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Recyclable Mn(I) Catalysts for Base‐Free Asymmetric Hydrogenation: Mechanistic, DFT and Catalytic Studies
Author(s) -
Jayaprakash Harikrishnan,
Coburger Peter,
Wörle Michael,
Togni Antonio,
Grützmacher Hansjorg
Publication year - 2022
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202201522
Subject(s) - catalysis , base (topology) , chemistry , combinatorial chemistry , organic chemistry , mathematics , mathematical analysis
We report here a mechanistic, DFT and catalytic study on a series of Mn(I) complexes 1 , 2 ( a – d ), 3 , 4 . The studies apprehended the requirements for Mn(I) complexes to be active in both asymmetric direct ( AH ) and transfer hydrogenations ( ATH ). The investigations disclosed 6 vital factors accelerating the formation of a resting species, which plays a significant role in lowering the activities of the Mn(I) complex 1 in ATH and AH , respectively. In addition, we also report here a base free Mn(I) catalyzed ATH of aryl alkyl ketones with high enantioselectivity (up to 98 % ee) and improved activity. More significantly, a novel and simple single‐step process for recycling the resting species from the catalytic leftover has been discovered. Notably, the studies provide evidence for the existence of two different temperature dependent mechanisms for AH and ATH , in contrast to previous studies on related systems.