Highly selective synthesis of a 1,3,5-tris-protected calix[6]arene-type molecular platform through coordination and host-guest chemistry

An elegant methodology based on the synergistic combination of coordination and host-guest chemistry led to the highly efficient synthesis of a unique C-3v-symmetrical, calix[6]-arene-based molecular platform with three protected amino arms in alternating positions. The key step involves the formation of a stable supramolecular host-guest Zn-II complex from a C-6v-symmetrical calix[6]hexaamine. Indeed, in the presence of a polar neutral guest and a strong donor that acts as an exogenous ligand, three alternating amino groups of this calix[6]hexaamine are selectively coordinated to the Zn-II ion while the three others remain free and are thus much more reactive