigues Antonio L. Braga 《Tetrahedron letters》2010,51(43):5728-5731
A series of thio and selenoesters were efficiently obtained employing stable diorganyl chalcogenides, acyl chlorides, and In as reducing agent in BMIM·PF6. Recycling of the ionic liquid was also performed, which was reused three times. 相似文献
14.
A. Donini E. Fernandez-Martinez P. Migliozzi S. Rigolin L. Scotto Lavina M. Selvi T. Tabarelli de Fatis F. Terranova 《The European Physical Journal C - Particles and Fields》2008,53(4):599-606
High density magnetized detectors are well suited to exploit the outstanding purity and intensities of novel neutrino sources
like neutrino factories and beta beams. They can also provide independent measurements of leptonic mixing parameters through
the observation of atmospheric muon-neutrinos. In this paper, we discuss the combination of these observables from a multi-kT
iron detector and a high energy beta beam; in particular, we demonstrate that even with moderate detector granularities the
neutrino mass hierarchy can be determined for θ13 values greater than 4°.
PACS 14.60.Pq; 14.60.Lm 相似文献
15.
Silica modified with zirconium oxide for on-line determination of inorganic arsenic using a hydride generation-atomic absorption system 总被引:1,自引:0,他引:1
Greice T. Macarovscha 《Talanta》2007,71(3):1150-1154
In the present work, an on-line pre-concentration system, using SiO2/ZrO2 as solid phase adsorbent, for the determination of low concentrations of arsenic was developed.In this procedure, total inorganic arsenic present in the sample is reduced to As (III) with l-cysteine and the solution is passed into a glass column (?i = 3 mm; h = 35 mm) containing 70 mg of SiO2/ZrO2 (100-230 mesh) to retain the As (III), with the solution flowing at 3.2 mL min−1. After 2 min, the concentrated species are eluted with 3 mol L−1 HCl (3.2 mL min−1) loading a 150 μL loop while a 1.0% (m/v) sodium borohydride solution loads the other loop of a FI-HG AAS system. The elution step is carried out during 7 s and, at the same time, the SiO2/ZrO2 phase is regenerated for the next concentration cycle. The arsine generated is carried with N2 (flow rate = 90 mL min−1) to a quartz cell where the electrothermal atomization process occurs.Under these conditions, a 20-fold enrichment factor is obtained considering the increase of sensitivity in the analytical curve after the concentration step. The limits of detection and quantification were 0.05 and 0.35 μg L−1, respectively, with an injection frequency of about 28 h−1 and relative standard deviation lower than 8%. Four metallurgical reference materials were analyzed with the proposed method after their acid dissolution. The results obtained were in good agreement with certified values. 相似文献