2-Ferrocenyl-2-[(2-ferrocenylethen-yl)(morpholin-4-yl)meth-yl]-1,3-di-thiol-ane

The mol-ecular structure of 2-ferrocenyl-2-[(2-ferrocenylethen-yl)(morpholin-4-yl)meth-yl]-1,3-di-thiol-ane, [Fe2(C5H5)2(C19H21NOS2)] or C29H31Fe2NOS2, has the ferrocenyl fragments in a trans disposition with respect to the vinyl group. One of the methyl-ene groups is disordered over two sites with occupancies of 0.782 (13):0.218 (13). In the crystal, cyclo-penta-dienyl-C-H⋯O(morpholin-yl) inter-actions feature within helical chains parallel to the c-axis direction. The chains are connected by methyl-ene- and cyclo-penta-dienyl-C-H⋯O(cyclo-penta-dien-yl) inter-actions.

The Amoebicidal Activity of Diferrocenyl Derivatives: A Significant Dependence on the Electronic Environment

Amoebiasis is the second leading cause of death worldwide associated with parasitic disease and is becoming a critical health problem in low-income countries, urging new treatment alternatives. One of the most promising strategies is enhancing the redox imbalance within these susceptible parasites related to their limited antioxidant defense system. Metal-based drugs represent a perfect option due to their extraordinary capacity to stabilize different oxidation states and adopt diverse geometries, allowing their interaction with several molecular targets. This work describes the amoebicidal activity of five 2-(Z-2,3-diferrocenylvinyl)-4X-4,5-dihydrooxazole derivatives (X = H (3a), Me (3b), iPr (3c), Ph (3d), and benzyl (3e)) on Entamoeba histolytica trophozoites and the physicochemical, experimental, and theoretical properties that can be used to describe the antiproliferative activity. The growth inhibition capacity of these organometallic compounds is strongly related to a fine balance between the compounds' redox potential and hydrophilic character. The antiproliferative activity of diferrocenyl derivatives studied herein could be described either with the redox potential, the energy of electronic transitions, logP, or the calculated HOMO-LUMO values. Compound 3d presents the highest antiproliferative activity of the series with an IC50 of 23 µM. However, the results of this work provide a pipeline to improve the amoebicidal activity of these compounds through the directed modification of their electronic environment.

4,6-Diferrocenyl-5-(morpholin-4-yl)-1,2,3-triazine

The structure of the title Fe complex, [Fe(C5H5)2(C17H16N4O)], was determined at 130 K, and has ortho-rhom-bic (Pna21) symmetry. It is of inter-est with respect to the class of triazine heterocyclic compounds: the triazine ring is substituted by two ferrocenyl and one morpholine groups. The crystal structure features C-H⋯O and C-H⋯N non-classical hydrogen bonds.

4,5-Diferrocenyl-1,2-dithiole-3-thione

The structure of 4,5-diferrocenyl-1,2-dithiole-3-thione, [Fe2(C5H5)2(C13H8S3)] or C23H18Fe2S3, at 130 K has monoclinic (P21/c) symmetry. The molecule has two ferrocenyl units attached to a 1,2-dithiole-3-thione moiety. It is of interest with respect to the question if the introduction of ferrocenyl substituents into biologically active molecules offers the potential to obtain more efficacious therapeutic drugs. The crystal structure displays intermolecular contacts of the C—H...S and S—π(C—C) types.

5-Chloro-2-ferrocenylbenzo[d]oxazole

The asymmetric unit of the title compound, [Fe(C5H5)(C12H7ClNO)], consists of one ferrocenyl group bonded to chlorobenzo[d]oxazole. The conformation of the ferrocenyl moiety is slightly away from eclipsed. The bond angles between the 5-chloro-benzoxazole and ferrocenyl fragments are N—C—C = 127.4 (7)° and O—C—C = 116.8 (7)°. The benzo[d]oxazole ring is planar (r.m.s. deviation = 0.0042 Å) and makes an angle of 11.3 (4)° with the cyclopentadienyl ring attached to it. The crystal packing is characterized by intermolecular π–π contacts, resulting in chain formation along the b-axis direction. The centroid-to-centroid distance between the six- and five-membered rings is 3.650 (5) Å. Together with a C—H...π interaction, these intermolecular contacts form laminar arrays along the ac plane.

