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Journal
Publications |
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2-Aryl-5,5-bisoxazolin-2-yl[1,3]dioxanes
as solution phase and immobilized ligands for highly enantioselective
cyclopropanations.
Julian G. Knight and Paul E. Belcher,
Tetrahedron: Asymmetry, 2005, 16, 1415. |
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Abstract:
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. |
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