Butyl ferrocenyl

Figure 27 Cyclic voltammogram recorded in a CH2CI2 solution of polyf tert-butyl-ferrocenyl) persulfide...

Ci7H2oFe02 Methyl t-butyl-ferrocenyl semidione Nr.83,X = t-butyl O2 oxidation/ DMSO EPR/ 2.00706 3H 0.420 2H 0.050 71Mcdl... 

Fi7H2oFe02 1-Methyl 2-(n-butyl)-ferrocenyl semidione Nr. 84 O2 oxidation from ketone/ DMSO EPR/ 300 2.00706 (1) H(4,7) 0.050 HCCHj) 0.420 69Mcdl... 

A decisive improvement in the stereoselective performance of the Ugi reaction was achieved by the use of 1-ferrocenylalkylamines, in particular, l-ferrocenyl-2-methylpropylamine. as the inducing chiral auxiliary 18, S7. The iminc formed from the (/ )-enantiomer and isobutyralde-hyde reacts at — 78 °C with tm-butyl isocyanidc and benzoic acid to give the (S )-valine derivative with a diastereoselectivity of about 100 1. 

The interesting zwitterionic compound (39) with the cationic component a butadien-2-yl cation was obtained by reaction of l,4-di(t-butyl)butadiyne with 2 mol of di(r-butyl)aluminium hydride, with the structure being established by X-ray analysis.80 The reactions of the l,2-diferrocenyl-3-(methylthio)cyclopropenylium ion with carbanions derived from active methylene compounds were investigated.81 Products were derived by ring opening of the cyclopropene ring after the initial carbanion addition. The bis(ferrocenylethynyl)phenylmethylium cation (Fc-C=C-)2C+Ph (Fc = ferrocenyl) was prepared 82 This cation proved to be much less stable than its bis-ethenyl analogue (Fc-CH=CH-)2C+Ph. 

An addition to the literature on the arylation of protected hydrazines was recently contributed by Skerlj et al. [186]. In addition to the reactions of halopyridines with tert-butyl carbazate (H2NNHBoc) discussed in Section 4.3.2.3, these authors have reported the reaction of electron-deficient aryl bromides with this substrate. Reactions occurred when using DPPF or the ferrocenyl 11 as the ligand along with CS2CO3 as the base at temperatures of 100-110 °C. 

Naturally, it is possible to synthesise a similar ligand system without central chirality and in fact without the unnecessary methylene linker unit. A suitable synthesis starts with planar chiral ferrocenyl aldehyde acetal (see Figure 5.30). Hydrolysis and oxidation of the acetal yields the corresponding carboxylic acid that is transformed into the azide and subsequently turned into the respective primary amine functionalised planar chiral ferrocene. A rather complex reaction sequence involving 5-triazine, bromoacetal-dehyde diethylacetal and boron trifluoride etherate eventually yields the desired doubly ferrocenyl substituted imidazolium salt that can be deprotonated with the usual potassium tert-butylate to the free carbene. The ligand was used to form a variety of palladium(II) carbene complexes with pyridine or a phosphane as coligand. 

BBN = 9-borabicyclo[3.3.1]nonyl cat = Catecholato cod = 1,5-cyclooctadiene coe = Cyclooctene Dur = Duryl = 2,3,5,6-tetramethylphenyl Fc = 1-ferrocenyl fc = l,l -ferrocenediyl Ipc = Isopinocampheyl (derived from (+)-a-pinene) Mes = Mesityl = 2,4,6-trimethylphenyl Np = 2-naphthyl OLED = Organic light-emitting diode Pf = Pentafluorophenyl pin = Pinacolato SCE = Standard calomel electrode thexyl = 2,3-dimethyl-2-butyl TMP = 2,2,6,6-tetramethylpiperidide tripyl = 2,4,6-tri-fro-propyl-phenyl. 

Related Reagents. 2,2 -Bis(diphenylphosphino)-l,l -bina-phthyl 2,3-Bis(diphenylphosphino)butane (R)-N-[2-(NJ -Dimc-thylamino)ethy l]-A -methy 1-1 -[(5)- l, 2-bis(diphenylphosphino)-ferrocenyl]ethylamine (lS,9S)-l,9- Bis[(f-butyl)dimethylsilyl-oxy]methyl -5-cyanosemicorrin (/ )-NA-Dimethyl-l-[(5)-2-(diphenylphosphino)ferrocenyl]ethylamine. 

Interaction of ferrocene and diazonium compounds, which is followed by loss of nitrogen, leads to a large number of derivatives 17, HI, 1, 14s, 30S) most of them, naturally, are aryl-substituted compounds. Ferrocene cannot only be mercuriated, but can also be metalled by lithium butyl or similar compounds such as sodium phenyl. A great variety of pt ibilities for substitution is afforded by the interaction of ferrocenyl lithium and halogen-containing compounds 5, 128, 143, 162). Carboxylic acids, in particular, may easily be obtained by formation of the lithium derivative of ferrocene and treatment with carbon dioxide. 

It was found that the reproducibility and activity of pre-formed cationic [Ir(COD)ferrocenyl diphosphine] complexes were superior to those of the neutral systems. A series of hydrogenations was carried out in a bi-phasic toluene/water system (see below). As anticipated, the activity and selectivity of the catalysts is strongly influenced by the nature of the phosphorous substituents of the ferroce-nyl diphosphine. These effects are summarized in Tab. 5. The final level of 89% enantioselectivity was achieved with the tert- butyl /4-methoxy-3,5 -di meth ylphenyl derivative. 

An alternative synthetic approach to Boc-protected l -aminoferrocene-l-carboxylic acid 40 was recently described by Rapic and co-workers, and is shown in Scheme 12.7. Hydrolysis of carbamate-ester by an equimolar amount of sodium hydroxide in aqueous ethanol gave 90% of tert-butyl l -carboxy-l-ferrocenecarbamate.52 During the synthesis the symmetrical ferrocenyl-substituted urea, dimethyl l, l -ureylenedi(l-ferrocenecarboxylate) 39 was formed as a by-product (Scheme 12.7).53 The ferrocenium molecules were conjugated through a urea linker, which upon deprotection may be used in condensation reactions. 

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