4,5-Diferrocenyl-1,2-dithiol-3-one

The title compound, [Fe2(C5H5)2(C13H8OS2)], crystallizes with two molecules in the asymmetric unit. Each molecule comprises a pair of ferrocenyl units bridged by a dithiol-3-one moiety. The dihedral angles between the dithiol-3-one ring and the substituted cyclopentadienyl rings are in the range 32.4 (3)–39.3 (3)°. One of the dithiol-3-one rings was refined as being disordered over two sets of sites while the same kind of disorder in the other molecule was negligible. The molecular packing is dominated by C—H...O hydrogen bonds and C—H...π interactions.

2,3-Diruthenocenylcyclopropenone

In the title compound, [Ru2(C5H5)2(C13H8O)], the Ru—C bond lengths in the two ruthenocenyl moieties are in the range of 2.155 (4)–2.196 (3) Å. Both cyclopentadienyl (Cp) rings are planar and parallel with staggered (18.6 °) and eclipsed (3.1°) conformations between the mutual orientations of rings in the independent sandwiches of each ruthenocenyl molecule. In the crystal, there are intermolecular C—H...O hydrogen bonds between Cp carbon donor atoms and the cyclopropenone O atom of adjacent molecules, formingR22(14) andR66(38) motifs along thebandcaxes.

N-alkyl-2-(1,2-diferrocenylvinyl)-4,5-dihydrooxazolinium salts, multi-component synthesis and breaking of their heterocyclic systems

A new multicomponent method for the synthesis of N-alkyl-2-(Z-1,2-diferrocenylvinyl)-4,5-dihydrooxazolinium salts 3a–f, 5-(N-alkyl-2′,3′-diferrocenyl-acryloylamido)-3-aza-3-alkylpentanols 4a–d, (E)-N-alkyl-N-(2-morpholinoethyl)-2,3-diferrocenylacrylamides 9a,b,e,f and (E)-N-alkyl-N-(2-piperidinoethyl)-2,3-diferrocenylacrylamides 10a,c from reactions of 2,3-diferrocenylcyclopropenone 1 with bis-1,4-N,O-nucleophiles in the presence of triethyloxonium tetrafluoroborate, alkyl iodides, morpholine, piperidine and Et3N is described. The characterization of the new compounds was done by IR, 1H- and 13C-NMR spectroscopy, mass-spectrometry, elemental analysis and X-ray diffraction studies.

Polycyclic ferrocenyl(dihydro)thiazepine derivatives: Diastereo-selective synthesis, characterization, electrochemical behavior, theoretical and biological investigation

The reaction of E-2-ferrocenylmethylidenetetralones and E,E-2,6-bis-(ferrocenylmethylidene)-cyclohexanone with 2-aminothiophenol proceed with high diastereoselectivity, forming the ~4.5:1 mixture of trans- and cis-isomers of polycyclic ferrocenylthiazepines, respectively. The reactions of E,E-2,5-bis-(ferrocenylmethylidene)cyclopentanone and E,E-3,5-bis-(ferrocenylmethylidene)-1-methyl-4-piperidone with 2-aminothiophenol take place stereo specifically to form the diastereomeric tricyclic thiazepines of cis- and trans-configuration, respectively. The structures of the obtained compounds were established by IR, ¹H and ¹³C NMR spectroscopy and mass-spectrometry. The structures of the trans-tetralino[1,2a]-, trans-5,7-dimethyltetralino[1,2a]-2-ferrocenyl [1,5]benzo-2,3-dihydrothiazepines and cis-5-ferrocenyl-methylidenecyclopentano[1,2a]-2-ferrocenyl- [1,5]benzo-2,3-dihydrothiazepine were confirmed by X-ray diffraction analysis. An electrochemical study reveals that the diferrocenyl derivatives belong to a Class I compounds of the Robin-Day classification. This behavior is explained by the analysis of frontier orbitals as calculated by density functional theory, showing that only one ferrocenyl unit participates in the generation of HOMO and LUMO orbitals. Compounds 4a and 4c showed similar capacity to inhibit the proliferation of HM1: IMSS trophozoite cultures than the first choice drug for human amoebiasis treatment, metronidazole. Morphological changes induced in the trophozoites after drug exposure suggest a redox in balance as the probable mechanism of the parasite death.

