Synlett 2009(2): 174-192  
DOI: 10.1055/s-0028-1087520
ACCOUNT
© Georg Thieme Verlag Stuttgart ˙ New York

Highly Stereoselective Aldol Reactions in the Total Syntheses of Complex Natural Products

Tobias Brodmann, Michael Lorenz, Romy Schäckel, Serkan Simsek, Markus Kalesse*
Institut für Organische Chemie, Leibniz-Universität Hannover, Schneiderberg 1B, 30167 Hannover, Germany
Fax: +49(511)7623011; e-Mail: Markus.Kalesse@oci.uni-hannover.de;
Further Information

Publication History

Received 21 June 2008
Publication Date:
15 January 2009 (online)

Abstract

More than ever, it is a challenging objective in synthetic chemistry to create efficient access to biologically active compounds. In particular, one structural element which is frequently incorporated in the framework of complex natural products is a β-hydroxy ketone. In this context, the aldol reaction as the most important transformation to generate this structural element not only creates new C-C bonds but also establishes stereogenic centers. In recent years, a large variety of highly selective methodologies for aldol and aldol-type reactions has been put forward. On this background, the vinylogous Mukaiyama aldol reaction became a pivotal transformation since it also allows for the immediate transformation of the olefin which is simultaneously introduced. This Account covers the application of various (vinylogous) aldol reactions from our laboratories in the syntheses of natural products with important bio-logical activities.

1 Introduction

2 Polyketides: Selected Natural Products

3 Vinylogous Mukaiyama Aldol Reaction (VMAR)

3.1 Triarylboranes in the Substrate-Controlled VMAR in the Synthesis of Ratjadone

3.1.1 Suppression of the Silyl Cation Catalyzed Pathway

3.1.2 Substrate-Controlled VMAR in the Synthesis of Oleandolide

3.1.3 Substrate-Controlled VMAR in the Synthesis of Amphidi-nolide H2 and Tedanolide

3.2 Oxazaborolidinones as Chiral Lewis Acids in the Enantio-selective VMAR

4 Aldol Reactions in Natural Product Syntheses

4.1 Tedanolide

4.2 Chivosazole

4.3 Disorazole

4.4 Epothilone

4.5 Spirangien

5 Conclusions and Outlook