Selective Modifications of Calix[6]arenes

Highly Selective Synthesis of a 1,3,5‐Tris‐Protected Calix[6]arene‐Type Molecular Platform through Coordination and Host–Guest Chemistry

“…[4] In the calixarene field, many selective functionalisations of calix [4]arenes either on the narrow or the wide rim have been reported. [5] In contrast, examples with the larger and more conformationally flexible calix [6]arenes are rare. [6] This is largely why these oligomers have been less studied despite the fact that their cavity size is much more suitable for host-guest chemistry applications than the tetramers.…”

“…[5] In contrast, examples with the larger and more conformationally flexible calix [6]arenes are rare. [6] This is largely why these oligomers have been less studied despite the fact that their cavity size is much more suitable for host-guest chemistry applications than the tetramers. Nevertheless, direct monomethylation or monobenzylation reactions at one phenolic position have been described in high yields.…”

“…Nevertheless, direct monomethylation or monobenzylation reactions at one phenolic position have been described in high yields. [7] However, calix [6]arenes displaying a 1,3,5-substitution pattern are more popular as starting materials because they possess an interesting and very useful C 3v symmetry. For example, 1,3,5-trimethoxy-ptBu-calix [6]arene has been used for the construction of cryptic endo receptors, [8] ligands for metal ions, [9] sensors for anions [10] or ammonium ions, [11] biomimetic metallic complexes, [12] chiral platforms, [13] cage molecules, [14] (pseudo)rotaxanes [15] or for the design of various self-assembled objects.…”

“…[7] However, calix [6]arenes displaying a 1,3,5-substitution pattern are more popular as starting materials because they possess an interesting and very useful C 3v symmetry. For example, 1,3,5-trimethoxy-ptBu-calix [6]arene has been used for the construction of cryptic endo receptors, [8] ligands for metal ions, [9] sensors for anions [10] or ammonium ions, [11] biomimetic metallic complexes, [12] chiral platforms, [13] cage molecules, [14] (pseudo)rotaxanes [15] or for the design of various self-assembled objects. [16] Unfortunately, this compound [17] and the related 1,3,5-tribenzyl derivatives [18] are obtained in only moderate Abstract: 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]-A C H T U N G T R E N N U N G arene-based molecular platform with three protected amino arms in alternating positions.…”

“…[16] Unfortunately, this compound [17] and the related 1,3,5-tribenzyl derivatives [18] are obtained in only moderate Abstract: 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]-A C H T U N G T R E N N U N G 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 6vsymmetrical 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 toward chemical reagents.…”