Ligand exchange reactions of ferrocene with phenanthrene or 9,10-dimethylphenanthrene in the presence of aluminum chloride and aluminum

Ligand exchange reactions between phenanthrene or 9,10-dimethylphenanthrene with ferrocene effected in the presence of AlCl₃-Al were carried out under a variety of conditions. With phenanthrene (I), hydrogenation at the C-9 and C-10 positions could take place during the reaction and the cationic products obtained were the η⁶-phenanthrene-η⁵-cyclopentadienyliron and η⁶-9,10-dihydro-phenanthrene-η⁵-cyclopentadienyliron moncations (II and III), and the η⁶-phenanthrene-$\text{trans}$-$\text{bis}$-η⁵-cyclopentadienyliron and η⁶-9,10-dihydrophenanthrene-$\text{trans}$-$\text{bis}$-η⁵-cyclopentadienyliron dications (IV and V). With 9,10-dimethylphenanthrene (VI), reactions carried out in refluxing cyclohexane gave the non-hydrogenated η⁶-9,10-dimethylphenanthrene-η⁵-cyclopentadienyliron monocation (VII) and η⁶-9,10-dimethylphenanthrene-$\text{trans}$-$\text{bis}$-η⁵-cyclopentadienyliron dication (VIII). When higher temperatures were used in an attempt to promote hydrogenation, decomposition predominated and no cationic product could be obtained. These finding are discussed and contrasted with previous results obtained from similar reactions using anthracene or 9,10-dimethylanthracene.     

Polymers as reagents and catalysts. part x. Halogenations of acetophenone and 1,3-diketones with polymer-supported reagents

A crosslinked copolymer of styrene and 4-vinylpyridine (40-43% of monomer units) was reacted with hydrogen iodide to give a polymer containing pyridinium iodide residues. Reaction of this with chlorine in chloroform at 0° gave a polymer containing pyridinium tetrachloroiodate residues. In a similar manner but using methyl iodide in place of hydrogen iodide, crosslinked polymers containing N-methylpyridinium iodide and N-methylpyridinium tetrachloroiodate residues were prepared. The latter contained up to three chlorine molecules per iodine atom. Both reagents reacted with acetophenone, thus forming iodomethyl-phenyl ketone ($\text{4}$) and chloromethyl-phenyl ketone ($\text{5}$), the ratios depending on the reagent used and the reaction time. Chlorinations of 5,5-dimethyl cyclohexane-l,3-dione and indane-1,3-dione with polymer-supported reagent ($\text{2}$) resulted in the formation of geminal dichlorides in high yields.     

Studies on the reactions of (η5cyclopentadienyl)dicarbonylcobalt with phenyl-1-naphthylacetylene and with phenyl-2-naphthylacetylene,and an X-ray crystallographic determination of one of the products: (η5cyclopentadienyl)-[η4-3,3-di-(1-naphthyl)-2,4diphenylcyclobutadiene]cobalt

The reactions of (η⁵-C₅H₅)Co(CO)₂ with both phenyl-1-naphthylacetylene and phenyl-2-naphthylacetylene have been shown to produce all four possible η⁵-cyclobutadiene-cobalt complexes and all six possible η⁴-cyclopentadienone-cobalt derivatives. The structures of the η⁴-cyclobutadiene-cobalt complexes have been assigned on the basis of proton NMR and mass spectral studies, and unequivocally established by means of an X-ray diffraction investigation for one of the isomers as (η⁵-cyclopentadienyl)[η⁴-1,3-di(1-naphthyl)-2,4-diphenylcyclobutadiene]cobalt. This compound is triclinic, a = 10.88(2), b = 15.710(6), c = 8.728(4) Å, α = 95.09(4)°, β = 101.94(2)°, γ = 86.93(3)°. The space group is P$\text{1}$ with Z = 2. The structure was solved by Patterson and Fourier methods and refined by full-matrix least squares methods (4128 reflections above 3σ) to a final R = 0.036. Bond distances and angles are normal but the cyclobutadiene ring is not quite planar. One of the atoms is 0.047 Å out of the plane of the other three apparently to relieve steric stress. The two phenyl rings are almost coplanar with the cyclobutadiene ring (torsion angles 3.9 and 20.4°) while the naphthyl rings are almost perpendicular to it (torsion angles 63.8, 64°).     

