Chiroptical properties of C2-symmetric N-haloaziridines. Chiral rules for the N-haloaziridine chromophore

Abstract

N-Chloro(a) and N-bromo (b) derivatives of C 2 -symmetricaziridines (2S,3S)-1-halogen-2,3-dimethylaziridines 1a,b and (2S,3S)-1-halogen-2,3-bis(alkoxycarbonyl)aziridines 2a,b and 3a,b were obtained. Haloaziridines 1a,b are an example of the «pure» N-haloaziridine chromophore which has the first Cotton effect (CE) in the region of 260-300 nm. A quadrant rule which connects the first CE sign with the stereochemical environment of the chromophore is offered. Haloaziridinecarboxylic esters are a specific case of the N-haloaziridine chromophore. The second CE sign at 220-230 nm in the CD spectra of these compounds obeys a reverse quadrant rule