En route to new chiral ferrocene derivatives: Dead ends, detours, and avenues

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.