Ferrocene alcohols

Reaction of ferrocene acid chloride with appropriate diols in pyridine, with a catalytic amount of (dimethylamino)pyridine (DMAP), gave the corresponding ferrocene alcohol compounds. Formation of bis (ferrocene) compounds was minimized by working at high dilution with a 3-fold excess of diol. The ferrocene alcohols... 

Regarding the structural diversity of the primary alcohols, which have been successfully resolved, there seems to be almost no limitation, as demonstrated by the axial-chiral diols 112-114, the ferrocene alcohols 116-122 and the chiral chromium carbonyl complex 123, and most remarkably the helicenediol 115 (Table 11.1-19). 

Diastereospecific reduction of ferrocenic alcohols by ionic hydrogenation. 

This reaction, derived from the Kursanov Fames reaction, consists of the reduction of an alcohol by a hydride in an acidic medium. In the case of a-ferrocenic alcohols this reaction takes place, in general, with retention of configuration due to the fact that the iron atom stabilizes the carbocation formed. However, diastereospecific reactions are observed when the substituents at the carbon atom bearing the hydroxyl group are bulky. Figure 2.75 shows that there is retention of configuration for one of the diastereomers and inversion for the other. 

Alcohols are often used as cosurfactants in microemulsions, and insight has been obtained from the electrochemistry of ferrocene alcohols (4). Oxidations of FcOHCio, FcOHCu, and FcOHCig [34] were nearly reversible and controlled by diffusion in microemulsions of DDAB, CTAC, or SDS. In micellar solutions, electrode reactions were more complex and reflected strong adsorption of the ferrocene alcohols onto the electrode. 

C and melts at 173°C. It is iasoluble ia water but dissolves ia alcohols, ether, and benzene. Ferrocene can be prepared by numerous methods, including the reaction of cyclopentadienyl anion, with anhydrous FeCl2. Its extensive reaction chemistry is notable for the aromaticity of the... 

Highly enantioselective hydrosilylation of aliphatic and aromatic carbonyl compounds such as acetophenone, methyl phenethyl ketone 1813, or deuterobenz-aldehyde 1815 can be readily achieved with stericaUy hindered silanes such as o-tolyl2SiH2 or phenyl mesityl silane 1810 in the presence of the rhodium-ferrocene catalyst 1811 to give alcohols such as 1812, 1814, and 1816 in high chemical and optical yield [47] (Scheme 12.14). More recently, hydrosilylations of aldehydes... 

A colloidal suspension of conductive vanadium pentoxide [130] can be used to perform intercalation, adsorption or encapsulation of electroactive molecules or biomolecules for electrodes or biosensor realization [131]. Encapsulation of glucose oxidase in nanocomposite films made with polyvinyl alcohol and V205 sol-gel matrix or in ferrocene intercalated V2Os sol-gel [132] were envisaged to prepare glucose biosensors. 

The dithiophosphonic acid monoesters, RP(OR )(S)SH can be conveniently prepared by cleavage of dimeric, cyclic diphosphetane disulfides, [RP(S)S]2 with alcohols, silanols, or trialkylsilylalcohols180 and then can be converted into metal complexes M[SPR(OR )]2 without isolation.181 The substituted ferrocenyl anion, (N3C6H4CH20)(CpFeC5H4)PS2 has been prepared in two steps from P4Sio, ferrocene and hydroxymethylbenzotriazole (and its salt was used for the preparation of some nickel and rhodium complexes).182 Zwitter-ionic ferrocenylditiophosphonates,... 

Due to the potential problems associated with f3-H elimination, the first examples that were reported involved the intramolecular formation of G-O bonds between tertiary alcohols and aryl bromides using Pd(OAc)2 with 2,2 -bis(di-/>-tolylphosphino)-l,l -binapthyl (tol-BINAP) or bis(diphenylphosphino)ferrocene (dppf) as the ligands (Equation (12)).91 Although the coupling with primary and secondary alcohols was troublesome with this system, the more recent introduction of ligands 23-28 (Figure 3) has ameliorated many of these difficulties (Equation (13)).92... 

