title: Enantioselective [4 + 1] Annulation Reactions of α-Substituted Ammonium Ylides To Construct Spirocyclic Oxindoles.
abstract: Ammonium ylides have a long history in organic synthesis, but their application in asymmetric catalysis is still underdeveloped in regard to both substrate scope and reaction pathways compared with phosphorus and sulfur ylides. Here a previously unreported asymmetric [4 + 1] annulation reaction of 3-bromooxindoles and electron-deficient 1-azadienes has been developed through ammonium ylide catalysis of a newly designed 2'-methyl α-isocupreine (α-MeIC), efficiently delivering spirocyclic oxindole compounds incorporating a dihydropyrrole motif in excellent enantioselectivity (up to 99% ee). To the best of our knowledge, this work represents the first example of asymmetric catalysis of ammonium ylides bearing α-substitutions, and the catalytic [4 + 1] annulation pathway of ammonium ylides is also unprecedented. Moreover, (1)H NMR, mass spectroscopy, and computational calculation studies were conducted, and the catalytic cycle and a tentative explanation of the enantioselective mechanism have been successfully elucidated.
authors.affiliation: †College of Pharmacy, Third Military Medical University, Chongqing 400038, China.
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Zheng
authors.affiliation: †College of Pharmacy, Third Military Medical University, Chongqing 400038, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Ouyang
authors.affiliation: †College of Pharmacy, Third Military Medical University, Chongqing 400038, China.
authors.forename: Sheng-Li
authors.initials: SL
authors.lastname: Niu
authors.affiliation: †College of Pharmacy, Third Military Medical University, Chongqing 400038, China.
authors.forename: Li
authors.initials: L
authors.lastname: Shuai
authors.affiliation: †College of Pharmacy, Third Military Medical University, Chongqing 400038, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: †College of Pharmacy, Third Military Medical University, Chongqing 400038, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Jiang
authors.affiliation: †College of Pharmacy, Third Military Medical University, Chongqing 400038, China.
authors.forename: Tian-Yu
authors.initials: TY
authors.lastname: Liu
authors.affiliation: †College of Pharmacy, Third Military Medical University, Chongqing 400038, China.|‡Key Laboratory of Drug-Targeting and Drug Delivery System of the Ministry of Education, West China School of Pharmacy, and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Ying-Chun
authors.initials: YC
authors.lastname: Chen
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry*; D002384:Catalysis; D007211:Indoles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D000078183:Oxindoles; D013237:Stereoisomerism
chemical_list: D064751:Ammonium Compounds; D007211:Indoles; D000078183:Oxindoles; C022960:2-oxindole