An<i>Atropos</i>Chiral Biphenyl Bisphosphine Ligand Bearing Only 2,2′-Substituents and Its Application in Rh-Catalyzed Asymmetric Hydrogenation
作者:Jia Jia、Zheng Ling、Zhenfeng Zhang、Ken Tamura、Ilya D. Gridnev、Tsuneo Imamoto、Wanbin Zhang
DOI:10.1002/adsc.201701281
日期:2018.2.15
19.9 kcal/mol). This ligand avoids the time‐consuming optical resolution generally needed for the preparation of axially chiral ligands and shows high reactivity and enantioselectivity in Rh‐catalyzedasymmetric hydrogenations.
Ni(<scp>ii</scp>)-Catalyzed vinylic C–H functionalization of 2-acetamido-3-arylacrylates to access isotetronic acids
作者:Biswajit Roy、Eshani Das、Avijit Roy、Dipakranjan Mal
DOI:10.1039/d0ob00557f
日期:——
reaction for the synthesis of 4-aryl-substituted isotetronic acids from 2-acetamido-3-arylacrylates via vinylic C-H functionalization is reported. The reaction proceeds through heteroatom guided electrophilic insertion of nickel to the vinylic double bond followed by annulation with dibromomethane. This unconventional route features cascade steps, sole product formation, multiple functional group tolerance
Temperature-Controlled Bidirectional Enantioselectivity in a Dynamic Catalyst for Asymmetric Hydrogenation
作者:Golo Storch、Oliver Trapp
DOI:10.1002/anie.201412098
日期:2015.3.16
enantiomerically pure catalysts is one of the most widely used methods for the preparation of enantiomerically pure compounds. The separate synthesis of both enantiomerically pure compounds requires tedious and time‐consuming preparation of both enantiomerically pure catalysts or chiral separation of the racemic products. Here, we report a stereochemically flexible diastereomeric rhodium(I) catalyst
Practical Enantioselective Hydrogenation of α-Aryl- and α-Carboxyamidoethylenes by Rhodium(I)-{1,2-Bis[(<i>o</i>-<i>tert</i>-butoxyphenyl)(phenyl)phosphino]ethane}
作者:Barbara Mohar、Michel Stephan
DOI:10.1002/adsc.201200780
日期:——
The rhodium(I)-1,2-bis[(o-tert-butoxyphenyl)(phenyl)phosphino]ethane} [Rh(I)-(t-Bu-SMS-Phos)] catalyst system displayed prime efficiency in the hydrogenation of large series of α-amidostyrenes and α-amidoacrylates. Up to >99.9% enantiomeric excesses coupled with very high reaction rates were attained operating routinely under 1–10 bar of hydrogen at 22 °C in methanol. Examples include industrial substrates
MaxPHOS is an active and robust P‐stereogenic ligand for asymmetric catalysis. The presence of an NH bridge between the two phosphine moieties allows the NH/PHtautomerism to take place. The neutral ligand, in which the NH form predominates, is an air‐sensitive compound. However, protonation of MaxPHOS leads to the stable PH form of the ligand, in which the overall positive charge is distributed