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Lucie Loukotková Eva Tesařová Zuzana Bosáková Pavel Repko Daniel W. Armstrong 《Journal of separation science》2010,33(9):1244-1254
Retention and enantioseparation behavior of ten 2,2′‐disubstituted or 2,3,2′‐trisubstituted 1,1′‐binaphthyls and 8,3′‐disubstituted 1,2′‐binaphthyls, which are used as catalysts in asymmetric synthesis, was investigated on eight chiral stationary phases (CSPs) based on β‐CD, polysaccharides (tris(3,5‐dimethylphenylcarbamate) cellulose or amylose CSPs) and new synthetic polymers (trans‐1,2‐diamino‐cyclohexane, trans‐1,2‐diphenylethylenediamine and trans‐9,10‐dihydro‐9,10‐ethanoanthracene‐(11S,12S)‐11,12‐dicarboxylic acid CSPs). Normal‐, reversed‐phase and polar‐organic separation modes were employed. The effect of the mobile phase composition was examined. The enantiomeric separation of binaphthyl derivatives, which possess quite similar structures, was possible in different enantioselective environments. The substituents and their positions on the binaphthyl skeleton affect their properties and, as a consequence, the separation system suitable for their enantioseparation. In general, the presence of ionizable groups on the binaphthyl skeleton, substitution with non‐identical groups and a chiral axis in the 1,2′ position had the greatest impact on the enantiomeric discrimination. The 8,3′‐disubstituted 1,2′‐binaphthyl derivatives were the most easily separated compounds in several separation systems. From all the chiral stationary phases tested, cellulose‐based columns were shown to be the most convenient for enantioseparation of the studied analytes. However, the polymeric CSPs with their complementary behavior provided good enantioselective environments for some derivatives that could be hardly separated in any other chromatographic system. 相似文献
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《Liquid crystals》2012,39(12):1763-1768
ABSTRACTWe report the synthesis of 7,7?-disubstituted 2,2?-methylenedioxy-1,1?-binaphthyls and demonstrate their application as chiral dopants in the nematic mixture MLC-6260 to produce highly twisted cholesteric phases. Especially mesogenic and/or polarizable groups in the 7,7?-positions of the bridged binaphthyls generate unusually high helical twisting powers. 相似文献
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Naphthylboronic acids prepared as reported in the literature are contaminated with HCl. A very simple purification prior to their use in Suzuki-Miyaura couplings has been found to be crucial, rendering efficient some reactions that had been reported in the literature either to fail or to give extremely poor yields. With this improvement, parent boronic acids can be used instead of esters at moderate temperatures, and bromo derivatives can be used instead of iodo derivatives. Convenient access to chiral sterically hindered binaphthalene derivatives has been achieved through the use of boronic acids, bromonaphthalenes, and ferrocenylphosphane ligands. The products were obtained in good yields (95-55 %) and with good enantioselectivities (90-50 %). Bulkier ligands are less efficient in the coupling of hindered partners. 相似文献
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The lithiation of 2,7-dihydrodinaphthoheteroepines (5) with 2.2 equiv of lithium naphthalenide in THF at −78 °C gives dianionic intermediates 8, which by reaction with different electrophiles [H2O, D2O, tBuCHO, Me2CO, Et2CO, (CH2)4CO, (CH2)5CO] at the same temperature, followed by hydrolysis, leads to unsymmetrically 2,2′-disubstituted binaphthyls 6. When the lithiation is performed with an excess of lithium in the presence of a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 10 mol %), a double reductive cleavage takes place to give dianionic intermediate 9, which by reaction with different electrophiles [H2O, Me2CO, Et2CO, (CH2)4CO, (CH2)5CO], followed by hydrolysis with water, yields symmetrically 2,2′-disubstituted binaphthyls 7. In the case of starting from (R)-5a, the reductive opening by treatment with 2.2 equiv of lithium naphthalenide followed by reaction with H2O or (CH2)5CO as electrophiles and final hydrolysis, leads to enantiomerically pure compounds (R)-6aa and (R)-6af, respectively. 相似文献
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Hui-Chang ZhangLin Pu 《Tetrahedron》2003,59(10):1703-1709
An efficient strategy has been developed to incorporate new chromophores into chiral binaphthyl polymers. The repeating units of these polymers are made of conjugated structures with strongly electron-donating amino groups at the both ends. These optically active materials contain the highest possible density of chromophores in a polymer chain since every repeating unit in these polymers is a chromophore. They are soluble in common organic solvents and can be easily processed. The spectroscopic properties of these polymers are studied. The structural similarity of the chromophores in these chiral conjugated polymers with those of two-photon absorbing molecules may lead to interesting optical properties. 相似文献
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