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Synlett 2010(2): 165-173  
DOI: 10.1055/s-0029-1218558
ACCOUNT
© Georg Thieme Verlag Stuttgart ˙ New York

Strategies for Heterocyclic Synthesis via Cascade Reactions Based on Ketenimines

Ping Lu, Yanguang Wang*
Department of Chemistry, Zhejiang University, Hangzhou 310027, P. R. of China
Fax: +86(571)87951512; e-Mail: orgwyg@zju.edu.cn;
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Publication History

Received 15 April 2009
Publication Date:
10 December 2009 (online)

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Abstract

The development of highly efficient methodologies for constructing heterocyclic compounds is a major challenge in organic chemistry. This Account presents the recent progresses on cascade strategies for heterocyclic synthesis based on ketenimine intermediates. Three types of cascade reactions for the synthesis of a variety of heterocycles, involving nucleophilic addition to the central carbon of ketenimine, radical addition to the central carbon of ketenimine, and pericyclic reaction of ketenimine, are highlighted in this Account. A brief discussion on the mechanism of copper-­catalyzed azide-alkyne cycloaddition (CuAAC) providing ketenimines is also included.

1 Introduction

2 Nucleophilic Addition to the Central Carbon of Ketenimines

3 Radical Addition to Ketenimines

4 Pericyclic Reactions of Ketenimines: Cycloaddition Reaction

4.1 Ketenimine-Imine [2+2] Cycloadditions

4.2 Ketenimine-Alkene [2+2] Cycloadditions

5 Pericyclic Reactions of Ketenimines: Electrocyclic Ring Closure

6 Pericyclic Reactions of Ketenimines: Sigmatropic Migration

7 Conclusions and Outlook

Key words

ketenimine - cascade reaction - heterocyclic compound - nucleophilic addition - radical addition - cycloaddition - electrocyclic ring closure - sigmatropic migration