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Synthesis 2005(12): 1907-1922  
DOI: 10.1055/s-2005-869996
REVIEW
© Georg Thieme Verlag Stuttgart · New York

Directly Linked Polyazoles: Important Moieties in Natural Products

Estela Riego*a, Delia Hernándeza,b, Fernando Albericio*a,b, Mercedes Álvarez*a,c
a Barcelona Biomedical Research Institute, Barcelona Scientific Park, University of Barcelona, Josep Samitier 1, 08028 Barcelona, Spain
Fax: +34(93)4037126; e-Mail: eriego@pcb.ub.es; e-Mail: albericio@pcb.ub.es; e-Mail: malvarez@pcb.ub.es;
b Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain
c Laboratory of Organic Chemistry, Faculty of Pharmacy, University of Barcelona, Avda. Joan XXIII s/n, 08028 Barcelona, Spain
Further Information

Publication History

Received 17 February 2005
Publication Date:
13 July 2005 (online)

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Abstract

Directly linked 1,3-azoles are found as substructures in important naturally occurring products that have interesting biological activities as well as fascinating structures. Therefore, many research groups are working on their total syntheses. Although new approaches have been developed to prepare these targets, classical 1,3-azole formation methodologies are still being used for this purpose. This report provides an overview of polyazole-containing natural products and the different strategies for the synthesis of directly linked 1,3-azole moieties.

  • 1 Introduction

  • 2 Biogenesis

  • 3 Synthesis of Polythiazole Fragments

  • 3.1 Construction of the Thiazole Ring

  • 3.1.1 Hantzsch Cyclization

  • 3.1.2 Formation and Oxidation of Thiazoline

  • 3.1.3 Miscellaneous

  • 3.2 Cross-Coupling Reactions

  • 4 Synthesis of Polyoxazole Fragments

  • 4.1 Construction of the Oxazole Ring

  • 4.1.1 Blümlein-Lewy Cyclization

  • 4.1.2 Polyoxazoles from Amino Acids and Peptide Derivatives

  • 4.1.2.1 Formation and Oxidation of Oxazoline

  • 4.1.2.2 Cyclodehydration of β-Keto Amides

  • 4.1.2.3 Polyoxazoles from Dehydropeptides

  • 4.1.3 Rhodium(II)-Catalyzed Cycloaddition Reactions

  • 4.1.4 Chan-Type Rearrangement

  • 4.1.5 Polyoxazoles from α-Chloroglycinates

  • 4.1.6 Polyoxazoles from N-Acylisoxazol-5-ones

  • 4.1.7 Miscellaneous

  • 4.2 Cross-Coupling Reactions

  • 5 Synthesis of Thiazole-Oxazole Fragments

  • 5.1 Polyazoles from Amino Acids

  • 5.2 Hantzsch Cyclization Followed by Azoline Formation

  • 6 Overview

Key words

natural products - heterocycles - peptides - cyclizations - cross-coupling reactions