it both ways: A novel class of chiral sulfoxide‐olefin ligands was synthesized from a single chiral source. These ligands were evaluated in rhodium‐catalyzed 1,4‐additions of arylboronic acids to electron‐deficient olefins, and remarkable olefin‐directed reversal of stereoselectivity (up to >99 % ee, R isomer; 98 % ee, S isomer) was observed when the reversal ligand pair L1 (branched olefin) and L2
New chiral phosphorus–olefin hybrid ligands derived from the rigid “privileged” l‐proline have been conveniently prepared and applied in the rhodium‐catalyzed asymmetric arylation of electron‐deficient olefins with arylboronic acids at room temperature; this reaction provides the desired products in excellent yields and high enantioselectivities. The origin of observed stereoselectivity has been investigated
Asymmetric 1,4-Addition of Arylboronic Acids to 2,3-Dihydro-4-pyridones Catalyzed by Axially Chiral NHC−Pd(II) Complexes
作者:Qin Xu、Rui Zhang、Tao Zhang、Min Shi
DOI:10.1021/jo1006224
日期:2010.6.4
Axiallychiral cis-chelated bidentate bis(N-heterocyclic carbene)−palladium(II) complexes are effective catalysts for the asymmetric conjugate addition of arylboronicacids to 2,3-dihydro-4-pyridones, producing the synthetically and biologically important 2-aryl-4-piperidones in moderate-to-high yields (up to 96%) along with excellent enantioselectivities (up to >99.5% ee) in most cases under mild
Vicinal-Diamine-Based Chiral Chain Dienes as Ligands for Rhodium(I)-Catalyzed Highly Enantioselective Conjugated Additions
作者:Yazhou Wang、Xichao Hu、Haifeng Du
DOI:10.1021/ol1023536
日期:2010.12.3
A variety of readily accessible vicinal-diamine-based chiral chain dienes were successfully synthesized and utilized as steering ligands for rhodium-catalyzed conjugatedadditions of organoboronic acids to α,β-unsaturated carbonyl compounds to afford the desired adducts in good to excellent yields and ee’s.
electron-deficient DIFLUORPHOS and SYNPHOS analogues in the rhodium-catalyzedasymmetric conjugate addition of boronic acids to α,β-unsaturatedketones afford the 1,4-addition adducts in yields up to 92% and with 99% ee. Particularly, a Rh-catalyzed asymmetric1,4-addition of arylboronic acids to nonsubstituted maleimide substrates using the (R)-3,5-diCF3-SYNPHOS ligand is also reported. This protocol provides access