Ruthenium(0) Catalyzed Isomerization of Allylbenzene. The Detection and Isolation of A Hydrido-η3-Allyl Intermediate

Allylbenzene is isomerized to $\text{cis}$- and $\text{trans}$-β-methylstyrene at 35–60°C in the presence of [(C₆H₅)₃P]₄Ru(π-CH₃CN)·CH₃CN. Two hydrido-η³-1-phenylallyl ruthenium complexes have been detected by proton nmr spectroscopy during the reaction and the predominant one of formula [(C₆H₅)₃P]₂RuH(η³-C₃H₄C₆H₅)(CH₃CN) has been isolated. The structure of this intermediate contains cis phosphines, mutually trans hydrido and acetonitrile ligands and the 1-phenylallyl ligand in a $\text{syn}$-configuration. A similar structure with an $\text{anti}$-configuration of the 1-phenylallyl ligand is suggested for the other detected intermediate. These complexes indicate that this isomerization is initiated by oxidative-addition of ruthenium(0) to an allylic C-H bond with the formation of distinct η³-allyl metal hydride species as has been proposed in a number of metal catalyzed olefin transformations.     

Complexes chiraux derives du monocyclopentadienyltitane(IV). Diastereotopie et diastereoisomerie des complexes Cp′TiA(ZZ′) presentant un ligand bidente σ

The reaction 1 has been used to obtain monocyclopentadienyltitanium(IV)

(HZZ′H = disymmetric diphenol or dithiol; R^? = Cl^? or SR^? from CCl₄ or RSSR) chiral complexes with three σ bonds. The chirality at the titanium atom is detected either by NMR analysis (diastereotopy of methyl groups when Cp′ = η⁵-C₅H₄CHMe₂) and by characterization of diastereoisomer pairs (Cp′ = η⁵-C₅H₄$\text{C}\text{*}$CHMeC₆H₅).     

X-ray molecular structure of the 1:1 adduct of [FeH(CO)4]− and dimethyl acetylenedicarboxylate. η3-[trans-2,3-bis(methoxycarbonyl)acryloyl]tricarbonylferrate

The crystal structure of a bis(triphenylphosphine)iminium salt of the 1:1 adduct of [FeH(CO)₄]^? and dimethyl acetylenecarboxylate has been determined from three-dimensional X-ray data collected by the counter method. Single crystals belong to the triclinic space space group P$\text{1}$, with two units of [C₃₆H₃₀NP₂]⁺[C₁₀H₇FeO₈]^? in a cell of dimensions: $\text{a}$ = 13.918(2), $\text{b}$ = 15.669(5), $\text{c}$ = 9.909(2) Å, $\text{α}$ = 91.22(3), $\text{β}$ = 94.83(2), and $\text{γ}$ = 77.62(2)°. The structure was refined to a conventional $\text{R}$ of 0.068 for 5373 observed

reflections. The resulting structure indicates that the complex anion is η³-[$\text{trans}$-2,3-bis(methoxycarbonyl)acryloyl]tricarbonylferrate, the coordination around the iron atom being described as a considerably distorted trigonal bipyramid. A comparison of the present structure with the structures of related complexes suggests that the η³-acryloyl portion is best represented as an intermediate of (η³-allyl) with the oxygen atom and (η²-olefin + η¹-acyl). The short Fe-C(acyl) length of 1.897(5) Å implies an enhanced back-donation of electrons from the iron atom to the acyl group.     

Indenyl and fluorenyl transition metal complexes: XIV. Synthesis and reactions of chromium tricarbonyl complexes of 5,10-dihydroindeno[2,1-α]indene

1-4,4a,10b-η⁶-5,10-dihydroindeno[2,1-α]indene chromium tricarbonyl (III) has been obtained by Rausch's method. Deprotonation of III by t-BuOK in THF solution, by potassium solution in HMPTA or by KH in THF at −65°C yields an η⁶-anion IV, which is irreversibly rearranged into η⁵-anion V at 20°C. Action of n-BuLi/t-BuOK mixture in THF at −65°C results in the formation of η⁶-dianion VI, which is irreversibly converted into η⁵-dianion VII above 0°C. Alkylation of IV with benzyl iodide yields 5-exo-benzyl(III). Reaction of V with benzyl iodide leads to the σ-benzyl derivative, which is isomerized into 5-endo-benzyl(III). The reaction of V with N-nitroso-N-methyltosylamide yields the η⁵-nitrosodicarbonyl complex of chromium (XI).     

