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141.
[reaction: see text] Silver salts in the presence of a chelating ligand efficiently catalyze the stereospecific imination of sulfoxides and sulfides with sulfonylamides and PhI(OAc)(2) to afford sulfoximines and sulfilimines, respectively, in good yields. 相似文献
142.
Copper-mediated cross-coupling reactions of N-unsubstituted sulfoximines and aryl halides 总被引:1,自引:0,他引:1
[reaction: see text] Copper-mediated cross-coupling reactions of sulfoximines with aryl iodides and aryl bromides provide N-arylated sulfoximines in high yields. The method is complementary to the known palladium-catalyzed N-arylation and allows the preparation of N-arylated sulfoximines, which have previously been inaccessible. 相似文献
143.
Polyelectrolyte multilayer thin films were prepared via the alternate deposition of poly(allylamine hydrochloride) (PAH) and a blend of poly(acrylic acid) (PAA) and poly(styrenesulfonate) (PSS). When the pH of the blend solution was 3.5, the presence of PAA in this solution significantly increased the total film thickness. With only 10 wt % PAA in the blend adsorption solution, a large increase in film thickness was observed (92 nm cf. 18 nm). It was also demonstrated that the total amount of PSS adsorbed was enhanced by the presence of PAA in the blend solution, showing that the blend solution composition influenced that of the multilayer films. Thin films prepared with nanoblended layers also showed improved pH stability, because they exhibited reduced film rearrangement upon exposure to acidic conditions (pH = 2.5). 相似文献
144.
Homogeneous fluorescent derivatization of large proteins 总被引:1,自引:0,他引:1
A method of homogeneously derivatizing large proteins for highly sensitive analysis is described. Homogeneity of the derivative was realized by tagging all the free amino groups of proteins. With this method, alpha-chymotrypsinogen A, ovalbumin and bovine serum albumin were derivatized with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). Prior to the derivatization, all the proteins were reduced and alkylated. After reacting the resulting unfolded proteins with excessive amounts of AQC, the samples were analyzed with matrix assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) to determine the derivatization degree. The results indicated that all three proteins had been, or had almost been, fully derivatized. HPLC and CE were used for characterizing these protein derivatives. Under the optimized fluorescence detection conditions, the detectability of the tagged proteins was 2400-6200 times better than that detected at UV 280 nm, 170-300 times better than detected at UV 214 nm, and 150-420 times better than measured with their native fluorescence. 相似文献
145.
Ei-Ichi Terada Hiroshi Nishikawa Jinsh Cho Eishun Tsuchida 《Journal of polymer science. Part A, Polymer chemistry》1979,17(3):807-813
The equilibrium constants of the coordination reaction of chlorodimethylformamide·cobaloxime with 4-vinylpyridine–styrene copolymers (PPS) were determined. The constants for PPS, which contain 20–50% 4-vinylpyridine (4VP) unit, measured about 1.3 × 105 liter/mole larger than those in the pyridine system (6.8 × 104 liter/mole). When the polymer ligand is 4VP homopolymer or contains less than 20% 4VP unit, K values are lower. The rate constants (kf) of the coordination reactions of the cobaloxime with polymer ligands were also measured in dimethylformamide (DMF) and benzene. In DMF kf decreased with an increase in 4VP unit content of the polymer ligand; in benzene it was increased by the 4VP fraction. These results can be explained by the variation in conformation of the polymer chain in each solvent. The effect of the polymer chain on complexation was discussed on the basis of the kinetic data. 相似文献
146.
[reaction: see text] Palladium-catalyzed alpha-arylation of N-benzoyl sulfoximine ethyl ester with various aryl bromides leads to alpha-arylated products that can easily be hydrolyzed, giving the corresponding N-protected benzyl phenyl sulfoximines. In this manner, new sulfoximine derivatives are accessible that have so far been difficult to prepare in enantiopure form. 相似文献
147.
Hidetsura Cho Yoshiko Ohnaka Mariko Hayashimatsu Masaru Ueda Keiyuu Shima 《Tetrahedron letters》1986,27(52):6377-6380
Chlorination of 5,6-dihydropyrimidine-4-(3H)-one derivatives (1) with POCl3 gave 1,4(3,4)-dihydropyrimidines (3), whose alkoxycarbonylation (ClCOOREt3N or NaH) afforded regioselectively novel compounds (4). A new Pummerer
rearrangement of compound (1, X=
---S(O)CH3) with
3, gave compound (5h). 相似文献
148.
Sung-Kyu Kim Su-Dong Cho Deok-Heon Kweon Yong-Jin Yoon Jung-Ho Kim Jung-Nyoung Heo 《Journal of heterocyclic chemistry》1997,34(1):209-214
Alkylations of 4,5-dichloropyridazin-6-one (1) with dibromoalkanes 2 or 3 in the presence of potassium carbonate or tetrabutylammonium bromide/potassium hydroxide were investigated under restricted condition. Reactions of 1 with 2 or 3, except for 2b and 3b , in the presence of potassium carbonate or tetrabutylammonium bromide/potassium hydroxide gave only the N-alkylation products 3 and/or 4. Alkylation of 1 with 2b or 3b in the presence of potassium carbonate yielded the N-alkylation products 3b and/or 4b and the O-alkylation product 5 as the main product, whereas treatment of 1 with 2b or 3b in the presence of tetrabutylammonium bromide/potassium hydroxide afforded selectively the N-alkylation products 3b and/or 4b. 相似文献
149.
150.