Solvent‐ and Catalyst‐Free Selective Mannich Reaction on Catechols and Para Substituted Phenols: A Convenient Route to Catechol‐ and Phenol‐Iminodiacetic Acid Ligands

Abstract

We have developed a convenient solvent‐ and catalyst‐free selective Mannich reaction of a variety of para‐substituted phenols or catechols with paraformaldehyde and ethyl iminodiacetate. With para‐substituted phenols and electron‐poor catechol, only the monosubstituted benzyliminodiacetic ester is selectively formed in good yield and no disubstituted product is detected. In contrast, electron rich catechols gave mono‐ or disubstituted derivatives depending on the stoichiometry of ethyliminodiacetate. Furthermore, the reaction is highly regioselective with catechols, since no para derivatives are formed. In addition, we describe a mild acidic hydrolysis of the ester functions, which avoids the degradation of the benzylamine moiety by the quinone methide pathway. So, pure o‐hydroxybenzyliminodiacetic acid ligands are obtained in overall good yields.     

Tetraphenylporphyrins monosubstituted with a crown ether in one phenyl ring. Synthesis and characterization

Summary The synthesis and spectroscopic characterization of seven new tetraphenyl-porphyrins (1–7) derivatized with 12-crown-4, 14-crown-4, 15-crown-5, or 18-crown-6 ether units inortho orpara position of one of the phenyl rings is described.

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In einem Phenylring mit Kronenethern monosubstituierte Tetraphenylporphyrine. Synthese und Charakterisierung

Zusammenfassung Die Synthese und die spektroskopische Charakterisierung sieben neuer Tetraphenylporphyrine (1–7), die mit 12-Krone-4, 14-Krone-4, 15-Krone-5 oder 18-Krone-6 in derortho-oderpara-Position eines Phenylrings substituiert sind, werden beschrieben.

     

2,3-dimethoxyperhydro-1,4,2,3-dioxadiazine: Synthesis,conformation, and conversion to 1-(2-hydroxyethoxy)-2-methoxydiazene-1-oxide. Crystal structure of 1-[2-(para-nitrobenzoyloxy)-ethoxy]-2-methoxydiazene-1-oxide

The oxidation of 1,2-bis(methoxyaminooxy)ethane (3) with PbO₂ afforded 2,3-dimethoxyperhydro-1,4,2,3-dioxadiazine (4) in the form of the 55:45 mixture of thetrans-4ee- andcis-4 isomers. The barrier of the ring conversion (G₂₃₈ =11.3 kcal/mole) of thecis-4 isomer was determined by the method of¹³C NMR. The regio- and stereospecific stereoelectronically controlled reaction of (4) withpara-nitrobenzoic acid gives the equimolar mixture of methylpara-nitrobenzoate and the 1,2-dialkoxydiazene oxide (5), the structure of which, and the (E)-configuration, were shown by the x-ray structural data of its acylation product — the diazene oxide (6).N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2624–2632, November, 1992.     

Aromatic polymides. VII. Synthesis of sulfonated poly(para-phenyleneterephthalamide): Polymerization of 1,4-bis(trichloromethyl) benzene with para-phenylenediamine sulfate in SO3

para-Phenylenediamine sulfate polymerized with 1,4-bis(trichloromethyl)benzene in SO₃ at > 20% polymer concentration to form highly anisotropic (liquid crystalline) sulfonated poly(para-phenyleneterephthalamide) (S-PPT) solutions with inherent viscosities as high as 1.2. Analogous to the polymerization of para-phenylenediamine sulfate with terephthalic acid in SO₃ reported previously, sulfonation of the aromatic diamine ring of S-PPT was not competitive with the polymerization reaction, but it was a major side reaction.     

The effect of a pendant amine in phosphine ligand on the structure and electrochemical property of diiron dithiolate complexes

Abstract

In order to explore the effect of a pendant amine on a phosphine ligand on the structure and electrochemical properties of diiron dithiolate complexes, this work reports the crystallographic and electrocatalytic comparisons of three diiron monophosphine complexes Fe₂(μ-pdt)(CO)₅{Ph₂P(NHR)} [pdt?=?propanedithiolate (SCH₂CH₂CH₂S); R?=?para-methoxycarbonylphenyl (C₆H₄CO₂Me-p) (1), para-methoxyphenyl (C₆H₄OMe-p) (2) and phenyl (Ph) (3)] with a pendant amine and one reference analogue Fe₂(μ-pdt)(CO)₅{Ph₂P(CH₂Ph)} (4). While the new complex 4 has been characterized by elemental analysis and various spectroscopic techniques, the molecular structures of 3 and 4 were further determined by X-ray crystallography. In addition, the electrochemical properties of 1–4 were studied in acetonitrile (MeCN) in the absence and presence of acetic acid (HOAc) as a mild proton source using cyclic voltammetry (CV). This may demonstrate that they are found to be active electrocatalysts for proton reduction to hydrogen (H₂).     

