Synthesis of mono- and diboronic acid calix[4]arene receptors

2003 ARKIVOC  
Various boronic acid appended calixarene assemblies were constructed on the macrocyclic lower rim. Treatment of the appropriate calix[4]arene with controlled amounts of base and 2bromomethylphenylethylene boronate affords the monoboronic acid triphenol or the distally separated diboronic acid of choice. Upper rim p-allyl calix[4]arene phenyl boronic acids were prepared. These ligands were designed to allow further study of guest complexation in nonaqueous, aqueous and on solid substrates. Route
more » ... d substrates. Route to Mono-and Disubstituted Calix[4]arene boronic acids The synthetic methodology for the monosubstitution of calix[4]arenes was first devised by Reinhouldt and co-workers 14 and was adapted for the monoboronation of p-tert-butyl-, p-allyl and p-Hcalix[4]arenes. Treatment of the appropriate calix[4]arene with limiting amounts of base and 2bromomethylphenylethylene boronate 6 affords the crude monoboronic acid calixarene as shown in Figure 2 . Increasing the proportion of base allows the incorporation of distally separated diboronate functionalities 9. Purification by chromatography eluting with dichloromethane:ethyl acetate (10:1) was necessary in each case to isolate the desired mono-and diboronic acids products.
doi:10.3998/ark.5550190.0004.728 fatcat:u7x4fiv5qjgglbcsdjk7ckryzm