Three-component reaction of tautomeric amidines with 3-ferrocenylmethylidene-2,4-pentanedione. Formation of polymeric coordination complexes of potassium ferrocenyl-(hexahydro)pyrimidoxides

Acetamidine hydrochloride and p-aminobenzamidine dihydrochloride interact with 3-ferrocenylmethylidene-2,4-pentanedione at 80-82 °C in the presence of K2CO3 in the water-alcohol medium in two tautomeric forms (the amidoimine and enediamine ones) with formation of mixtures of pyrimidine and piperidone derivatives and polymeric coordination complexes of potassium ferrocenyl(hexahydro)pyrimidoxides. The structure of the resultant compounds is elucidated on the basis of IR, 1H- and 13C-NMR spectroscopy, mass spectrometry and elemental analysis data. The crystal structures of 6-ferrocenyl-4-hydroxy-4-methyl-2-piperidone, potassium 6-ferrocenyl-4-methyl-2-methylidene(hexahydro)pyrimidin-4-oxide and 2-(4-aminophenyl)-4-ferrocenyl-6-methyl-pyrimidine were determined by X-ray analysis of suitable single crystals.

4-Ferrocenylpyridine- and 4-ferrocenyl-3-ferrocenylmethyl-3,4-dihydropyridine-3,5-dicarbonitriles: multi-component synthesis, structures and electrochemistry

The reactions of 2-cyano-3-ferrocenylacrylonitrile (1) with malononitrile (2) in a MeOH/H₂O or 2-PrOH/H₂O medium in the presence of Na₂CO₃ afforded 6-alkoxy-2-amino-4-ferrocenylpyridine-3,5-dicarbonitriles 3a,b (multi-component condensation) and 6-alkoxy-2-amino-4-ferrocenyl-3-ferrocenylmethyl-3,4-dihydropyridine-3,5-dicarbonitriles 4a,b (multi-component cyclodimerization). Analogous reactions of 1 with 2 in an MeOH/H₂O medium in the presence of NaOH, piperidine, or morpholine gave compounds 3a, 4a and 2-amino-4-ferrocenyl-6-hydroxy-, 6-piperidino- and 6-morpholinopyridine-3,5-dicarbonitriles 3c–e, respectively. The structures of the compounds 3b, 4a and 4b were established by the spectroscopic data and X-ray diffraction analysis. The electrochemical behaviour of compounds 3b, 3d and 4b was investigated by means of cyclic voltammetry.

Intramolecular Conversions of (Aminoferrocenylpenta-1,4-dienyl)-ferrocenylcarbenes: Synthesis of Diferrocenylmono-, bi-, tricycles and Amino(diferrocenyl)hexa-1,3,5-trienes

Synthesis of 3,4-diferrocenyltoluene (7), 1-morpholino- and 1-piperidino-2,3-diferrocenylbicyclo[3.1.0]hex-2-enes 8a, 8b, 1-morpholino- and 1-piperidino-7-ferrocenyl-3,4-ferrocenobicyclo[3.2.1]oct-6-enes 9a, 9b, 2- and 3-amino(diferrocenyl)-hexa-1,3,5-trienes 10a,b, 11a,b by reactions of amino(diferrocenyl)cyclopropenylium tetrafluoro-borates with 1-methylprop-2-enylmagnesium chloride at 80 °C is described. The structures of the compounds obtained were determined by IR, ¹H- and ¹³C-NMR spectroscopy and mass spectrometry. X-ray diffraction data for 1-piperidino-7-ferrocenyl-3,4-ferroceno-bicyclo[3.2.1]oct-6-ene (9b), 2-morpholino- and 2-piperidino-1,3-diferrocenyl-4-methyl-hexa-1,3,5-trienes 10a and 10b is presented. The electrochemical behaviour of compounds 7, 8a, 10a and 10b was investigated by means of cyclic voltammetry and square wave voltammetry. For 7 and 8a two electrochemical processes (I-II), attributed to the oxidation of the ferrocene moieties were found. On the other hand for compounds 10a and 10b a single electron transfer for both ferrocene groups and the electrochemical generation of the monocation and dication species were detected.

