Condensation of ferrocene

More recently, recognition of H2PO and ATP2- anions has been observed with dendrimers obtained by condensation of ferrocene-terminated dendrons on octahedral Moe cluster27 (compound 3 in Fig. 6.3) or Au nanoparticles28 cores. 

Several interesting derivatives of tpy have been prepared in which a ferrocene is linked to the 4 -position. The condensation of ferrocene carbaldehyde with 2-acetyl pyridine leads to the parent system (31a).34 Alternatively, l,5-bis(2-pyridyl)-3-(ferrocenyl)pentane-l,5-dione may be easily prepared in 77% yield, and subsequent treatment with ammonium acetate provides a 78% yield of (31a).35 If ferrocene l,l -dicarbaldehyde is used in the first procedure, the bisterpyridyl ferrocene can be synthesized.36 Addition of the anion derived from (25i) to ferrocene carbaldehyde affords the alcohol (31b), which can be dehydrated to the ethylene derivative (31c).37 Coupling of alkynyl ferrocene with the bromo-derivative (25e) leads to a tpy linked to ferrocene by a phenylacetylene bridge (31d).38... 

A multicyclic soluble polymer was obtained from the zinc chloride-catalyzed condensation of ferrocene and acetone (IV-18) (27, 28). The polymer was a brown powder softening at 320°-360°C, and was soluble in benzene. Its molecular weight was determined cryoscopically and was about 3000. No crystallinity was detected by X-ray analysis. The material exhibits a signal in its ESR spectrum and has semiconducting properties. Its specific electroconductivity (50°C) was 1.23 x 10 i2 ohm- cm i with an activation energy of 0.67 eV. 

Dialkylation preferentially occurs homoannularly, as expected, and indeed the occurrence of large yields of polyalkylated products may be understood since alkyl substituents increase the reactivity of the substituted ring. Direct alkylation of ferrocene may also be achieved by the condensation of ferrocene with formaldehyde in liquid hydrogen fluoride [314, 315]. 

Properties of ferrocene-containing polymers have been improved by inclusion of pyrazole systems in the backbone. The synthesis of (748) was achieved by condensation of bis()3-diketoferrocenes) with aromatic dihydrazines to give polyhydrazones that were later cyclo-dehydrated (B-80MI40408). 

The reaction is carried out under argon in a 2-liter three-necked flask fitted with a mechanical stirrer, reflux condenser, 250-ml pressure-equalizing addition funnel, and gas inlet and outlet. After purging with argon, the flask is charged with a solution of 89 g (0.48 mole) of ferrocene in 1 liter of dry tetrahydrofuran. The solution is next heated to 45°, and there is added dropwise with stirring, 155 ml (0.29 mole) of an -butyllithium solution (15% in heptane-pentane, 2 1, Foote Mineral Co.) during a period of 75 minutes. The resultant solution is maintained at 45° for an additional 2 hours, then is cooled to —77° by means of an external Dry Ice-chloroform bath. 

On the other hand, the yield of ferrocene in a [CpFe(CO)2]2 matrix (50) is not altered up to 80° C, so that here either Cp transfer is not possible or the position on the Fe atom is blocked by CO groups. It seems plausible to consider a rapid ligand condensation as a very early prethermal competitive reaction. One can thus set up a hypothetical reaction scheme such as [using PhHCr(CO)3 as the matrix compound] ... 

One previous synthesis of ferrocene-containing condensation polymers via interfacial methods at room temperature has been reported by Knobloch and Rauscher, who formed low molecular weight polyamides and polyesters by reacting l,l -bis(chloro-formyl)ferrocene with various diamines and diols. Further, Carraher and co-workers have utilized interfacial techniques in the formation of other types of organometallic polymers. 

The reaction of ferrocene and formaldehyde in either concentrated sulfuric acid or liquid hydrogen fluoride, followed by reduction, produces a compound containing two ferrocenyl and two methylene groups (57, 98, 123). After several incorrect assignments had been proposed for the structure of this condensation product, Rinehart and coworkers showed by an unequivocal synthesis that the product was 1,2-diferrocenylethane (XIX) (104). The mechanism of the reaction presumably involves the initial formation of ferrocenylcarbinol (XX) followed by ionization in the strongly acidic medium to the ferrocenylmethyl-carbonium ion (XXI). Conversion to radical ion XXII followed by dimerization and subsequent reduction produces the product. 

