Recent Developments in the Chemistry of Heteroaromatic N-Oxides

• Published in: Synthesis (Stuttgart) Vol. 47; no. 3; pp. 289 - 305
• Main Authors: Wang, Youliang, Zhang, Liming
• Format: Journal Article
• Language: English
• Published: Stuttgart · New York Georg Thieme Verlag 14.01.2015
• Subjects: review; carbenes; oxidations; cycloadditions; pyridines; alkynes
• ISSN: 0039-7881; 1437-210X
• DOI: 10.1055/s-0034-1379884

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