Amine ferrocene derivative

The novel aspect disclosed by this study, i.e. the appearance a single wave of constant intensity or of two distinct waves of varying intensity, depending upon the way the acidity has been adjusted (either by buffering or by titrating the solution), cannot be confined to ferrocenylcarboxylic acids, but should be evident every time a redox subunit is coupled to a not too distant protonic site. This is, for instance, the case of the tertiary amine ferrocene derivative FcCH2N(CH3)2-... 

Better yields are obtained when polar solvents are utilized and an amine such as tetramethylethyl-enediamine is present, which also facilitates the formation of the dilithium compound. The lithium derivatives undergo a large number of reactions that can be used to produce the enormous number of ferrocene derivatives. Rather than trying to show a great number of reactions, a few of the common reactants and the substituents that they introduce on the cyclopentadienyl rings are shown in Table 21.3. 

In another report published near the same time, this group demonstrated the electrochemical detection of electroactive enantiomers, d- and L-3,4-dihydroxypheny-lalanine (DOPA) and (R)- and (.S )-A, A /-dimcthylfcrroccnylcthylamine (FcN) in imprinted sol-gel-derived thin films.68 To improve response times, the imprinted films were made to be very thin, — 70 nm, which is about 3 to 10 times thinner than typical sol-gel-derived films. The functional monomer used to imprint DOPA was PTMOS (Fig. 20.2) because it was expected to exhibit tt-tt and hydrophobicity interactions. For the ferrocene derivative, both PTMOS (Fig. 20.2) and carboxyethylsila-netriol sodium salt (CTES) were used for hydrophobicity and tt-tt interactions and electrostatic interactions between the amine and carboxy groups, respectively.68... 

Ferrocene reacts with acetyl chloride and aluminum chloride to afford the acylated product (287) (Scheme 84). The Friedel-Crafts acylation of (284) is about 3.3 x 10 times faster than that of benzene. Use of these conditions it is difficult to avoid the formation of a disubstituted product unless only a stoichiometric amount of AlCft is used. Thus, while the acyl substituent present in (287) is somewhat deactivating, the relative rate of acylation of (287) is still rapid (1.9 x 10 faster than benzene). Formation of the diacylated product may be avoided by use of acetic anhydride and BF3-Et20. Electrophilic substitution of (284) under Vilsmeyer formylation, Maimich aminomethylation, or acetoxymercuration conditions gives (288), (289), and (290/291), respectively, in good yields. Racemic amine (289) (also available in two steps from (287)) is readily resolved, providing the classic entry to enantiomerically pure ferrocene derivatives that possess central chirality and/or planar chirality. Friedel Crafts alkylation of (284) proceeds with the formation of a mixture of mono- and polyalkyl-substituted ferrocenes. The reaction of (284) with other... 

Reaction of (284) with an aldehyde, ketone, or enol ether in the presence of acid results in an electrophilic substitution that produces a -ferrocenylalkyl carbocations that may be trapped by nucleophiles (azides, amines, thiols). This chemistry may be used to prepare enantiomerically pure ferrocene derivatives in a maimer that avoids resolution procedures (Scheme 86)." For example, the enol ether from (-)-menthone affords a kinetic carbocation (302) that may be trapped or allowed to rearrange to the more thermodynamically stable cation (303) and then trapped, thus offering a means of controlling the configuration of the stereocenter adjacent to the ferrocene unit. Use of an enantiomerically pure aldehyde derived from Q -pinene (304) affords a 1 1 carbocationic mixture that similarly isomerizes to a single cation. 

With chiral stationary phases, chromatographic separation of enantiomeric ferrocene derivatives is possible. An apparatus for the resolution of ferrocenyl alcohols and other compounds on triacetylcellulose has been described [60]. Analytical enantiomer separation of ferrocenyl alcohols, ethers, sulfides, and amines for the determination of enantiomeric excesses is best achieved on cyclodextrin bonded phases [61]. 

Kinetic resolution of ferrocene derivatives, mainly alcohols, had an important place during the early stage of stereochemical investigations of ferrocene derivatives. The reaction of (partially) resolved ferrocenylalkyl alcohols and amines with racemic 2-phenylbutyric acid anhydride (Korean s method) was the basis for the configurational assignment before the establishment of structures by X-ray crystallography [41]. There has been some debate on the reliability of the method [62, 63], and additional chirality information seems necessary for certainty. Recently, the kinetic resolution of 1-ferrocenylethanol by transesterification with vinyl acetate, catalyzed by a lipase from PseudomonasJluorescens, led to an enantiomeric excess of 90—96% of both enantiomers [64], opening new preparative aspects. 

The nitrogen atom in a-ferrocenylalkylamines generally shows the same reaction pattern as that in other amines alkylation and acylation do not provide synthetic problems. Due to the high stability of the a-ferrocenylalkyl carbocations, ammonium salts readily lose amine and are, therefore, important synthetic intermediates. Acylation of primary amines with esters of formic acid gives the formamides, which can be dehydrated to isocyanides by the standard POClj/diisopropylamine technique (Fig. 4-16) [92]. Chiral isocyanides are obtained from chiral amines without any racemization during the reaction sequence. The isocyanides undergo normal a-addition at the isocyanide carbon, but could not be deprotonated at the a-carbon by even strong bases. This deviation from the normal reactivity of isocyanides prompted us to study the electrochemistry of these compounds, but no abnormal redox behaviour, compared with that of other ferrocene derivatives, was detected [93]. The isocyanides form chromium pentacarbonyl complexes on treatment with Cr(CO)s(THF) (Fig. 4-16) and electrochemistry demonstrated that there is no electronic interaction between the two metal centres. 

