Asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated aldehydes proceeded in the presence of a rhodium catalyst (3 mol %) coordinated with a chiral diene ligand ((R,R)-Bn-bod*) to give the corresponding β-arylaldehydes with perfect 1,4-selectivity and with 88–97% enantioselectivity.
Highly optically active 3-phenylalkanals were obtained by the reaction of alkyl halides and a chiral homoenolate equivalent derived from the cinnamyl ether 3 and potassium diisopropylamide, followed by acidic hydrolysis.
improved generation of chiral cationic iridium catalysts for the asymmetricisomerization of primaryallylicalcohols is disclosed. The design of these air‐stable complexes relied on the preliminary mechanistic information available, and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation. Sterically unbiased chiral aldehydes
A General Organocatalytic System for Enantioselective Radical Conjugate Additions to Enals
作者:Emilien Le Saux、Dengke Ma、Pablo Bonilla、Catherine M. Holden、Danilo Lustosa、Paolo Melchiorre
DOI:10.1002/anie.202014876
日期:2021.3
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 radicalsfrom 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
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