5555-71-5Relevant academic research and scientific papers
A Rhodium Catalyst Superior to Iridium Congeners for Enantioselective Radical Amination Activated by Visible Light
Shen, Xiaodong,Harms, Klaus,Marsch, Michael,Meggers, Eric
supporting information, p. 9102 - 9105 (2016/07/14)
A bis-cyclometalated rhodium(III) complex catalyzes a visible-light-activated enantioselective α-amination of 2-acyl imidazoles with up to 99 % yield and 98 % ee. The rhodium catalyst is ascribed a dual function as a chiral Lewis acid and, simultaneously, as a light-activated smart initiator of a radical-chain process through intermediate aminyl radicals. Notably, related iridium-based photoredox catalysts reported before were unsuccessful in this enantioselective radical C?N bond formation. The surprising preference for rhodium over iridium is attributed to much faster ligand-exchange kinetics of the rhodium complexes involved in the catalytic cycle, which is crucial to keep pace with the highly reactive and thus short-lived nitrogen-centered radical intermediate.
Enantioselective direct α-amination of aldehydes via a photoredox mechanism: A strategy for asymmetric amine fragment coupling
Cecere, Giuseppe,Koenig, Christian M.,Alleva, Jennifer L.,MacMillan, David W. C.
supporting information, p. 11521 - 11524 (2013/09/02)
The direct, asymmetric α-amination of aldehydes has been accomplished via a combination of photoredox and organocatalysis. Photon-generated N-centered radicals undergo enantioselective α-addition to catalytically formed chiral enamines to directly produce stable α-amino aldehyde adducts bearing synthetically useful amine substitution patterns. Incorporation of a photolabile group on the amine precursor obviates the need to employ a photoredox catalyst in this transformation. Importantly, this photoinduced transformation allows direct and enantioselective access to α-amino aldehyde products that do not require postreaction manipulation.
