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71.
Yamamoto M Nakaoka S Ura Y Kataoka Y 《Chemical communications (Cambridge, England)》2012,48(8):1165-1167
A palladium-catalyzed reaction of vinylarenes, allyl ethers, and 1,5-dienes with pinacol proceeded via a selective anti-Markovnikov nucleophilic attack to afford corresponding terminal acetals as major products. The bulkiness of pinacol was found to be critical in controlling the regioselectivity. 相似文献
72.
The reaction of Mn(III) salen-type complexes with di- and tetraanionic α-Keggin-type polyoxometalates (POMs) was performed, and three types of Coulombic aggregations containing Mn(III) out-of-plane dimeric units (abbreviated as [Mn(2)](2+)) that are potentially single-molecule magnets (SMMs) with an S(T) = 4 ground state were synthesized: [Mn(2)(5-MeOsaltmen)(2)(acetone)(2)][SW(12)O(40)] (1), [Mn(2)(salen)(2)(H(2)O)(2)](2)[SiW(12)O(40)] (2), and [Mn(5-Brsaltmen)(H(2)O)(acetone)](2)[{Mn(2)(5-Brsaltmen)(2)}(SiW(12)O(40))] (3), where 5-Rsaltmen(2-) = N,N'-(1,1,2,2-tetramethylethylene)bis(5-R-salicylideneiminate) with R = MeO (methoxy), Br (bromo) and salen(2-) = N,N'-ethylenebis(salicylideneiminate). Compound 1 with a dianionic POM, [SW(12)O(40)](2-), is composed of a 1:1 aggregating set of [Mn(2)](2+)/POM, and 2, with a tetraanionic POM, [SiW(12)O(40)](4-), is a 2:1 set. Compound 3 with [SiW(12)O(40)](4-) forms a unique 1D coordinating chain with a [-{Mn(2)}-POM-](2-) repeating unit, for which a hydrogen-bonded dimeric unit ([Mn(5-Brsaltmen)(H(2)O)(acetone)](2)(2+)) is present as a countercation. Independent of the formula ratio of [Mn(2)](2+)/POM, Mn(III) dimers and POM units in 1-3 form respective segregated columns along a direction of the unit cell, which make an alternate packing to separate evenly identical species in a crystal. The nearest intermolecular Mn···Mn distance is found in the order 2 < 3 < 1. The segregation of the [Mn(2)](2+) dimer resulted in interdimer distances long enough to effectively reduce the intermolecular magnetic interaction, in particular in 1 and 3. Consequently, an intrinsic property, SMM behavior, of Mn(III) dimers has been characterized in this system, even though the interdimer interactions are still crucial in the case of 2, where a long-range magnetic order competitively affects slow relaxation of the magnetization at low ac frequencies. 相似文献
73.
Separations of neutral and basic racemates were performed using five different anionic cyclodextrin (CD) derivatives as chiral selectors, viz. carboxymethylated β-CD, β-CD phosphate sodium salt, sulfobutyl ether β-CD sodium salt, carboxymethylated γ-CD, and γ-CD phosphate sodium salt. For the separation of neutral racemates, an untreated fused silica capillary was employed and various neutral racemates were successfully separated. Since the pH of the buffer affected the electroosmotic flow (EOF), the resolution was improved by changing the buffer pH. A polyacrylamide coated capillary was employed for the separation of basic racemates to suppress EOF and to prevent adsorption of cationic analyte on the capillary surface. By choosing an appropriate type and concentration of anionic CD, about 40 basic racemates were successfully separated. Some rough binding constants of basic analytes with an anionic β-CD were measured to discuss the optimum concentration of the CD. The migration direction was dependent on the binding constants and the concentration of the CD. The analyte strongly bound to the anionic CD migrated towards the anode but the weakly bound one moved towards the cathode. Anionic γ-CDs were also very useful for the separation of basic enantiomers. Five neutral CDs were employed as chiral selectors to compare selectivity between charged and neutral CDs, and eleven racemates could only be resolved using anionic CDs. The separation of some basic racemates in human plasma was also described. The direct injection of plasma samples was possible for some enantiomers that did not interact strongly with plasma proteins. 相似文献
74.