Selective cyclization of S-substituted pyrimidinethione: Synthesis and antimicrobial evaluation of novel polysubstituted thiazolopyrimidine and thiazolodipyrimidine derivatives

The synthetic strategy is based on alkylation of 4-aryl-N-(4-chlorophenyl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxamide derivatives IV a–g , with some alkyl halides and α-haloketones, namely, methyl iodide, chloroacetonitrile, and phenacyl bromide to give the corresponding S-substituted derivatives Va–c . Treatment of IVa–c with ethyl bromoacetate in ethanol under reflux in the presence of potassium hydroxide solution led to the formation of N-(4-chlorophenyl)-7-methyl-3-oxo-5-(aryl)-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxamide derivative VIII a–c in a single-step synthesis. On the other hand, compound IVa reacted with α-halo carbonitriles, namely, chloro acetonitrile, and monobromo malononitrile, to produce directly thiazolo[3,2-a]pyrimidine derivatives Xa and Xb , respectively, Compound Xb also reacted with each of formic acid, formamide, and ammonium thiocyanate to form thiazolodipyrimidine derivatives XI–XIII , respectively. Compound VIIIa–c coupled with arenediazonium salts in pyridine to give the corresponding 2-arylhydrazo derivatives XVIa–e . Compounds IV a–g and VIIIa–c were resynthesized under microwave irradiation. Some of the newly synthesized compounds were tested for their antimicrobial activities.     

Synthetic photochemistry. Synthesis of (±)oliveroline and (±)ushinsunine

Sodium borohydride reduction of 1-(2′-Bromobenzoyl)-2-methyl-3,4-dihydro-6,7-methylenedioxyisoquinolinium iodide ($\text{4}$) gave a mixture of alcohols which on irradiation in dil.HCl afforded (±) oliveroline and (±)ushinsunine.     

Molecular structures of acetyl fluoride and acetyl iodide

The molecular structures of acetyl fluoride and acetyl iodide have been determined by making use of the average distances obtained in the present study together with the moments of inertia reported in the literature. The large amplitude theory for a molecule with an internal top was used in the joint analysis. The thermal-average values of internuclear distances r_g and the bond angles in the zero-point average structure Φ_z are as follows: r_g(C-O) = 1.185 ±0.002 $\text{}\text{?}$rA, r_g(C-F) = 1.362± 0.002 Å, r_g(C-C) = 1.505±0.002 Å, r_g(C-H) = 1.101 ±0.004 Å, Φ_z(OCF) = 120.7°±0.4°,Φ_z(CCF) = 110.5° ± 0.5°, Φ_z(HCH) = 109.3°±0.6° tilt(CH₃) = 0.1°±1°, for acetyl fluoride; r_g(C=O) = 1.198±0.013 $\text{}\text{?}$rA, r_g(C-I) = 2.217±0.009 Å, r_g(C-C) = 1.492±0.015 $\text{}\text{?}$rA, r_g(C-H) = 1.101 ± 0.004 Å, Φ_z(OCI) = 119.5°± 0.8°,Φ_z(CCI) = 111.7°±0.9°, Φ_z(HCH) = 110.8°±0.8° and tilt(CH₃) = 1.7°+5.4° for acetyl iodide. The uncertainties represent the estimated limits of error. The barriers V₃ to internal rotation have been reanalyzed making use of the effective moments of inertia of the methyl top estimated on the basis of the large amplitude theory and resulted in 1039 and 1176 cal mol^?1 for acetyl fluoride and acetyl iodide, respectively. The structure parameters have been compared with those of other CH₃COX (X = Cl, Br, H, CH₃) type molecules.     

