Reaction of 1,1′‐Divinyl Ferrocene with One‐Electron Oxidants: Entry into Functionalised [4]Ferrocenophanes and Observation of an Isotope‐Dependent Chemoselectivity Effect

1,1′‐Divinyl ferrocene ( 2 ) reacts with K₃[Fe(CN)₆] under basic biphasic conditions to give a [4]ferrocenophane ( 4 ) in good yield. Incorporating deuterium labels into the internal positions of the vinyl groups of 2 affects the chemoselectivity of the reaction; thus under identical reaction conditions, [D₂]‐ 2 reacts to provide a diol‐functionalised [4]ferrocenophane, [D₂]‐D /L ‐ 6 in addition to the expected keto‐alcohol, [D₁]‐ 4 . Variants on this one‐electron oxidative cyclisation methodology can be used to give other [4]ferrocenophanes; thus, the reaction of 2 with CuCl₂ in MeOH or iPrOH leads to dialkoxy [4]ferrocenophanes 19 and 20 , respectively, whereas the reaction of 2 with benzyl carbamate in the presence of tBuOCl gives a bis(carbamate)[4]ferrocenophane, 21 . Mechanisms to account for the formation of the products, the stereoselectivity, and the unusual isotope‐dependent chemoselectivity in the reaction of 2 and [D₂]‐ 2 with K₃[Fe(CN)₆] are proposed.     

Synthesis and some transformations of methyl [4-(oxoacetyl)phenyl]carbamate

The oxidation of methyl (4-acetylphenyl)carbamate with selenium dioxide in dioxane–water (30: 1) gave methyl [4-(oxoacetyl)phenyl]carbamate whose condensation with ethyl acetoacetate or diethyl malonate and hydrazine hydrate afforded ethyl 3-methyl-6-[4-(methoxycarbonylamino)phenyl]pyridazine-4-carboxylate and methyl {4-[5-(hydrazinecarbonyl)-6-oxo-1,6-dihydropyridazin-3-yl]phenyl}carbamate, respectively. The reaction of methyl [4-(oxoacetyl)phenyl]carbamate with o-phenylenediamine in dimethylformamide–ethanol on heating led to the formation of methyl [4-(quinoxalin-2-yl)phenyl]carbamate. Methyl {4-(5,7-dioxo- 4,4a,5,6,7,8-hexahydropyrimido[4,5-c]pyridazin-3-yl)phenyl}carbamate and methyl {4-(5-oxo-7-sulfanylidene- 4,4a,5,6,7,8-hexahydropyrimido[4,5-c]pyridazin-3-yl)phenyl}carbamate were synthesized by reactions of methyl [4-(oxoacetyl)phenyl]carbamate with barbituric and thiobarbituric acids, respectively, and hydrazine hydrate in the presence of zirconyl chloride octahydrate at room temperature.     

Synthesis of new functionally substituted hetarylcarbamates from methyl {4-[(2<Emphasis Type="Italic">E</Emphasis>)-3-(4-methoxyphenyl)-prop-2-enoyl]phenyl}carbamate

Three-component condensation of methyl {4-[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]phenyl}- carbamate with ninhydrin and L-proline in methanol–water (10: 1) afforded methyl {4-[1,3-dioxo-1′- (4-methoxyphenyl)-1,1′,2′,3,5′,6′,7′,7a′-octahydrospiro[indene-2,3′-pyrrolizin]-2′-ylcarbonyl]phenyl}carbamate. Heating of methyl {4-[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]phenyl}carbamate with isatin and benzylamine in methanol gave methyl {4-[4′-(4-methoxyphenyl)-2-oxo-5′-phenyl-1,2-dihydrospiro[indole-3,2′-pyrrolidin]-3′-ylcarbonyl]phenyl}carbamate. The condensation of methyl {4-[(2E)-3-(4-methoxyphenyl)prop-2- enoyl]phenyl}carbamate with sarcosine and 11H-indeno[1,2-b]quinoxalin-11-one generated in situ from ninhydrin and o-phenylenediamine in boiling ethanol led to the formation of methyl {4-[4′-(4-methoxyphenyl)-1′-methyl-11,11a-dihydro-5aH-spiro[benzo[b]phenazine-6,2′-pyrrolidin]-3′-ylcarbonyl]phenyl}carbamate.     

