Oxidation of Tricarbonyl (η1 η2-but-3-en-1-yl)iron(0)and Tricarbonyl (η3-allyl)iron(0) Anion Complexes with Dioxygen

The addition of reactive carbanions to tricarbonyl(η⁴-1,3-diene)iron(0) complexes proceeded at ?78 °C to give putative tricarbonyl(η¹,η²-but-3-en-1-y1)iron(0) anion complexes and at 25 °C to produce postulated tricarbonyl(η³-allyl)iron(O) anion complexes; trapping of reactive intermediates with dioxygen produced γ,δ-unsaturated acids and allylic alcohols, respectively.     

Reaction of Tricarbonyl(η3-allyl)iron(0) Anions with Bromine

The addition of reactive carbanions to tricarbonyl(η⁴-1,3-diene)iron(0) complexes proceeded at 23°C to give putative tricarbonyl(η³-allyl)iron(0) anion complexes. Trapping of the reactive intermediates with bromine produced nucleophilic-substituted tricarbonyl(η⁴-1,3-diene)iron(0) complexes.     

Tricarbonyl(N,N-Disubstituted-Cyclohexadienecarboxamide)iron Complexes: Investigation of the Possible Intramolecular Interaction between the Iron Center and the Amide Substituent

Direct reaction of iron pentacarbonyl with 1-N,N-disubstituted-cyclohexa-2,5-dicnecarboxamide and 1-N,N-disubstituted-cyclohexa-1,3-dienecarboxamide mixture (in which the disubstkuted group is diethyl or diphenyl) gave the isomeric tricarbonyl iron complexes of 2-N,N-disubstituted-1,4-η-cyclohexa-1,3-dienccarboxamide (1), 1-N,N-disubslituted-1,4-η-cyclohexa-1,3-dienecarboxamide (2), and 5-N,N-disubstituted-1,4-η-cyclohexa-1,3-dienecarboxamide (3) and tricarbonyliron complexes of l-N,N-disubstituted-cyclohexenecarboxamide (4). These complexes were separated and characterized by IR, UV-VIS, ¹H NMR, elemental analysis, and mass spectra. Only 1 isomerized to give 2 under acidic conditions; both 1 and 2 undergo hydride abstraction with triphenylmethyl hexafluorophosphatc. Complexes 3, undergo neither isomcrization nor hydride abstraction. According to the spectral data, the possible interaction between carboxamide and iron carbonyl moiety was investigated. The irreversible electrochemical behavior of these complexes were studied.     

Fluxional behavior of methyl-substituted tricarbonyl(tropone)iron complexes and their different reactivity

The compositions of regioisomeric mixtures of tricarbonyliron complexes of 2-methyltropone (1a,b), 3-methyltropone (2a,b) and 2,6-dimethyltropone (3a,b) are studied and compared with the results of ab initio computations. The structures, frontier orbitals, and population analysis are evaluated by means of density functional theory. The thermodynamic and kinetic parameters of regioisomerizations are determined using dynamic ¹H NMR technique. The influence of methyl-substituent(s) on the equilibrium ratio of regioisomers resulting from the haptotropic rearrangement is discussed. Significant differences in the reactivity of C-protonized methyl- and dimethyl-substituted tricarbonyl(tropone)iron complexes 4–6 in nucleophilic additions and corresponding O-trimethylsilylated complexes 7–9 in [3+2] cycloadditions are explained in terms of electronic and steric effects of the methyl group(s). Various hydroazulenone cycloadducts of tricarbonyl(η⁴-2,6-dimethyltropone)iron 3a,b have been prepared by stereoselective [3+2] cycloaddition with Fp-reagents 12–14 and characterized. Formerly proposed mechanism of [3+2] cycloaddition was approved.     

(η3: η1 allylcarbonyl)iron tricarbonyl complexes. I. Transformation of complexes from electrophilic gem-dimethylcyclopropenes into functionalized isoprenic diene-iron tricarbonyl complexes by thermolysis or photolysis

Electrophilic gem-dimethyl cyclopropenes react with diiron enneacarbonyl to give (η³: η¹ allylcarbonyl)iron tricarbonyl complexes. These complexes, bearing in this work electron withdrawing substituents, are shown to be rather labile thermally and photochemically, leading easiyl to isoprenic diene-iron tricarbonyl complexes.     

