Cyclopolycondensation. XIII. New synthetic route to fully aromatic poly(heterocyclic imides) with alternating repeating units

Fully aromatic poly(heterocyclic imides) of high molecular weight were prepared by the cyclopolycondensation reactions of aromatic diamines with new monomer adducts prepared by condensing orthodisubstituted aromatic diamines with chloroformyl phthalic anhydrides. The low-temperature solution polymerization techniques yielded tractable poly(amic acid), which was converted to poly(heterocyclic imides) by heat treatment to effect cyclodehydration at 250–400°C under reduced pressure. In this way, the polyaromatic imideheterocycles such as poly(benzoxazinone imides), poly(benzoxazole imides), poly(benzimidazole imides) and poly(benzothiazole imides) were prepared, which have excellent processability and thermal stability both in nitrogen and in air. The poly(amic acids) are soluble in such organic polar solvents as N,N-dimethyl-acetamide, N-methylpyrrolidone, and dimethyl sulfoxide, and the films can be cast from the polymer solution of poly(amic acids) (η_inh = 0.8–1.8). The film is made tough by being heated in nitrogen or under reduced pressure to effect cyclodehydration at 300–400°C. The polymerization was carried out by first isolating the monomer adducts, followed by polymerization with aromatic diamines. On subsequently being heated, the open-chain precursor, poly(amic acid), undergoes cyclodehydration along the polymer chain, giving the thermally stable ordered copolymers of the corresponding heterocyclic imide structure.     

Characterization of Novel Aminobenzylcantharidinimides and Related Imides by Proton NMR Spectra and Their Effects on NO Induction

Various acidic anhydrides including cantharidin were converted into corresponding aminobenzylcantharidinimide 3a and analogous imides 3b～k (at the ortho, meta, and para positions) with 35%～87% yields by reacting with aminobenzylamines and triethylamine. The two methyl side chains of cantharidinimides 3ao , 3am , and 3ap, and related imides had more than two chiral centers; the lone pair of electrons of nitrogen displayed a different chemical shift and coupling constant in H‐NMR spectra when the amino group of benzylamine was in the ortho position. These cantharidinimides had parent aniline, pyridine, and naphthalene plane structures, and the primary amine nucleophilicity and basicity might reflect the inductive electron’s negative effect on chemical shifts. We prepared cantharidinimides by heating the reactants cantharidin 1a , aliphatic and aromatic acid anhydrides, primary benzylic amines, and aniline derivatives to ca. 200 °C with 3 mL of dry toluene, and 1～2 mL of triethylamine in high‐pressure sealed tubes (Buchi glasuster 0032) to produce cantharidinimides and their analogues in good yields. The para‐aminobenzylic imides showed greater inhibition of nitric oxide (NO) synthesis by NO synthase (NOS) than did ortho‐ and meta‐aminobenzylic imides. Compound 3fp , para‐aminobenzylic norbonane‐imide, had the most potent effect on inducible NOS among the tested compounds and showed 35% inhibition.     

Synthese von Makrocyclen durch Ringerweiterung von 14gliedrigen cyclischen Imiden

Synthesis of Macrocyles by Ring Enlargement of 14-Membered Cyclic Imides In the presence of a base, cyclododecanone derivative 2 , activated in α-position by an allyloxycarbonyl group, underwent ring enlargement with isocyanates to give 14-membered imides (Schemes 1–3). Cleavage of the activating group gave new 14-membered imides which could be transformed by further ring-enlargement reactions into new macrocyclic compounds.     

Preparation of crystalline polyamides by the alternating copolymerization of aziridines and cyclic imides

The copolymerization of aziridines and cyclic imides was studied. Aziridines copolymerized alternately with cyclic imides to give crystalline polyamides. Ethylenimine and succinimide copolymerized to nylon 2,4, melting near 300°C., without any catalyst. Similarly, the corresponding crystalline polyamides were obtained from the systems of 1,2-propylenimine–succinimide, ethylenimine–glutarimide, and ethylenimine–phthalimide. The copolymerization of aziridines and cyclic imides in the presence of BF₃OEt₂ gave a copolymer which was rich in aziridine units, whereas, the addition of triethylamine had no influence on the copolymer composition. A mechanism of copolymerization was proposed based on the facts that N-tetramethylenesuccinamide was obtained by the reaction of pyrrolidine and succinimide, N-acetylethylenimine reacted with acetamide to yield N,N′-diacetylethylenediamine and that the rate of this copolymerization was dependent on the electrophilicity of imide.     

