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241.
Yuichiro Haramoto Tomomi Miyashita Masato Nanasawa Yoshio Aoki Hiroyuki Nohira 《Liquid crystals》2013,40(1):87-90
New pyridinium type chiral ionic liquid crystal materials having a 1,3-dioxane ring in the central core, (+)- N -2-methylbutyl-4-(5-alkyl-1,3-dioxan-2-yl)pyridinium bromides (6), were synthesized. Mixture A was made by adding 5.9 wt % of compound 6?3 to the ferroelectric liquid crystal mixture Merck 4655-100; its phase transitions and some liquid crystal properties were measured. In spite of a large decrease of Ps for mixture A, its response time A was the same as that of Merck 4655-100. The dielectric constants perpendicular to the molecular axis for the smectic C* and smectic A phases were measured for the mixture and Merck 4655?100: in the smectic C phase, these dielectric constants were almost the same (4.5~5.5), but in the smectic A phase, the perpendicular dielectric constant of the mixture was 47.0 and that of Merck 4655?100 was 4.5. 相似文献
242.
Yumiko MatsutaTakayuki Kobari Sachiko KurashimaYuhsuke Kumakura Masashi ShinadaKazuhiro Higuchi Tomomi Kawasaki 《Tetrahedron letters》2011,52(46):6199-6202
An efficient approach to spirocyclic oxindole architecture with vicinal quaternary carbon centers is described. The reaction of 2-allyloxyindolin-3-ones with cyanomethylphosphonate at low reaction temperature proceeds smoothly with consecutive olefination, isomerization, deacylation, and anion-accelerated Claisen rearrangement to give the 3,3-disubstituted oxindoles with vicinal quaternary all-carbon centers in high yield and diastereoselectivity. The oxindoles are readily converted into more synthetically advanced spiro-products. 相似文献
243.