Nuclear magnetic resonance VI. Some quantitative applications of carbon-13 NMR spectroscopy to phenylindoles

Summary The number of carbons represented by each signal of the phenylindoles1,4, and5 is measured quantitatively by integration of their¹³C NMR spectra, recorded after adding chromium(III) acetylacetonate to the sample solutions as a paramagnetic relaxation agent. Their carbon chemical shifts are assigned unambiguously; the literature assignments of4 are confirmed. By a comparative study of the carbon chemical shifts of1,4, and5, those of2 and3 are also assigned. Theortho carbons of the phenyl group of4 resonate upfield with respect to thepara carbon. Theortho carbons of the 2- and 3-phenyl moieties of1–3 and5, however, are found to absorb downfield from the correspondingpara carbons, probably because of steric and/or electronic effects exerted by their neighbouring phenyl group.

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Kernresonanzspektroskopie, 6. Mitt. Einige quantitative Anwendungen der¹³C-NMR-Spektroskopie auf Phenylindole

Zusammenfassung Die Anzahl der durch jedes Signal der Phenylindole1,4 und5 repräsentierten Kohlenstoffatome wird durch Integration der nach Zusatz von Chrom(III)acetonylacetat als Relaxationsreagens aufgenommenen¹³C-NMR-Spektren bestimmt. Ihre chemischen Verschiebungen werden eindeutig zugeordnet; die Literaturwerte für4 werden bestätigt. Durch eine vergleichende Untersuchung der¹³C-chemischen Verschiebungen von1,4 und5 können jene von2 und3 ebenfalls zugeordnet werden. Dieortho-Kohlenstoffe der Phenylgruppe von4 sind gegenüber denpara-Kohlenstoffatomen zu höherem Feld verschoben. Für die 2- und 3-Phenyl-Substituenten von1–3 und5 kehren sich die Verhältnisse um, wahrscheinlich wegen sterischer und/oder elektronischer Effekte der benachbarten Phenylgruppe.

     

Intermolecular Order of Poly-(2,5-dimethyl-para-phenylene vinylene) and Poly-(para-phenylene vinylene) – A Comparison

Summary.  Poly-(para-phenylene vinylene) (2b, PPV) and poly-(2,5-dimethyl-para-phenylene vinylene) (1b) were prepared via the formation of a double bond by thermal elimination of an octylsulfinyl side group at 200°C under vacuum. X-Ray diffraction experiments revealed a certain degree of long-range order within both polymers. However, considerable differences in the diffraction pattern were observed, the packing of the polymer chains within the bulk structure being responsible for these differences. Within the crystal structure of 2b, neighbouring PPV chains pack in a zig-zag arrangement (herringbone pattern). Analysis of the diffraction pattern of 1b on the basis of the crystal structure of a model compound (2,5,2′,5′-tetramethylstilbene) revealed that the molecular planes of neighbouring polymer chains pack parallel to each other. A model for the crystal structure of 1b is given. The change of packing from a herringbone to a parallel arrangement of the molecular planes is related to the introduction of methyl groups as side chains to PPV. Received December 14, 2000. Accepted (revised) December 20, 2000     

Thermal elimination of isobutene from meta and para tert-di-butyl pyromellitic acid

An investigation of the kinetics of the thermal elimination of isobutene from the meta and para isomers of the tert-butyl diesters of pyromellitic acid has been carried out using Fourier transform-Raman spectroscopy and mass spectroscopy. These studies indicate that the elimination of the tert-butyl group occurs at a temperature 26°C lower for the meta isomer than for the para isomer; the maximum rate of elimination occurs at 184°C for the former and at 210°C for the latter. Analysis of the Raman spectra of the compounds indicates that this effect results from the better packing arrangement in the para monomer compared with the meta monomer. Formation of pyromellitic dianhydride in the tert-butyl diesters of pyromellitic acid occurred only after formation of the pyromellitic acid; thus it occurred at lower temperatures for the meta isomer. When the meta and para tert-butyl diesters of pyromellitic acid are dissolved at 1% concentration in poly (vinyl acetate), the elimination of isobutene occurs at 173°C for both isomers, indicating that it is the differences in crystal packing which give rise to the 26°C difference in the solid-state samples. For the meta, para, and 50/50 mixed isomers of the tert-butyl esters of oxydianiline/pyromellitic dianhydride polyamic acid, the elimination of the tert-butyl group occurs at the same temperature (177°C). This result indicates that the packing arrangement of the tert-butyl group is disrupted in the polymer chain, so that intermolecular bonding does not hinder thermal deprotection of the tert-butyl group from the polymer. © 1992 John Wiley & Sons, Inc.     

