Heterocyclic Polyimides

This paper presents the synthesis of certain polyimides which contain one of the following heterocycles: oxadiazole, benzox-azinone, benzthiazole. Their properties, particularly thermal stability and hydrolytic stability, are compared to fully aromatic polyimides. Poly-1,3,4-oxadiazole-imides have been synthesized either by the reaction of ditetraeole monomers which contain preformed imide cycles with diacid chlorides, or by the reaction of an aromatic diamine containing a preformed oxadiazole ring with diacid chlorides containing preformed imide rings. Polybenz-oxazinone-imides have been synthesized by polycondensation of a bis(amino acid), 4,4′-diaminodiphenylmethane-3,3′-dicarboxylic acid, with diacid chlorides containing preformed imide rings. Polybenzthiazole-imides have been obtained by polycondensation of aromatic diamines containing a preformed benzthiazole ring with diacid chlorides containing preformed imide rings. Thermal stabilities of these heterocyclic polyimides are similar and in certain cases are higher than those of fully aromatic polyimides. It was also found that the hydrolytic stability of heterocyclic polyimides is definitely superior to that of aromatic polyimides.     

Efficient synthesis of spiroisoxazoline oxindoles

The synthesis of spiroisoxazoline oxindoles containing ester groups at position 4′ and aromatic or ester groups at position 3′ of the isoxazoline ring is reported. The compounds were synthesized in yields up to 94% by 1,3-dipolar cycloaddition of 3-methylene indolin-2-ones and chlorooximes in the presence of triethylamine or zinc.     

New π-electron donors: Ethanediylidene-2,2′-bis(1,3-diselenole) and ethanediylidene-2-(1,3-dithiole)-2′-(1,3-diselenole)

This communication describes synthesis and electrochemical properties of new type of π-donors containing 1,3-diselenole ring, ethanediylidene-2,2′-bis(1,3-diselenole)(1a) and ethanediylidene-2-(1,3-dithiole)-2′-(1,3-diselenole)(2a). The conductivities of the charge-transfer complexes of these donors with tetracyanoquinodimethane (TCNQ) are also demonstrated.     

Ring transformations of heterocyclic compounds. XIII. Bis(2,4,6-triarylphenyl) substituted bispyridinium salts from methyl derivatives by double pyrylium and thiopyrylium ring transformations

The synthesis of hitherto unknown 4,4′-bis(2,4,6-triarylphenyl) substituted bispyridinium diperchlorates 3 , in which the N-atoms are linked by a carbon chain, a heteroatom containing a carbon chain or a bis(methylene) substituted aromatic/heteroaromatic ring, from 4,4′-dimethylbispyridinium derivatives 2 by a double 2,6-[C₅+C] ring transformation of 2,4,6-triarylpyrylium and 2,4,6-triarylthiopyrylium salts 1/4 is reported. Spectroscopic data of the bispyridinium diperchlorates 3 and their mode of formation are discussed.     

Different specificities in the bromination of 6-(2-furyl)imidazo[2,1-b]thiazole and its derivatives with 1 mole of bromine

The action of 1 mole of bromine on 6-(2′-furyl)imidazo[2,1-b]thiazole, its 2-methyl-, 3-methyl-, and 2,3-dimethyl-substituted derivatives, and their hydrobromides in chloroform and glacial acetic acid was studied. The bromination of bases containing a methyl group in the 3 position leads primarily to the 5′-derivatives with respect to the furan ring in chloroform, whereas in the remaining cases 5-bromo derivatives with respect to the imidazothiazole system are formed. Compounds of the latter type are formed by the action of bromine in glacial acetic acid or of sodium hypobromite in alkaline media on the bases. The hydrobromides are brominated in both acetic acid and chloroform, regardless of the substituents in the thiazole ring, primarily in the 5′ position of the furan ring. The structures of the bromination products were proved by means of alternative syntheses, thin-layer chromatography, and the PMR spectra.     

