Synthesis of Double-Armed Lariat Ethers with Pyrene Moieties at Each End of Two Sidearms and Their Fluorescence Properties in the Presence of Alkali Metal and Alkaline Earth Metal Cations
suppression of both the crown ring and one of the two sidearms based on complexation with the metal cation. The selectivity for alkalineearth metal cations was highly dependent on the fitness of the host cavity and the guest size. Although most of the fluorophores did not respond to alkali metal cations, only trans-7a containing an 18-crown-6 ring showed K+ selectivity.
(rac-1a) and 15-crown-5 diol (rac-1c) was achieved by lipase-catalyzed acetylation. The enantiomeric excess of the chiralcrown diols (95% ee and 82% ee) was determined by 1H NMR spectroscopy, using (R)-(+)-1-(1-naphthyl)ethylammonium hydrochloride as a shift reagent. The C2-symmetric chiral 15-crown-5 diol (>95% ee) was also obtained by kinetic resolution of the racemic diacetate (rac-2c) using lipase-catalyzed
C 2对称的18冠-6二醇(rac - 1a)和15冠5二醇(rac - 1c)外消旋混合物的动力学拆分通过脂肪酶催化的乙酰化作用实现。使用(R)-(+)-1-(1-萘基)乙基铵盐酸盐作为位移试剂,通过1 H NMR光谱法测定手性冠二醇的对映体过量(95%ee和82%ee)。通过使用脂肪酶催化的溶剂分解动力学拆分外消旋二乙酸酯(rac - 2c),也可以获得C 2对称的手性15冠-5二醇(> 95%ee)。