The structure of some transition metal fluorides

The structures of the solid fluorides MF₂, MF₃, MF₄ and MF₅, in which M has the coordination number 6 and belongs to the 3$\text{d}$, 4$\text{d}$- and 5$\text{d}$-periods and the Vb to VIII groups, can be divided into 3 types: (a) cubic close packing ($\text{ccp}$) of F with an MFM bridging angle of 180°; (b) hexagonal close packing ($\text{hcp}$) with an MFM-bonding angle of 132°; (c) intermediate packing between (a) and (b). The linear bridging is assumed to be a consequence of π-back bonding (or charge transfer) between $\text{p}$F-orbitals and $\text{d}$-orbitals of the metal. If such bonding is not possible then $\text{hcp}$ with the bridging angle of 132° will result. Weaker π-interactions give the intermediates (c).     

Übergangsmetall-Fulven-Komplexe: XXXII. Heteronukleare Zweikernkomplexe des Azulens

The molecular structure of the dinuclear complex [(η⁶-benzene)M$\text{o(μ-η}{}^6\text{: η}{}^4\text{-azulene)C}$r(CO)₃ was determined by an X-ray diffraction study. The reaction of [(η⁶-azulene)(η⁶-benzene)Mo] with [RhCI(CO)₂]₂ gives the salt [η⁶-benzene)M$\text{o(μ-η}{}^6\text{: η}{}^4\text{-azulene)R}$h(CO)₂]₊[RhCl₂(CO)₂]^?, the structure of which was also characterized by X-ray crystallography. The cation of this salt can also be synthesized from [(η⁶-azulene)(η⁶-benzene)Mo] and [Rh(CO)₂]⁺. The fluxionality of the cation was studied by temperature-dependent ¹H-NMR measurements. The complex [(η⁶-azulene)(η⁶-benzene)Mo] reacts with Fe₂(CO)₉ to give the dinuclear complex [(η⁶-benzene)M$\text{o(μ-η}{}^5\text{:}{}_3\text{-azulene)F}$e(CO)₃], as confirmed by X-ray diffraction.     

Synthesis of (2S,3R,1'R)-stegobinone,the pheromone of the drugstore beetle,with stereocontrol at C-2 and C-1'

(2$\text{S}$,3$\text{R}$,1'$\text{R}$)-Stegobinone [2,3-dihydro-2,3,5-trimethyl-6-(1'-methyl-2'-oxobutyl)-4H-pyran-4-one], the pheromone of $\text{Stegobium}$ $\text{paniceum}$ L., was synthesized with stereocontrol at C-2 and C-1' starting from ethyl ($\text{R}$)-3-hydroxybutanoate and methyl ($\text{R}$)-3-hydroxy-2-methylpropanoate. The dihydro-γ-pyrone ring of the pheromone was constructed by an intramolecular acylation followed by acid-catalyzed cyclization.     

The effect of environment on the reactions of thiiranium ions

The thiiranium ion formed by the reaction of $\text{Z}$-1-phenylpropene and (4-ClC₆H₄S)₂SC₆H₄ClSbCl₆ in CH₂Cl₉ at ?70°C reacts with Cl^? to form both $\text{erythro}$- and $\text{threo}$-Markownikoff B-chlorosulfides.     

Structural effects on valence tautomerism : VII. An NMR and molecular mechanics study of the steric effects of t-butyl substituents on the cycloheptatriene-norcaradiene equilibrium of 7-cyano-7-m

7-Cyano-7-methylcycloheptatrienes containing one t-butyl group on the 1-position ($\text{2}$) or two t-butyl groups on the 1- and 3-, 1- and 4-, or 1- and 5-positions ($\text{3}$, $\text{4}$, or $\text{5}$, respectively) were synthesized and their cyclo- heptatriene (CHT)-norcaradiene (NCD) equilibria measured by variable-temperature ¹H NMR for CS₂-CD₂Cl₂ solutions. The ¹H NMR chemical shifts of the 7-methyl group indicate that these compounds are composed of essentially one CHT and one NCD tautomer with an endo geometry of the methyl group. The introduction of a t-butyl group at the 1-position of 7-cyano-7-methylcycloheptatriene ($\text{1}$) markedly shifts the equilibrium to the NCD side and the addition of the second t-butyl group further favors the NCD form, with the NCD populations for $\text{2}$, $\text{3}$, $\text{4}$, and $\text{5}$ at 25 °C 70.9, 96.5, 92.3, and 99.3%, respectively. An application of molecular mechanics (MMPI) calculations to various t-butylated CHT-NCD systems suggests that the t-butyl groups sterically destabilize the CHT form more than the NCD form, bringing about increased NCD populations.     