Synthesis and spectral analysis of 8-substituted dinaphtho [2,1-d:1′,2′-g] [1,3,6,2]dioxathiaphosphocin 8-oxides

Synthesis and spectral analysis of several 8-substituted dinaphtho[2,1-d:1′,2′-g][1,3,6,2]dioxathiaphosphocin 8-oxides have been described. An X-ray crystallographic study of 8-(2′,3′- dimethylphenoxy)dinaphtho[2,1 - d:1′,2′-g][1,3,6,2]dioxathiaphosphocin 8-oxide has indicated that, in the solid state, the dioxathiaphosphocin ring is in a distorted-boat–like conformation with the P = O group and bridged S atom directed away from each other. Electron impact mass spectra showed M⁺ and (M–OR)⁺ ions, containing the dioxathiaphosphocin ring system, confirming the structures of the esters. © 1995 John Wiley & Sons, Inc.     

Phosphorinane and Enol Rings in One Molecule. Evidence for Reciprocal Stabilization of Half-Chair Conformations

Abstract.

The X-ray crystal structure of 2-(2′,4′-dioxo-3′-pentyl)-5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinane (2) reveals significant half-chair distortion of the axially oriented cisenol ring. The molecule also undergoes in-plane deformations. R(O...O) = 2.410 Å in the enol moiety indicates a very strong hydrogen bonding. The enol content, δ_OH and thermodynamic parameters for the axial-equatorial conformational and keto-enol equilibriums were obtained from ¹H, ³¹P NMR and IR measurements in comparison with the planar 4,6-dimethyl isomer (1) containing equatorially oriented enol ring. The X-ray single crystal structure of 5,5-dimethyl-2-(methoxycarbonyl-3′-oxo-2′-butyl)-2-oxo-1,3,2-dioxaphosphorinane (3) reveals the unusual half-chair conformation of the dioxaphosphorinane cycle disposed a trans-enol ring substituent. ¹H, ³¹P NMR and IR solution data support the same structure displays a strong conformational preference while the minor forms are chair conformers with an axial or equatorial cis-enol ring.     

Multinuclear magnetic resonance study of the structure and tautomerism of azide and iminophosphorane derivatives of chloropyridazines

Some azido‐ and iminophosphorane derivatives of 3,6‐dichloro‐ and 3,4,5,6‐tetrachloropyridazine were synthesized and studied by means of NMR measurements. Based on multinuclear data (chemical shifts, coupling constants) for compounds containing the azide group, no potentially possible tetrazole–azide equilibrium can be observed, even under acidic conditions. An unusual substitution of a chlorine atom (in position 4) of tetrachloropyridazine in the reaction with hydrazine was demonstrated by NMR measurements of two newly synthesized compounds containing azido‐ and iminophosphorane groups. Using multinuclear magnetic resonance data, the sites of ethylation and protonation of azido‐ and iminophosphorane derivatives of chloropyridazines were established. In the case of the tetrazolopyridazines, ethylation occurs at the N1′ and N2′ atoms, whereas for monocyclic compounds it takes place at the N1 and/or N2 atoms of the pyridazine ring. Preferred sites of protonation are the N1′ atom of the tetrazole ring and the N1 atom of the pyridazine ring. Moreover, the structures of potassium salts of 6‐(3‐cyano‐1‐triazeno)tetrazolo[1,5‐b] pyridazine and its amido derivative were established using NMR data, especially ¹⁵N NMR chemical shifts. Copyright © 2002 John Wiley & Sons, Ltd.     

4,5-Dihydroisoxazoles in the synthesis of new metallomesogens

A new approach to the synthesis of metallomesogens containing β-enaminoketone fragments as chelating moieties was developed. The corresponding enaminoketone was synthesized by the oxidation of 3-(4′-butoxybiphenyl-4-yl)-5-pentyl-4,5-dihydroisoxazole to 3-(4′-butoxybiphenyl-4-yl)-5-pentyl-4,5-isoxazole, followed by opening of the isoxazole ring. The reaction of the enaminoketone with copper(II) and nickel(II) acetates gave the target mesogenic metal complexes.     

