Abstract
This account describes the different synthetic approaches used for the preparation
of sulfur-containing chiral ferrocenes in which a CFc-S bond is present and the strategies for introducing planar and central chirality.
The advantages of using these compounds as ligands for soft metals like palladium
and copper are highlighted for several catalytic reactions, including the palladium-catalyzed
enantioselective allylic alkylation, epoxidation, and aza-Diels-Alder reactions.
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1 Introduction
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2 Synthesis of Planar Chiral Ferrocenes Containing Sulfur Functionalities
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2.1 Diastereoselective ortho-Lithiation of Ferrocenyl Derivatives Bearing Carbon-Based Chiral Auxiliaries
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2.2 Planar Chirality by Enantioinduction Using Alkyllithium/
(-)-Sparteine Reagent
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2.3 Diastereoselective ortho-Metalation of Ferrocenyl Derivatives Bearing Chiral Sulfur Directing Groups
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2.3.1 Diastereoselective ortho-Lithiation of Chiral Ferrocenyl Sulfoxides
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2.3.2 Other Chiral Sulfur ortho-Directing Groups
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2.3.3 Ortho-Directed Metalation Involving Chiral Phosphorus Auxiliaries
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2.4 Chiral Ferrocenyl Sulfoxides as Interchangeable Directing Groups
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3 Thio-Substituted Ferrocenyl Derivatives as Ligands in Asymmetric Catalysis
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3.1 S,S Ferrocenyl Ligands
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3.2 S,P Ferrocenyl Ligands
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3.3 S,N Ferrocenyl Ligands
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3.4 S,Oxazoline Ferrocenyl Ligands
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4 Thioferrocenyl-Based Pincer Ligands
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5 Potentially Biologically Active Ferrocenyl Derivatives
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5.1 Ferrocene-Containing β-Lactams
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6 Conclusions and Outlook
Key words
metallocenes - sulfur - chirality - ligands - asymmetric catalysis