Cyanosugars III : The reaction of trimethylsilyl cyanide with keto,epoxy and acetal derivatives of carbohydrates

Reaction of methyl 2-acetamido-4,6-$\text{O}$-benzylidene-2-deoxy-α-$\text{D}$-$\text{ribo}$-hexopyranosid-3-ulose with Me₃SiCN afforded methyl 2-acetamido-4,6-$\text{O}$-benzylidene-3-$\text{C}$-cyano-2-deoxy-3-$\text{O}$-trimethylsilyl-α-$\text{D}$-$\text{allo}$- Reaction of ethyl 4,6-di-$\text{O}$-acetyl-2,3-anhydro-α-$\text{D}$-mannopyranoside with Me₃SiCN gave the corresponding ethyl 4,6-di-$\text{O}$-acetyl-2-$\text{C}$-cyano-2-deoxy-α-$\text{D}$-glucopyranoside. Reaction of methyl 4,6-$\text{O}$-benzylidene-2,3-anhydro-α-$\text{D}$-allopyranoside or methyl 4,6-$\text{O}$-benzylidene-2,3-di-$\text{O}$-tosyl-α-$\text{D}$-glucopyranoside with Me₃SiCN at - 75° or - 50° gave the corresponding methyl 6-$\text{O}$-[(R)-cyano phenyl methyl]-α-$\text{D}$-glyco-pyranosides with high or total regio and stereoselectivity.     

Prototropic rearrangements of unsaturated hydrocarbons promoted by iron carbonyls

Results from the thermal and photochemical reactions of $\text{cis}$-1,3-pentadiene and 4-methyl-1,3-pentadiene with iron pentacarbonyl are described together with those obtained from the thermolysis and photolysis of their η²-iron tetracarbonyl and η⁴-iron tricarbonyl complexes. Consideration of these results, and some recent related work of others, allows a new reaction path to be formulated for alkene and diene isomerizations promoted by iron carbonyls.     

Coulometric titration of iodide and iodine with electrolytically generated hypobromite

Conditions for the quantitative coulometric titration of iodide and iodine with electrolytically generated hypobromite in the presence of borax buffer have been established. Iodide and iodine are oxidized to iodate. The method, with biamperometric indication of the equivalence point, was successfully applied for a wide range of iodide concentrations (6.21–2115μg with reliability intervals of ±0.21–±11μg) and iodine concentrations (24.26–3311μg with reliability intervals of ±0.36–±11.7μg). The determinations are accurate and sensitive even in the presence of large amounts of bromides and chlorides ($\text{Br}{}^{\mathrm{?}}\text{I}{}^{\mathrm{?}}$= 1.2·10⁶ and $\text{C}\text{l}$^?I^?=4.0·10^{3), as well as in the presence of oxidizing agents such as IO₃?, BrO₃? and CrO₄2? ($\text{I}\text{O}$₃?/I₂)=3.2·105, $\text{I}\text{O}$₃?/I₂=3.1·103, $\text{Br}\text{O}$-₃/I₂}=1.1·10⁴ and $\text{Cr}\text{O}$^2-₄/I₂=1.0·10⁴, as was confirmed by statistical tests. The oxidation mechanism under the conditions of coulometric titrations is discussed.     

Functionalization at C-12 in labdanic diterpenes: synthesis of the natural diterpenic lactones isolated from cistus ladaniferus L.

Oxidative cyclization of Labdanediol (XII) and methyl Labdanolate (Ib) with Pb(OAc)₄, and subsequent oxidation with reagents as RuO₄, O₃, CrO₃, or (Bu^t)₂ CrO₄ affords, in excellent yield, the natural diterpenic lactones II, III, VII, VIII, XI and XIII, isolated from $\text{Cistus ladaniferus L.}$