Synthesis 2015; 47(03): 289-305
DOI: 10.1055/s-0034-1379884
review
© Georg Thieme Verlag Stuttgart · New York

Recent Developments in the Chemistry of Heteroaromatic N-Oxides

Youliang Wang
Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA   Email: zhang@chem.ucsb.edu
,
Liming Zhang*
Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA   Email: zhang@chem.ucsb.edu
› Author Affiliations
Further Information

Publication History

Received: 01 September 2014

Accepted after revision: 23 October 2014

Publication Date:
14 January 2015 (online)


Abstract

Selected developments in the chemistry of heteroaromatic N-oxides since 2001 are presented in this review. The use of these N-oxides, both in late-transition-metal-catalyzed oxidations of carbon–carbon triple bonds and in regioselective C–H functionalizations of the heteroarene, are contemporary topics of interest and the focus of the discussion.

1 Introduction

2 Synthesis of Heteroaromatic N-Oxides

2.1 Direct Oxidation of Hindered Heteroarenes

2.2 Through Construction of Heteroaromatic Rings

3 Heteroaromatic N-Oxides as Oxidants

3.1 Alkyne Oxidation

3.2 Allene Oxidation

3.3 Carbene Oxidation

4 Heteroaromatic N-Oxides as Substrates

4.1 Deoxygenative ortho-C–H Functionalization with Prior Activation

4.2 Deoxygenative ortho-C–H Functionalization with Nonstabilized Carbanions

4.3 Nondeoxygenative C–H Functionalization

4.3.1 ortho-C–H Functionalization

4.3.2 N-Oxide Directed ortho-Alkyl C–H Functionalization

4.3.3 N-Oxide Directed Remote C–H Functionalization

4.4 1,3-Dipolar Cycloaddition

5 Conclusion and Outlook