title: Organocatalytic asymmetric inverse-electron-demand 1,3-dipolar cycloaddition of N,N'-cyclic azomethine imines.
abstract: The first organocatalytic asymmetric inverse-electron-demand 1,3-dipolar cycloaddition (IED 1,3-DC) of N,N'-cyclic azomethine imines has been established in the presence of chiral phosphoric acid. This approach assembles N,N'-cyclic azomethine imines and o-hydroxystyrenes into chiral N,N-bicyclic pyrazolidin-3-one derivatives with the creation of two stereogenic centers, one of which is quaternary, in excellent diastereoselectivities and good enantioselectivities (up to >95:5 dr, 88:12 er). The investigation of the activation mode of the reaction revealed that the dual hydrogen-bonding interaction between the two substrates and the catalyst together with the conjugative effect initiated by the o-hydroxyl group played a crucial role in the designed IED 1,3-DC. This study will not only greatly enrich the underdeveloped research potential of catalytic asymmetric IED 1,3-DCs but will also facilitate the design of other enantioselective IED 1,3-DCs based on different activation modes.
authors.affiliation: School of Chemistry & Chemical Engineering, and Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Jiangsu Normal University , Xuzhou, 221116, China.
authors.forename: Ren-Yi
authors.initials: RY
authors.lastname: Zhu
authors.forename: Cong-Shuai
authors.initials: CS
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Zheng
authors.forename: Feng
authors.initials: F
authors.lastname: Shi
authors.forename: Shu-Jiang
authors.initials: SJ
authors.lastname: Tu