85000-00-6Relevant articles and documents
A General Organocatalytic System for Enantioselective Radical Conjugate Additions to Enals
Le Saux, Emilien,Ma, Dengke,Bonilla, Pablo,Holden, Catherine M.,Lustosa, Danilo,Melchiorre, Paolo
supporting information, p. 5357 - 5362 (2021/02/01)
Herein, we report a general iminium ion-based catalytic method for the enantioselective conjugate addition of carbon-centered radicals to aliphatic and aromatic enals. The process uses an organic photoredox catalyst, which absorbs blue light to generate radicals from stable precursors, in combination with a chiral amine catalyst, which secures a consistently high level of stereoselectivity. The generality of this catalytic platform is demonstrated by the stereoselective interception of a wide variety of radicals, including non-stabilized primary ones which are generally difficult to engage in asymmetric processes. The system also served to develop organocatalytic cascade reactions that combine an iminium-ion-based radical trap with an enamine-mediated step, affording stereochemically dense chiral products in one-step.
Direct Stereoselective Installation of Alkyl Fragments at the β-Carbon of Enals via Excited Iminium Ion Catalysis
Verrier, Charlie,Alandini, Nurtalya,Pezzetta, Cristofer,Moliterno, Mauro,Buzzetti, Luca,Hepburn, Hamish B.,Vega-Pe?aloza, Alberto,Silvi, Mattia,Melchiorre, Paolo
, p. 1062 - 1066 (2018/02/14)
The direct introduction of sp3 carbon fragments at the β position of α,β-unsaturated aldehydes is greatly complicated by competing 1,2-addition manifolds. Previous catalytic enantioselective conjugate addition methods, based on the use of organometallic reagents or ground-state iminium ion activation, could not provide general and efficient solutions. We report herein that, by turning them into strong oxidants, visible light excitation of chiral iminium ions triggers a stereocontrolled radical pathway that exclusively affords highly enantioenriched β-substituted aldehydes bearing a variety of alkyl fragments.
Highly enantioselective asymmetric isomerization of primary allylic alcohols with an iridium-N,P complex
Li, Jia-Qi,Peters, Byron,Andersson, Pher G.
supporting information; experimental part, p. 11143 - 11145 (2011/10/31)
Access to chiral aldehydes: The asymmetric isomerization of primary allylic alcohols was studied with a bicyclic phosphine-oxazoline iridium catalyst. This method displays a broad substrate scope and leads to the desired chiral aldehydes with excellent enantioselectivities (see scheme; R1, R 2=Ar or alkyl). Copyright
