122712-87-2Relevant academic research and scientific papers
Enantioselective Rh-Catalyzed Hydroboration of Silyl Enol Ethers
Dong, Wenke,Lei, Yaqin,Lin, Zhenyang,Ma, Honghui,Xu, Xin,Zhao, Wanxiang
supporting information, p. 10902 - 10909 (2021/07/31)
The asymmetric hydroboration of alkenes has proven to be among the most powerful methods for the synthesis of chiral boron compounds. This protocol is well suitable for activated alkenes such as vinylarenes and alkenes bearing directing groups. However, the catalytic enantioselective hydroboration of O-substituted alkenes has remained unprecedented. Here we report a Rh-catalyzed enantioselective hydroboration of silyl enol ethers (SEEs) that utilizes two new chiral phosphine ligands we developed. This approach features mild reaction conditions and a broad substrate scope as well as excellent functional group tolerance, and enables highly efficient preparation of synthetically valuable chiral borylethers.
Rhodium-Catalyzed Enantioselective Radical Addition of CX4 Reagents to Olefins
Chen, Bo,Fang, Cheng,Liu, Peng,Ready, Joseph M.
supporting information, p. 8780 - 8784 (2017/07/17)
We describe the synthetically useful enantioselective addition of Br?CX3 (X=Cl or Br) to terminal olefins to introduce a trihalomethyl group and generate optically active secondary bromides. Computational and experimental evidence supports an asymmetric atom-transfer radical addition (ATRA) mechanism in which the stereodetermining step involves outer-sphere bromine abstraction from a [(bisphosphine)RhIIBrCl] complex by a benzylic radical intermediate. This mechanism appears unprecedented in asymmetric catalysis.
Synthesis of efficient chiral bisphosphine ligands, modified DIOPs, (4R,5R)-4-(Diaryl- or dialkylphosphino)methyl-5-(diarylphosphino)methyl-2,2- dimethyl-1,3-dioxolanes, and their use in rhodium(I)-catalyzed asymmetric hydrogenations
Morimoto,Chiba,Achiwa
, p. 1149 - 1156 (2007/10/02)
Modified DIOPs, (4R,5R)-4-(diaryl- or dialkyphosphino)methyl-5- (diarylphosphino)methyl-2,2-dimethyl-1,3-dioxolanes, were prepared on the basis of our design concept, and used as ligands for the rhodium(I)-catalyzed asymmetric hydrogenations of ketopantolactone, itaconic acid, dimethyl itaconate, and β-aryl-substituted itaconic acid derivatives. A neutral rhodium(I)-complex of (4R-trans)-dicyclohexyl[[5- [(diphenylphosphino)methyl]-2,2-dimethyl-1,3-dioxolan-4-yl]methyl]phosphine (DIOCP) bearing both a dicyclohexylphosphino group and a diphenylphosphino group was found to be a more efficient catalyst than the original DIOP in the asymmetric hydrogenation of ketopantolactone. Modified DIOPs bearing electron-donating groups at their para positions were efficient ligands for the rhodium(I)-catalyzed assymetric hydrogenations of itaconic acid and its derivatives; in particular, (4R-trans)-[(2,2-dimethyl-1,3-dioxolane-4,5- diyl)bis(methylene)]bis[bis(4'-methoxy-3',5'-dimethylphenyl)phosphine] (MOD- DIOP) bearing both a p-methoxy group and two m,m'-methyl groups on each phenyl group showed much higher enantioselectivity and catalytic activity than DIOP.
Einfluesse von in para-Position zum Phosphor eingefuehrten Substituenten in das Diop-System auf die optische Induktion bei der asymmetrischen Hydrierung von Acylaminoacrylsaeureethylester und (Z)-Acylamino-zimtsaeuremethylester mit kationischen Rhodium-(Diop-Derivat)-Komplexen. I
Werz, Udo,Brune, Hans-Albert
, p. 377 - 386 (2007/10/02)
(R,R)-Diop was modified at the diphenylphosphino group by the introduction of substituents in para-position to the phosphorus atoms.The influence of the substituents on the optical induction was examined for the hydrogenation of ethyl α-acylaminoacrylate (AAEE) and (Z)-methyl α-acylaminocinnamate (AZME) with + BF4- as catalyst.For both substrates the substituents affected the optical induction markedly.The observed effects can be attributed to the electronical features, solvation and in special cases also to the size of the substituents.