While Josiphos 41 also possessed an element of atom-centered chirality in the side chain, Reetz reported a new class of ferrocene-derived diphosphines which had planar chirality only ligands 42 and 43, which have C2- and C -symmetry, respectively.87 Rhodium(i)-complexes of ligands (—)-42 and (—)-43 were used in situ as catalysts (0.75 mol%) for the hydroboration of styrene with catecholborane 1 for 12 h in toluene at — 50 °C. The rhodium/ i-symmetric (—)-43 catalyst system was the more enantioselective of the two - ( -l-phenylethanol was afforded with 52% and 77% ee with diphosphines (—)-42 and (—)-43, respectively. In both cases, the regioselectivity was excellent (>99 1). With the same reaction time but using DME as solvent at lower temperature (—60 °C), the rhodium complex of 43 afforded the alcohol product with an optimum 84% ee. 

Eleven aromatic and aliphatic aldehydes have been alkylated with Et2Zn in the presence of homoannularyl bridged hydroxyamino ferrocene (—>123. The resulting carbinols have ee values varying from 66% to 97%. This new ferro-cenyl catalyst has been used successfully to alkylate aromatic and linear or branched chain aliphatic aldehydes to secondary alcohols with up to 97% ee. This ligand is effective even for -branched aliphatic substrate. 

Fig. 7. Horse-liver alcohol dehydrogenase (HLADH) catalyzed alcohol oxidation at a graphite felt anode modified by poly(acrylic acid) (PAA) under coimmobilization of ferrocene derivatives (Fc), diaphorase (Dp), and HLADH [39]...

Fig. 12. Electroenzymatic oxidation of p-cresol under catalysis by PCMH in. long-time batch electrolysis under formation of p-hydroxy benzylalcohol (alcohol) and p-b. .roxy benzaldehyde (aldehyde) (PCMH 16 U = 5.6 nmol PEG-20000 ferrocene 3 0.51 mmr - 9.45 pmol ferrocene starting concentration of p-cresol 41.25 mM = 0.66 mmol additions o. substrate after 4140 min (0,0925 mmol), 5590 min (0.0784 mmol), 6630 min (0.184 mmol), 11253 min (0.371 mmol), in 10 ml tris/HCl-buffer of pH 7.6 divided cell Sigraflex-anode 26 cm2)...

The enzyme p-ethylphenol methylene hydroxylase (EPMH), which is very similar to PCMH, can also be obtained from a special Pseudomonas putida strain. This enzyme catalyzes the oxidation of p-alkylphenols with alkyl chains from C2 to C8 to the optically active p-hydroxybenzylic alcohols. We used this enzyme in the same way as PCMH for continuous electroenzymatie oxidation of p-ethylphenol in the electrochemical enzyme membrane reactor with PEG-ferrocene 3 (MW 20 000) as high molecular weight water soluble mediator. During a five day experiment using a 16 mM concentration of p-ethylphenol, we obtained a turnover of the starting material of more than 90% to yield the (f )-l-(4 -hydroxyphenyl)ethanol with 93% optical purity and 99% enantiomeric excess (glc at a j -CD-phase) (Figure 14). The (S)-enantiomer was obtained by electroenzymatie oxidation using PCMH as production enzyme. 

Constantinos G. Tsiafoulis et al. report the electrochemical behaviour of a composite film based on ferrocene intercalated V205.nH20 xerogel (FeCp2-VXG) with photocrosslinkable polyvinyl alcohol with styrylpyridinium residues (PVA-SbQ), in order to be used as an electrocatalyst and host protein platform to develop an amperometric biosensor. 

Alcohols have been converted into aldehydes mediated by a lipophilic / -cyclodextrin bearing a ferrocene moiety [139]. Efficient indirect in situ electroregeneration of NAD+ and NADP+ for enzymatic oxidations of butanol and 2-hexen-l-ol leading to the corresponding aldehydes using Fe bipyridine and phenanthroline complexes as redox... 

Sihcon chemistry also provides a means for preparing dendrimers capped with metal ions [3,65]. For example, ferrocene [78,79], Co +, [80], Ru [81], and [9] have been hnked to the periphery of sihcon-based dendrimers. These materials are prepared by displacing reactive Si-Cl functional groups with any of a variety of nucleophiles, such as amines, alcohols, or Grignard reagents, containing the metal complexes or hgands. 

Starting from the alcohols,/erroceno/ (Fe(C5H5)(C5H4-OH), Fc-OH) and l,T-ferro-cenediol (Fe(C5pl4-OH)2, Fc((3H)2), a series of new ferrocene derivatives has been prepared, in which the oxygen is directly connected with the ferrocene unit. The reactions... 

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