Asymmetric resolution and molecular recognition. Part 1. The crystal structure of N-benzoyl-L-alanyl–strychninium dihydrate

Abstract

The crystal structure of the 1 : 1 complex of strychnine +N-benzoyl-L-alanine·2H₂O (a=10.751, b=30.366, c=8.608 Å, space group P2₁2₁2₁) provides an insight into the mechanism of Pasteur's method for resolving racemic mixtures. Strychnine molecules pack in bilayers separated by impenetrable hydrogen-bonded sheets. A charge–charge interaction between the amino group on strychnine and a carboxy oxygen atom of the benzoyl-L-alanine provides the strongest intermolecular interaction, though specific van der Waals interactions involving the phenyl, amide, and indole π-electrons also play an important role in molecular recognition.