Preorganization in highly enantioselective diaza-Cope rearrangement reaction.

Crystal structure and activation entropy data indicate that H-bond directed diaza-Cope rearrangement of chiral diimines takes place with a high degree of preorganization. CD spectroscopy and HPLC data show that there is inversion of stereochemistry for the reaction with excellent enantioselectivity.

Stereoselective recognition of an aziridine with a Co(III) complex: a potential transition-state analogue for catalytic epoxidation.

Reversible and stereoselective coordination of 1-(R)-phenyl-2-(S)-methylaziridine to (S,S)L-Co(III) and (R,R)L-Co(III) (where L represents a salen ligand obtained from diamino cyclohexane and 2,4-di-tert-butyl salicylaldehyde) has been investigated. 1H NMR data indicate that the aziridine binds about three times more tightly to (S,S)L-Co(III) than to (R,R)L-Co(III). Crystal structures of two molecules of the aziridine coordinated to the Co(III) complexes have been determined.