Photoreactivity and photopolymerization of silicon-bridged [1]ferrocenophanes in the presence of terpyridine initiators: unprecedented cleavage of both iron-cyclopentadienyl bonds in the presence of chlorosilanes

The photopolymerisation of sila[1]ferrocenophane [Fe(eta-C5H4)2SiMe2] (3) with 4,4',4'-tri-tert-butyl-2,2':6',2'-terpyridine (tBu3terpy) as initiator has been explored. High-molecular-weight polyferrocenylsilane (PFS) [{Fe(eta-C5H4)2SiMe2}n] (5) was formed in high yield when a stoichiometric amount of tBu3terpy was used at 5 degrees C. Photopolymerisation of ferrocenophane 3 at higher temperatures gave PFS 5 in lower yield and with a reduced molecular weight as a result of a slower propagation rate. Remarkably, when Me3SiCl was added as a capping agent before photopolymerisation, subsequent photolysis of the reaction mixture resulted in the unprecedented cleavage of both iron-Cp bonds in ferrocenophane 3: iron(II) complex [Fe(tBu3terpy)2Cl2] (7Cl) was formed and the silane fragment (C5H4SiMe3)2SiMe2 (8) was released. The iron-Cp bond cleavage reaction also proceeded in ambient light, although longer reaction times were required. In addition, the unexpected cleavage chemistry in the presence of Me3SiCl was found to be applicable to other photoactive ferrocenes such as benzoylferrocene. For benzoylferrocene and ferrocenophane 3, the presence of metal-to-ligand charge transfer (MLCT) character in their low-energy transitions in the visible region probably facilitates photolytic iron-Cp bond cleavage, but this reactivity is suppressed when the strength of the iron-Cp bond is increased by the presence of electron-donating substituents on the cyclopentadienyl rings.     

Synthesis of 2,5-diaryl-1,3-oxazoles containing a carbamate group

Acetophenones containing a methoxycarbonylamino group in position 2, 3, or 4 of the aromatic ring reacted with phenylglycine in the presence of 2 equiv of iodine and 0.5 equiv of sulfanilic acid in DMSO at 100°C for 6 h to give methyl [2(3,4)-(2-phenyl-1,3-oxazol-5-yl)phenyl]carbamates. The reaction was presumed to involve intermediate formation of methyl [(iodoacetyl)phenyl]carbamate. This was confirmed by the isolation of methyl [2-(iodoacetyl)phenyl]carbamate in the reaction of methyl (2-acetylphenyl)carbamate with iodine in glacial acetic acid and its subsequent transformation to methyl [2-(2-phenyl-1,3-oxazol-5-yl)-phenyl]carbamate.     

基于1,5,9-三硒杂[9]二茂铁环蕃的一维链状汞(Ⅱ)配位聚合物的合成与晶体结构(英文)

Amercury(Ⅱ)coordinationpolymerwith1,5,9-triselena[9]ferrocenophane(L),[HgI2L·0.5C4H4O·0.5CH3OH]n, has been synthesized and characterized. The X-ray crystal structure shows that bridging by the ligand L causes compound to form one-dimensional chain. The half-wave potential of 1,1′-ferrocenylene group is more negative than that of the "free" ligand, which reveals no through-space interaction Hg…Fe in the coordination polymers.     

Synthesis of

A series of 1,1'-dicinnamoylferrocenes were converted to the corresponding [3]ferrocenophane diols (4a-e) in a stereoselective manner by using samarium diiodide to effect the intramolecular coupling reaction, aldol reaction, and reduction in one-pot operation. The major reaction pathway might be derived from a samarium chelated transition state (I(A)()) having the moieties of s-cis enone and (Z)-enolate. A solid-state structure of such [3]ferrocenophane diol product showed that the cyclopentadienyl groups were in an eclipsed orientation and slightly tilted.     

Syntheses and structural characterization of some mono- and di-p-nitrophenyl[3]ferrocenophanes: X-ray structure of [3]ferrocenophane, 3-p-nitrophenyl[3]ferrocenophane, and 3,4′-bis-(p-nitrophenyl)[3]ferrocenophane; DFT calculations on ferrocene derivatives

[3]Ferrocenophane (3a) reacts in a Gomberg reaction with diazotized p-nitroaniline to give a mixture of mono- and di-substituted products. The isomeric pairs of 3- and 2-(p-nitrophenyl)[3]ferrocenophanes (4 and 5), as well as 3,4′- and 3,4-bis-(p-nitrophenyl)[3]ferrocenophanes (6 and 7) were separated from the mixture by column chromatography on Al₂O₃ and characterized by means of mass, IR, UV, ¹H-NMR spectroscopy, and by X-ray analysis (4 and 6). PM3/tm and density functional theoretical calculations on ferrocene (1) and ferrocenophane derivatives are reported. A refined X-ray structure determination of [3]ferrocenophane (3a) is given.     