Substituent chemical shift correlations. Hammett σp+ values and shifts for exocyclic protons in para-substituted benzene derivatives

The methyl ¹H NMR shifts for series of para-substituted N,N-dimethylanilines as their conjugate acids in trifluoroacetic acid, and series of para-substituted N,N,N-trimethylphenyl-ammonium iodides in acetonitrile and in deuterium oxide, and the methylene shifts for series of para-substituted N,N-diethylanilines as their conjugate acids in deuteriosulfuric acid, are shown to be linearly related to the Hammett σ_p+ parameter. It is proposed that this dependence reflects a response of the chemical shift of the proton of the probe moiety to the electron density at the point of attachment of the probe to the aromatic ring and that this response is determined by the electric field effect of the charge at the point of attachment. Literature data are cited to indicate that Hammett σ_p+–¹H NMR shift relationships may be general for probe moieties lacking a through-resonance mechanism for interaction between the probe and the aromatic ring.     

Synthese von para-substituierten phenyl-terpyridin liganden

Up to now the synthesis of para-substituted phenyl-terpyridine ligands was difficult with respect to the purification of the reaction products. We have found that these compounds can easily be isolated as hydrobromides from acetic acid. Starting from the hydrobromides the purification turned out to be easy. Synthesis of para-substituted Cl-, Br-, H₃C-, H₂BrC-, HO- 2,6-Bis(2-pyridyl)-4-phenylphyridine is reported.     

Two iso-closo 11-vertex ruthenaborane clusters with exo-polyhedral cyclization of para-iodobenzoate

The reaction of [RuCl₂(PPh₃)₃] and closo-[B₁₀H₁₀]^2? with p-IPhCOOH in CH₂Cl₂ solution affords two para-iodobenzoate exo-cyclized 11-vertex closo-ruthenaborane clusters [(PPh₃)(p-IPhCO₂)₂RuB₁₀H₈] (1) and [(PPh₃)₂ClRu(PPh₃)(p-IPhCO₂)RuB₁₀H₉]?···?CH₂Cl₂ (2) that have been characterized by elemental analysis, FT-IR, ¹H and ¹³C?NMR spectra and single-crystal X-ray diffraction analysis. Both clusters are based on a closo-type C _{2 v} 1?:?2?:?4?:?2?:?2 RuB₁₀ stack with the metal occupying the unique six-connected apical position. In 1, the metal center has three exo-polyhedral ligands: one triphenylphosphine and two native oxygen atoms of para-iodobenzoates. The other oxygen atoms of two para-iodobenzoates are additionally bonded to B(2) and B(3) atoms respectively, resulting in two exo-cyclic five-membered Ru–O–C–O–B rings and engendering a symmetrical conformation. For 2, the metal center also has three exo-polyhedral ligands, one triphenylphosphine and one para-iodobenzoate to form one exo-cyclic five-membered Ru–O–C–O–B ring. There is an additional exo-polyhedral ruthenium atom bonding to the {RuB₁₀} center via a {Ru–Ru} linkage and two {RuH _μ B} bridges resulting in one closo distorted exo-polyhedral Ru(1)–Ru(2)–B(2)–B(4) tetrahedron.     

Transition-metal-free mono- or dinitration of protected anilines

Abstract

An amide-assisted arene nitration is presented, and both mono- and dinitration of protected anilines could be effected by using NaNO₂ and NaNO₃ as the mono- and bisnitrating agents, respectively. This divergent synthesis is transition-metal- and acid-free, and features a broad substrate scope, low cost, and ortho–para selectivity.     

Composition and Microstructure Determination of the Syndiotactic Copolymer of para-Methylstyrene and Styrene by Pyrolysis Gas Chromatography

The composition and microstructure of syndiotactic para-methylstyrene/styrene copolymer was determined by a pyrolysis gas chromatography (Py-GC) method. This method uses the styrene and para-methylstyrene monomer peak intensities to determine the styrene and para-methylstyrene composition in the copolymer. The number average sequence length of styrene was calculated by using the triad peak intensities. Because of the low concentration of para-methylstyrene in the copolymer, the number average sequence length of para-methylstyrene was determined with formulas that incorporate the copolymer composition and the number average sequence length of styrene. The distribution of para-methylstyrene defined by the terms “percent of single units” and “percent of desired distribution” was calculated by the number average sequence of para-methylstyrene. This method has been tested with copolymers containing up to 24 mole% of para-methylstyrene. The composition results from Py-GC of para-methylstyrene and styrene copolymers used in this study were in excellent agreement with ¹H-NMR results.     

