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排序方式: 共有311条查询结果,搜索用时 31 毫秒
301.
Murata Y Maeda S Murata M Komatsu K 《Journal of the American Chemical Society》2008,130(21):6702-6703
An open-cage C70 derivative having a 13-membered ring opening (2) was synthesized by a three-step reaction; thermal reaction of C70 with a pyridazine derivative, oxidative cleavage of the CC double bond, and insertion of a sulfur atom to the opening. The structure of 2 was determined by X-ray analysis. One H2 molecule was introduced into 2 to give H2@2 in 97% yield. Furthermore, two H2 molecules were encapsulated in 2 in 3% yield. The positional exchange of two H2 molecules inside 2 was clearly observed by the dynamic low-temperature NMR measurements. 相似文献
302.
Taniguchi T Fukuba TA Nakatsuka S Hayase S Kawatsura M Uno H Itoh T 《The Journal of organic chemistry》2008,73(10):3875-3884
Candida antarctica lipase B (CAL-B) is one the most frequently used enzymes in organic synthesis for the preparation of optically active alcohols. However, it has not been used for the optical resolution of (+/-)-2,2'-binaphthol. We established an efficient linker-oriented design of 2,2'-binaphthol derivatives that is appropriate for optical resolution using CAL-B-catalyzed hydrolysis reaction. Methyl 4-(1-(6-bromo-2-methoxymethoxynaphthalen-1-yl)-6-bromonaphthalen-2-yloxy)butanoate was hydrolyzed by CAL-B to afford a corresponding acid with excellent enantioselectivity ( E > 200). Two types of optically active binaphthol derivatives, 1-(2-hydroxy-6-(naphthalen-1-yl)naphthalen-1-yl)-6-(naphthalen-1-yl)naphthalen-2-ol and 6-butyl-1-(6-butyl-2-hydroxynaphthalen-1-yl)naphthalen-2-ol, were prepared by this chemo-enzymatic reaction protocol and were used as chiral templates for symmetric reactions. 相似文献
303.
304.
Mebs S Weber M Luger P Schmidt BM Sakurai H Higashibayashi S Onogi S Lentz D 《Organic & biomolecular chemistry》2012,10(11):2218-2222
The experimental electron density of sumanene, C(21)H(12), was extracted from a high resolution X-ray data set measured at 100 K and topologically analyzed. In addition to bond topological and atomic properties, information about the density distribution between adjacent molecules, which show close C···C approaches of ~3.4 ? within the columnar π-stacks in the crystal lattice, are discussed. A comparison is made with the electron density of the related corannulene molecule based also on the analysis of Electron Localizability Indicator (ELI-D) calculations. 相似文献
305.
Fusano A Sumino S Nishitani S Inouye T Morimoto K Fukuyama T Ryu I 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(30):9415-9422
The atom-transfer carbonylation reaction of various alkyl iodides thereby leading to carboxylic acid esters was effectively accelerated by the addition of transition-metal catalysts under photoirradiation conditions. By using a combined Pd/hν reaction system, vicinal C-functionalization of alkenes was attained in which α-substituted iodoalkanes, alkenes, carbon monoxide, and alcohols were coupled to give functionalized esters. When alkenyl alcohols were used as acceptor alkenes, three-component coupling reactions, which were accompanied by intramolecular esterification, proceeded to give lactones. Pd-dimer complex [Pd(2)(CNMe)(6)][PF(6)](2), which is known to undergo homolysis under photoirradiation conditions, worked quite well as a catalyst in these three- or four-component coupling reactions. In this metal/radical hybrid system, both Pd radicals and acyl radicals are key players and a stereochemical study confirmed the carbonylation step proceeded through a radical carbonylation mechanism. 相似文献
306.
Hirai K Furukawa S Kondo M Meilikhov M Sakata Y Sakata O Kitagawa S 《Chemical communications (Cambridge, England)》2012,48(52):6472-6474
Spatiospecific functionalisation of a shell crystal was performed in a core-shell crystal of a porous coordination polymer (PCP) via post-synthetic modification (PSM). The shell crystal allowed the core crystal to selectively accumulate N,N-dimethylaniline (DMA) and afford the intense exciplex fluorescence. 相似文献
307.
