Calixarenes esterification

Reports which have clear applications in DNA hydrolysis include one of a dinuclear lanthanum(III) complex that catalyses phosphate diester hydrolysis to give unprecidented rates of reaction and one describing the preparation of two new dinuclear bisimidazolyl-Cu(II) calixarenes and an investigation of these complexes as metalloenzyme models for phosphate diester cleavage. The importance of tuning microenvironments when designing synthetic nucleases is illustrated by a report that intramolecular trans-esterification of 2-hydroxy-propyl-4-nitrophenyl phosphate (84) is up to 5000 times faster in organic solvents than in water/ ... 

Treatment of calixarenes with acetyl chloride or benzoyl chloride in the presence of AICI3 at or below room temperature generally results in esterification to give 176. To achieve p-substitution the calixarene ethers have been used to give 177 (Y = alkyl n = 4, 6). The esters 176, however, can be converted to 177 (Y = H) by the Fries rearrangement, carried out with AICI3 at higher... 

The most obvious way to generate a chiral calixarene is by attachment of a chiral moiety. This was achieved as far back as 1979 by esterification with camphorsul-fonyl chloride,a chiral moiety which has again more recently been incorporated into a calix[4]arene. Several other examples have also been published describing the attachment of the chiral moiety at the lower rim via ether linkage. 

Calixarenes have also been modified by functionalization of phenolic groups by attaching organometallic moieties. Thus, esterification with ferrocene-, ruthenocene-,... 

The preferred way to append new groups at the endo rim of calixarene macrocycles is the 0-alkylation of the phenolic ring by a base-promoted Williamson s reaction to give partially or fully alkylated derivatives [1], Another less popular route is provided by any esterification reaction [20],... 

Simultaneous, multiple ester formation was employed to assemble larger multitopic assemblies. For example, self-assembled molecular capsules via boronate esterification have been demonstrated. Two calix[3]arenes, one having the upper rim functionalized with diols, the other functionalized with boronic acids, were combined in the presence of a templating agent to form the heterodimeric capsule (Fig. 25). Extensive NMR analysis was performed to show that the two calixarenes in solution by themselves do not interact. It is only when tetramethyl ammonium acetate is added that the capsule forms. NMR diffusion studies have further demonstrated that the ammonium cation is included within the cavity. In addition, reversible decomposition-reconstruction of the capsule was observed in response to pH. 

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