The study of methods to synthesize silylated calixarenes in the 1,3-alternate conformation
Calixarenes are macrocyclic compounds that have aromatic rings that are connected by methylene bridges. They are useful in both biological and chemical industries, as receptors, and in catalysis. Silylated calixarenes are of potential interest in molecular recognition. We investigated the synthesis of C-silylated calixarenes in the 1,3-alternate conformation. p-tert-Butylcalixarene was dealkylated, and the 1,3-alternate conformation was established via the two-pot procedure of sequential treatment with propyl iodide/K2CO 3 followed by propyl tosylate/CsCO3. The corresponding bromocalixarene was prepared using NBS. Silylation was carried out via halogen-metal exchange using tert-BuLi, followed by the supernatant from a mixture of silylating reagent and Et3N. Calixarenes were prepared having the Me3Si, Me2PhSi, Me2HSi, and the Me 2(allyl)Si groups.
Although the halogen metal exchange reactions proved to be successful, the use of tert-BuLi reagents is impractical for large scale reactions. Therefore, we investigated new ways to synthesize silylated compounds. We studied the use of Mg reagents to make the silylated compounds. We used the monocyclic compound bromoanisole as a model for the new reactions before trying them on the calixarene. The results indicated that some of these reaction were successful on the model compound, but not on the calixarenes.