An Insoluble Polymer-Bound Bis-Oxazoline Copper(II) Complex: A Highly Efficient Heterogeneous Catalyst for the Enantioselective Mukaiyama Aldol Reaction

The polystyrene-supported bis-oxazoline 1 forms a complex with copper(II)triflate that is a highly effective catalyst for the heterogeneously catalyzed enantioselective Mukaiyama aldol reaction of silylthioketene acetals with methyl pyruvate (ca. 90 % yield, ca. 90 % ee). The catalyst can be recovered by simple filtration and reused several times without a decline in enantioselectivity.