Planar chiral compounds should also be accessible from the chiral pool. An example (with limited stereoselectivity) of such an approach is the formation of a ferrocene derivative from a -pinene-derived cyclopentadiene (see Sect. 4.3.1.3 [81]). A Cj-symmetric binuclear compound (although not strictly from the chiral pool, but obtained by resolution) has also been mentioned [86]. Another possibility should be to use the central chiral tertiary amines derived from menthone or pinene (see Sect. 4.3.1.3 [75, 76]) as starting materials for the lithiation reaction. In these compounds, the methyl group at the chiral carbon of iV,iV-dimethyl-l-ferrocenyl-ethylamine is replaced by bulky terpene moieties, e.g., the menthane system (Fig. 4-2 le). It was expected that the increase in steric bulk would also increase the enantioselectivity over the 96 4 ratio, as indicated by the results with the isopropyl substituent [118]. However, the opposite was observed almost all selectivity was lost, and lithiation also occurred in the position 3 and in the other ring [134]. Obviously, there exists a limit in bulkiness, where blocking of the 2-position prevents the chelate stabilization of the lithium by the lone pair of the nitrogen. 

A chiral auxiliary is a compound that is incorporated into a larger molecule, where it transmits its chirality information to newly formed chiral elements. It is cleaved from the target molecule in a later step of the reaction sequence and should in principle be recycled, to avoid loss of the precious chiral material. Among the ferrocene derivatives, chiral primary amines are typical auxiliaries for their synthesis, see Section 4.3.3. All applications involve the intermediate formation of imines with carbonyl compounds. 

In principle, the synthesis of peptide derivatives by the U-4CR in the presence of the a-ferrocenyl alkyl amines is a perfect way of accomplishing such syntheses. However, in practice the optimal ferrocene derivatives and their reaction conditions have not yet been found, and ongoing attempts seek to find the ideal way of applying such chemical technique. 

Kinetic resolution of ferrocene derivatives, mainly alcohols, had an important place during the early stage of stereochemical investigations of ferrocene derivatives. The reaction of (partially) resolved ferrocenylalkyl alcohols and amines with racemic... 

As we will see, the choice of electron donors associated with porphyrins has not evolved much over the years. In previous review articles, electron donors such as carotenes, aryl amines, and ferrocene derivatives have been examined. Concerning the class of energy donors, over the past decade, boron dipyrylmethanes (BODIPY) are probably the most widely used series of compounds. A very detailed study of their association and their excitation energy transfer to porphyrins has been carried out by LindseyIt should be noted that condensed aromatics such as anthracene, and especially perylene derivatives, may be good substitutes for BODIPYs. 

A series of ferrocene derivatives with amine substituents behave as anion or neutral molecule receptors and can recognize various anions, a property facilitated by their... 

The scope of aminocarbonylations was extended by the works from various groups. For example, Skoda-Fbldes and Kollar studied the carbonylation reactions of ferrocene derivatives in the presence of Pd(OAc)2/PPh3 [126-128]. Ferrocene amides and novel ferrocene a-ketoamides were synthesized in good yields based on palladium-catalyzed aminocarbonylation or double carbonylation of iodofer-rocene at 40-50 bar of CO. The double-carbonylated products were favored at 40-60 °C and amides were produced almost exclusively at 100 °C, as the selectivity of the reaction with less sterically hindered secondary amines is highly dependent on the reaction temperature. Analogous aminocarbonylation reactions of l,l -diiodoferrocene led to I -iodo-ferrocenecarboxamides and I -iodo-ferro-ceneglyoxylic amide-type products. 

Fig. 2.6 a SEM images of (a) 3 x 3 electrode array, (b) array of MWNT bundles on one of the electrode pads, (c) and (d) array of MWNTs at UV-lithography and e-beam patterned Ni spots, respectively, (e) and (f) the surface of polished MWNT array electrodes grown on 2 ira and 200 nm spots, respectively. Panels (a-d) are 45° perspective views and panels (b-f) are top views. The scale bars are 200,50,2,5,2, and 2 im, respectively, (b) (a) The Functionalization Process of the Amine- Terminated Ferrocene Derivative to CNT Ends by Carbodiimide Chemistry and (b) the Schematic Mechanism of Ru(bpy) Mediated Guanine Oxidation [85]... 

Dependent upon the conditions, 1, T-dilithioferrocene or lithioferrocene may be obtained in tetramethylethylenediamine. Lithioferrocene and 1, I -dilithioferrocene are utilized for the preparation of various ferrocene derivatives [schemes (9.142) and (9.143)]. Lithioferrocenes, mercurioferrocenes, and derivatives of ferrocene containing various functional groups such as amines, carboxyls, phosphines, etc. are utilized for the... 

---