Title
Bridging Chiral Calix[4]arenes: Description, Optical Resolution, and Absolute Configuration Determination
Author
Feng-Jing An, Wen-Qiang Xu, Shuang Zheng, Shi-Kun Ma, Shao-Yong Li, Run-Ling Wang, Jun-Min Liu
Year
2016
Journal
European Journal of Organic Chemistry
Abstract
A new chiral calix[4]arene constructed from asymmetric substitution on bridging methylenes, phenyl rings, and (or) oxygen atoms was tentatively named as “bridging chiral” calix[4]arene that have point chirality on its substituted bridging methylene. A new approach to enantiopure bridging chiral calix[4]arenes through optical resolution is presented for the first time. As a result, a pair of enantiopure bridging chiral calix[4]arene carboxylic acids monobridge-substituted with an equatorial N,N′-dimethylformamidyl group (4a and 4b) were easily prepared by the optical resolution of their racemate with chiral auxiliary (S)-Binol. The absolute configurations of the enantiomers were determined by X-ray crystallographic analysis.
Instrument
J-815
Keywords
Circular dichroism, Absolute configuration