Catalytic asymmetric dihydroxylation of alkenes induced by polymeric chiral ligands

Chiral catalysts immobilized on achiral polymers: effect of the polymer support on the performance of the catalyst

“…19), is strongly affected by the appropriate design of the polymeric matrix. 166 The rate of dihydroxylation of styrene depends on the hydrophobic/hydrophilic properties of the polymeric backbone. The activity increases for supports with a more hydrophilic backbone (98) (introduction of HEMA and EGDMA as comonomers), showing similar results to those obtained under homogeneous conditions (96).…”

Catalytic Asymmetric Dihydroxylation of Olefins Using a Recoverable and Reusable Ligand.

“…H 2 O (20 mL) was added and the mixture was extracted with CHCl 3 (30 mL × 3). The combined organic layers were subsequently dried over anhydrous MgSO 4 and concentrated under vacuum. The residue was purified by flash column chromatography (eluent MeOH-CHCl 3 1:6) to give a white solid (3) …”

“…NaSO 3 (6 g) was added and stirred for another 2 h. The mixture was subsequently filtered. The filtrate was dried over anhydrous MgSO 4 and concentrated under vacuum. The residue was then purified by flash column chromatography (eluent MeOH-CH 2 Cl 2 1:5) to afford a white solid (1) 6 (1.96 g, 6.0 mmol), K 2 CO 3 (0.82 g, 6.0 mmol) were dissolved in t-BuOH-H 2 O (20 mL, y = 1:1) at room temperature, followed by addition of OsO 4 in toluene (26 mL, 0.01 mmol) and ligand 1 (0.92 g, 0.10 mmol).…”

“…Many efforts were made to address this issue in the past decade. The ligand immobilized on an insoluble polymer was synthesized in order to recover the expensive ligand and a small amount of OsO 4 . But, low catalytic activity and enantioselectivity were reported.…”

“…This is because the restrictions of the polymer matrix resulted in limited mobility and accessibility to the active sites and thus obstructed the ligand-accelerated catalysis in the AD reaction. [2][3][4] To take advantage of homogeneous catalysis with respect to the easy separation of a ligand bound to the solid phase, cinchona alkaloidtype ligands were attached to a soluble polymer, polyethylene glycol monomethyl ether. [5][6][7][8][9] However, complicated synthetic manipulations were required for the preparation of PEG-bound ligand.…”