Asymmetric Hydrogenation of β-Keto Esters Catalyzed by Ruthenium Species Supported on Porous Organic Polymer

Highly efficient and recyclable chiral phosphine-functionalized polyether ionic liquids for asymmetric hydrogenation of β-keto esters

“…TOF 30 and ee values decreased signicantly with the increase of the steric hindrance of the R 1 , R 2 and R 3 groups due to the repulsion effect of the bulky group on the substrate to phenyl groups of the 3a. 15,34,35 In addition, the incorporation of the electron-withdrawing substituent -CH 2 Cl (4h) or -CF 3 (4i) led to a reduction in the electron cloud density surrounding the carbonyl oxygen, which negatively impacted the interaction between the substrate and the Ru(II) center, consequently causing a signicant decline in the TOF 30 and/or ee values. 35,36 In particular, Ru-3a gave only 65% yield and 10% ee value when the R 1 was a strong electron-withdrawing group -CF 3 (entry 9, Table 3).…”

Chiral Porous Organic Frameworks: Synthesis, Chiroptical Properties, and Asymmetric Organocatalytic Applications

“…Sonogashira coupling was used to incorporate chiral tetraaryl-1,3-dioxolane-4,5-dimethanol (TADDOL) building block (Scheme 3B) [47,48], a pyrrolidine compound (Scheme 3C) [49], and an imidazolidinone MacMillan catalyst (Scheme 3C) [50]. BINAP-containing POFs were prepared using copper-catalyzed alkyne-azide click reaction starting from diethynyl 2,2 -bis(diphenylphosphino)-1,1 -binaphthlyl (BINAP) compound (Scheme 3D) [51]. POFs composed of BINOL building blocks have been prepared using various couplings [52], such as FeCl 3 -induced oxidative homocoupling polymerization (Scheme 3E) [53] or Suzuki coupling (Scheme 3E) [54].…”