Intermolecular aromatic C(sp2)–H amination promoted by neutral rhodium nitrenoids has been developed. The reactions proceeded with various oxygen-substituted arenes (1.5 equiv.) in a chemo- and regioselective manner. The aromatic C(sp2)–H amination took place at the para position of the oxygen substituent in the presence of benzylic C(sp3)–H bonds and/or C(sp3)–H bonds α to ethereal oxygen.
Graftable chiral ligands for surface organometallic materials: calixarenes bearing asymmetric centers directly attached to the lower rim
作者:Andrew Solovyov、Justin M. Notestein、Kathleen A. Durkin、Alexander Katz
DOI:10.1039/b801434p
日期:——
center to the calixarene core, and the extent of hydrogen bonding at the calixarene lower rim. The asymmetry of the calixarene core is quantified using 1H NMR spectroscopic shifts of aromatic meta and methylene bridge hydrogens and supported using ab initio calculations. The results demonstrate that calixarene core asymmetry is most strongly induced for rigid calixarene cores—an attribute that is expected
Calix[4]arene-cholic acid conjugates: a new class of efficient synthetic ionophores
作者:Nakia Maulucci、Francesco De Riccardis、Cinzia Barbara Botta、Agostino Casapullo、Elena Cressina、Massimo Fregonese、Paolo Tecilla、Irene Izzo
DOI:10.1039/b415908j
日期:——
The synthesis of a new class of amphiphilic calix[4]arene-based ionophores, relying on direct reductive amination as a key step, and the evaluation of their H+ and Na+ transporting properties is described.
A convenient method for the preparation of bis-calix[4]arenes was established. Using the system of acetonitrile-potassium carbonate sealed in a Schlenk tube at 100 °C allows facile syntheses of symmetric biscalix[4]arenes and 25,27-dibromoalkyl calix[4]arene. The latter can be tethered by another equivalent of calix[4]arene to furnish an unsymmetric biscalix[4]arene that exhibits superior selectivity
建立了制备双杯[4]芳烃的简便方法。使用在 100 °C 下密封在 Schlenk 管中的乙腈-碳酸钾系统可以轻松合成对称双杯[4]芳烃和 25,27-二溴烷基杯[4]芳烃。后者可以被另一种当量的杯[4]芳烃束缚,以提供对铯表现出优异选择性的不对称双杯[4]芳烃。
Improved precious metal adsorption by introduction of carboxylic acid groups on methylene crosslinked calix[4]arene resin matrix
A methylene crosslinked calix[4]arene tetracarboxylic acid resin that exhibits high precious metal adsorption properties was prepared. The maximum loading capacity of this resin was compared with that of an unmodified methylene crosslinked calix[4]arene resin to verify its applicability for platinum and palladium adsorption. The introduction of multiple acetic acid groups improved the adsorption capacity