Transition metal complexes in organic synthesis. Part 68: Iron-mediated total synthesis of mukonine and mukonidine by oxidative cyclization with air as the oxidizing agent

The oxidative cyclization of 5-(2-amino-5-methoxycarbonylphenyl)-substituted tricarbonyl[η⁴-cyclohexa-1,3-diene]iron complexes by air in protic medium provides the corresponding tricarbonyl[η⁴-4a,9a-dihydro-9H-carbazole]iron complexes. This procedure is applied to the total synthesis of the 3-methoxycarbonylcarbazole alkaloids mukonine and mukonidine.     

Iron-mediated preparation of vinylcyclopropanecarboxylates: scope,mechanism, and applications

The addition of stabilized carbon nucleophiles to tricarbonyl(1-methoxycarbonylpentadienyl)iron(1+) cation (1a) proceeds via attack at C2 on the face of the ligand opposite the Fe(CO)(3) group to generate tricarbonyl(pentenediyl)iron complexes 2. Oxidation of complexes 2 affords vinylcyclopropanecarboxylates in good yield. In general, the relative stereochemistry about the cyclopropane ring reflects reductive elimination with retention of configuration. In cases where the C2 substituent is bulky (i.e., 2b) the major cyclopropane product 9b represents ring closure with inversion at C3. A mechanism involving pi-sigma-pi rearrangement of the initially oxidized (pentenediyl)iron species is proposed to account for these results. Experiments which probe the stereochemistry of deuterium labeling in the vinyl group of the vinylcyclopropanecarboxylate products were carried out, and these results are consistent with the proposed mechanism. This methodology for the preparation of vinylcyclopropanecarboxylates was applied to the synthesis of 2-(2'-carboxycyclopropyl)glycines (+)-22 and (-)-23 and the cyclopropane triester (-)-26.     

INDO-Type calculations on the ground state and various ionic states of transition metal tricarbonyls

By means of the ΔSCF and transition operator (TO) methods based on a recently developed INDO extension to the first transition metal series, the first ionization potentials of benzene—chromium tricarbonyl ( I ), cyclopentadienyl manganese tricarbonyl ( II ), the iron—tricarbonyl complexes with trimethylenemethane ( III ), and cyclobutadiene ( IV ) have been calculated and compared with experimental data. It is shown that the electronic structure of I to IV can be rationalized by Hoffmann's fragment approach in both the ground state and the cationic hole states. Within the series I—IV there are remarkable energy differences in the ground state for MOs derived from the 1a₁ and 1e orbitals of the M(CO)₃ fragment. The observation that only one band is associated with the ionization events from MOs predominantly localized at the metal site is traced back to large relaxation effects. In the cationic hole states the split of the M(CO)₃ fragment orbitals 1a₁ and 1e is minute in all four compounds.     

含烯烃配体的过渡金属卡宾配合物的研究VI: 两个新奇的铁内盐配合物的合成和晶体结构

肉桂醛缩(2,4-二甲基苯胺)三羰基铁(1)与苯基锂和对氯苯基锂在低温下反应,所生成的加合物继后Et3OBF4在CH2Cl2中于-60℃烷基化, 分别生成两个组成为C19H22N(CO)3FeC6H5(2)和C19H22N(CO)3FeC6H4Cl(3)的新奇的铁内盐配合物. 2晶体属单斜晶系, 空间群为P21/n, 晶胞参数为: α=10.624(3), b=25.155(6),c=19.375(9)A, β=101.13(3)°, V=5042.2A^3, Z=8, Dc=1.27g/cm^3. 2的结构用直接法解出, 并用矩阵最小二乘法修正后得最后偏离因子R为0.071.     

An Extended Dienylium Terminus to Nucleophilic Addition with Tricarbonyl [3-(1-5-η-4-Isopropoxycyclohexa-2, 4-Dienyl) Ethyl Acetate] Iron Hexafluorophosphate

A study of the regioselectivity in nucleophilic addition to tricarbonyl (dienylium) iron complexes having an acetoxyethyl group (or methoxyethyl group) is reported. Reaction of the acetoxyethyl dienylium complex with the potassium salt of methyl 2-oxocylopentanecarboxylate was found to give a new product and a mechanism is proposed. The regioselectivity to nucleophilic addition was shown to be dependent on the use of an alcohol protecting group as in tricarbonyl (dienylium) iron complexes (5) and (15).     