Synthesis of [3]ferrocenophane-bridged Cp-amido zirconium complexes and ansa-zirconocene complexes and their use in catalytic polymerisation reactions

Starting from 1,1'-diacetylferrocene the ortho-amino,α-dimethylamino[3]ferrocenophane system 3 was prepared. This was converted to the o-imino,α-Cp-derivative 6. Subsequent treatment with e.g. an excess of methyllithium followed by ZrCl(2)(NMe(2))(2)(thf)(2) and Me(2)SiCl(2) eventually gave the [3]ferrocenophane based Cp-amido zirconium complex 11b. In a similar way the [3]ferrocenophane derived fluorenyl-Cp ansa-zirconocene dichloride complex 20 was obtained. The 20-methylalumoxane (MAO) system is an active homogeneous Ziegler-Natta catalyst for ethylene polymerization. The 11b-MAO system reacts efficiently with an ethene-1-octene mixture to yield a mixture of linear polyethylene plus the ethene-1-octene copolymer. The compounds 5, 8, 10b, 11b, 13, 14, and 20 were characterized by X-ray diffraction.     

N/S- und As/S-verbrückte [3]- und [5]-Ferrocenophane

Zusammenfassung Es wurden neue heterocyclische Ferrocenophane isoliert. 1,1-Dilithioferrocen reagiert mit den elektronenreichen Heterocyclen S₄N₄ und As₄S₄ zu 1,3-Dithia-2-aza[3]ferrocenophan (1) bzw. 1,5-Diarsa-2,3,4-trithia[5]ferrocenophan (2). Beide Verbindungen wurden mittels¹H- und¹³C-NMR-Spektroskopie, EI-Massenspektroskopie und CV-Messungen charakterisiert. Die Hauptprodukte aller Reaktionen sind Oligomere und Polymere.

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N/S- and As/S-bridged [3]- and [5]-ferrocenophanes

Summary New heterocyclic ferrocenophanes have been isolated. 1,1-Dilithioferrocene reacts with the electron rich heterocycles S₄N₄ and As₄S₄ to give 1, 3-dithia-2-aza[3]ferrocenophane (1) and 1,5-diarsa-2,3,4-trithia[5]ferrocenophane (2), respectively. Both compounds were characterized by¹H and¹³C NMR spectroscopy as well as by EI mass spectrometry and CV measurements. The main products of all reactions were oligomers and polymers.

     

3.3]Ferrocenophanes with guanidine bridging units as multisignalling receptor molecules for selective recognition of anions, cations, and amino acids

The synthesis, electrochemical, and optical properties of a new [3.3]ferrocenophane framework in which two ferrocene subunits, with similar electronic environments, are linked through two substituted guanidine moieties, are reported. The receptors 4-7 have been prepared in good yields by the reaction of bis(carbodiimide) 3 with primary amines. This architecture is exceptionally "tunable" because a variety of "legs" may be appended to the basic [3.3]ferrocenophane scaffold to give a wide range of signaling units. These receptors show remarkable ion-sensing properties, due to the presence of a redox active unit (ferrocene), and an amphoteric binding site (guanidine). In this nitrogen-rich structural motif the guanidine bridges act as multipoint binding sites for anions, cations, and amino acids. Sensing of anions takes place both by unprecedented redox-ratiometric measurements (F-, Cl-, AcO-, NO3-, HSO4-, H2PO4-, and HP2O7(3-)), and colorimetric change (F-, AcO-, H2PO4-, and HP2O7(3-)). Sensing and discrimination of amino acids takes place by redox-ratiometric measurements, whereas the recognition of metal cations (Zn2+, Ni2+, and Cd2+) is achieved either by electrochemical or fluorescence measurements. Moreover, the reported receptors display splitting of the oxidation wave of the Fe(II)/Fe(III) redox couple, and form the mixed-valence species 4+* -7+* by electrochemical partial oxidation which, interestingly, show intervalence charge-transfer transitions associated to the appearance of absorption bands in the near infrared spectral region.     

