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141.
Reaction of the laterally lithiated (S)-4-isopropyl-2-(2-methoxy-6-methylphenyl)oxazoline with p-tolualdehyde gave an inseparable mixture of the addition products in low diastereoselectivity. However, the (S,S)-product cyclized to the corresponding 3,4-dihydroisocoumarin faster than the (S,R)-product on silica gel, which allowed to be produced both enantiomers of 8-methoxy-3-(p-tolyl)-3,4-dihydroisocoumarin in moderate to good optical purity [S-enantiomer: 75% ee; R-enantiomer: 96% ee]. This procedure was applied to the short-step synthesis of optically active 3,4-dihydroisocoumarin natural products such as (R)-8-hydroxy-3-(1-tridecyl)-3,4-dihydroisocoumarin and (R)-phyllodulcin. 相似文献
142.
The chiral selector L -t-leucine-t-butylamide has been anchored to a polysiloxane by nucleophilic displacement of 2,2,2-trifluoroethyl ester-functionalized block polysiloxanes with L -t-leucine-t-butylamide. Attempts were made to immobilize the chiral polysiloxanes inside the capillaries by thermal treatment at 300°C for 30–90 min. The polysiloxanes were found to be more resistant than Chirasil-Val to the racemization caused by such high temperature treatment. Capillary columns coated with this type of immobilized polysiloxane have shown very high enantioselectivity and thermal stability. 相似文献
143.
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145.
Iwao Sato 《Discrete Mathematics》2008,308(12):2600-2606
We define the weighted Bartholdi zeta function and a weighted L-function of a graph G, and give determinant expressions of them. Furthermore, we present a decomposition formula for the weighted Bartholdi zeta function of a regular covering of G by weighted L-functions of G. 相似文献
146.
Ryoichi Nakagaki Noriko Kitamura Iwao Aoyama Hiromi Ohtsubo 《Journal of photochemistry and photobiology. A, Chemistry》1994,80(1-3):113-119
The absorption and fluorescence spectra of 7-aminocoumarins and 7-aminocarbostyrils with different degrees of alkylation were studied in 2-propanol (IP), polyfluorinated alcohols and water. The spectral properties of substituted 7-aminocoumarins and 7-aminocarbostyrils in hexafluoro-2-propanol (HFP) are very different from those in 2-propanol due to the strong hydrogen-bonding (HB) interaction between the solute and the solvent (HFP). The spectral behaviour can be explained in terms of the strength of the HB interaction which depends on the degree of alkylation of the amino group and the electron affinity of the electron-accepting moiety. The absorption spectra indicate that a structural change at the amino nitrogen is induced on formation of strong hydrogen bonds. 相似文献
147.
Kazuchika Ohta Takuya Watanabe Satoshi Tanak Testsuya Fujimoto Iwao Yamamoto Pierre Bassoul Nathalie Kucharczyk Jacques Simon 《Liquid crystals》1991,10(3):357-368
Octakis(alkyloxyphenyl)-phthalocyanine derivatives ((CnOph)8PcH2 n = 8, 10 12 and 18), their corresponding copper (II) complexes ((CnOph)8PcCu, n = 10, 12 and 18) and octakis(2-ethylhexyl)-PcH2 have been synthesized and their mesomorphic properties characterized. (CnOph)8PcH2, (n = 12 and 18) exhibit hexagona disordered columnar mesophases whereas (CnOph)8PcCu (n = 12 and 18) yields a rectangular disordered columnar liquid crystal. An alkylphenyl-oxymethyl derivative, (C12phOCH2)8PcH2, was synthesized to determine the influence of the connecting link between the side chains and the phthalocyanine macrocycle on the mesomorphic properties. 相似文献
148.
Mori K Tokumoto S Kubo H Higo N Nozawa I Sato S Sugibayashi K 《Chemical & pharmaceutical bulletin》2003,51(6):617-619
Few studies have been reported on the design of topical formulations consisting of electrodes and active drugs for electroporation as a means to increase skin permeability of the drugs, although many studies were reported for the effect of this physical means using aqueous drug solutions. We, therefore, designed a prototypic reservoir and matrix topical formulations that are suitable for electroporation in the present study. Plate-plate Ag electrodes and sodium diclofenac were used as model electrodes and the drug, respectively. The in vitro skin permeations of the drug obtained from the reservoir and matrix formulations were slightly higher than that from an aqueous suspension. This may be due to slightly higher electric field in the skin barrier for the presently designed formulations than that for the aqueous suspension. The present feasibility test suggests that these reservoirs and matrix formulations are useful prototypic topical formulations for electroporation application to improve the drug permeability through skin. 相似文献
149.
Iwao Tabushi Lung Chi Yuan Kazuhiro Shimokawa Kan-ichi Yokota Tadashi Mizutani Yasuhisa Kuroda 《Tetrahedron letters》1981,22(24):2273-2276
Doubly capped β-cyclodextrin was firstly prepared in good yield by the treatment of β- cyclodextrin with an excess amount (2.6/1 mol/mol) of benzophenone-3,3′-disulfonyl chloride. This successful double capping demonstrates that benzophenone-3,3′-disulfonyl capping takes place on A,C rings. The present double cap is a useful key intermediate for the preparation of regiospecifically tetrasubstituted cyclodextrins. 相似文献
150.