Cyclodimerization of 1-(Dimethoxyniethyl)-5,6-dimethylidene-7-oxa-bicyclo[2.2.1]hept-2-ene Induced by Nonacarbonyldiiron. Crystal Structure of (1RS, 2SR, 3RS, 4RS, 4aRS, 9aSR)- Tricarbonyl[C, 2,3, C-η-(1,4-epoxy-1,5-bis(dimethoxymethyl)-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene)]iron

The transition-metal-carbonyl-induced cyclodimerization of 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene is strongly affected by substitution at C(1) While 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept–2-ene-l-methanol ( 7 ) refused to undergo [4 + 2]-cyclodimerization in the presence of [Fe₂(CO)⁹] in MeOH, 1-(dimethoxymethyl)-5,6-di-methylidene-7-oxabicyclo[2.2.1]hept-2-ene ( 8 ) led to the formation of a 1.7:1 mixture of ‘trans’ ( 19, 21, 22 ) vs. ‘cis’ ( 20, 23, 24 ) products of cyclodimerization together with tricarbonyl[C, 5,6, C-η-(l-(dimethoxymethyl)-5,6-di-methylidenecyclohexa-1,3-diene)]iron ( 25 ) and tricarbonyl[C,3,4, C-η-(methyl 5-(dimethoxymethyl)-3,4-di-methylidenecyclohexa-1,5-diene-l-carboxylate)]iron ( 26 ). The structures of products 19 and of its exo ( 21 ) and endo ( 22 ) [Fe(CO)₃(1,3-diene)]complexes) and 20 (and of its exo ( 23 ) and endo (24) (Fe(CO)₃(1,3-diene)complexes) were confirmed by X-ray diffraction studies of crystalline (1RS, 2SR, 3RS, 4RS, 4aRS, 9aSR)-tricarbonyl[C, 2,3, C-η-(1,4-epoxy-1,5-bis(dimethoxymethyl])-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene)iron ( 21 ). In the latter, the Fe(CO)₃(1,3-diene) moiety deviates significantly from the usual local C_s symmetry. Complex 21 corresponds to a ‘frozen equilibrium’ of rotamers with η-alkyl, η³-allyl bonding mode due to the acetal unit at the bridgehead centre C(1).     

Complexes du type (η3 : η1-allylcarbonyl)fer tricarbonyle : III. Reactions de decomplexation

Several functionalized (η³ : η¹-allylcarbonyl)iron tricarbonyl complexes obtained from electrophilic gem-dimethylcyclopropenes were oxidized with trimethylamine oxide or iron trichloride in methanol. The products which were obtained in good yields show that these complexes can chemically be regarded as valuable vinylketene precursors, which allows their rapid structure determination.     

Stabilization of highly reactive cyclic polyolefins by coordination to iron carbonyls: cis-cyclononatetraene-iron tricarbonyl

Reaction of cis-bicyclo[6.1.0]nona-2,4,6-triene (C₉H₁₀) (I) with Fe₂(CO)₉, at room temperature, yields a number of complexes (IV)–(IX). One of the e, (IX), is the Fe₂(CO)₆ derivative of the starting polyolefin (I), whereas the others are Fe(CO)₃ or Fe(CO)₄ complexes of isomeric C₉H₁₀ polyolefins.(IV) is (h⁴-l,2,3,4-cis-8,9-dihydroindene)iron tricarbonyl, (V) is tentatively formulated as (h²-or h²-5,6-cis-bicyclo[5.2.0]nona-2,5,8-triene)iron tetracarbonyl, (VI) has been characterized only as C₉H₁₀Fe(CO)₃, and (VII) and (VIII) are the asymmetric and symmetric isomers (h⁴-cis-cyclononatetraene)iron tricarbonyl. Characterization of the complexes has been obtained through PMR, IR, and mass spectra.Peculiar features of this reaction are the promotion of the polyolefin (I) rearrangement by iron carbonyls and the stabilization of highly reactive intermediates through coordination to the metal carbonyl groups. fa]Work presented in part at the 3rd International Symposium on Reactivity and Bonding in Transition Organometallic Compounds, Venice, September 9–10, 1970.     

Reactivity patterns in cationic tricarbonyliron complexes: crystallographic proof of stereoselectivity in long range asymmetric induction in the 1,3/1′,2′ series

The analysis of patterns of regioselectivity in cyclohexadienyl complexes illustrates the versatility and power of the iron‐based methodology in reaction sequences that make multiple use of the metal to establish a series of chiral centres. The conversion of tricarbonyl(η⁴‐cyclohexadienone)iron(0) into the dimethyl malonate adduct 4 , which contains two chiral centres at carbon besides the controlling chirality of the tricarbonyliron complex itself, provides an example of long‐range asymmetric induction. The relative stereochemistry of the 1,3/1′,2′ product has been defined as S,S,R*,R*.     