Cross-conjugated Z- and E-3-ferrocenylmethyl-idene-4-methyl-2-phenylpenta-1,4-dienes — Synthesis and some chemical properties

Dehydration of (Z)- and (E)-4-ferrocenyl-3-isopropenyl-2-phenylbut-3-en-2-ols and Z-3-ferrocenyl methyl idene-4-methyl-2-phenylpentane-2,4-diol affords (Z)- and (E)-3-ferrocenylethylidene-4-methyl-2-phenylpenta-1,4-dienes with a system of three cross-conjugated double bonds. One of the methylidene groups of the trienes obtained is smoothly protonated under the action of tetrafluoroboric acid etherate to yield (Z)- and (E)-3-ferrocenyl-2-isopropenyl-1-methyl-1-phenylallyl tetrafluoroborates. The cross-conjugated trienes undergo cationic cycloaddition to these allylic cations as well as proton-induced cyclodimerization resulting in 7-ferrocenyl-4-ferrocenylmethylidene-1,3-dimethyl-5-phenyl-8-(1-phenylethylidene)bicyclo[3.3.1]non-2-ene and isomeric 1,5-diferrocenyl-2,6-diisopropenyl-3,7-diphenylocta-1,3,6-trienes.Key words: cross-conjugated trienes, ferrocenylallylic cations, cyclodimerization, cycloaddition, ferrocene.

1,3-bis(diarylmethylidene)-2-methylidenecyclohexanes in cycloaddition and cyclodimerization reactions. The role of stereoelectronic factors

Cycloaddition and cyclodimerization reactions of 1,3-dibenzylidene- and 1,3-bis(p-methoxybenzylidene)-2-methylidenecyclohexanes, i.e., the diaryltrienes with fixed S-cis-configurations of exocyclic double bonds are studied. These compounds undergo in situ cyclodimerization of the [4 + 2]-type upon dehydration of the precursor tertiary alcohols and form endo-adducts in the Diels-Alder reaction with N-phenylmaleimide. In the presence of CF3COOH, acid-catalyzed cyclodimerization takes place leading to methylidene-substituted spirocyclodimers, which undergo intramolecular cyclization upon prolonged contact with CF3COOH to form a fused carbocyclic system containing a central, 'three-petal' fragment of six-membered rings.

3,3-Diethyl- and 3,3-dibenzyl-1,2-diferrocenylcyclopropenes

Reactions of 2,3-diferrocenylcyclopropenone 1 with ethyl- and benzylmagnesium chlorides afford 3,3-diethyl-and 3,3-dibenzyl- 1,2-diferrocenylcyclopropenes 2 and 3, respectively, and products of nucleophilic opening of the three-membered ring resulting from the addition of RMgCl to the carbonyl group, viz., saturated ketones(4,5-diferrocenylheptan-3-ones 4a,b and 3,4-diferrocenyl-1,5-diphenylpentan-2-ones 5a,b as ca. 3: 1 mixtures of two diastereomers) and other products. The spatial structures of compounds 2 and 4a were established by X-ray diffraction analysis of single crystals. Protonation of the cyclopropenes 2 and 3 with tetrafluoroboric acid at -40 degrees C yields the corresponding 3,3-dialkyl-1 ,2-diferrocenylcyclopropylium tetrafluoroborates. Transformation of the latter into diferrocenylallylic cations upon increasing the temperature to 20 degrees C and their eprotonation under the action of N,N-dimethylaniline were studied. Electrochemical investigation of 1 and 2 shows that in both complexes the cyclopropene spacer allows electronic communication between the two outer ferrocenyl groups, this being notably greater for 2 than for 1.