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1.
Reaction of cyclic sulfates of vic-diols with sodium hydroxide in THF-MeOH produced the corresponding epoxides in excellent isolated yields at room temperature. Cyclic sulfates of trans-diols gave cis-epoxides, and cyclic sulfates of cis-diols afforded trans-epoxides exclusively. Various cyclic sulfates of vic-diols can be converted into the epoxides under the conditions. 相似文献
2.
Reaction of cyclic sulfates of vic-diols with magnesium iodide in acetonitrile produced the corresponding olefins in excellent isolated yields at room temperature. Cyclic sulfates of trans-diols gave trans-alkenes exclusively. Cyclic sulfates of cis-diols gave a mixture of cis- and trans- alkenes. However, the cyclic sulfate of cyclic cis-diol afforded the corresponding cis-alkene only. 相似文献
3.
Treatment of cyclic sulfates of vic-diois with triphenylphosphine and iodine offers the corresponding olefins in high yields at room temperature. Both cyclic sulfates of d,l-hydrobenzoin and meso-hydrobenzoin give trans-stilbene. 相似文献
4.
水热条件下合成了具有超大孔道和层状结构的有机模板稀土硫酸盐。超大孔道的稀土硫酸盐(1)的分子式为[(CH3)2NH2]9[Pr5(SO4)12]·2H2O,它展现出有趣的交叉二十元环孔道结构。层状的稀土硫酸盐的分子式为[H3O]3[(CH3)2NH2]3[Ln2(SO4)6](Ln=Pr,2;Nd,3),它可以被看作是由双链和八元环结合而成。这3种化合物的合成揭示了大的有机胺(三聚氰胺)可能用作为第二结构导向剂,阻止形成高维数的无机骨架,从而诱导了二维层状结构稀土硫酸盐晶体的生长。对化合物1和3的磁性进行了研究,测试的温度范围在2~300 K。 相似文献
5.
水热条件下合成了具有超大孔道和层状结构的有机模板稀土硫酸盐。超大孔道的稀土硫酸盐(1)的分子式为[(CH3)2NH2]9[Pr5(SO4)12]·2H2O,它展现出有趣的交叉二十元环孔道结构。层状的稀土硫酸盐的分子式为[H3O]3[(CH3)2NH2]3[Ln2(SO4)6](Ln=Pr,2;Nd,3),它可以被看作是由双链和八元环结合而成。这3种化合物的合成揭示了大的有机胺(三聚氰胺)可能用作为第二结构导向剂,阻止形成高维数的无机骨架,从而诱导了二维层状结构稀土硫酸盐晶体的生长。对化合物1和3的磁性进行了研究,测试的温度范围在2~300 K。 相似文献
6.
Arlen W. Frank 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):207-212
Abstract An unexpected displacement of one of the phosphorus groups occurred when the chloride 1a was replaced by the sulfate 1b in its reactions with 1,3-dimethylurea. The products, 2c and 5c, were bisulfates rather than sulfates. In contrast, no displacement occurred when 1a was replaced by the sulfonates 1e or 1f. A method was developed for preparing the sulfonates 1d-h, all new compounds, by metathesis of the sulfate 1b with the appropriate barium sulfonate. The sulfates 2b and 5b, prepared from the chlorides 2a and 5a by ion exchange, yielded the bisulfates 2c and 5c upon treatment with sulfuric acid. The significance of the findings is discussed. 相似文献
7.
《液相色谱法及相关技术杂志》2012,35(1):139-149
Abstract We reported previously inhibition of Na+,K+-ATPase by a fraction (fraction 2–3) of medium size uremic toxins. Due to considerable amount of sulfates in this fraction, a semi preparative high performance liquid chromatography turned out to be inadequate to isolate the active compound. Therefore we developed a novel chromatographic method using ion exchanger Sephadex QAE A25 in acidic medium. This method allows the elimination of sulfates and the partial purification of the active component. 相似文献
8.
Vijay Nair Joseph P. Joseph John F. Poletto Seymour Bernstein 《Journal of carbohydrate chemistry》2013,32(4):639-644
Abstract A satisfactory procedure for the sulfation of flavonoid glycosides is described and is illustrated by the preparation of rutin nona and deca sulfates. Compounds of this type are important modulators of the complement part of the immune system. 相似文献
9.
Jérôme LalotTony Tite Anne WadouachiDenis Postel Albert Nguyen Van Nhien 《Tetrahedron》2011,67(33):6006-6017
C-branched-chain sugars and nucleosides were obtained by organocatalysis from ulose derivatives. After a reduction step, the corresponding 1,3-diol was derivatized into 3′-spiro-sulfamidates and unexpected sulfates by treatment with a Burgess reagent. Deprotection of the Boc-derivatives was carried out while preserving the cyclic sulfate. An example of ring opening of the cyclic sulfate derivative with sodium azide leading to the corresponding 3′-C-azidoalkyl branched-chain nucleosides is given. 相似文献
10.
Direct formation of cyclic sulfates utilising hypervalent iodine species and sulfur trioxide adducts
Richard I. RobinsonSimon Woodward 《Tetrahedron letters》2003,44(8):1655-1657
PhIO reacts with SO3·DMF at 0°C to form an active sulfating reagent; subsequent addition of alkenes results in the direct formation of cyclic sulfates in moderate to good yield (35-75%). Terminal, 1,1-disubstituted and cyclopentenes participate in the reaction which is technically very straightforward to carry out. 相似文献
11.
A new cyclic peptide, prepatellamide A (1), along with three known cyclic peptides (2)— (4), was isolated from the ascidianLissoclinum patella. The structure of prepatellamide A was determined from one- and two-dimensional1H and13C NMR spectra. The known cyclic peptides were identified as patellamides A (2), B (3) and C (4). 相似文献
12.
