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21.
5-Methyl-4-phenyl-2-styryipyridine has been oxidized to 5-methyl-4-phenylpyridinie-2-carboxylic acid. The decarboxylation of this acid has given 3-methyl-4-phenylpyrldine. To prove the structure of -(5-methyl-4-phenyl-2-pyridyl)acetophenone, it has been converted into 2, 5-dimethyl-4-phenylpyridine. The reaction of benzyl chloride with the lithium derivative of 2, 5-dimethyl-4-phenylpyridine has been studied. 3,7-Dimethyl-2-azafluorene has been obtained from 2,5-dimethyl-4-p-tolylpyridine. 相似文献
22.
The scope of reductive decyanation and spiroannulation reactions has been expanded to include secondary electrophiles for potentially useful transformations. Secondary phosphates and chlorides, as well as terminal epoxides, cyclize in a stereospecific fashion. Both endo and exo modes of cyclization were observed with terminal epoxides. 相似文献
23.
Gaunt AJ May I Helliwell M Richardson S 《Journal of the American Chemical Society》2002,124(45):13350-13351
The reaction between PW9O349- and NpO2+ has yielded the first structurally characterized neptunyl(V) polyoxometalate complex, [Na2(NpO2)2(A-PW9O34)2]14-. This complex is isostructural with the uranyl(VI) analogue, and there is also spectroscopic evidence for its existence in solution. The complex is readily extracted into toluene, and this may have significance in the sequestering and/or separation of the neptunyl ion in terms of nuclear waste management. 相似文献
24.
25.
Matthew T. HancockAllan R. Pinhas 《Tetrahedron letters》2003,44(29):5457-5460
The conversion of an aziridine to the corresponding oxazolidinone using only carbon dioxide and a catalytic amount of lithium iodide is discussed. In all cases, either no reaction occurred or a high yield of product was obtained. HMPA has been added to the reaction mixture, as needed, to drastically improve the regioselectivity. Net retention of stereochemistry between the starting aziridine and the product oxazolidinone was observed. 相似文献
26.
Matthew T. AllinghamAndrew Howard-Jones Patrick J. MurphyPeter W.R. Caulkett 《Tetrahedron letters》2003,44(48):8677-8680
The preparation of the tetracyclic C2-symmetric guanidinium salts 5 and 11-13 is reported together with their application to enantioselective transformations. 相似文献
27.
Matthew R OatesWilliam Clarke Alden Zimlich IIDavid S Hage 《Analytica chimica acta》2002,470(1):37-50
Various practical and theoretical considerations were examined in the creation and optimization of a high-performance liquid chromatography (HPLC)-based one-site immunometric assay. This method used an HPLC analyte analog column and post-column chemiluminescence detection. The specific analyte chosen as the model for this study was l-thyroxine (also known as T4). In this technique, a sample containing thyroxine was first combined with an excess of anti-T4 antibody Fab fragments that had earlier been conjugated with chemiluminescent acridinium ester labels. After incubation, the mixture was injected onto a column that contained immobilized T4. The amount of thyroxine in the original sample was then determined by measuring the labeled Fab fragments that appeared in the non-retained fraction, or the decrease in excess Fab fragments that were bound to and later eluted from the column. Items considered in creating this assay included the preparation of acridinium ester-labeled Fab fragments, the detection of these fragments with a post-column reactor, and the creation of a suitable immobilized analog column for capturing excess labeled Fab fragments. The final method could measure T4 in standards at clinically-relevant concentrations and provided a response within 1.5 min of sample injection, following a 20-45 min incubation with the labeled Fab fragments. Possible applications of this method include its use in clinical chemistry and the screening of proteomic or combinatorial libraries. 相似文献
28.
[reaction: see text] Diastereoselective [2 + 2] cyclizations of aldehyde- and ketone-derived silyl enol ethers with acrylates is described. The use of the tris(trimethylsilyl)silyl group allows for unprecedented reactivity, yields, and selectivity for these cyclizations. The presence of silicon-silicon bonds proved to be important for this transformation, where typical silyl groups (TBS and TIPS) failed to give any desired product. The bulky bis(2,6-diphenylphenoxide) aluminum triflimide catalyst was essential for high diastereoselectivity. 相似文献
29.
Synthesis of amides from coupling esters with a range of primary amines can be conveniently achieved in moderate to excellent yields (69-99%) using an air-stable adduct of trimethylaluminium (AlMe3)2·DABCO (DABCO is 1,4-diazobicyclo[2.2.2]octane), referred to as DABAL-Me3. Reactions can be run without requiring the exclusion of atmospheric oxygen or the drying of solvents. 相似文献
30.
Rudd DJ Sazinsky MH Merkx M Lippard SJ Hedman B Hodgson KO 《Inorganic chemistry》2004,43(15):4579-4589
The diiron active site in the hydroxylase of Methylococcus capsulatus (Bath) methane monooxygenase (MMOH) has been studied in the oxidized form by X-ray absorption spectroscopy (XAS). Previous investigations by XAS and X-ray crystallography have identified two different distances (3.0 and 3.4 angstroms) between the two Fe atoms in the dinuclear site. The present study has employed a systematic extended X-ray absorption fine structure (EXAFS) fitting methodology, utilizing known and simulated active site and relevant model structures, to determine unambiguously the Fe-Fe separation in the oxidized form of MMOH. Consistent and unique fits were only possible for an Fe-Fe distance of 3.0 angstroms. This methodology was then applied to study potential changes in the active site local structure in the presence of MMOD, a protein of unknown function in multicomponent MMO. Fe K-edge and EXAFS analyses revealed negligible changes in the diiron site electronic and geometric structure upon addition of MMOD to oxidized MMOH. 相似文献