Thiacalix[4]arenes possessing carboxylic groups were used for the design of potential dendritic cores with amino surface groups. The known tetraacetic acid in the 1,3-alternate conformation gave the desired product in very low yield because of steric hindrance on thiacalix[4]arene moiety. Therefore, synthetic strategy based on withdrawing of the carboxyl groups via benzylic spacer from the thiacalix[4]arene moiety was successfully applied for the realization of novel thiacalix[4]arenes bearing two or four protected lysine units. (C) 2004 Elsevier Ltd. All rights reserved.
The Chemistry of Amine−Azide Interconversion: Catalytic Diazotransfer and Regioselective Azide Reduction
作者:Paul T. Nyffeler、Chang-Hsing Liang、Kathryn M. Koeller、Chi-Huey Wong
DOI:10.1021/ja0264605
日期:2002.9.1
previously reported. Azides can be reduced with good regioselectivity in moderate yields by a modification of the Staudinger reaction using trimethylphosphine at low temperatures. Electronic factors determine the selectivity for azidereduction, and the reaction is predictable by NMR analysis of the starting material. Several examples for the diazotransfer and regioselective azidereduction reactions are
Cone-type and spherical lysine dendrimers up to generation 3 based on thiacalix[4]arene core units were successfully prepared and characterized in order to use as molecular scaffolds for supramolecular host systems.