Catalytic Enantioselective Synthesis of Aryl Substituted 3-hydroxy-2-oxindoles and 3,3-disubstituted-2-oxindoles

Released on by Aziza Hatice Sahin
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  • Catalytic Enantioselective Synthesis of Aryl Substituted 3-hydroxy-2-oxindoles and 3,3-disubstituted-2-oxindoles Book Detail

  • Author : Aziza Hatice Sahin
  • Release Date : 2010
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  • ISBN 13 : 9781124223438
  • File Size : 94,94 MB
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Catalytic Enantioselective Synthesis of Aryl Substituted 3-hydroxy-2-oxindoles and 3,3-disubstituted-2-oxindoles by Aziza Hatice Sahin PDF Summary

Book Description: In Chapter One, a catalytic enantioselective method for the synthesis of 3- hydroxy-2-oxindoles is described. 3-Hydroxy-2-oxindoles were synthesized by a nucleophilic addition of electron-rich arenes and aromatic heterocycles to substituted indole-2,3-diones (isatins) catalyzed by scandium(III) and indium(III)-inda-pybox complexes. The use of a bulky chiral ligand hindered the formation of the achiral 3,3-diaryl-2-oxindole side product. Substituted 3-hydroxy-2-oxindoles were formed in high yield and high enantioselectivity (up to 99% ee). In Chapter Two, a method for the synthesis of chiral 3,3-disubstituted-2-oxindoles from a nucleophilic substitution at the stereocenter of a substituted 3-hydroxy-2-oxindole is described. This SN̳1-like process is catalyzed by a Lewis or a Brønsted acid, which eliminates water to form an indolenium ion intermediate. Chiral BINOL-derived phosphoric acids and phosphoramides are promising catalysts for an asymmetric process, as the conjugate base can act as a counteranion that coordinates to the carbocation intermediate to direct an asymmetric nucleophilic addition. Catalyst and solvent effects have been investigated with yields ranging from 68-97%. Preliminary enantioselectivity has been observed and further optimization is underway.

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Studies in Natural Products Chemistry

Studies in Natural Products Chemistry

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Functional diversity and molecular architecture in biologically active oxindoles. Transition metal-catalyzed intramolecular Heck reactions and amide alpha-aryla