Amino Surface‐Functionalized Tris(calix[4]arene) Dendrons with Rigid C3‐Symmetric Propeller Cores
Dendrons composed of three functionalized cone calix[4]arene substructures covalently bound to rigid C3-symmetric tris-anilino cores through amide linkages have been obtained by a divergent synthetic protocol involving the coupling of p-nitrocalix[4]arene butanoic acid 9 with tris(4-aminophenyl)amine (TAPA), 1,3,5-tris(4-aminophenyl)benzene (TAPB), and 2,4,6-tris(4-aminophenyl)-s-triazine (TAPT). Two different amidation procedures were used to generate the dodecanitro intermediates (through activation of acid 9 with PyBOP catalyst or transformation into its acid chloride). The final reduction to the title dodecaamino dendrons was smoothly carried out with H2 and Raney-Ni catalyst.