Diastereoselective aziridination of chiral electron-deficient olefins with N-chloro-N-sodiocarbamates catalyzed by chiral quaternary ammonium salts

Chiral quaternary ammonium salt-catalyzed diastereoselective aziridination of electron-deficient olefins that possess a chiral auxiliary with N-chloro-N-sodiocarbamates was developed. The key to high stereoselectivity was found to be the employment of the "matching" stereochemical combination of chiral auxiliary/ammonium salt. For example, when 3-phenyl-(4R,7S)-4-methyl-7-isopropyl-4,5,6,7-tetrahydroindazole (L-menthopyrazole) as a chiral auxiliary and a cinchonidine-derived chiral ammonium salt as a catalyst were applied to the reaction system, perfect diastereoselectivity was realized. Furthermore, the preparation of enantiomerically pure aziridines by removal of the chiral auxiliary was demonstrated.