Synthesis of camphor based chiral crown ethers and their interactions with amino acid derivatives

Abstract

Three camphor based crown ethers have been prepared, starting from (–)-(1R)-camphorquinone, in which 2- and 3-endo-substituents are used to regulate the availability of the endo-l8-crown-6 face for binding organic guests and the bridge head methyl group is available to impart enantioselectivity at the exo-face. The stereochemistry of the key intermediate 2-endo-3-endo-dimethyl bornane-2,3-diol (6) has been confirmed by a single crystal X-ray structure determination. Interactions between these crowns and antipodal phenylglycine salts have been probed using NMR and modelling techniques.