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چکیده
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Chiral C2-symmetric bis(oxazoline)s have been successfully employed as ligands with various metals in numerous catalytic asymmetric processes, such as allylic oxidation. [1,2] As a part of a broader program aimed at the development of new chiral metal complexes for asymmetric synthesis, herein we have focused on synthesis of chiral C2-symmetric 2,2′ bisoxazoline ligands and their application in copper-catalyzed asymmetric allylic oxidation. We first generated Cu(II) complexes 1-2 from Cu(OTf)2 and the respective ligands (Scheme 1). To probe the catalytic capability of the latter complexes, we used them in asymmetric allylic oxidation reaction of five to seven membered cycloalalkenes 3-5 with tert-butyl p- nitroperbenzoate(Scheme 1). Similar results were obtained for cycloalalkenes 3 and 5, whereas cyclohexane (4) exhibited notably higher enantioselectivity. Interestingly, the chiral copper- bisoxazoline complex 1 has shown very similar results in copare to the homolge chiral complex 2.
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