897963-50-7Relevant academic research and scientific papers
Tandem Iridium Catalysis as a General Strategy for Atroposelective Construction of Axially Chiral Styrenes
He, Ying,Liu, Peng,Min, Xiao-Long,Qi, Xiaotian,Wang, Jie,Yi, Wenbin
supporting information, p. 10686 - 10694 (2021/07/26)
Axially chiral styrenes are of great interest since they may serve as a class of novel chiral ligands in asymmetric synthesis. However, only recently have strategies been developed for their enantioselective preparation. Thus, the development of novel and efficient methodologies is highly desirable. Herein, we reported the first tandem iridium catalysis as a general strategy for the synthesis of axially chiral styrenes enabled by Asymmetric Allylic Substitution-Isomerization (AASI) using cinnamyl carbonate analogues as electrophiles and naphthols as nucleophiles. In this approach, axially chiral styrenes were generated through two independent iridium-catalytic cycles: iridium-catalyzed asymmetric allylic substitution and in situ isomerization via stereospecific 1,3-hydride transfer catalyzed by the same iridium catalyst. Both experimental and computational studies demonstrated that the isomerization proceeded by iridium-catalyzed benzylic C-H bond oxidative addition, followed by terminal C-H reductive elimination. Amid the central-to-axial chirality transfer, the hydroxyl of naphthol plays a crucial role in ensuring the stereospecificity by coordinating with the Ir(I) center. The process accommodated broad functional group compatibility. The products were generated in excellent yields with excellent to high enantioselectivities, which could be transformed to various axially chiral molecules.
Sequential catalytic isomerization and allylic substitution. Conversion of racemic branched allylic carbonates to enantioenriched allylic substitution products
Shekhar, Shashank,Trantow, Brian,Leitner, Andreas,Hartwig, John F.
, p. 11770 - 11771 (2007/10/03)
A catalytic protocol for the conversion of readily accessible racemic, branched aromatic allylic esters to branched allylic amines, ethers, and alkyls has been developed. Palladium-catalyzed isomerization of branched allylic esters to terminal allylic esters, followed by sequential iridium-catalyzed allylic substitution, gave the branched allylic products in good yield with high regioisomeric and enantiomeric selectivity. Both electron-rich and electron-poor branched allylic esters gave products in >90% ee. High enantiomeric excesses were also observed for the products from the reactions of 2-thienyl acetates and dienyl carbonates. Copyright
