Diastereoselective Aziridination of Chiral Electron-Deficient Olefins with N-Chloro-N-sodiocarbamates Catalyzed by Chiral Quaternary Ammonium Salts
journal contributionposted on 05.08.2011, 00:00 by Yuta Murakami, Youhei Takeda, Satoshi Minakata
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.