Synthesis of 2-alkyl- and 2-carboxy-p-tert-butylcalix[4]arenes via the lithiation of tetramethoxy-p-tert-butylcalix[4]arene.
Synthesis of 2-alkyl- and 2-carboxy-p-tert-butylcalix[4]arenes via the lithiation of tetramethoxy-p-tert-butylcalix[4]arene.
复制标题
通过四甲氧基-对叔丁基杯[4]芳烃的锂化合成2-烷基-和2-羧基-对叔丁基杯[4]芳烃。
作者：
Peter A. Scully;Timothy M. Hamilton;Jordan L. Bennett
[反应：见正文]。四甲氧基-对叔丁基杯[4]芳烃容易与正丁基锂反应，得到推定的单锂化中间体，其被卤代烷和二氧化碳取代，以60-75%的产率得到构象上移动的杯[4]芳烃，其在亚甲基桥（2-位）处单取代。通过用三溴化硼处理，2-烷基-和2-苄基-取代的四甲氧基杯[4]芳烃以62-68%的总产率转化为相应的四羟基-对-叔丁基杯[4]芳烃。核磁共振谱表明，四羟基对叔丁基杯[4]芳烃在室温下以锥形构象存在。
[reaction: see text]. Tetramethoxy-p-tert-butylcalix[4]arene reacts readily with n-butyllithium to give a putative monolithiated intermediate that is substituted with alkyl halides and carbon dioxide to give in 60-75% yield conformationally mobile calix[4]arenes monosubstituted at the methylene bridge (2-position). 2-Alkyl- and 2-benzyl-substituted tetramethoxycalix[4]arenes are converted in 62-68% overall yield to the corresponding tetrahydroxy-p-tert-butylcalix[4]arenes by treatment with boron tribromide. The tetrahydroxy-p-tert-butylcalix[4]arenes exist in the cone conformation at room temperature in CDCl3 as judged by NMR spectroscopy.