Aerobic Fujiwara-Moritani alkenylation and dienylation of ferrocene

Pd(OAc)₂-catalyzed aerobic alkenylation and dienylation of ferrocene with electron-poor olefins and dienes (ethyl acrylate, methyl (E)-cinnamate, diethyl fumarate and maleate, ethyl sorbate and sorbic acid) is reported. In the case of acrylate and cinnamate the reaction leads to mixtures of mono- and dialkenylated ferrocenes. In other cases the products of mono alkenylation and dienylation are formed in low yield. The relatively slow (∼1 week) reaction takes place in AcOH solutions at room temperature.     

N-acylbenzotriazole mediated microwave assisted synthesis of protected and novel unprotected ferrocenoylamidoamino acids

In this study, crystalline and chirally stable carboxyl-protected and novel unprotected N-ferrocenoyl amino acid derivatives of Ser, Cys, Ala, Phe, Trp, Asp and Asn have been prepared. These amino acids undergo substitution reaction with 1-(ferrocenylcarbonyl)-1H-benzotriazole, 1, in partially aqueous media under microwave irradiation.     

Ferrocenylpyrazole—A versatile building block for hydrogen-bonded organometallic supramolecular assemblies

The crystal architectures of 5-ferrocenylpyrazole (1) and its metal complexes were investigated. Compound 1 can form non-solvated and chloroform-solvated crystals. In both cases, 1 forms a zigzag one-dimensional architecture via NH?N hydrogen bonds. The hydrogen bond exhibits a twofold disorder, which was shown to be static by solid-state ¹³C NMR. In the solvated crystal, the chloroform is released at 415 K, associated with melting of the crystal. The reaction of 1 with metal salts provided metal-centered ferrocenyl clusters [Zn(NO₃)₂(1)₄] (4), [Co(NO₃)₂(1)₄] (5), [CoCl₂(1)₄] (6), [Zn(NCS)₂(1)₂] (7), cis-[Pt(NH₃)₂(1)₂](PF₆)₂ (8), and trans-[Pt(NH₃)₂(1)₄](PF₆)₂ (9). In all of these complexes, 1 acts as a monodentate ligand. In 4, 5, and 7, the multinuclear units are joined via hydrogen bonds to form supramolecular chains. Two polymorphs were found for the crystals of 4. Both are composed of the same hydrogen-bonded chains, but their arrangements are different. 5-Ferrocenyl-1-tritylpyrazole (2) and 4-ferrocenyl-1-methylpyrazole (3) were also crystallographically characterized.     

Synthesis, IR-, NMR-, DFT and X-ray study of ferrocenyl heterocycles from thiosemicarbazones. Part 21: Study on ferrocenes

Cyclization reactions of the thiosemicarbazones of formyl- and acetylferrocene and their S-methyl derivatives with DMAD afforded novel ferrocenyl-hydrazono-substituted thiazolones, one-one dimethylthiazole-4,5-dicarboxylate and 1,3-thiazin-4-one, N-ferrocenylimino-pyrimidones/imidazolones, one intermediate β-adduct and via oxidative cyclization, a ferrocenyl-1,2,4-triazole. Ring isomerization of 1,3-thiazin-4-ones to a 1,3-thiazolones was detected. The structure of the new compounds was established by IR and NMR spectroscopy, including HMQC, HMBC and DEPT measurements and supported with GIAO NMR calculations and controlled also synthetically by phase-transfer methylation. For three compounds the stereostructure was also proved by X-ray diffraction.     

Intermolecular Interactions in Mixed Self‐Assembled Monolayers of Ferrocene

Electrochemical characterization of mixed self‐assembled monolayers (SAMs) of 6‐ferrocenyl‐1‐hexanethiol (FcH) and mercaptoundecanoic acid tyrosinamide (MUATyr) on gold is reported. Single‐component SAMs of FcH presented repulsive intermolecular interactions (vGθ_T=?1.12), while mixed SAMs of FcH/MUATyr (1 : 1) exhibited attractive interactions (vGθ_T=+0.20), with a homogeneous distribution of both components. Electrochemical kinetic determinations on mixed SAMs of FcH/MUATyr, indicated a secondary electron transfer pathway between the redox centers of both components. Higher amounts of FcH in the mixed SAMs lowered the observed rate of electron transfer of MUATyr. The oxidation of FcH caused an anodic shift of 160 mV in the voltammetric wave of MUATyr.     

