Stereoselective reaction of 2-carboxythioesters-1,3-dithiane with nitroalkenes: an organocatalytic strategy for the asymmetric addition of a glyoxylate anion equivalent
Self-association-free dimeric cinchona alkaloid organocatalysts: unprecedented catalytic activity, enantioselectivity and catalyst recyclability in dynamic kinetic resolution of racemic azlactones
作者:Ji Woong Lee、Tae Hi Ryu、Joong Suk Oh、Han Yong Bae、Hyeong Bin Jang、Choong Eui Song
DOI:10.1039/b917882a
日期:——
Self-association-free, bifunctional, squaramide-based dimeric cinchonaalkaloidorganocatalysts show unprecedented catalytic activity, enantioselectivity and catalyst recyclability in the dynamic kinetic resolution (DKR) reaction of a broad range of racemic azlactones.
Stereoselective reaction of 2-carboxythioesters-1,3-dithiane with nitroalkenes: an organocatalytic strategy for the asymmetric addition of a glyoxylate anion equivalent
Under mild reaction conditions γ-nitro-β-aryl-α-keto esters with up to 92% ee were obtained, realizing a formal catalytic stereoselective conjugate addition of the glyoxylate anion synthon.
Design and synthesis of chiral hyperbranched polymers containing cinchona squaramide moieties and their catalytic activity in the asymmetric Michael addition reaction
作者:Sadia Afrin Chhanda、Shinichi Itsuno
DOI:10.1016/j.jcat.2019.07.060
日期:2019.9
Chiral hyperbranched polymers (HBP) containing cinchona alkaloids were synthesized using a Mizoroki–Heck (MH) coupling polymerization reaction between a cinchona squaramide dimer and tri- or tetra-substituted aromatic iodides. This is a new type of polymeric chiral organocatalyst. We found that the as-obtained chiral HBPs show excellent catalyticactivity in the asymmetric Michael reaction. Almost