The formation of cyclic sulfates (4) from syn,syn-3-[N-(benzyloxycarbonyl)amino] 1,2-diols provides a common intermediate to access other diastereomers via two inversion procedures. Thermolysis of the cyclic sulfates in acetonitrile normally leads to inversion of the distal hydroxyl group to form a 1,3-oxazin-2-one (6). Catalytic hydrogenation of the cyclic sulfates under basic conditions (NEt(3)) results in inversion at the proximal hydroxyl group to form a 1,3-oxazolidin-2-one (5). 相似文献
13.
Jens Hartung Irina Kempter Thomas Gottwald Michaela Schwarz Rainer Kneuer 《Tetrahedron: Asymmetry》2009,20(18):2097-2104
Esterification of cyclic thiohydroxamic acids, for example, N-hydroxypyridine-2(1H)-thione, N-hydroxy-4-methylthiazole-2(3H)-thione, and N-hydroxy-4-(p-chlorophenyl)-thiazole-2(3H)-thione, occurred with inversion of configuration at the attacked stereocenter, as evident from the use of chiral alcohols, alkyl p-toluene sulfonates, and cyclic sulfates. Stereochemical analysis of enantiomerically pure O-alkyl thiohydroxamates was performed on the basis of CD-spectroscopy and chemical derivatization. The assignment of the relative configuration in cyclic O-esters was feasible via NMR spectroscopy, whereas chiral aliphatic glycolato monoesters required hydroxyl group derivatization with chloro-(4R,5R)-bis[(1R,2S,5R)-menth-1-yloxycarbonyl)]-1,3,2-dioxaphospholane for this purpose. 相似文献
14.
Zheng-Jie He Wen-Bin Chen Cheng-Xiang Zhang Zheng-Hong Zhou And Chu-Chi Tang 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):223-232
Abstract Starting from L-serine, cyclic thiophosphoramidate conjugates (2 and 3) of Tegafur and uridine were synthesized via a multiple-step procedure of esterification, cyclic phosphorylation, and sulfurization, etc. L-serinoate was N-alkylated, then cyclized with phosphorus oxychloride, and further reacted with N3-(2-hydroxyethyl) Tegafur to afford cyclic phospholipid conjugate 4. The resultants (2, 3, and 4) were successfully separated in the form of pure diastereomer by column chromatography on silica gel. Their configurations were discussed and assigned according to their NMR spectra. The asymmetric induction effects of the carbon-based chiral centre on the diastereomer preference were also observed in these two synthetic phosphorylation cyclizations. The bioassay on their antitumor activities is under investigation. 相似文献
15.
Katarzyna Kulig Agnieszka Boba Anna Bielejewska Magdalena Gorska Barbara Malawska 《Tetrahedron: Asymmetry》2009,20(3):322-326
The synthesis of enantiomers of 1-[3-(4-aryl-piperazin-1-yl)-2-hydroxy-propyl]-pyrrolidin-2-one derivatives is described. These enantiomers were synthesized starting from (R)- or (S)-1-chloro-2,3-dihydroxypropane using relevant cyclic sulfates as chiral intermediates. The enantiomeric purities of the final compounds were in the range of 99.3–100.0%, as determined by high performance liquid chromatography. The final compounds were found to display moderate potency as ligands for α1-adrenoreceptors. 相似文献
16.
A stereodivergent synthetic route has been developed to make the optically pure anti- and syn-beta-substituted cysteine and serine derivatives. In this approach, the key intermediates, > 94% enantiomerically pure cyclic sulfates 3 and aziridines 7, were prepared from alpha,beta-unsaturated esters 1, employing the Sharpless asymmetric dihydroxylation. The high regio- and stereoselective ring-opening reactions of cyclic sulfates and aziridines provided enantiomerically pure beta-substituted cysteine and serine derivatives. 相似文献
17.
A series of aryl hydroxylactams (2a, 2b, 2d–2g, 2i–2k, 2m, and 2n) was synthesized by partially reducing aryl cyclic imides in moderate to excellent yields with activated zinc dust alone in acetic acid. This method was regiospecific and can be employed as an alternative for reported methods to partially reduce aryl cyclic imides. 相似文献
18.
Keshab Ch Ghosh Indranil Duttagupta Chandra Bose Priyanjalee Banerjee Anuran Kumar Gayen 《合成通讯》2019,49(2):221-236
A solution phase method was adopted for the synthesis of proline-containing cyclic pentapeptide 2 and total synthesis of naturally occurring cyclic heptapeptide Reniochalistatin B 3. For the synthesis of 3, both divergent and convergent strategies were used to improve the overall yield from 12 to 25%. Different N and C terminal modified linear analogs and congeners of 2 and 3 were synthesized. Both cyclic peptides 2 and 3 and their linear analogs/congeners were evaluated for anti-cancer activity against HeLa cell line, among which pentapeptide 2?h and hexapeptide 3n with N-terminal protected hexafluoroisopropyl carbamates (HFIPC) interestingly showed higher cytotoxicity with an IC50 of 2.73 and 4.3?µM, respectively compared to their Boc-protected analogs 2a (IC50 20?µM) and 3c (IC50 38.51?µM) and cyclic peptides 2 (>100?µM) and 3 (47?µM). These results were further validated by biological experiments such as colony formation and wound healing assays. 相似文献
19.
Optically active cyclic bis(binaphthyl)s (4a–d), which are composed of aromatics, ethers, and ketonic carbonyls, were synthesized through a two‐step nucleophilic aromatic substitution reaction. Bis(binaphthyl) cyclic compounds (4a and 4b) were obtained in moderate yields when difluoride 3a and 3b were employed. On the other hand, bis(binaphthyl)s 4c and 4d were scarcely obtained when 3c and 3d were employed. 相似文献