Kinetics and mechanism of the protonation of 6-(triphenylphosphonio-3′-cyclopentadienyl)-2,3,5-trihalocyclohexa-2,5-diene-1,4-dione by trifluoroacetic acid in aprotic media

6-(Triphenylphosphonio-3′-cyclopentadienyl)-2,3,5-trihalocyclohexa-2,5-diene-1,4-diones (2) are a new class of phosphorus containing dyes that behave as weak bases. Mono-protonation occurs at the cyclopentadiene ring leading to three isomers as assessed by NMR. The kinetics of the protonation were studied by the stopped-flow technique in aprotic media. The activation energies and deuterium isotope effects suggest that the rate-limiting step is the addition of trifluoroacetic acid to the quinone ring rather than direct protonation of the cyclopentadiene ring. © 1997 John Wiley & Sons, Inc.     

Synthesis of poly condensed oxygen-containing helical heterocycles via rearrangement of benzofused-2,2′-diphenoquinone derivatives

The thermal rearrangement reaction of helical-shaped quinone (benzofused-2,2′-diphenoquinone derivative) afforded three types of poly-condensed oxygen-containing heterocyclic compounds. One type of them was spiro compound which is consisting of cyclopentadiene and γ-butyrolactone. The other two compounds were helically condensed compounds, one of them containing as cyclopentadiene and pyranone ring and the other consists of fused furan and oxepin ring. These products were could be selectively synthesized by the choosing modification of reaction conditions. Moreover, the mechanistic aspects of these reactions are also discussed.     

A study of polyurethanes synthesized from an arylsilane,bis(4,4′-phenylisocyanato)dimethylsilane,and its carbon analog, 2,2-bis(4,4′-phenylisocyanato)propane

Bis(4,4′-phenylisocyanato) dimethylsilane (SiDI) and 2,2-bis (4,4′-phenylisocyanato)propane (PrDI) were synthesized, polymerized to polyurethanes, and their chemical, thermal and physical properties studied. Nuclear magnetic resonance spectra confirm deshielding by silicon of both the phenyl ring and the urethane linkage. The glass transition temperatures, solubility parameters, and mechanical properties were independent of the diisocyanates. The silicon containing polyurethanes are more thermally stable than their carbon counterparts. © 1993 John Wiley & Sons, Inc.     

Synthesis and crystal structure of novel [1,2,4]oxadiazolo[5,4‐d][1,5]benzothiozepine derivatives containing pyrazole moiety

A series of new substituted‐[1,2,4]oxadiazolo[5,4‐d][1,5]benzothiazepine derivatives containing pyrazole ring 4 / 4′ was synthesized by substituted‐pyrazolo[1,5]benzothiazepines 2 / 2′ and substituted‐benzohydroximinoyl chlorides 3 through the 1,3‐dipolar cycloaddition reaction in the presence of Et₃N at room temperature, and characterized by MS, IR, ¹H NMR and elemental analyses. In addition, the structure of 4′l was determined by X‐ray crystallography. J. Heterocyclic Chem., 2011.     

Synthesis of Chiral Phenolic 1,1′-Binaphthocrown Ethers and Some Proton-ionisable Chromogenic Derivatives

Synthesis of mono- and bis(1,1′-bi-2-naphthocrown)ethers containing bis(2,6-methylene)anisyl subunit in the crown ring were developed. These chiral macrocycles are suitable precursors to introduce a chromogenic function, as exemplified by two novel crowned azophenol chromoionophores. Their coloration process induced by various achiral and chiral amines was studied by UV–vis spectrophotometry.     

A novel sulfur containing C35 hopanoid in sediments.

A C₃₅ pentacyclic triterpenoid of the hopane series containing a thiophene ring, 30-(2′-methylene thienyl)-17β(H),21β(H)-hopane 1, has been confirmed in immature sediments by synthesis, suggesting incorporation of bacterial sulfur into geological organic matter at early stages of sedimentation.     

