title: Iron-Carbonyl-Catalyzed Redox-Neutral [4+2] Annulation of N-H Imines and Internal Alkynes by C-H Bond Activation.
abstract: Stoichiometric C-H bond activation of arenes mediated by iron carbonyls was reported by Pauson as early as in 1965, yet the catalytic C-H transformations have not been developed. Herein, an iron-catalyzed annulation of N-H imines and internal alkynes to furnish cis-3,4-dihydroisoquinolines is described, and represents the first iron-carbonyl-catalyzed C-H activation reaction of arenes. Remarkablely, this is also the first redox-neutral [4+2] annulation of imines and alkynes proceeding by C-H activation. The reaction also features only cis stereoselectivity and excellent atom economy as neither base, nor external ligand, nor additive is required. Experimental and theoretical studies reveal an oxidative addition mechanism for C-H bond activation to afford a dinuclear ferracycle and a synergetic diiron-promoted H-transfer to the alkyne as the turnover-determining step.
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Teng
authors.initials: T
authors.lastname: Jia
authors.affiliation: BNLMS, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Chongyang
authors.initials: C
authors.lastname: Zhao
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Ruoyu
authors.initials: R
authors.lastname: He
authors.affiliation: BNLMS, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China. chenh@iccas.ac.cn.
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China. wangcy@iccas.ac.cn.
authors.forename: Congyang
authors.initials: C
authors.lastname: Wang
keywords: C−H activation; alkynes; annulations; heterocycles; iron