ortho-metalated dirhodium(II) catalysts immobilized on a polymeric cross-linked support by copolymerization. Study of their catalytic activity in the asymmetric cyclopropanation of styrene with ethyl diazoacetate

摘要

Chiral ortho-metalated dirhodium(H) compounds containing the phosphine P(p-CH2=CHC6H4)(3) have been efficiently immobilized by radical copolymerization with styrene and 1,4-divinylbenzene. Their catalytic activity has been tested in the cyclopropanation reaction of styrene with ethyl diazoacetate, achieving yields considerably higher that those obtained with the counterpart homogeneous catalysts, but having lower diastereo- and enantioselectivities. Immobilized catalysts anchored on the polystyrene (PS) by six positions have been shown to be more robust that those generated from compounds that have only three groups for anchoring.