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Using supramolecular interactions, a novel macrocyclic receptor is able to selectively extract zwitterionic phenylglycine from neutral aqueous solutions into chloroform with up to 91.8% ee. Modeling studies, nuclear magnetic resonance experiments, and X-ray diffraction analysis were carried out to explain the high enantioselectivity observed.

The synthesis of 5-chloro-8-nitro-1-naphthoyl chloride and its use as a protective group for amines is described. Protection is carried out with an auxiliary amine or under mild Schotten-Baumann conditions in high yield (>86%), while deprotection can be achieved easily under gentle reducing conditions due to the large steric tension between C-1 and C-8 naphthalene substituents. The reaction has been successfully tested in dipeptide synthesis and amino alcohols protection, and it has proved selective for the ε-amine group of lysine.