Iron in the service of chromium: the ortho-benzannulation of trans,trans-dienyl Fischer carbene complexes

Chromium Fischer carbene complexes with trans,trans-dienyl substituents on the carbene carbon will react with diiron nonacarbonyl to give 2-alkoxycyclohexa-2,4-dienone iron tricarbonyl complexes and/or 2-alkoxyphenols in excellent yields. In the presence of silica gel or base, the cyclohexadienone complex will suffer loss of the iron and aromatization to give 2-alkoxyphenols. The formation of 2-alkoxyphenols from dienyl chromium carbene complexes is a known process (ortho-benzannulation) that only occurs with certain cis,trans-dienyl complexes. Control experiments show that trans,trans-dienyl chromium carbene complexes do not undergo conversion to 2-alkoxyphenols in the absence of an iron source. The process most likely occurs either via coordination of the dienyl unit in the chromium carbene complex to an iron tricarbonyl group and then loss of the chromium or via direct trans-metalation of the carbene ligand to give an iron carbene complex and then internal coordination to the dienyl unit such that cis to trans isomerization of the alpha,beta-double bond occurs.     

Haptotropic rearrangement of tricarbonyl(2-acyloxytropone)iron

Respective two isomeric iron tricarbonyl complexes of 2-acetoxy- and 2-benzoyloxytropones were synthesized. These complexes rearranged to equilibrium mixtures of diastereomeric isomers, respectively, by 1,3-haptotropic rearrangement of iron tricarbonyl group but not by acyl migration and successive 1,2-haptotropic rearrangement, the mechanism having been clarified by the reaction of optically active complexes.     

Cyclodextrins as chiral stationary phases in capillary gas chromatography. Part VI: Octakis (2,3,6-tri-O-pentyl)-γ-cyclodextrin

Perpentylated γ-cyclodextrin is a very hydrophobic liquid which exhibits enantioselectivity toward a number of non-polar chiral substrates including the saturated hydrocarbons cis- and trans-pinane, β-chiral olefins, iron(O) tricarbonyl complexes of prochiral olefins and 3,3,8,8-tetramethyl-trans-cyclooctene, a compound with planar chirality.     

13C NMR spectra of iron tricarbonyl complexes of benzolonium ions

Conclusions The¹³C NMR spectroscopy data obtained for the iron tricarbonyl complexes of the benzolonium ions are in agreement with the postulate that the iron tricarbonyl fragment takes an effective part in a delocalization of the positive charge.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 705–707, March, 1973.     

Face Selectivity of the Diels-Alder Reaction of Hexadienone Moieties Grafted onto the Bicyclo[2.2.2]octene Skeleton and Perturbed by a Remote Tricarbonylbutadieneiron Group

Selective oxidations of bis(tricarbonyliron) complexes of methyl (3,7,8-trimethylidenebicyclo[2.2.2]oct-5-en-2-ylidene)methyl ketones 15 – 17 afforded selectively the tricarbonyl {(1RS,4SR,7SR,8RS)-C,7,8,C-η-[methyl (3,7,8-trimethylidenebicyclo[2.2.2]oct-5-en-(2Z)-2-ylidene)methyl ketone]}iron ( 12 ), the corresponding (2E)-derivative 13 and the tricarbonyl{(1RS,2RS,3SR,4SR)-C,2,3,C-η-[methyl (3,7,8-trimethylidenebicyclo[2.2.2]oct-5-en-(2Z)-2-ylidene)methyl ketone]}iron ( 18 ). The stereoselectivity of the Diels-Alder reactions of the uncomplexed (Z)- and (E)-hexadienone 12 and 13 , respectively, was established. The face of the diene syn with respect to the C(5), C(6) etheno bridge was preferred for the cycloadditions of N-phenyltriazolinedione (NPTAD). In contrast, the reactions of dimethyl acetylenedicarboxylate (DMAD) and methyl propynoate showed a slight preference for addtion to the face of the hexadienones anti with respect to the etheno bridges of 12 and 13 . The crystal structure of the adduct 25 resulting from the cycloaddition of NPTAD to 12 is reported.     

Stereo- and enantioselective synthesis of some e,z dienols and ethers.

Functionnalized E,Z dienes (?) 2 have been prepared in a highly stereo- and enantioselective manner using chiral pentadienyl iron tricarbonyl complexes 1.