Polypyrazoles of the type 62 have been prepared.65 These polymers are formed from the low-temperature solution condensation of 1,1 -bis(diketo)ferrocenes with aromatic or pseudoaromatic dihydrazines to give polyhydrazones which are transformed thermally to the polypyrazoles. Polybenzimadazole (63) has been prepared68 from l,l -ferrocenedicarboxylic acid and 3,3 -diaminobenzidine. 

Hartwig reported that ferrocene-based diphosphine 13 catalyzes the arylation of aniline at room temperature, Eq. (91) [72]. Additionally, the (f-BuljP/Pd-based system effects the room-temperatuxe condensation of anilines and aryl bromides. However, the (f-BuljP/Pd-catalyst is considerably more active [50]. While the reaction with 4-bromotoluene and anihne proceeded in 20 h using 5 mol% 15/Pd(dba)2, the reaction between bromoben-zene and aniline was complete in 1 h using only 1 mol% of the (f-BuljP-derived catalyst. 

Ferrocene-based phosphine 24 is also an effective supporting ligand for the Pd-catalyzed condensation of chloroarenes and sodium ferf-butoxide [148]. The coupling of 2-chloro-para-xylene, followed by acid mediated cleavage of the ferf-butyl group, yielded the desired phenol in 71 % yield, Eq. (190). 

The common procedure for adding reactants consists either in simultaneously mixing all the chemical species involved in the reaction, or in allowing the amine and the aldehyde to react first and then adding the substrate. In some cases, however, the condensation of substrate and formaldehyde is carried out first in order to isolate the corresponding methylol derivative, which is subsequently submitted to react with the amine (X-methylation of amino derivatives see Fig. 12) this is advantageous with several substrates, such as nitroalkanes, ferrocenes,- sulfonic acids, and phosphines. ... 

An aza-Wittig reaction utilizing isocyanates leads to ferrocene-containing imidazolones. Thus, condensation of P-ferrocenylvinyliminophosphorane 1377 with isocyanates provides the carbodiimide intermediate 1378, which can then be reacted with various amines to give the imidazolones 1379 in good yields (Scheme 356) <1996TL7829> (see Section 4.02.9.2(i)(b)). 

The synthesis of dppf was first recorded in 1965 by the lithiation of ferrocene with M-butyllithium, followed by condensation with chlorodiphenylphosphine [17]. A higher yield can be obtained in the presence of N, N, N, TV -tetramethylethylene-... 

Ferrocene has been reported to be very effective as a soot reducing agent in combustion [42 — 44]. Thus, when ferrocene compounds are incorporated in a fire retardant polymer, such as a phenolphthalein-based polymer and poly(phosphate ester)s, they have shown added advantages in that they promote extinction and reduce smoke formation by accelerated char reduction [45, 46]. The synthesis of such ferrocene-containing poly(phosphate ester)s was achieved by interfacial polycondensation using a phase transfer catalyst [47]. Accordingly, l,l -bis(p-hydroxy-phenylamido)ferrocene and l,l -bis(p-hydroxyphenylcarbonyl)ferrocene underwent condensation with various aryl phosphoroic acid dichlorides to yield two series of ferrocene-containing polymers, i.e., poly (amide-phosphate ester)s 38a and poly(ester-phosphate ester)s 38b respectively, as shown in Scheme 10-17. 

SB-containing ferrocene groups have received much attention in the late 1990s. Thus, [1 + 1] and [2 + 2] macrocycles and a variety of acyclic SB-containing ferrocene groups have been prepared by reaction of formyl- and l,l -diformylferrocene with the appropriate diamine or by condensation of aminomethylferrocene with (56a), (57a), or 3-methoxy-2-hydroxybenzaldehyde.41 The compounds have been characterized by IR, NMR, Mossbauer spectroscopy, and FAB mass spectroscopy. 

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