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Synlett 2009(12): 1863-1886  
DOI: 10.1055/s-0029-1217514
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© Georg Thieme Verlag Stuttgart ˙ New York

En Route to New Chiral Ferrocene Derivatives: Dead Ends, Detours, and Avenues

Albert Moyano*, Ramon Rios
Unitat de Recerca en Síntesi Asimètrica, Departament de Química Orgànica, Facultat de Química , Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Catalonia, Spain
Fax: +34(93)3397878; e-Mail: amoyano@ub.edu;
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Publication History

Received 17 November 2008
Publication Date:
23 June 2009 (online)

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Abstract

The enantioselective synthesis of β-amino-β-ferrocenyl alcohols, a new class of chiral ferrocene derivatives suitable for the elaboration of auxiliaries and ligands for asymmetric synthesis, can be efficiently achieved by the catalytic asymmetric dihydroxylation of 1-ferrocenylalkenes, followed by the regio- and stereoselective substitution of the hydroxy group adjacent to the ferrocene moiety by nitrogen nucleophiles. En route to these compounds, several previously unknown metallocene derivatives such as α-ferrocenyl epoxides, interannularly cyclopalladated ferrocenyloxazolines, and α-amino-α-ferrocenyl acids have been obtained. The first examples of an organocatalytic approach to the enantioselective synthesis of chiral ferrocenes are also presented.

1 Introduction

2 The Quest for a Stable α-Ferrocenyl Epoxide

3 The Asymmetric Dihydroxylation Route to β-Amino-β-­ferrocenyl Alcohols

4 Applications of Chiral Auxiliaries and Ligands Derived from β-Amino-β-ferrocenyl Alcohols to Asymmetric Synthesis

4.1 Asymmetric Diels-Alder Reactions

4.2 Asymmetric Palladium-Catalyzed Allylic Substitution Reactions

4.3 Catalytic Enantioselective Nucleophilic Additions to Aldehydes

5 Interannular Cyclopalladation of 4-Ferrocenyloxazolines

5.1 Synthesis and Structural Characterization of Cyclopalladated 4-Ferrocenyl-1,3-oxazolines

5.2 Applications of Interannularly Cyclopalladated 4-Ferro­cenyl-1,3-oxazolines in Catalysis

6 Enantioselective Synthesis of Novel Ferrocenyl Amino ­Acids

7 The Kinetic Resolution Approach to Planar Chiral ­Ferrocenes

8 Enantioselective Organocatalytic Synthesis of Chiral ­Ferrocenes

9 Summary and Outlook

Key words

amino alcohols - asymmetric catalysis - epoxides - ferrocenes - palladacycles

1

ICREA Junior Researcher at the University of Barcelona

77

For a recent critical review on the nature of the active species in the Heck-Mizoroki coupling, see ref. 68g.

121

When, under the same reaction conditions, the p-methoxy-phenylimine of benzaldehyde was reacted with butanone, a 1:1.2 mixture of diastereomers (linear/branched) was obtained.