Chemoselectivity issues of the asymmetric interaction between cyclohexanone, β-nitrostyrene,and benzoic acid under 5-aryl prolinate's organocatalysis |
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Authors: | Polina M Ivantcova Konstantin V Kudryavtsev |
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Institution: | Department of Chemistry, Lomonosov Moscow State University, Moscow, Russian Federation |
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Abstract: | 4-l -menthyloxycarbonyl 5-aryl prolinates were studied as organocatalysts of a novel three-component reaction of cyclohexanone, benzoic acid, and β-nitrostyrene. The presence of ortho-halogen atom in 5-aryl fragment of the catalyst is favored for driving the formation of chiral 7a-hydroxyoctahydro-2H-indol-2-one scaffold. 5-(o-Chlorophenyl) prolinate selectively afforded 3-phenyl-7a-hydroxyoctahydro-2H-indol-2-one with ee 63%, whereas 5-phenyl prolinate led to conjugation of β-nitrostyrene to cyclohexanone (the Michael adduct). Plausible chlorine effect is accounted for the specific interaction of the 5-aryl prolinate enamine intermediate with β-nitrostyrene in the transition state. |
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Keywords: | enamine catalysis multicomponent reactions proline β-peptides |
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