Ferrocen Dimethylamino-methyl

The structure of [Ir(cod)(dppf)]PF6 shows approximately square-planar geometry at Ir, and the cp rings of the dppf ligand are close to parallel and staggered.592 The systems [Ir(cod)(LL)]C104, where LL = dppf, l-diphenylphosphino-2-(7V,7V-dimethylamino)methyl ferrocene and 1,6-diferrocene-2,5-diazahexane, catalytically trimerize PC=CH to 1,3,5-triphenylbenzene.593 The electrochemistry of [Ir(dppf)2]BPh4 shows two one-electron reductions at —1.560 V and -1.755 V vs. ferrocenium/ ferrocene.753... 

Apart from these compounds with l,l/-bis(diphenylphosphino)ferrocene, other organogold(I) complexes containing lj -ferrocenediyl (Fc/) or 2,2/-bis(dimethylamino-methyl)ferrocenediyl (FcN/), such as bidentate aryl ligands, have been reported.106 They are also obtained via the organolithium, which is treated in this case with [AuCl(PPh3)] in a 1 2 molar ratio [see Eq. (40)]. 

More contrasting behavior is displayed by the somewhat related molybdenum complex of l-[(dimethylamino)methyl]-2-(diphenylphosphino)ferrocene, (FcCNP)-Mo(CO)4, in which the octahedral geometry around the molybdenum atom is achievd by coordination of one P atom and one N atom of the adjacent substituents attached to a single cyclopentadienyl ring (see the sketch in Fig. 7-10). In CH2CI2, the irreversible oxidation of the molybdenum fragment precedes the reversible oxidation of the ferrocene moiety [40],... 

Like the case of the molybdenum analog, in the l-[(dimethylamino)methyl-2-(diphenylphosphino)ferrocene complex (FcCNP)W(CO)4 the one-electron oxidation of the tungsten fragment ( ° = 4- 0.78 V) precedes that of the ferrocenyl fragment ( ° = 4-0.92 V). Both steps are reversible in dichloromethane solution and occur at potential values similar to that of the corresponding molybdenum complex [40],... 

Treatment of mono-lithiated l-((dimethylamino)methyl)ferrocene with tpy resulted in the formation of 6-ferrocenyltpy in unspecified yield.41... 

Plenio and co-workers synthesized and polymerized of l-iodo-2-methoxymethyl-3-ethynylferrocene and l-iodo-2-(A,lV-dimethylamino methyl)-3-ethynylferrocene to give 1,3-linked ferrocene-acetylene polymers.176,177 These polymers were synthesized by Sonogahira coupling reactions. These polymers showed optical activity176 or possessed functionalized side chains.177,178 Scheme 2.28 shows the reaction of diiodoferrocenes with diethynyl monomers.178,179 The palladium-catalyzed reactions led to polymers 93a,b, which when doped with iodine displayed semiconducting properties. The iodine-oxidized polymer 93a displayed an electrical conductivity of 1.3 X 10 4S/cm. 

Soon after, Cui, Wu, and co-workers reported a highly efficient oxidative Heck reaction for the synthesis of planar chiral ferrocene derivatives (Scheme 5.10). By employing a similar catalytic system, all kinds of 2-alkenylated ferrocene derivatives were easily accessed via Pd/MPAA catalyzed asymmetric C—H bond functionalization. It was suggested that the Pd° species was oxidized to Pd at the end of the catalytic cycle by Ai,Ai-dime-thylaminomethylferrocenium which is generated from Ai,Ai-dimethylamino-methyl-ferrocene oxidized by air. 

The polycondensation of acetylene-substituted metallocenes has yielded polymers containing backbone aUcyne bridges. The synthesis of l-iodo-2-methoxy-methyl-3-ethynylferreocene and l-iodo-2-(N,N-dimethylamino methyl)-3-ethynyl-ferreocene was reported by Plenio and coworkers. Polymerization of these ferrocene-based complexes gave rise to soluble bimodal 1,3-linked ferrocene-acetylene polymers. Polymers exhibiting optical activity or functionalized sidechains were produced via Sonogashira coupling reactions. 

Togni s synthetic route to a planar chiral (trimethylsilyl group on ferrocene) and central chiral (asymmetric carbon in the NHC-Cp alkyl linker) carbene ligand starts from a central chiral aminomethyl ferrocene (see Figure 5.29) [9]. Lithiation and subsequent reaction with trimethylsilyl chloride introduces planar chirality on ferrocene. Quartemisation of the dimethylamino group with methyl iodide enables reaction with imidazole to the double Fc substituted imidazolium salt which can then be deprotonated to the free carbene with potassium rerf-butylate. 

If an achiral ferrocene derivative is converted to a chiral one by chiral reagents or catalysts, this may be called an asymmetric synthesis. All asymmetric syntheses of ferrocene derivatives known so far are reductions of ferrocenyl ketones or aldehydes to chiral secondary alcohols. Early attempts to reduce benzoylferrocene by the Clemmensen procedure in (5)-l-methoxy-2-methylbutane as chiral solvent led to complex mixtures of products with low enantiomeric excess [65]. With (25, 3R)-4-dimethylamino-l,2-diphenyl-3-methyl-2-butanol as chiral modifier for the LiAlH4 reducing agent, the desired alcohol was formed with 53% ee (Fig. 4-9 a) [66]. An even better chiral ligand for LiAlH4 is natural quinine, which allows enantioselective reduction of several ferrocenyl ketones with up to 80% ee [67]. Inclusion complexes of ferrocenyl ketones with cyclodextrins can be reduced by NaBH4 with up to 84% enantioselectivity (Fig. 4-9 b) [68 — 70]. 

Taniaphos (Rp) 2- (P)-(dimethylamino)-2-[(diphenylphosphino)phenyl]methyl -l-(di-phenylphosphino)ferrocene... 

Aminomethylated compounds (eqs. (15.13) and (15.16), Scheme 15.1) obtained by the Mannich reaction yield various kinds of 2-metalated compounds. The aminomethylated compounds yield quaternary amine salts by the Menshutkin reaction with an alkyl halide, and a methylol derivative is prepared by adding alkali to the salt. Dihydrocholesterol (cholestanol) reacts with dimethylamino-methylferrocene in the presence of methyl iodide and acetone to afford the ferrocene derivatives as shown in Scheme 15.5 [76,77],... 

Readily available chiral amines related to the Betti base [phenyl(2-hydroxy-l-naphthyl)methanamine] catalyse enantioselective addition of diethylzinc to aldehydes in moderate to excellent ee Observed enantioselectivities in addition of diethylzinc to aldehydes catalysed by a series of (5)-proline-derived pyrrolidines have been explained in terms of steric effects. New 2,5-diazabicyclo[2.2.1]heptanes have been applied to enantioselective addition of diethylzinc to benzaldehyde. (S)-2-(3-Methyl-2-pyridyl)-3,5-di-r-butylphenol (76) has been used as an enantioselective catalyst of diethylzinc addition to benzaldehydes. Reaction in toluene shows a significant variation in % ee with temperature, including observation of an inversion temperature with maximum ee. This value varies with the nature of the para-substituent in the aldehyde, and the overall behaviour may be due to a shift in the rate-determining step of the reaction. Other reports of zinc reagents include enantioselective addition of diethylzinc to aldehydes addition of diphenylzinc to aldehydes using a chiral ferrocene-based hydroxyoxazoline catalyst in up to 96% ee and 3-exo-morpholinoisoborneol has been proposed as a more convenient and efficient enantioselective catalyst of alkylzincs than Noyori s original 3-exo-dimethylamino catalyst. ... 

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