Azuma S Nishio K Kubo K Sasamori T Tokitoh N Kuramochi K Tsubaki K 《The Journal of organic chemistry》2012,77(10):4812-4820
Three types of dimeric naphthoquinones, which possess structurally diverse skeletons, can be prepared in one step from 2-bromo-3-methyl-1,4-naphthoquinones. 2,2'-Dimeric naphthoquinones were prepared by a one-pot Stille-type reaction via vinylstannanes. Oxepines are formed by unexpected domino reactions via 1,4-dihydroxynaphthalene species. Epoxides are formed by a Michael/Darzens reaction via the o-quinone methides. 相似文献
308.
Kazuhiro Kobayashi Yuta Okamura Shuhei Fukamachi Hisatoshi Konishi 《Tetrahedron》2010,66(40):7961-7964
A facile method for the synthesis of 3-substituted 3H-indol-3-ols has been developed. Thus, 2-isocyanophenyl ketones are allowed to react with various Grignard reagents to give the corresponding desired indolol derivatives in generally fair to good yields. The formation of 3-aryl-2,3-dimethylindolin-3-ols by the reaction of 2-isocyanobenzophenones with 2 M amounts of methylmagnesium bromide is also reported. 相似文献
309.
Ninomiya K Ogino C Oshima S Sonoke S Kuroda S Shimizu N 《Ultrasonics sonochemistry》2012,19(3):607-614
Our previous study suggested new sonodynamic therapy for cancer cells based on the delivery of titanium dioxide (TiO2) nanoparticles (NPs) modified with a protein specifically recognizing target cells and subsequent generation of hydroxyl radicals from TiO2 NPs activated by external ultrasound irradiation (called TiO2/US treatment). The present study first examined the uptake behavior of TiO2 NPs modified with pre-S1/S2 (model protein-recognizing hepatocytes) by HepG2 cells for 24 h. It took 6 h for sufficient uptake of the TiO2 NPs by the cells. Next, the effect of the TiO2/US treatment on HepG2 cell growth was examined for 96 h after the 1 MHz ultrasound was irradiated (0.1 W/cm2, 30 s) to the cells which incorporated the TiO2 NPs. Apoptosis was observed at 6 h after the TiO2/US treatment. Although no apparent cell-injury was observed until 24 h after the treatment, the viable cell concentration had deteriorated to 46% of the control at 96 h. Finally, the TiO2/US treatment was applied to a mouse xenograft model. The pre-S1/S2-immobilized TiO2 (0.1 mg) was directly injected into tumors, followed by 1 MHz ultrasound irradiation at 1.0 W/cm2 for 60 s. As a result of the treatment repeated five times within 13 days, tumor growth could be hampered up to 28 days compared with the control conditions. 相似文献
310.
Hyaluronidases (HYALs) are endo-beta-N-acetylhexosaminidases that depolymerize not only hyaluronan but also chondroitin sulfate (CS) at the initial step of their catabolism. Although HYAL1 hydrolyzes both CS and HA, HYAL4 is a CS-specific endoglycosidase. The substrate specificity of HYAL4 and identification of amino acid residues required for its enzymatic activity have been reported. In this study, we characterized the properties of HYAL4 including the expression levels in various tissues, cellular localization, and effects of its overexpression on intracellular CS catabolism, using cultured cells as well as mouse tissues. Hyal4 mRNA and HYAL4 protein were demonstrated to be ubiquitously expressed in various organs in the mouse. HYAL4 protein was shown to be present both on cell surfaces as well as in lysosomes of rat skeletal muscle myoblasts, L6 cells. Overexpression of HYAL4 in Chinese hamster ovary cells decreased in the total amount of CS, suggesting its involvement in the cellular catabolism of CS. In conclusion, HYAL4 may be widely distributed and play various biological roles, including the intracellular depolymerization of CS. 相似文献