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Lewis Base Promoted Delayed Copper Catalysis: Borylative α-C-H Allylation of Alicyclic Amines

preprint
submitted on 21.08.2020 and posted on 21.08.2020 by Borja Pérez-Saavedra, Álvaro Velasco-Rubio, Carlos Saá, Martín Fañanás-Mastral
Functionalized alicyclic amines are important building blocks for the synthesis of bioactive natural compounds and drugs. Existing methods of functionalization are typically limited to the synthesis of protected amines or the use of highly basic organometallic reagents that can compromise functional group tolerance. Here, we report a novel approach for the synthesis of α-functionalized cyclic secondary amines. The method employs a copper/bisphosphine catalyst which promotes a regio-, stereo- and chemoselective coupling between allenes, bis(pinacolato)diboron and O-benzoyl hydroxylamines that involves trapping of an in-situ generated alicyclic imine by a catalytic boron-substituted allylcopper intermediate. Successful implementation requires that competing reaction between the allylcopper complex and hydroxylamine is suppressed while imine is formed. This challenge was met by using a catalytic amount of Lewis base additive which delays the catalyst function towards C-N coupling thus enabling selective C-C coupling.

Funding

Spanish Ministry of Science and Innovation (CTQ2017-88451-R, CTQ2017-87939-R and the ORFEO-CINQA network RED2018-102387-T)

Xunta de Galicia (ED431C 2018/04; Centro singular de investigación de Galicia accreditation 2019-2022, ED431G 2019/03)

European Union (European Regional Development Fund - ERDF)

History

Email Address of Submitting Author

martin.fananas@usc.es

Institution

Universidade de Santiago de Compostela. CiQUS

Country

Spain

ORCID For Submitting Author

0000-0003-4903-0502

Declaration of Conflict of Interest

The authors declare no competing financial interests

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