Macrocyclische Imide: Vielseitige Synthese-Bausteine bei Ringerweiterungsreaktionen

Macrocyclic Imides: Versatile Synthons in Ring-Enlargement Reactions Macrocyclic imides differ from phthal- or succinimids in their increased electrophilicity. This property makes them versatile synthons for reactions with several nucleophiles. If a nucleophile is attached to the N-substituent of the imide, an intramolecular reaction will occur leading to ring-enlarged products. Use of N, O, and C nucleophiles for this synthetic pathway is reported. Synthetic transformations of e.g. cyclododecanone leads to 17-, 18-, or 19-membered macrolides, 11, 12, 15, 16, 21, 27, 30 , in three to five steps.     

Preparation of Heteroaromatic (Aryl)iodonium Imides as I−N Bond‐Containing Hypervalent Iodine

Hypervalent iodine(III) compounds containing iodine–nitrogen bonds are very attractive amination reagents in organic synthesis. Heteroaromatic (aryl)iodonium imides containing a iodine–nitrogen bond and a hypervalent iodine(III) atom were prepared from heteroarenes, bis(sulfon)imides and (diacetoxyiodo)arenes under mild conditions. These compounds were stable under air and in organic solvents, and could be easily purified by precipitation. X‐ray crystal structure analysis indicated that the structure of N‐pivaloyl indolyl(phenyl)iodonium bis(tosyl)imides and N‐pivaloyl indolyl(2‐butoxyphenyl)iodonium bis(tosyl)imides was a dimer with a T‐shaped geometry at the iodine atom linked to an indole group and a bis(tosyl)imide by a monomer unit. Moreover, the use of substituted iodoarenes facilitated the purification of some of the heteroaromatic (aryl)iodonium imides.     

Synthesis and Reactions of Some Heterocyclic Candidates Based on 2‐Amino‐4,5,6,7‐tetrahydrobenzo[b]thiophene Moiety as Anti‐Arrhythmic Agents

In continuation of our previous work, a series of novel thiophene derivatives 4 , 5 , 6 , 8 , 9 , 9a , 9b , 9c , 9d , 9e , 10 , 10a , 10b , 10c , 10d , 10e , 11 , 12 , 13 , 14 , 15 , 16 were synthesized by the reaction of ethyl 2‐amino‐4,5,6,7‐tetrahydrobenzo[b]thiophene‐3‐carboxylate ( 1 ) or 2‐amino‐4,5,6,7‐tetrahydrobenzo[b]thiophene‐3‐carbonitrile ( 2 ) with different organic reagents. Fusion of 1 with ethylcyanoacetate or maleic anhydride afforded the corresponding thienooxazinone derivative 4 and N‐thienylmalimide derivative 5 , respectively. Acylation of 1 with chloroacetylchloride afforded the amide 6 , which was cyclized with ammonium thiocyanate to give the corresponding N‐theinylthiazole derivative 8 . On the other hand, reaction of 1 with substituted aroylisothiocyanate derivatives gave the corresponding thiourea derivatives 9a , 9b , 9c , 9d , 9e , which were cyclized by the action of sodium ethoxide to afford the corresponding N‐substituted thiopyrimidine derivatives 10a , 10b , 10c , 10d , 10e . Condensation of 2 with acid anhydrides in refluxing acetic acid afforded the corresponding imide carbonitrile derivatives 11 , 12 , 13 . Similarly, condensation of 1 with the previous acid anhydride yielded the corresponding imide ethyl ester derivatives 14 , 15 , 16 , respectively. The structures of newly synthesized compounds were confirmed by IR, ¹H NMR, ¹³C NMR, MS spectral data, and elemental analysis. The detailed synthesis, spectroscopic data, LD₅₀, and pharmacological activities of the synthesized compounds are reported.     

Reaction of Hexamethyldisilazane with Cyclic Anhydrides of Organic Acids: A New Route to N-Trimethylsilylimides of Di- and Tetracarboxylic Acids

Cyclic anhydrides of di- and tetracarboxylic acids react with hexamethyldisilazane to give the corresponding N-trimethylsilylimides in 90-96% yields. However, cyclic anhydrides of succinic, 4-nitrophthalic, and tetrachlorophthalic acids react differently, giving acyclic trimethylsilyl esters of mono-N-trimethylsilylamides of these acids in 90-93% yields. The ¹H NMR, IR, and mass spectra of the compounds synthesized were studied.     

