Ferrocene 3 ferrocenophanes

Keywords Anti-androgen Anti-oestrogen/Anti-oestrogenic Breast cancer Cytoto x i c/Cytotox i c i ty. Electrochemistry/Electrochemical Oestradiol Ferricenium Ferrocene Ferrocenophane Hydroxyferrocifens Hydroxytamoxifen (OH-Tam) Oestrogen receptor (ER) Oestrogen/Oestrogenic Phenol Prostate cancer Quinone Raloxifen RBA ROS Steroid Tamoxifen Testosterone Vectorisation... 

Elimination of hydrogen halides from dihalogenoorganylboranes by reaction with ferrocene-1,1 -dithiol resulted in l,3-dithia-2-boryl[3]ferrocenophanes.170 These borylferrocenophanes were air sensitive, but were characterized by NMR, MS, and elemental analysis.170 A series of l,3-dibora-2-X-[3]fer-rocenophanes (X=S, Se, Te) were prepared and characterized and the crystal structure of [Se N Pr2)BC5Fl4 2Fe] has been reported.171... 

Germanium-bridged [l]ferrocenophanes undergo a number of ring-opening polymerization reactions to yield ferrocene-containing polymers, and the versatility of this interconversion has been reviewed. A -GeMe2-... 

Recently, Plenio and co-workers have published a number of papers on ferrocenophanes, ferrocene cryptands and simple ferrocene amines (Plenio et ai, 1993, 1994 Plenio and Diodone, 1995a). They have synthesized 22... 

To conclude the matter of monoferrocene molecules we consider those cases in which the cyclopentadienyl substituents form bridges between the two rings. Such derivatives are named ferrocenophanes. The best known ferrocenophanes are those which contain saturated (tri- or tetra-methylene) carbon chains. Like ferrocenes, these molecules also exhibit reversible one-electron oxidation to the corresponding ferrocenium ions. 

Attempts to make C2-symmetric ferrocenes by double lithiation of a bis-acetal met with only limited success . A second lithiation of the ferrocenylacetal 298 leads to functionalization of the lower ring of the ferrocene, in contrast with the second adjacent lithiation of the oxazolines described below. This can be used to advantage if, for example, the first-formed aldehyde 301 is protected in situ by addition of the lithiopiperazine 53 °, directing f-BuLi to the lower ring (Scheme 139) °. The same strategy can be used to introduce further functionalization to products related to 302. For example, silane 303, produced in enantiomerically pure form by the method of Scheme 138, may be converted to the ferrocenophane 304 by lithiopiperazine protection, lithiation and functionalization (Scheme 140) . 

A number of molecular mechanics studies of metal-cyclopentadienyl complexes have been reported recently. The systems studied include linear metallocenes (in particular ferrocene), ferrocene derivatives (such as complexes with substituted cy-clopentadienyl ligands, bis(fulvalene)diiron complexes, ferrocenophanes and mixed-ligand complexes with carbonyls and phosphines), and nonlinear cyclopentadienyl complexes 8,153,221 231]. 

Mass spectrometry has proved extremely useful in determining the composition of various polyferrocene products such as those formed by trimerization of ferrocenylacetylenes (180), reactions of ferrocenyl-acetylenes with metal carbonyls (175), oxidative coupling of ferrocenyl polyacetylenes (179), and lithiation of ferrocene (186). The 1,12-dimethyl-[l,l]ferrocenophane (XC) shows a very strong molecular ion and fragments [M—Me]+ [M—2 Me]+ and the doubly charged species M2+, [M —Me]2+, and [M —2 Me]2+ (197). 

Although a selection of ferrocene crown ethers (Scheme 4) were initially reported by Biernat and Wilczewski (44), Saji (45) described the first evidence of anodic shifts in the oxidation potential of pentaoxa[13]-ferrocenophane (6) resulting from the addition of alkali metal salts. Two distinct electrochemical CV waves corresponding to complexed and uncomplexed (6) were observed for both Na+ and Li+ guest cations (Fig. 4). The respective anodic shifts correspond to a decrease of the... 

Besides the ferrocene crown ether ligands described earlier, a variety of related macrocyclic ferrocenophanes containing various sulfur, oxygen, and nitrogen heteroatoms have been reported by a number of groups (110-115) (Scheme 21). These ligands complex transition metal guest cations such as Ag(I), Cu(I), and Pd(II) (116,117). Of particular... 

In the case of the ferrocenophanes 36 and 37, the CVs also suggest a similar mechanism to that shown in Scheme 2. Although the ferrocene moiety remains conjugated to the molecule in 36,37 possesses a methylene spacer which breaks the conjugation. In the former case, the intramolecular proton coupled electron transfer from the phenol to the ferricenium can be explained by the classical Ji-delocalized mechanism [128, 129]. For the unconjugated 37, one must consider either that the electron transfer proceeds through space or via the formation of an intermediate a-methylene radical (such as a-methylene ferricenium molecules possess acidic... 

The first dibora[2] ferrocenophane (94) was prepared from l,L-dilithioferrocene and l,2-dichlorobis(dimefhylamino)di-borane. A dynamic process due to motion of the cyclopenfa-dienyl rings between staggered and eclipsed conformations was revealed by low-temperature NMR spectroscopy. A number of l,3-dibora[3]ferrocenophanes with B-E-B bridges (95 E=0, S, Se, Te, NR) were reported. Moreover, Wagner used diborylated ferrocenes for the synthesis of doubly bridged switchable ania-metallocenes (96) and (97), in which the bridges are created and... 

Bridged ferrocenes, or ferrocenophanes, have been known for many years. These compounds, in which the two Cp rings are linked by carbon and/or heteroatom chains, are... 

Bridged Ferrocene Derivatives Conformational Energy Surfaces of [3]-, [4], and (4,- -Ferrocenophanes. 

The binding of a redox system such as ferrocene to endoreceptors has been used to recognize particular guests. The first example concerned with the recognition of alkali-metal cations by a crown ether incorporating a ferrocenophane moiety [366] as shown on Figure 3. 

Considering the high efficiency of enzymes, model compounds have been developed that mimic their functions (Fig. 4-21). Among them, -cyclodextrin occupies a prominent place, as it forms inclusion complexes with suitably constructed ferrocene derivatives that then may undergo kinetic resolution (Fig. 4-21 d). An ester of an unsaturated acid derived from a 1,2-ferrocenophane is the best substrate for this technique the rate of hydrolysis of one enantiomer is enhanced by 3.2 x 10 [133]. 

The smallest rings that are able to incorporate a ferrocene building block without deformation of the sandwich structure (with its two planar and parallel cyclopenta-dienyl rings) are [3]ferrocenophanes. This becomes evident in the series of sila-ferrocenophanes fc[(SiMe2) ] ( = 2, 3) (Scheme 5-41) [243]. 

Ferrocene derivatives containing a single disulfide link are occasionally obtained from reactions of fc(SH)2, e.g., with norbornene [84] or with the oxonium salt [(Ph3PAu)30]BF4 (Scheme 5-18) [90]. Splitting of l,2,3-trithia-[3]ferrocenophane, fc(S3), by organolithium reagents followed by air oxidation is another pathway to disulfides (Scheme 5-51) [95]. 

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