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چکیده
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Asymmetric 1,3-dipolar cycloaddition reactions between nitrones and alkenes is still of great interest in organic synthesis since the resulting optically active isoxazolidines are valuable precursors to biologically active γ-amino acids, γ-aminoalcohols, lactams, amino sugars, and alkaloids1. They are also easily ring opened to the corresponding aminoalcohols which can serve as attractive building blocks for the construction of other natural products and bioactive substances2. Due to the above reasons and also as a part of our ongoing research program on the 1,3- Dipolar cycloaddition reaction of nitrones3, we herein report a highly diastereoselective [3+2] cycloaddition of nitrones 1 with dipolarophile 2 which catalyzed by a chiral complex of Cu(II)-Bisimine 3. The prepared chiral isoxazolidines 4 efficiently transformed, through the cleavage of N-O bond, to the useful chiral β-hydroxy amino acid derivatives 5 in high to excellent yields and optical purity. Following our experimental work, we used semiempreical quantum chemical calculation to investigate the effect of the chiral complex on the rate, regio-, diastereo-, and enantioselectivity of the reaction.
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