Photoinduced Fe-Cp bond cleavage and insertion reactions of strained silicon- and sulphur-bridged [1]ferrocenophanes in the presence of transition-metal carbonyls

The photochemical reactions of the moderately strained sila[1]ferrocenophane [Fe(eta-C(5)H(4))(2)SiPh(2)] (1) and the highly strained thia[1]ferrocenophane [Fe(eta-C(5)H(4))(2)S] (8) with transition-metal carbonyls ([Fe(CO)(5)], [Fe(2)(CO)(9)] and [Co(2)(CO)(8)]) have been studied. The use of metal carbonyls has allowed the products of photochemically induced Fe-cyclopentadienyl (Cp) bond cleavage reactions in the [1]ferrocenophanes to be trapped as stable, characterisable products. During the course of these studies the synthesis of 8 from [Fe(eta-C(5)H(4)Li)(2)TMEDA] (TMEDA=N,N,N',N'-tetramethylethylenediamine) and S(SO(2)Ph)(2) has been significantly improved by a change of reaction solvent and temperature. Photochemical reaction of 1 with excess [Fe(CO)(5)] in THF gave the dinuclear complex [Fe(2)(CO)(2)(mu-CO)(2)(eta-C(5)H(4))(2)SiPh(2)] (9). The analogous photolytic reaction of 8 with [Fe(CO)(5)] in THF gave cyclic dimer [Fe(eta-C(5)H(4))(2)S](2) (10) and [Fe(2)(CO)(2)(mu-CO)(2)(eta-C(5)H(4))(2)S] (11), with the former being the major product. Photolysis of 1 with [Co(2)(CO)(8)] afforded the remarkable tetrametallic dimer [(CO)(2)Co(eta-C(5)H(4))SiPh(2)(eta-C(5)H(4))Fe(CO)(2)](2) (13). The corresponding photochemical reaction of 8 with [Co(2)(CO)(8)] gave a trimetallic insertion product in high conversion, [Co(CO)(4)(CO)(2)Fe(eta-C(5)H(4))S(eta-C(5)H(4))Co(CO)(2)] (14). These reactivity studies show that UV light promotes Fe-Cp bond cleavage reactions of both of the [1]ferrocenophanes 1 and 8. We have found that, whereas the less strained sila[1]ferrocenophane 1 requires photoactivation for Fe-Cp bond insertions to occur, the highly strained thia[1]ferrocenophane 8 undergoes both irradiative and non-irradiative insertions, although the latter occur at a slower rate. Our results suggest that such photoinduced bond cleavage reactions may be general and applicable to other related strained organometallic rings with pi-hydrocarbon ligands.     

Development of a convenient new synthetic route to [3]ferrocenophanones

[3]Ferrocenophanone rac-8 was prepared by several non-Friedel-Crafts pathways starting from a Mannich-type coupling of 1,1'-diacetylferrocene followed by catalytic hydrogenation. Hydride abstraction from the resulting alpha-dimethylamino[3]ferrocenophane rac-14 with B(C6F5)3 followed by hydrolysis gave the ketone rac-8. Several variants of the Sommelet reaction, using ethylglyoxylate, formaldehyde or hexamethylenetetramine (urotropine) as the "oxidizing" reagent gave the alpha-[3]ferrocenophanone 8 in good to excellent yield. Some variants of these reactions were also used for the preparation of the pure enantiomer (R)-8. The electrochemical behaviour of 8 has been investigated and compared with related derivatives.     

Structure and properties of protonated N-alkyl-2-aza[3]ferrocenophanes

Protonation of N-alkyl-2-aza[3]ferrocenophanes by HCl and NH₄PF₆ affords hexafluorophosphate salts having a trialkylammonium group. Structures of the protonated and unprotonated N-(p-methylbezyl)-2-aza[3]ferrocenophanes were determined by X-ray crystallography. Variable temperature ¹³C{¹H} NMR spectra of the N-protonated N-hexyl-2-aza[3]ferrocenophane revealed inversion of the nitrogen of the 2-aza[3]ferrocenophane on the NMR time scale probably via partial deprotonation of the nitrogen atom. Cyclic voltammograms of the N-protonated compounds exhibited reversible redox peaks at higher potentials than those of the corresponding neutral ferrocenophanes.     

Synthesis and properties of a new class of nitrogen-rich multinuclear[m.n] ferrocenophanes

The synthesis of the first tetraaza[3,3]ferrocenophane, from the previously unreported 1,1'-bis(triphenylphosphoranylidenamino)ferrocene and its conversion into a nitrogen-rich [2,2]bis[3,3]ferrocenophane is described. The electronic behaviour of these multinuclear ferrocenophanes indicates a strong electronic coupling between the iron centers.     

