Polymer-supported bis(oxazoline)-copper complexes as catalysts in cyclopropanation reactions

Bis(oxazolines) are easily immobilized by functionalization of the central methylene bridge with polymerizable groups and subsequent polymerization. P olymers are transformed into copper catalysts active in the cyclopropanatio n of styrene with ethyl diazoacetate. The results are similar or even bette r than those obtained with the similar homogeneous systems, and the catalys ts can be easily recovered and reused. The substitution in the methylene br idge leads to a slight reduction in the enantioselectivity and an unexpecte d cis preference.