Auto-condensation of aryl- and aralkylferrocenes via ligand exchange

An intermolecular exchange is described between two molecules of aryl- or aralkyl-ferrocene with AlCl₃ as catalyst. The cyclopentadienyl ring of one molecule is replaced by the phenyl nucleus of another similar molecule. In the case of a 1,1′-diaralkylferrocene, this auto-condensation reaction occurs exclusively to give a single salt containing the ferrocene moiety.     

Über Phosphorstickstoffverbindungen,XXXII. Über Vier- und fünfgliedrige Heterocyclen mit Phosphor,Stickstoff und Kohlenstoff im Ring

On reacting of oxamide with PCl₅ the syntheses of the new N-, C- and pentavalent phosphorus containing heterocycles I and II (see “Inhaltsübersicht”), built up from interconnected four- and fivemembered ring systems, have been achieved. Reaction of N, N′- dimethyloxamide with PCl₃ yields the compound III which may be chlorinated to IV. An intermolecular reaction between the PCl₃- and carbonyl groups of IV gives V. The fivemembered ring systems III and V may each be linked together via N? CH₃ bridges, i. e. via P? N(CH₃)? P and P(O)? N(CH₃)? P(O) units, respectively. N, N′- dimethyloxamide reacts with PCl₅ to form a mixture of fivemembered heterocycles containing trivalent phosphorus (as a PCl group) and chlorinated carbon.     

The synthesis of 4'-azido-3',5'-ditritio-l-phenylalanine peptides as "photo-affinity probes" for ligand-receptor interaction (author's transl)]

The Synthesis of 4′-Azido-3′,5′-ditrito-L -phenylalanine Peptides as « Photoaffinity Probes » for Ligand-Receptor Interaction The synthesis of L -p-azido-phenylalanine and peptides thereof containing tritium atoms in the m,m′-positions of the phenyl ring is described. Starting materials are L -p-amino-phenylalanine and L -p-amino-m,m′-diiodo-phenylalanine. Such peptides are being used for specific photoaffinity labelling of receptor and enzyme molecules.     

Synthesis and characterization of polyamides containing s-triazine rings in the main chain

Polyamides were synthesized from diacids containing a s-triazine ring and two aromatic diamines, namely 4,4′-diaminodiphenyl ether (ODA) and 4,4′-diaminodiphenylmethane (MDA), by direct polycondensation using the phosphorylation reaction. Polymers thus obtained were characterized by viscosity measurement, IR spectroscopy, thermogravimetry, X-ray diffraction, and solubility tests. These polyamides had inherent viscosities in the range of 0.51–0.77 dL/g, and were amorphous in nature. All the polymers were readily soluble in various organic solvents and did not lose weight below 270°C in air.     

Synthesis and characterisation of rubbing-resistant polyimides with naphthalimide side-chain for liquid-crystal alignment layers

A novel diamine with a side-chain containing naphthalimide ring and non-polar alkyl end group, N-octyl-4-(3,5-dinitrobenzoyl)-amido-1,8-naphthalimide (N8), was synthesised and its chemical structure was confirmed by FTIR (fourier transform infrared) spectroscopy and nuclear magnetic resonance spectroscopy (¹H-NMR). Then, a new family of polyimides (PIs) containing naphthalimide unit in the side-chains has been successfully synthesised by reaction of 4,4′-oxydiphthalic anhydride (ODPA) and 3,3′-dimethyl-4,4′-methylenediamine (DMMDA) with the novel functional diamine N8. The obtained polymers showed excellent solubility in a broad range of solvents, including tetrahydrofuran. Thermal properties of polymers were good enough to permit the use of these PIs on liquid-crystal displays (LCDs) applications. Alignment films obtained by casting offered outstanding rubbing-resistant ability, meanwhile kept the pretilt angle high above 89°. The PI seems to be prospective materials for alignment layers in LCDs.