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61.
Hong Xia Yoshio Hashimoto Toru Morita Toshihiro Hirai 《Journal of Polymer Science.Polymer Physics》2014,52(13):887-892
Few solvents are capable of dissolving polyketones (PKs). 1,1,1,3,3,3‐Hexafluoro‐2‐propanol (hexafluoroisopropanol, HFIP) is a better solvent than trifluoroethanol and m‐cresol. When HFIP was evaporated from a PK/HFIP solution, a porous cast‐film with a microparticle structure was formed because the isotactic PKs adopted a helical conformation, and convection during evaporation of the high polarity and low‐boiling‐point HFIP caused aggregation and rolling of the polymer molecules. The addition of plasticizer suppressed particle formation, improving the surface structure and mechanical properties of the film. In particular, the dielectric properties of the film improved significantly. This will enable PKs, which are rigid insulating materials, to be used as dielectric materials, broadening their range of applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 887–892 相似文献
62.
M. Campagnole 《合成通讯》2013,43(7):1077-1090
β‐Damascenone and β‐damascone derivatives, important fragrant compounds, were directly obtained from β‐ionone by a new way via retro‐α‐ionol. 相似文献
63.
《Angewandte Chemie (International ed. in English)》2017,56(36):10796-10800
Unified, efficient, and scalable syntheses of the halichondrin natural products are reported. A newly developed Zr/Ni‐mediated one‐pot ketone synthesis was used to couple the two halves of the final product at a late stage in the synthesis. With the use of a slight excess of the left halves, the desired ketones were isolated in yields of 80–90 %. The halichondrins were obtained from these ketones in two steps, namely desilylation and [5,5]‐spiroketal formation. The new synthetic route was effective for the total synthesis of all members in the homohalichondrin subgroup. The scalability of this process was demonstrated with halichondrin B; 150 mg of halichondrin B (68 % overall yield) were obtained from 200 mg of the right‐half precursor. 相似文献
64.
《Green Chemistry Letters and Reviews》2013,6(1):25-30
Abstract The enzymatic reduction of prochiral heterocyclic ketones by carrot (Daucus carota) root in water afforded the corresponding S-alcohols in accordance with the Prelog's rule. The reaction was performed under various conditions in order to optimize the procedure of bioreduction regarding reaction time, yield, and optimal mass of carrot. The optimized procedure was used to test the ability of other plants to carry out the reaction. In the latter experiment, it was observed that, with regard to stereospecificity, most vegetables tested were poorer reducing agents compared to D. carota. 相似文献
65.
Krishna Sai Gajula Naresh Mameda Srujana Kodumuri Durgaiah Chevella Rammurthy Banothu Vasu Amrutham 《合成通讯》2013,43(22):2866-2876
The synthesis of 2,3-dihydroquinazolin-4(1H)-ones by cyclocondensation of anthranilamide with ketones in aqueous media using Hβ zeolite is reported. The scope of the reaction was explored by various ketones such as aromatic, aliphatic and cyclic ketones. Based on the preliminary mechanistic results, a tentative mechanism for the formation of 2,3-dihydroquinazolin-4(1H)-ones using zeolite catalyst (Hβ) is predicted. The reusability study, large-scale experiment and water as solvent showed significant benefits of this catalytic protocol in comparing to earlier methods. 相似文献
66.
The highly reactive 1:1 intermediate generated in the reaction of tert-butyl isocyanide and dialkyl acetylenedicarboxylate is trapped by α-halo ketones to produce halogenated iminolactones as the sole product in good yields. 相似文献
67.
A general and efficient synthetic method of 1,3-bis(phenylseleno)-2-propanol by reducing diphenyl diselenides with sodium borohydride in basic environment and then reacting with epichlorohydrin are described. 相似文献
68.
A simple synthetic route to 1-p-methoxyphenyl and 1-p-methoxyphenyl-4-methylbicyclo [2.2.1]heptan-7-one 6b,a has been developed through benzilic acid rearrangement of the bicyclo[2.2.1]octandiones 2b,a. The oxidation of 7-hydroxy-1-p-methoxyphenyl-4-methylbicyclo[2.2.1]heptan-7-carboxylic acid 3a with lead tetraacetate gives the carbolactone 7a which is also formed by the reaction of the ketone 6a with m-chloroperbenzoic acid. 相似文献
69.
Two new spirostanol saponins, namely elephanosides G and H ( 1 and 2 , resp.) were isolated from the leaves of Yucca elephantipes (Agavaceae), together with the two known furostanol saponins 3 and 4 and the six known flavonoid O‐ and C‐glycosides 5 – 10 . The new structures were elucidated as (3β,25S)‐spirost‐5‐en‐3‐yl O‐β‐D ‐glucopyranosyl‐(1→3)‐O‐β‐D ‐glucopyranosyl‐(1→4)‐β‐D ‐galactopyranoside ( 1 ) and (3β,5β,25R)‐3‐[(2‐O‐β‐D ‐glucopyranosyl‐β‐D ‐galactopyranosyl)oxy]spirostan‐12‐one ( 2 ) on the basis of detailed spectroscopic analysis and acidic hydrolysis. 相似文献
70.
Ketones and aldehydes are conveniently and rapidly reduced to the corresponding alcohols in good yields using sodium borohydride under sealed-tube microwave conditions in either 95% ethanol or water. In purely aqueous systems, highly aliphatic substrates are sluggish, but this can be overcome by introducing sodium dodecyl sulfate (SDS) at the critical micelle concentration. With a 2:1 substrate/borohydride ratio and a reaction temperature of 100 °C, reduction is typically complete within 1 min in 95% ethanol and 5 min in water/SDS. The methodology is well suited for parallel and combinatorial synthetic approaches. 相似文献