Ferrocenoyl

In 2003, Bonini et al. reported a new synthesis of ferrocenyloxazolines based on an iodide-mediated ring expansion of A-ferrocenoyl-aziridine-2-carboxylic esters. The thus-formed ligands were successfully employed as palladium chelates for the test reaction, since they allowed the product to be formed in quantitative yields and good to high enantioselectivities (Scheme 1.69). According to the results, it seemed that the additional chiral centre present in the oxazoline backbone of these ligands did not play a major role for the asymmetric induction and the activity of the corresponding catalysts. 

H.S. Mandal and H.-B. Kraatz, Ferrocene-histidine conjugates N-ferrocenoyl-histidyl(imN-ferrocenoyl)methylester synthesis and structure. J. Organomet. Chem. 674, 32-37 (2003). 

Electrochemical complexation studies of [5], disappointingly, revealed that the reversible ferrocenoyl oxidation wave was not perturbed on addition of either sodium or potassium cations, implying that the complexed group 1... 

The acid chloride method was successfully employed to produce a number of 1,1 -disubstituted ferrocenoyl peptide and amino acid systems.42-44 Active esters, initially employed by Degani and Heller for introducing the Fc-label into larger proteins at the... 

The preparation of a bis-O-ferrocenoyl-L-tyrosine peptide 106 has been reported (Scheme 31 ).t69i This compound was rationally designed to be used as a model peptide to study the binding ability of a fullerene-modified silica gel. The attachment of the ferrocenyl units was performed presumably in solution using the free hydroxy tyrosine peptide and ferrocenoyl chloride. 

Beer, P. D., Gale, P. A., Chen, Z., Drew, M. G. B., New bis- and tris-ferrocenoyl and tris-benzoyl lower-rim substituted calix[5]arene esters Synthesis, electrochemistry and X-ray crystal structures. Supramol. Chem. 1996, 7, 241-255. 

Auzias M, Therrien B, Siiss-Fink G, Stepnicka P, Ang WH, Dyson PJ (2008) Ferrocenoyl pyridine arene ruthenium complexes with anticancer properties synthesis, structure, electrochemistry, and cytotoxicity. Inorg Chem 47 578-583... 

Chantson JT, Varga Falzacappa MV, Crovella S, Metzler-Nolte N (2005) Antibacterial activities of ferrocenoyl- and cobaltocenium-peptide bioconjugates. J Organomet Chem 690 4564-4572... 

By condensation of acyl chlorides with phenothiazines, numerous new iV-acylphenothiazines have been prepared recently, including, for example, the ferrocenoyl derivative. ... 

Ferrocenoyl chloride (318), ethyl ferrocenecarboxylate (319), and cyanoferrocene (320) are all used as starting materials for the synthesis of 2-ferrocenyloxazolines (321) (Scheme 87). Chirality may be incorporated into the oxazoline ring, and these important chiral compounds have been used to prepare a great number of ferrocene derivatives that are used as catalysts in asymmetric synthesis." " ... 

The reactions of diferrocenoyhnethane and of spacer-bridged bis-, tris- and tetrakis (ferrocenoyl)- ,3-diketones with NaOMe, KH or chloro complexes of Pd(II), Ru(II), Rh(III) and Ir(III) in the presence of K2CO3 afford a series of mono-, bis-, tris- and tetrakis(/l -diketonato) complexes . 

The standard method of synthesis involves the reaction of suitable transition metal halides with Fc-Li [49, 113, 171 — 180, 189, 190], although HgFcj has also been used as ferrocenyl transfer reagent [181 — 183]. A different approach to ferrocenyl complexes proceeds via thermal or photo-induced decarbonylation of the corresponding ferrocenoyl compounds [178,184]. All three routes have been applied to prepare the half-sandwich/sandwich complex CpFe(CO)2-Fc, which contains two different iron centers (Scheme 5-24). It is surprising that Fc-SnMej has rarely been used [185] for ferrocenyl transfer. 

Thus, all possible acyl derivatives of the three ferrocenyl chalcogenols and the three l,l -ferrocenylene dichalcogenols (E = S, Se, Te) have been obtained [89] by treating the lithio compounds with the carboxylic acid chlorides benzoyl, 2-thenoyl, and ferrocenoyl chloride (Scheme 5-31). 

The chalcogeno esters (E = S, Se, Te) presented in Scheme 5-31 are yellow to red-brown compounds that are air-stable in the solid state [89] the benzoic acid derivatives Fc-S-C(0)Ph [82] and fc(E-C(0)Ph)2 (E = S, Se) [91] had been described earlier. The orange derivatives of the ferrocenyl carboxylic acid contain two or three metallocene units connected by ester links (Fig. 5-12). The corresponding esters of the alcohols Fc-OH and fc(OH)2 (E = O) can be obtained [73] by direct ferrocenoylation using Fc-C(0)Cl. 

Scheme 12.1 Synthesis of ferrocenoyl amino acid esters (4) via the acid chloride and active ester methods (i) PCI5 or SOCI2 (ii) carbodiimide such as DCC (N Ji -dicy clohexy lcarbodiimide) or EDC (1 -ethyl-3-(3-dimethyl-aminopropyl)carbodiimide), HOBt (1-hydroxybenzotriazole) (iii) and (iv) peptide or amino acid and base.

This class of compounds is a convenient starting material en route to asymmetrically substituted ferrocenoyl derivatives, which may potentially have applications in proteomics and protein sensing. An unusual procedure was reported in 1996 by Erker and co-workers leading to the formation of Fc-Val-OMe (Val = Valine) 22, Fc[Val-OMe]2 12 (Scheme 12.4) from two equivalents of the Li-salt of a Cp-Val = OMe conjugate with anhydrous FeCl2 in tetrahydrofuran (THF) 43... 

The ferrocenoyl 1-hydroxybenzotriazole ester 66 reacts with aminoferrocene to give difer-rocenyl diamide 68 (Scheme 12.16).54 Heinze was able to make use of this flexible building block and used it to incorporate it into a peptide backbone by solid-phase synthesis.90... 

Scheme 12.16 Coupling of ferrocenoyl benzotriazole ester 66 with aminoferrocene 67 to give the diferrocenyl diamide 68 (i) THF, 12 h.

Derivatives for electrospray ionization mass spectrometry. To enhance the range of analytes that are suitable, neutral derivatives of ferrocene have been examined these were designed to be "elec-trochemically ionizable" and are therefore inherently compatible with the operation of the electrospray source. Ferrocenoyl carbamates of alkanols were prepared by reaction with ferrocenoyl azide which, on heating, forms the reactive isocyanate (van Berkel et al. 1998). 

The bentonite-supported polytrifluoromethanesulfosiloxane (B-PTF-MSS) shows good catalytic activity in the electrophilic acylation of ferrocene with different acyl chlorides to afford products 66 (Scheme 4.40). The catalyst B-PTFMSS can be prepared by refluxing a stirred suspension of bentonite and trifle acid in ethanol and calcining at 200°C for 4 h. The maximum efficiency achieved is -80% ferrocene conversion. The catalyst can be reused with similar activity for two further cycles. Similar good results are achieved with aliphatic acyl chlorides ( 60%-75% yield of product 66), whereas poor yields are obtained with chlorobutyryl chloride (18%), ferrocenoyl chloride (8%), and BC (8%). 

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