Developing salen-based initiators for atom transfer radical polymerization (ATRP) for preparing new polymer-supported catalysts

The synthesis of polymer-supported salen metal complexes 1 using atom transfer radical polymerization (ATRP) was described. The polymer supp01ied catalyst can be recovered and reused through the use of a latent biphasic mixed solvent system. In the case of poly(t-butyl styrene )-supp01ied Cr(III) complexes, the polymer-supported salen species can be dissolved in nonpolar solvent phase and recovered as solids by removing the solvent under reduced pressure. The polymer-supported catalyst was used to catalyze the ring-opening of cyclohexene oxide with nucleophiles, such as trimethylsilyl azide (TMSN3), in which the Cr (III) catalyst can be recycled and reused for five times without the loss of activity and selectivity. Compare to conventional chiral polymer-supported catalysts, this poly(styrene )-supported catalyst can be used in a neat substrate at the concentration of 0.5 mol/L to produce relatively high enantioselectivity in the ring­opening products, with the enantiomer excess 77%