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

Abstract

The enantioselective synthesis of b-amino-b-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 a-ferrocenyl epoxides, interannularly cyclopalladated ferrocenyloxazolines, and aamino-a-ferrocenyl acids have been obtained. The first examples of an organocatalytic approach to the enantioselective synthesis of chiral ferrocenes are also presented. 6

Palladacycle from Cyclometalation of the Unsubstituted Cyclopentadienyl Ring in Ferrocene: Synthesis, Characterization, Theoretical Studies, and Application to Suzuki–Miyaura Reaction

“…In particular, ferrocenyl derivatives have been cyclopalladated at the substituted cyclopentadienyl ring since the 1960s, where the Pd–C bond was stabilized by the intramolecular coordination of donor atoms (N, P, O, or S). Moreover, palladation at the unsubstituted cyclopentadienyl ring gave heteroannular cyclopalladated derivatives, in which the carbon nitrogen double bond was not coplanar with the substituted cyclopentadienyl ring and might direct the palladium atom toward the lower one . Only scattered attention had been paid to the study of their properties.…”

Synthesis and Characterization of Multiferrocenyl‐Substituted Group 4 Metallocene Complexes

“…The working electrode was pretreated by polishing on a Buehler microcloth first with 1 mm and then 1/4 mm diamond paste. The reference electrode was constructed from a silver wire inserted into a solution of 0.01 mol L À1 AgNO 3 Successive experiments under the same experimental conditions showed that all formal reduction and oxidation potentials were reproducible within 5 mV. Experimental potentials were referenced against an Ag/Ag + reference electrode, but results are presented referenced against ferrocene as an internal standard, as required by IUPAC.…”

“…After 60 years of ferrocene chemistry, this sandwich complex is still of high interest in numerous research areas, for example, polymerization, [1] electrochemistry, [2] and catalysis. [3] Beside these applications, multiferrocenyl-substituted compounds possess an attractive molecular structure, some examples of which are shown in Figure 1. Hexaferrocenylbenzene (A) was synthesized by Vollhardt and co-workers and is accessible exclusively by a sixfold palladium-catalyzed CÀC bond coupling.…”