Synthesis of Polymeric Salen Complexes and Application in the Enantioselective Hydrolytic Kinetic Resolution of Epoxides as Catalysts

초록

These recently developed salen-based catalysts are appealing candidates for covalent attachment of homogeneous chiral salen ligands to the polymer and inorganic supports, and the corresponding immobilized salen derivatives were shown to be efficient for the hydrolytic kinetic resolution (HKR) of terminal epoxides and asymmetric epoxidation. we have synthesized two different salen polymers using chloromethylated salen and monomeric dialdehyde, respectively. The reaction using the polymeric Co(III) salen catalysts exhibited the almost same enantioselectivity as monomeric salen catalysts. Epichlorohydrin and epoxystyrene gave very high yield and ee% of optically pure epoxide over chiral Co(Ⅲ) salen polymers. The new polymeric chiral (salen) Co(III) catalysts showed to be effective in asymmetric hydrolytic resolution of epoxides with promising enantioselectivities. The catalysts could be recovered and reused several times without loss of activity and stereoselectivity. On the basis of asymmetric HKR of various epoxides, the polymeric chiral (salen) complexes obtained by the present procedure can be applied as an effective heterogenized homogeneous catalyst for the asymmetric reactions.