摘要：

A CuNaY catalyst was prepared and used to study the enantioselectiveaziridination of styrene, with PhINTs as the nitrogen source, inthe presence of a bis(oxazoline) chiral modifier. The chiral modifier usedwas a diimine ligand, (S)-()-2,2′-isopropylidenebis(4-phenyl-2-oxazoline).EPR spectroscopy provides the first direct experimental evidence for theformation of a copper(II)-bis(oxazoline) complex insidethe Y zeolite pores after stirring the calcined catalysts with the chiralligand using acetonitrile as solvent. The copper complexes possess squarepyramidal and square planar symmetries, with spin Hamiltonian parameters analogousto those of the equivalent homogeneous complex dissolved in solution. Thesecopper(II) complexes accounted for at least 40% of all available copper within the ion exchanged CuNaY catalyst and represent oneCu(II)-bis(oxazoline) complex per supercage. The remaininguncomplexed Cu(II) ions remain solvated to the acetonitrile molecules.After the aziridination reaction was carried out in the presence of styreneand PhINTs, EPR evidenced the selective loss of the signal due tothe copper(II)-bis(oxazoline) complex with square pyramidaland square planar symmetries but practically no loss in overall Cu(II)content. This was explained on the grounds of a changing co-ordinationenvironment of the encapsulated complex. However when PhINTs was addedseparately to the catalyst a dramatic loss in Cu(II) signal intensitywas observed. These results are discussed in terms of the reaction mechanismin operation.

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