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Synthesis 2010(5): 719-740  
DOI: 10.1055/s-0029-1218652
REVIEW
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Cyclic Hydrazino α-Carboxylic Acids

Christian-H. Küchenthal, Wolfgang Maison*
Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 58, 35392 Giessen, Germany
Fax: +49(641)9919864; e-Mail: wolfgang.maison@org.chemie.uni-giessen.de;
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Publication History

Received 9 October 2009
Publication Date:
05 February 2010 (online)

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Abstract

We present a review of different methods for the preparation of five- and six-membered cyclic hydrazino α-carboxylic acids­ and their derivatives. These heterocycles are common building blocks in pharmaceuticals and many natural products. In addition, hydrazino carboxylic acids have been used as auxiliaries and intermediates in organic syntheses and selected applications are highlighted in this summary. For six-membered heterocycles (piperazic acids), the literature since 1998 is covered as a follow-up to the review by Ciufolini and Xi.

1 Introduction

2 Synthesis of Five-Membered-Ring Systems

2.1 [3+2] Cycloadditions

2.2 Cyclization of N-Acyl Hydrazonium Ions

2.3 [4+2] Cycloadditions

2.4 Tandem and Multicomponent Syntheses

3 Synthesis of Six-Membered-Ring Systems

3.1 Hetero-Diels-Alder Reactions

3.2 Cyclization via Nucleophilic Displacement

3.3 Intramolecular N-Arylation

3.4 Intramolecular Hydrazone Formation

3.5 Intramolecular Lactam Formation

3.6 Ring-Closing Metathesis

4 Summary

Key words

piperazic acids - azaprolines - pyrazolidines - pyrazolines - heterocycles - hydrazine carboxylic acids