title: Rational tuning chelate size of bis-oxazoline ligands to improve enantioselectivity in the asymmetric aziridination of chalcones.
abstract: [reaction: see text] Chalcones were asymmetrically aziridinated with [N-(p-toluenesulfonyl)imino]phenyliodinane (PhI=NTs) as a nitrene source under catalysis of CuOTf and a series of cyclohexane-linked bis-oxazolines (cHBOXes), which are chelate size rationally tuned bis-oxazolines. The results indicate that highly enantioselective aziridination of chalcones with up to >99% ee have been achieved under catalysis of (S,S)-1,2-bis[(S)-(4-phenyl)oxazolin-2-yl]cyclohexane, which is the most-matched stereoisomer among cyclohexane-linked bis-oxazolines. It was also found that the enantioselectivity is not substituent-dependent with respect to chalcones in the present case, unlike with 1,8-anthracene-linked bis-oxazolines (AnBOXes).
authors.affiliation: Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Linge
authors.initials: L
authors.lastname: Ma
authors.forename: Da-Ming
authors.initials: DM
authors.lastname: Du
authors.forename: Jiaxi
authors.initials: J
authors.lastname: Xu