Well-Designed Phosphine–Urea Ligand for Highly Diastereo- and Enantioselective 1,3-Dipolar Cycloaddition of Methacrylonitrile: A Combined Experimental and Theoretical Study
A novel chiral phosphine-urea bifunctional ligand has been developed for Cu-catalyzed asymmetric 1,3-dipolar cycloaddition of iminoesters with methacrylonitrile, a long-standing challenging substrate in asymmetric catalysis. Distortion-interaction energy analysis based on density functional theory (DFT) calculations reveals that the distortion energy plays an important role in the observed enantioselectivity
synthesized and used in the copper(I)-catalyzed enatioselective [3 + 2] cycloaddition of iminoesters with alkenes. A variety of highly functionalized pyrrolidines were obtained in excellent yield and enatioselectivity. This is the first example of a pair of P-stereogenic ligands working as pseudoenantiomers to tune the enantio- and diastereoselective 1,3-dipolar cycloaddition, and providing a pair of
for asymmetric [3+2] cycloaddition reactions. A silver complex prepared from silver bis(trimethylsilyl)amide (AgHMDS) and (R)‐DTBM‐SEGPHOS worked well in asymmetric [3+2] cycloaddition reactions of α‐aminoester Schiff bases with several olefins to afford the corresponding pyrrolidine derivatives in high yields with remarkable exo‐ and enantioselectivities. Furthermore, α‐aminophosphonate Schiff bases
Metal Amides as the Simplest Acid/Base Catalysts for Stereoselective Carbon-Carbon Bond-Forming Reactions
作者:Yasuhiro Yamashita、Shū Kobayashi
DOI:10.1002/chem.201300908
日期:2013.7.15
paper, new possibilities for metalamides are described. Although typical metalamides are recognized as strong stoichiometric bases for deprotonation of inert or less acidic hydrogen atoms, transition‐metalamides, namely silver and copper amides, show interesting abilities as one of the simplestacid/basecatalysts in stereoselectivecarbon–carbon bond‐forming reactions.
A rapid and divergent access to chiral azacyclic nucleoside analogues via highly enantioselective 1,3-dipolar cycloaddition of β-nucleobase substituted acrylates
A rapid and divergent access to chiral azacyclic nucleoside analogues was developed via enantioselective 1,3-dipolar cycloaddition of β-nucleobase substituted acrylates.