Bridging chiral de-tert-butylcalix[4]arenes: Optical resolution based on column chromatography and structural characterization

Abstract

Abstract As the third-generation supramolecular main structure, calixarenes, especially chiral calixarenes, have been applied to various fields. In this study, the bridging chiral de-tert-butylcalix[4]arene derivatives with an amide group attached to a chiral point was synthesized for the first time, which provided a new group for its structural derivation at the bridging chiral position. The racemic compound 2 was optically resolved by column chromatography on silica gel with the aid of the chiral auxiliary (1S)-(+)-10-camphorsulfonyl chloride, and finally a pair of optically pure bridging chiral de-tert-butylcalix[4]arene derivatives 4a and 4b were obtained. The results of experimental and calculated ECD showed that compounds 4a and 4b were a pair of enantiomers, and their absolute configurations were designated S and R, respectively. This study provides new idea for the derivatization of specific chiral groups based on bridging chiral calix[4]arenes and their chiral resolution.