title: Diastereoselectivity-switchable and highly enantioselective 1,3-dipolar cycloaddition of nitrones to alkylidene malonates.
abstract: Trisoxazoline 1/Co(ClO(4))(2).6H(2)O catalyzed the 1,3-cycloaddition between nitrones 3 with alkylidene malonates 2 at 0 degrees C to give the isoxazolidines with both high enantioselectivity and high exo selectivity. However, when the temperature was lowered from 0 to -40 degrees C, the same cycloaddition afforded endo isomers as the major products with good to high enantioselectivity. A mechanism is provided.
authors.affiliation: State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Science, 200032 Shanghai, China.
authors.forename: Zheng-Zheng
authors.initials: ZZ
authors.lastname: Huang
authors.forename: Yan-Biao
authors.initials: YB
authors.lastname: Kang
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
authors.forename: Meng-Chun
authors.initials: MC
authors.lastname: Ye
authors.forename: Yong
authors.initials: Y
authors.lastname: Tang