Jun Zhang Dr. Wataru Kosaka Prof. Dr. Susumu Kitagawa Prof. Dr. Masaki Takata Prof. Dr. Hitoshi Miyasaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(12):3020-3031
Optimal control of gas adsorption properties in metal–organic frameworks (MOFs) or porous coordination polymers (PCPs) remains a great challenge in the field of materials science. An efficient strategy to capture electron-acceptor-type gas molecules such as nitrogen monooxide (NO) is to use host–guest interactions by utilizing electron-donor-type MOFs/PCPs as host frameworks. Herein, we focus on a highly electron-donating chain compound by using the paddlewheel-type [Ru2II,II] complex [Ru2(2,4,5-Me3PhCO2)4] (2,4,5-Me3PhCO2−=2,4,5-trimethylbenzoate) with the phenazine (phz) linker: [Ru2(2,4,5-Me3PhCO2)4(phz)] ( 1 ). Compound 1 exhibited a specific gated adsorption for NO under gas pressures greater than 60 kPa at 121 K, which finally resulted in approximately seven molar equivalents being taken up at 100 kPa followed by four molar equivalents remaining under vacuum at 121 K; its Rh isomorph ( 2 ) with weaker donation ability was inactive for NO. When the sample of 1 ⊃4 NO was heated to room temperature, the compound underwent a crystal-to-crystal phase transition to give [Ru2(2,4,5-Me3PhCO2)4(NO)2](phz) ( 1 -NO), involving a post-synthetic nitrosylation on the [Ru2] unit, accompanied by an eventful site-exchange with phz. This drastic event, which is dependent on the NO pressure, temperature, and time, was coherently monitored by using several different in situ techniques, revealing that the stabilization of NO molecules in nanosized pores dynamically and stepwisely occurred with the support of strong electronic/magnetic host–guest interactions. 相似文献
75.
76.
Shigeyuki Tasaka Hirokazu Tanabe Yoshiyuki Sasaki Toshiki Machida Mayumi Iino Akira Kiue Seiji Naito Michihiko Kuwano 《Journal of heterocyclic chemistry》1997,34(6):1763-1767
We have investigated 3-substituted-2-phenylimidazo[2,1-b]benzothiazole derivatives and herein we have discussed their pharmaceutical activities. We found that some 2-phenyl-5,6,7,8-tetrahydroimidazo[2,1-b]-benzothiazoles could overcome multidrug resistance for tumor cells. Among them, 2-phenyl-3-(N-methyl-3-piperidyl)carbonylammomiinomemyl-5,6,7,8-tetrahydVoimidazo[2,1-b]benzothiazole [N276-12] demonstrated the most potent activity for overcoming multidrug resistance. 相似文献
77.
New thermotropic ionic liquid crystals were prepared from trans-4-nitro-4'-stilbazole and alkyl halides. trans-N-Alkyl-4-nitro-4'-stilbazolium bromides containing alkyl chains with 7 to 10 carbons and the chloride homologues containing alkyl chains with 5 to 10 carbons exhibited smectic phases. For example, trans-N-decyl-4-nitro-4'-stilbazolium bromide and trans-N-hexyl-4-nitro-4'-stilbazolium chloride showed smectic phases from 175 to 186°C and from 129 to 190°C, respectively. The temperature range of mesophases increased with decreasing size of the counteranions. The miscibility of trans-N-alkyl-4-nitro-4'-stilbazolium bromide in Schiff's base compounds having various electronegative groups was examined by differential scanning calorimetry and polarizing microscopy. Miscible binary mixtures were prepared from trans-N-alkyl-4-nitro-4'-stilbazolium bromides and 4-alkoxy-N-(9-methyl-2-carbozolyl-methylene)anilines. The 1:1 (mole ratio) binary mixture of trans-N-hexyl-4-nitro-4'-stilbazolium bromide with 4-hexyloxy-N-(9-methyl-2-carbazolylmethylene)aniline exhibited a stable smectic phase between 83 and 149°C, though a smectic phase is not exhibited by both individual components. The miscibility in the binary mixtures might be caused by a combination of ionic and electron donor-acceptor interactions. 相似文献
78.
Mayumi Takasu Hiroaki Wakabayashi Kyoji Furuta Hisashi Yamamoto 《Tetrahedron letters》1988,29(52):6943-6946
Achiral and chiral crowns complexed with potassium bases catalyze the Michael additions of enolates to cycloalkenones. 相似文献
79.