Synthesis, computational modelling and liquid crystalline properties of some [3]ferrocenophane-containing Schiff’s bases and β-aminovinylketone: Molecular geometry-phase behaviour relationship

Rotationally fixed [3]ferrocenophane extends the variety of possible molecular geometries in its derivatives in comparison with unbridged ferrocenes. In this respect molecular geometry-liquid crystalline properties relationship studies in [3]ferrocenophane mesogens are of considerable interest. Different positional isomers of mono- and di-substituted [3]ferrocenophanes which are obtained by incorporating one or two promesogenic building blocks into the cyclopentadienyl rings are reported in this article. A series of mono-substituted [3]ferrocenophane-containing Schiff’s bases was synthesized by condensing isomeric p-aminophenyl [3]ferrocenophanes with appropriate aldehydes. Isomers of di-substituted [3]ferrocenophane amines gave rise to a series of azomethines with two promesogenic substituents in the cyclopentadienyl rings. Besides, a β-enaminoketone was prepared from 3-(p-aminophenyl)[3]ferrocenophane. Nematic and smectic mesophases were observed in the synthesized compounds under a polarizing optical microscope. The [3]ferrocenophane-containing β-enaminoketone showed complex mesomorphic behaviour connected with occurrence of the keto-enamine and imino-enol tautomeric equilibrium in this compound. On the base of computational models obtained by semi-empirical quantum chemistry calculations the molecular geometry-phase behaviour relationships were examined. It was demonstrated that mesomorphism of [3]ferocenophane azomethines depends on the spatial orientation of the substituents with respect to the propanediyl bridge in a case of mono-, and as well as to each other in a case of di-substituted derivatives.     

Bridged ferrocenes—VI Synthesis and stereochemistry of [1,1]ferrocenophanes

Synthetic routes to compounds of the [1.1]ferrocenophane class have been devised making use of fulvene and acid chloride precursors and the parent compound has been prepared by direct synthesis. The bridged ferrocenes obtained by these different approaches have been chemically interrelated and their structure and stereochemistry have been investigated through study of their spectral properties. Sodamide promotes intramolecular cyclisation of 1,1′-bis(-cyclopentadienylideneethyl)ferrocene to a [3]ferrocenophane derivative.     

57Fe NMR spectroscopy of ferrocenes bearing pi-acceptor substituents

Ferrocene derivatives bearing pi-acceptor substituents in 1- or 1,1'-positions such as carbonyl group(s) (1, 2), a sulfinyl group (4) or boryl group(s) (5, 6, 9) and related [3]ferrocenophanes (3, 7, 10, 12, 13) and a [4]ferrocenophane (8) were studied by 57Fe NMR spectroscopy. The deshielding effect of the respective pi-acceptor substituent can be partially or fully compensated by distortion of the ferrocene geometry. Both aspects become apparent by comparing delta57Fe data of the [n]ferrocenophanes with those of related non-cyclic derivatives.     

A bis-guanidine-based multisignaling sensor molecule that displays redox-ratiometric behavior or fluorescence enhancement in the presence of anions and cations

[structure: see text]The guanidine bridge in the new structural motif [3,3]ferrocenophane acts as a dual binding site for anions and metal ions. Sensing of anions (Cl(-), F(-), NO(3)(-), HSO(4)(-), and H(2)PO(4)(-)) takes place by redox-ratiometric measurements, whereas metal ion (Zn(2+), Ni(2+), and Cd(2+)) recognition is achieved by fluorescence measurements.     

一些含半夹心结构ⅥB族金属的1,1’-二硫(硒)二茂铁化合物的合成

CpCr(NO)(CO)_2与Fe(C_5H_4S)_2S反应,形成氧化-还原产物CpCr(NO)(SC_5H_4)_2Fe(1)。双杂核二茂铁化合物CpM(NO)(EC_5H_4)_2Fe[M=Mo,E=S(2a),Se(2b);M=W,E=S(4a),Se(4b)]、CpMo(NO)(SC_5H_4)_2Fe(3)、Cp_2Mo(SeC_5H_4)_2Fe(6)和Cp_2W(SC_5H_4)_2Fe(7)可通过Fe(C_5H_4ELi)_2·2THF(E=S,Se)与CpM(NO)I_2(M=Mo,W)、[CpMo(NO)I_2]_2或Cp_2MCl_2(M=Mo,W)反应制得。三核杂原子二茂铁化合物[CpCr(NO)_2]_2(EC_5H_4)_2Fe[E=S(8a),Se(8b)],由Fe(C_5H_4ELi)_2·2THF(E=S,Se)与二倍摩尔量的CpCr(NO)_2I反应制备。通过AgBF_4氧化2a得到二茂铁离子型化合物[CpMo(NO)(SC_5H_4)_2Fe]~ BF_4~-(5)。采用元素分析、红外光谱、~1H和~(13)C NMR谱以及EI-MS表征了所合成的新型化合物。