Conformational control in the synthesis of mixed tetraethers of calix[4]arene. Part 2

Main-Chain Calixarene Polymers: Conformational Effects on Polymerization

“…Monomer precursors 2a and 2b , which are protected at the two alternate phenols, were further functionalized by polymerizable arms. Monomers 3b and 4b are mixtures of conformers in dynamic equilibrium because the relatively small methyl protecting groups allow the aryl rings to freely rotate through the calixarene annulus . Bulky benzyl groups fix the conformations of 3a and 4a , and their ratios of the partial cone (paco) conformer and cone conformer are influenced by the synthetic conditions (see Supporting Information).…”

“…Monomers 3b and 4b are mixtures of conformers in dynamic equilibrium because the relatively small methyl protecting groups allow the aryl rings to freely rotate through the calixarene annulus. 15 Bulky benzyl groups fix the conformations of 3a and 4a, and their ratios of the partial cone (paco) conformer and cone conformer are influenced by the synthetic conditions (see Supporting Information). The paco/cone preference partially results from template effects of base counterions.…”

Synthesis of Bridged, Multifunctional Calixarenes via Ring Closing Metathesis

“…Microanalysis were carried out by the Service of Microanalysis of the School of Chemistry. Synthesis of compounds 4a , b , 6 , 8a − c , 15 , and 17 has been described in previous publications by our research group. , Melting points of mixtures of isomers are not stated.…”

“…Interestingly, the order in which the two different sets of substituents were introduced had an effect on the conformations of the final product, which enables us to study the metathesis of derivatives in more than one conformation. This effect, which was discovered when the two alkylation steps were reversed, is examined in detail elsewhere …”