Diastereodivergent asymmetric Michael-alkylation reactions using chiral N,N'-dioxide/metal complexes
Yulong Kuang1, Bin Shen1, Li Dai1
1Key Laboratory of Green Chemistry & Technology , Ministry of Education , College of Chemistry , Sichuan University , Chengdu 610064 , China . Email: liuxh@scu.edu.cn ; Email: xmfeng@scu.edu.cn ; ; Tel: +86 28 85418249.
Abstract:
A diastereodivergent asymmetric Michael-alkylation reaction between 3-chloro-oxindoles and β,γ-unsaturated-α-ketoesters has been achieved using L-RaPr /Sc(OTf)3 and L-PrPr /Mg(OTf)2 metal complexes as catalysts. Both rel-(1R,2S,3R) and rel-(1S,2S,3R) chiral spiro cyclopropane oxindoles were constructed in good yields, diastereoselectivities and ee values. The diastereodivergent control may originate from different alkylation pathways after the Michael addition, with either intramolecular trapping of the aza-ortho-xylylene intermediate or direct SN2 substitution.
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