2-Aryl-5,5-bisoxazolin-2-yl[1,3]dioxanes as solution phase and immobilised ligands for highly enantioselective cyclopropanations


  • 2-Aryl-5,5-bisoxazolin-2-yl[1,3]dioxanes 5, which can be easily prepared in three steps from diethyl bishydroxymethylmalonate, amino alcohol and an aromatic aldehyde, have been used for the copper catalysed asymmetric cyclopropanation of styrene with ethyl diazoacetate in up to 99% ee for the trans-cyclopropane. Grafting onto a bromo-Wang resin produced an immobilised ligand 9 which gave the trans-cyclopropane in 65% ee. © 2005 Elsevier Ltd. All rights reserved.
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