title: Amine-Catalyzed Highly Regioselective and Stereoselective C(sp(2) )-C(sp(2) ) Cross-Coupling of Naphthols with trans-α,β-Unsaturated Aldehydes.
abstract: A metal-free C(sp(2) )-C(sp(2) ) cross-coupling approach to highly congested (E)-α-naphtholylenals from simple naphthols and enals is described. The mild reaction conditions with pyridine hydrobromideperbromide (PHBP) as the bromination reagent in the presence of piperidine or diphenylprolinol trimethylsilyl (TMS) ether as promoters enable the process in good yields and with high chemoselectivity, regioselectivity, and stereoselectivity. The process involves an unprecedented pathway of in situ regioselective 4-bromination of 1-naphthols and the subsequent unusual aromatic nucleophilic substitution of the resulting 4-bromo-1-naphthols with the α-C(sp(2) ) of enals through a Michael-type Friedel-Crafts alkylation-dearomatization followed by a cyclopropanation ring-opening cascade process. The noteworthy features of this strategy are highlighted by the highly efficient creation of a C(sp(2) )-C(sp(2) ) bond from readily available unfunctionalized naphthols and enals catalyzed by non-metal, readily available cyclic secondary amines under mild reaction conditions.
authors.affiliation: Shanghai Key Laboratory of New Drug Design, School of Pharmacy, State Key Laboratory of Bioengineering Reactors, East China University of Science&Technology, 200237, Shanghai, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Shanghai Key Laboratory of New Drug Design, School of Pharmacy, State Key Laboratory of Bioengineering Reactors, East China University of Science&Technology, 200237, Shanghai, China.
authors.forename: Yueyue
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Shanghai Key Laboratory of New Drug Design, School of Pharmacy, State Key Laboratory of Bioengineering Reactors, East China University of Science&Technology, 200237, Shanghai, China.
authors.forename: Rengwei
authors.initials: R
authors.lastname: Sun
authors.affiliation: Shanghai Key Laboratory of New Drug Design, School of Pharmacy, State Key Laboratory of Bioengineering Reactors, East China University of Science&Technology, 200237, Shanghai, China. xhyu@ecust.edu.cn.
authors.forename: Xinhong
authors.initials: X
authors.lastname: Yu
authors.affiliation: Shanghai Key Laboratory of New Drug Design, School of Pharmacy, State Key Laboratory of Bioengineering Reactors, East China University of Science&Technology, 200237, Shanghai, China. xiehexin@ecust.edu.cn.
authors.forename: Hexin
authors.initials: H
authors.lastname: Xie
authors.affiliation: Shanghai Key Laboratory of New Drug Design, School of Pharmacy, State Key Laboratory of Bioengineering Reactors, East China University of Science&Technology, 200237, Shanghai, China. wwang@unm.edu.|Department of Chemistry & Chemical Biology, University of New Mexico, Albuquerque, NM 87131-0001, USA. wwang@unm.edu.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000478:Alkylation; D000588:Amines / Q000737:chemistry*; D002384:Catalysis; D054879:Halogenation; D008958:Models, Molecular; D009284:Naphthols / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000447:Aldehydes; D000588:Amines; D009284:Naphthols; C029350:1-naphthol
keywords: cascade reaction; cross-coupling; metal-free; organocatalysis; α-naphtholylation