Methylendiformamid: Ausgangsmaterial für oligomere Carbonsäureamide und-imide

Methylene diformamide (1) is a suitable reagent for the introduction of the diaminomethylene group into polymers. Melt condensation of1 with aromatic carboxylic anhydrides (e.g. pyromellitic anhydride) gives oligomeric methylene imides. Reaction of carboxylic chlorides is best carried out by interface condensation in alkaline medium. Higher yields are obtained from the more stable aromatic carboxylic anhydrides than from aliphatic compounds. Intrinsic viscosity measurements show that the reaction of difunctional carboxylic acid derivatives with1 gave so far only oligomeric products.     

Thiol–ene polymerizations using imide‐based monomers

New diene and dithiol monomers, based on aromatic imides such as benzophenone‐3,3′,4,4′‐tetracarboxylic diimide were synthesized and used in thiol‐ene polymerizations which yield poly(imide‐co‐thioether)s. These linear polymers exhibit limited solubility in various organic solvents. The molecular weights of the polymers were found to decrease with increasing imide content. The glass transition temperature (T_g) of these polymers is dependent on imide content, with T_g values ranging from ?55 °C (with no imide) up to 13 °C (with 70% imide). These thermal property improvements are due to the H‐bonding and rigidity of the aromatic imide moieties. Thermal degradation, as studied by thermogravimetric analysis, was not significantly different to the nonimide containing thiol‐ene polymers made using trimethyloylpropane diallyl ether and 3,5‐dioxa‐1,8‐dithiooctane. It is expected that such monomers may lead to increased glass transition temperatures in other thiol‐ene polymer systems as these normally exhibit low glass transition temperatures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4637–4642     

Versatile and Sustainable Synthesis of Cyclic Imides from Dicarboxylic Acids and Amines by Nb2O5 as a Base‐Tolerant Heterogeneous Lewis Acid Catalyst

Catalytic condensation of dicarboxylics acid and amines without excess amount of activating reagents is the most atom‐efficient but unprecedented synthetic method of cyclic imides. Here we present the first general catalytic method, proceeding selectively and efficiently in the presence of a commercial Nb₂O₅ as a reusable and base‐tolerant heterogeneous Lewis acid catalyst. The method is effective for the direct synthesis of pharmaceutically or industrially important cyclic imides, such as phensuximide, N‐hydroxyphthalimide (NHPI), and unsubstituted cyclic imides from dicarboxylic acid or anhydrides with amines, hydroxylamine, or ammonia.     

Derivate des 5, 6-Dihydro-p-dithiin-2, 3-dicarbonsäure-anhydrids,I: Imide

5. 6-Dihydro-p-dithiin-2. 3-dicarboxylic anhydride reacts with primary amines quite readily to form the substituted imides. The imide formation occurs much more easily than with maleic or phthalic anhydride. The imide and all N-substituted imides have a fairly strong, bright yellow colour. Their absorption spectra differ considerably from those of the anhydride, ester and dinitrile. Electron-attracting substituents on the imide nitrogen increase the absorption maximum somewhat, while strongly electron-releasing groups decrease it, and may even shift it to a shorter wave-length. It is therefore concluded that the imide nitrogen is part of the election acceptor group of the chromorphoric system.     

Polyetherimides. I. Preparation of dianhydrides containing aromatic ether groups

A general synthetic method and characterization of bis(ether anhydride)s, the ether containing aromatic dianhydrides of the following structure, are presented. The method involves aromatic nitro-displacement of N-substituted 3- or 4-nitrophthalimide with bisphenoxides to form N-substituted arylene-bis(phthalimido)ethers or bis(ether imide)s. Sixteen structurally different bis(ether imide)s have been prepared and subsequently converted to the corresponding bis(ether anhydride)s. Bis(ether anhydride)s are stable crystalline compounds of a moderate reactivity. Unlike highly reactive dianydrides such as pyromellitic and benzophenonetetracarboxylic dianhydrides bis(ether anhydride)s are semipermanently stable against hydrolysis in the presence of atmospheric moisture.     

Substituted 2,3-dihydro-4(1H)quinazoIinones, 2

Details are given for the reaction of isatoic anhydrides with different primary aromatic amines to give several new N-aryl-o-aminobenzamides. The latter were annulated with a variety of dialkyl and alkyl aryl ketones to give 2,3-dihydro-4(1H)quinazolinones. Several novel and efficient procedures for effecting the cyclization are described.     

Soluble and curable prepolymers from polyallyl ester monomers containing aromatic imide groups

Five polyallyl ester monomers that contain aromatic imide groups were synthesized as thermally stable laminating resins. From these monomers soluble and low-melting prepolymers were obtained by radical polymerization in aprotic polar solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, or N-methyl -2-pyrrolidone. The prepolymers are oligomeric compounds in which DP = 3–6 and have lower melting points than the corresponding monomers. It is assumed that the reaction of solvent molecule participates in the polymerization. Whereas, the bulk and the solution polymerization in n-butyl acetate or n-propyl alcohol yielded insoluble and infusible polymer. The relatively low-melting prepolymers were curable at 150–180°C without the evolution of volatile by-products. Resulting glass-fiber laminates have no glass transition point below 300°C and thermooxidative stability at 330°C.     