Bucky ferrocene and ruthenocene: serendipity and discoveries

An idea of making a ferrocene/fullerene hybrid, “bucky ferrocene”, has intrigued chemists for some time, but the compounds remained to be hypothetical. The synthesis of such hybrid molecules as Fe(C₆₀Me₅)Cp, Ru(C₆₀Me₅)Cp and Fe(C₇₀Me₃)Cp as well as their functionalized derivatives from [60] and [70]fullerenes has been achieved in recent years. With their esthetically pleasing structures and the dual character of metallocene and graphite, these molecules may stimulate the interest of both chemists and non-chemists.     

Synthesis of ferrocenoyl amino acid derivatives via homogeneous catalytic aminocarbonylation

Palladium-catalysed aminocarbonylation of iodoferrocene with amino acid esters as nucleophiles results in the selective formation of N-ferrocenoyl amino acid esters in the presence of Et₃N as the base. At the same time, the use of DBU leads to the formation of new N-ferrocenylglyoxyl amino acid derivatives with reasonable selectivity. In the latter reactions two new side products, formed via acylation of DBU, were also isolated and characterised.     

Preparation and chiral recognition of a novel chiral stationary phase for HPLC,based on mono(6A-N-1-(2-hydroxyl)-phenylethylimino-6A-deoxy)-β-cyclodextrin and covalently bonded silica gel

A novel chiral stationary phase (CSP) was prepared by immobilizing mono(6A-N-1-(2-hydroxyl)-phenylethylimino-6A-deoxy)-β-cyclodextrin onto the surface of silica gel via a longer spacer.This chiral stationary phase exhibited good enantios electivity for a variety of chiral compounds under reversed-phase conditions.     

Synthesis and Electrochemical Studies of Ruthenium(II) Dicarbonyl Bis(ferrocenyl-β-diketonates)

The reaction of [Ru₃(CO)₁₂] ( 1 ) with six equiv. of FcC(O)CH₂C(O)R ( 2a , R = Me; 2b , R = Fc; Fc = Fe(η⁵-C₅H₄)(η⁵-C₅H₅)) produced the Ru^II compounds [Ru(CO)₂(FcC(O)CHC(O)R)₂] ( 3a , R = Me; 3b , R = Fc) in moderate yields. IR studies and single-crystal X-ray analysis ( 3a ) confirmed that the CO ligands are cis-oriented and that the respective β-diketonates O,O'-chelate-bonded setting-up an octahedral surrounding at Ru^II. Electrochemical (cyclic and square-wave voltammetry) and spectroelectrochemical (UV/Vis-NIR, IR) measurements were additionally carried out. Compounds 3a , b display two ( 3a : E₁^o' = 140; E₂^o' = 255 mV; ΔE^o' = 115 mV for [ 3a ]⁺/[ 3a ]²⁺) or four ( 3b : E₁^o' = 80 mV, E₂^o' 190 mV (ΔE^o' = 110 mV, [ 3b ]⁺/[ 3b ]²⁺), E₃^o' = 355 mV (ΔE^o' = 165 mV, [ 3b ]²⁺/[ 3b ]³⁺), E₄^o' = 490 mV (ΔE^o' = 135 mV, [ 3b ]³⁺/[ 3b ]⁴⁺)) electrochemical reversible one-electron redox processes indicating electrostatic interactions among the ferrocenyl groups as oxidation progresses, which was confirmed by UV/Vis-NIR and in situ IR spectroscopy. One ferrocenyl group on each β-diketonate ligand is by this means 1^st oxidized before the 2^nd ferrocenyl group of the same β-diketonate building block follows.