Deactivation mechanisms of iodo-iridium catalysts in chiral amine racemization. (29th January 2021)

• Record Type: Journal Article
• Authors: Kwan, Maria H.T.; Pokar, Nisha P.B.; Good, Catherine; Jones, Martin F.; Munday, Rachel; Screen, Thomas; Blacker, A. John
• Is Part Of: Tetrahedron. Volume 80(2021)
• Publication Date: 2021-01-29
• Subjects: Chiral amine racemization -- Catalytic transfer hydrogenation dehydrogenation -- Catalyst deactivation mechanism -- Iridium -- Hydrogen borrowing; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2020.131823
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: The homogenous, [IrCp∗I2 ]2, SCRAM catalyst (1) is active in the racemization of chiral amines. NMR, kinetic and structural mechanistic studies have determined the cause of catalyst deactivation to occur when ammonia or methylamine are liberated by hydrolysis or aminolysis of the intermediate imine, which tightly coordinate to the iridium centre to block turnover. Control of moisture and substrate concentration can suppress deactivation, whilst partial reactivation of spent catalyst was identified using hydroiodic acid. Graphical abstract: Image 1