NHC-Catalyzed Ester Activation: Access to Sterically Congested Spirocyclic Oxindoles via Reaction of α-Aryl Esters and Unsaturated Imines

Lin Hao; Chan Wei Chuen; Rakesh Ganguly; Yonggui Robin Chi

doi:10.1055/s-0033-1338945

Synlett, Table of Contents

Synlett 2013; 24(10): 1197-1200
DOI: 10.1055/s-0033-1338945

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NHC-Catalyzed Ester Activation: Access to Sterically Congested Spirocyclic Oxindoles via Reaction of α-Aryl Esters and Unsaturated Imines

Lin Hao

Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore Fax: +65 67911961 Email: robinchi@ntu.edu.sg

,

Chan Wei Chuen

Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore Fax: +65 67911961 Email: robinchi@ntu.edu.sg

,

Rakesh Ganguly

Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore Fax: +65 67911961 Email: robinchi@ntu.edu.sg

,

Yonggui Robin Chi*

Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore Fax: +65 67911961 Email: robinchi@ntu.edu.sg

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Abstract

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Abstract

Carboxylic esters can be readily obtained at low cost. Therefore, asymmetric catalytic activation of esters should provide useful strategies for organic synthesis. Here we report a N-heterocyclic carbene (NHC)-mediated reaction of α-aryl acetic esters with oxindole-derived α,β-unsaturated imines. The reaction involves the formation of NHC-bound ester enolate intermediate from an ester as a key step, and furnishes spirocyclic oxindole products. The sterically congested spirocyclic oxindole bears a newly formed six-membered δ-lactams and cannot be easily prepared using other methods.

Key words

N-heterocyclic carbene - ester activation - enolate - spirocyclic - oxindole

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References

References and Notes

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