IONIC CHIRAL HANDLE-INDUCED SOLID-STATE ASYMMETRIC-SYNTHESIS - ORIGIN OF THE ASYMMETRIC INDUCTION ELUCIDATED THROUGH ABSOLUTE-CONFIGURATION CORRELATION STUDIES

Irradiation of crystals of two salts formed between prochiral, photochemically reactive carboxylic acids and non-absorbing, optically active amines is shown to lead to optically active photoproducts in > 95% enantiomeric excess, a process in which the ammonium ion has acted as an ’’ionic chiral handle’’. Through a combination of X-ray crystallography and chemical correlations, the absolute configurations of the photoproducts and the salts from which they are derived were determined. This allowed the absolute steric course of the photorearrangements to be charted and the structural factors responsible for the high enantioselectivity to be identified.