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Synlett 2009(20): 3237-3251  
DOI: 10.1055/s-0029-1218518
ACCOUNT
© Georg Thieme Verlag Stuttgart ˙ New York

Chemistry of 2-Arylhydrazonals

Ismail Abdelshafy Abdelhamid*a,b, Miead Adel Nasraa, Mohamed Hilmy Elnagdi*c
a Chemistry Department, Faculty of Science, Cairo University, 12613 Giza, Egypt
e-Mail: Ismail_shafy@yahoo.com ;
b Institut für Organische Chemie, Universität Hannover, Schneiderberg 1B, 30167 Hannover, Germany
c Chemistry Department, Faculty of Science, University of Kuwait, P. O. Box 5969, Safat 13060, Kuwait
Fax: +965(248)16482; e-Mail: shelmy1941@yahoo.com ;
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Publication History

Received 16 June 2009
Publication Date:
27 November 2009 (online)

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Abstract

Approaches for the preparation of 2-arylhydrazonals as well as the chemical reactivity profiles and structures of these substances are reviewed. Emphasis is given to the use of these substances in the synthesis of five- and six-membered heterocycles.

1 Introduction

2 Synthetic Approaches to 2-Arylhydrazonals

2.1 Synthesis via Coupling of Enamines with Aromatic Diazonium Salts

2.2 Coupling Reactions of Active Methylenes with Aromatic Diazonium Salts

2.3 Synthesis of Arylhydrazonals via Condensation Reactions with Phenylhydrazine

2.4 Synthesis of Arylhydrazonals via Oxidation of Methyl and Hydroxymethyl Arylhydrazones

3 Structural Investigations

4 Reactions of Arylhydrazonals

4.1 Reactions Involving the Aldehyde Group

4.1.1 Formation of Formazans

4.1.2 Condensation Reactions with Amines, Hydrazines and
Hydroxylamine

4.1.3 Condensation Reactions with Active Methylene Compounds

4.2 Reactions Resulting in the Formation of Heterocycles

4.2.1 Formation of Hydrazononitriles and 1,2,3-Triazoles

4.2.2 Synthesis of Pyrazoles and Fused Pyrazoles

4.2.3 Synthesis of Pyridazines and Fused Pyridazines

4.2.4 Miscellaneous

5 Conclusion

Key words

arylhydrazonals - synthesis - reactivity

37

Elnagdi, M. H. unpublished results.