New small-cavity cryptand chromoionophores for complexation of lithium and sodium ions

Two new chromoionophores based on small-cavity cryptands with inward-facing phenolic groups have been synthesized. Both compounds incorporate a diaza-12-crown-4 moiety and bear ap-nitrophenylazo chromogenic group attached to the cryptand phenol framework,para to the phenolic group. Chromogenic crytand3 exhibits selectivity for Li⁺ ions in the extraction mode but shows very little cation response in homogeneous aqueous media. A larger analog, chromogenic cryptand4, acts as a sodium scavenger and cannot be obtained in a sodium-free form.     

Unprecedented new nonadecyl para-hydroperoxycinnamate isolated from Erythrina excelsa and its cytotoxic activity

A new unprecedented cinnamate derivative (1) was obtained from Erythrina excelsa (Leguminosae) and identified as nonadecyl para-hydroperoxycinnamate. This compound was isolated together with three known compounds, namely lupeol (2), mixture of sitosterol and stigmasterol (3), and isoneorautenol (4). Their structures were established on the basis of NMR and mass spectroscopic data in conjunction with those reported in the literature. Compound 1 was evaluated for its capability of inhibiting cancer cell lines and growth of a panel of microbial strains. It turned out that 1 is moderately to significantly cytotoxic against six cancer cell lines and shows weak to no antimicrobial activity.     

Aromatic substitution of 4-phenylisothiazole

Aromatic substitutions on 4-phenylisothiazole by nitric acid, halogens, chlorosulfonic acid and acetic anhydride take place under relatively mild conditions to give predominantly para and ortho substitution on the benzene ring. By contrast, the 3-isothiazolyl group has been shown to be meta directing. Several derivatives of 4-phenylisothiazole are described.     

Alternative Approach to an AB2 Monomer for Hyperbranched Poly(Arylene Ether Ketone Imide)s

An alternative approach to an AB₂ monomer, N‐[3,5‐bis(4‐hydroxybenzoyl)benzene]‐4‐fluorophthalimde, 4, for hyperbranched poly(arylene ether ketone imide)s has been developed. The key steps were a para‐position selective electrophilic aromatic substitution of fluorobenzene with 5‐nitroisophthaloyl dichloride and a subsequent clean conversion of the aryl fluorides to phenol groups using potassium hydroxide as the nucleophile. The overall yield for the synthesis of 4 was 51.6%.     

Effect of Substituent Orientation on Selectivity between Polymerization and Cyclization: Polycondensation of (Alkylamino)benzoic Acid Dimer Phenyl Esters

Summary: The polymerization characteristics of (octylamino)benzoic acid dimer phenyl esters with para‐meta ( 2 ), meta‐para ( 3 ), and meta‐meta ( 4 ) orientation of the amino and carbonyl groups were investigated. While treatment of 2 or 3 with a base gave the cyclic dimer 6 as the main product, condensation of 4 with an initiator in the presence of a base afforded polymers with narrow molecular weight distributions.

The condensation of 4 with an initiator in the presence of a base afforded polymers with narrow molecular weight distribution.     

Cone di-ionisable calix[4]arene-1,3-crown-5 ligands with elongated pendant side arms: synthesis and metal ion extraction

Abstract

Syntheses of p-H-calix[4]arene-1,3-crown-5 and p-tert-butylcalix[4]arene-1,3-crown-5 ligands with two elongated, proton-ionisable side arms in the cone conformation are described. For solvent extractions from aqueous solution into chloroform, the influence of lengthening the lower rim proton-ionisable side arms and addition of para substituents to the upper rim of the calix[4]crown scaffold on the efficiency and selectivity of metal cation solvent extraction are evaluated.     

A convenient and efficient H2SO4-promoted regioselective monobromination of phenol derivatives using N-bromosuccinimide

Abstract

A convenient, rapid H₂SO₄-promoted regioselective monobromination reaction with N-bromosuccinimide was developed. The desired para-monobrominated or ortho-monobrominated products of phenol derivatives were obtained in good to excellent yields with high selectivity. Regioselective chlorination and iodination were also achieved in the presence of H₂SO₄ using N-chlorosuccinimide and N-iodosuccinimide, respectively.