889101-97-7Relevant academic research and scientific papers
Chiral phosphine-olefin ligands in the rhodium-catalyzed asymmetric 1,4-addition reactions
Duan, Wei-Liang,Iwamura, Hiroshi,Shintani, Ryo,Hayashi, Tamio
, p. 2130 - 2138 (2007)
A full overview on the use of chiral phosphine-olefin ligands 1 in the rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds is described. Effective chiral environment of a Rh/1 complex was shown to resemble that of a Rh/(R,R)-Ph-bod* complex by comparing the experimental results as well as the X-ray crystal structures. High catalytic activity of a Rh/1 complex was disclosed and the catalytic cycle involving a trimer-monomer equilibrium was established through mechanistic studies using a reaction calorimeter and 31P NMR spectroscopy. A negative nonlinear effect derived from an inactive trimer-active monomer equilibrium of the catalyst was also successfully observed.
Direct Synthesis of Chiral 3-Arylsuccinimides by Rhodium-Catalyzed Enantioselective Conjugate Addition of Arylboronic Acids to Maleimides
Gopula, Balraj,Yang, Shu-Han,Kuo, Ting-Shen,Hsieh, Jen-Chieh,Wu, Ping-Yu,Henschke, Julian P.,Wu, Hsyueh-Liang
supporting information, p. 11050 - 11055 (2015/11/10)
Chiral rhodium catalysts comprising 2,5-diaryl- substituted bicyclo[2.2.1]diene ligands L1-L10 were utilized in the enantioselective 1,4-addition reaction of arylboronic acids to N-substituted maleimides. In the presence of 2.5mol % of RhI/L2, enantioenriched conjugate addition adducts were isolated in 72-99 % yields with 86-98 %ee. This protocol offers a convenient method to access a variety of 3-arylsuccinimides in a highly enantioselective manner. Maleimides with readily cleavable N-protecting groups were tolerated enabling the synthesis of useful synthetic intermediates. Pyrrolidine 4, a biologically active compound, and pyrrolidine 5, an ent-precursor to an HSD-1 inhibitor, were synthesized to demonstrate the utility of this method. The road to rhodium! Enantioselective conjugate addition of a range of arylboronic acids to variously N-substituted maleimides, catalyzed by RhI complexes prepared in situ using chiral bicyclo[2.2.1]diene ligands, afforded the corresponding 3-arylsuccinimides with up to 98 %ee at 50 C (see scheme).