Bildung von 4-, 5- und 6gliedrigen Heterocyclen durch ambidoselektive Ringschlüsse von Enolat-Ionen

Formation of 4-, 5- and 6-membered heterocycles by ambidoselective cyclization of enolate anions N-Acylmethyl-N-chloracetyl-2,6-dimethylanilines 4 were cyclized with base to 4-, 5- or 6-membered ring compounds, depending on the substituent R² (Scheme 2). All products can be rationalized as derived from the intermediate enolate anions a and b . The enolate anion a reacts by intramolecular alkylation to yield either 1, 4-oxazines 5 or azetidines 6 (Schemes 1, 3 and 7). The regioselectivity observed is expected on the basis of the allopolarization principle. The enolate anion b reacts only with formation of a new C? C bond (Scheme 5). Comparison with the behaviour of the 2, 6-unsubstituted anilines 9, 1a and 12 , shows a strong dependence not only on electronic but also on steric factors (Scheme 4 and 6).     

New polymers syntheses. 104. Synthesis of poly(ester‐imide)s from nylon 6, nylon 11, or nylon 12

Nylon 6 was reacted with trimellitic anhydride (TMA) at 230 °C so that a complete degradation to N‐(5‐carboxy‐pentamethylene) trimellitimide was obtained. The crude imide dicarboxylic acid was reacted in situ with 4,4′‐bisacetoxy biphenyl whereby an enantiotropic smectic polyesterimide was obtained. Analogous degradation and polycondensation reactions were also performed with nylon 11 and nylon 12. Parallel syntheses were conducted with isolated imide dicarboxylic acids. Furthermore, the crude imide dicarboxylic acid obtained from nylons 6, 11, and 12 were polycondensed in situ with diacetates of hydroquinone or substituted hydroquinone in combination with various amounts of acetoxy benzoic acid or 6‐acetoxy‐2‐naphthoic acid. In this way enantiotropic nematic copoly(ester‐imide)s were prepared. The phase transition of all LC‐poly(ester‐imide)s were characterized by DSC measurement and optical microscopy. In addition, a series of isotropic poly(ester‐imides)s was prepared using nonmesogenic bisphenols, such as bisphenol A, as comonomers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1630–1638, 2000     

Atropisomers of meso Tetra(N-Mesyl Pyrrol-2-yl) Porphyrins: Synthesis,Isolation and Characterization of All-Pyrrolic Porphyrins

Atropisomerism has been observed in a variety of biaryl compounds and meso-aryl substituted porphyrins. However, in porphyrins, this phenomenon had been shown only with o-substituted 6-membered aromatic groups at the meso-position. We show herein that a 5-membered heteroaromatic (N-mesyl-pyrrol-2-yl) group at the meso-position leads to atropisomerism. In addition, we report a ‘one-pot’ synthetic route for the synthesis of ‘all-pyrrolic’ porphyrin (APP) with several N-protection groups (Boc, Cbz, Ms and Ts). Among these groups, we found that only the Ms group gave four individually separable atropisomers of meso-tetra(N-Ms-pyrrol-2-yl) porphyrin. Furthermore, the reductive removal of Cbz- was achieved to obtain meso-tetra(pyrrol-2-yl) porphyrin. Thus, our synthetic procedure provides an easy access to a group of APPs and stable atropisomers, which is expected to expand the application of novel APP-based materials.     

Studies on lactams—XXX : Synthesis of dihydropyrroles and tetrahydropyridines as intermediates for bicyclic β-lactams

N-Acetyl derivatives of 5,6 or 7-membered lactams were condensed with aromatic aldehydes, deacetylated and allowed to react with P₂S₅ in refluxing pyridine. The thio-lactams so obtained were methylated with MeI to give 5- and 6-membered thioimidates which were convenient intermediates for the synthesis of penam and cepham derivatives.     

Darstellung und reaktionen von 1,3-bis-trimethylsilyloxy-isobenzofuranen und -isoindolen

1,3-Bis-trimethylsilyloxy substituted isobenzofurane (isolated as dimer $\text{3}$) and isoindoles (isolated as addition products with maleic imide and dibenzoyl ethene) could be prepared by the electrochemical reduction of substituted phthalic anhydrides and phthalic imides in the presence of chlorotrimethylsilane.