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 of bridgehead nitrogen heterocycles

Reductive cyclizations of N-[2-(2-pyridyl)ethyl]imides were accomplished by employing a palladium on carbon catalyst in ethanolic acetic acid as the hydrogenation medium. Reduction of the corresponding N-[2-(2-quinolyl)ethyl]imides ceased at the 1,2,3,4-tetrahydroquinolyl stage. Controlled reduction of the tetrahydroquinolyl imides with sodium borohydride gave amido alcohols which afforded bridgehead nitrogen heterocycles upon cyclodehydration.     

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.     

Anionic ring-opening polymerization of several N-substituted diphenimides

Five N-substituted diphenimides were prepared from the corresponding N-substituted amic acids. Attempts to polymerize the prepared seven-membered ring imides were partially successful. N-phenyldiphenimide was relatively the best monomer that polymerized anionically using n-butyl lithium or sodium metal as the initiater. The other N-substituted imides were sluggish in anionic polymerization. The resistance of the seven-membered ring imides toward ring-opening polymerization was attributed to the stability of the rings caused by the two phenylene groups adjacent to the carbonyls. © 1993 John Wiley & Sons, Inc.     

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.     

Synthesis of N-substituted imides via solid-liquid phase-transfer catalytic reaction

Summary N-substituted imides (RSIs) were synthesized from the reactions of alkylbromides (RX) and potassium salts of imides (KSIs) under solid-liquid phase-transfer catalytic conditions (SL-PTC). No water is required in the reaction system. In this work, serious hydration of KSIs is avoided using SL-PTC to synthesize RSIs. The reaction catalyzed by quaternary ammonium salts is greatly enhanced in the solid-liquid solution     

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.     

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.     

Stereospecific hydrogen migration in retro-diels-alder fragmentation of some polycyclic imides

A stereospecific ‘retro-Diels-Alder’ fragmentation followed by hydrogen migration was found in the mass spectra of imides and phenyl imides of decahydroindacene 4,5-dicarboxylic acid. The fragmentation involves a one hydrogen atom rearrangement when the charge is retained on the diene moiety and double hydrogen rearrangement when the charge is on the dienophilic moiety.     

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.     

N‐Alkylation of imides using phase transfer catalysts under solvent‐free conditions

N‐Alkylation of imides in the reaction of imides and alkylhalides, catalyzed by PT catalysts under solvent‐free conditions, has been developed. The reaction occurs in the presence of K₂CO₃, and in many cases it takes place spontaneously. In the N‐benzylation reaction, it has been recognized that TBAB (tetrabutylammonium bromide) and TBATFB (tetrabutylammonium tetrafluoroborate) show highest catalytic effect. Versatility and synthetic capacity of the solvent‐free alkylation has been confirmed by N‐benzylation and N‐ethylation of various imides. The developed procedure gives easy access to N‐(ω‐bromoalkyl)imides.     

Hydrazine-based polyimides and model compounds

The reaction of hydrazine hydrate with aromatic anhydrides may give either N-amino imides or cyclohydrazides. The conditions that favor the formation of N-aminoimides, in which the imide contains respectively a 5- and 6-membered ring, are discussed. These compounds may be reacted with aromatic anhydrides to give N-N-linked imides. The properties of a number of model compounds and polymers are described, and it is shown that those compounds which have alternating 5- and 6-membered imide rings give the maximum oxidative stability in air at 400°C.     

Fluorescence reagents. I. Derivatization of carboxylic acids,imides and alcohols with 1-chloromethylbenz[c,d]indol-2(1H)-one (CMBI)

The derivatization and fluorodensitometric determination of carboxylic acids (CA), imides and alcohols with 1-chloromethylbenz[c,d]indol-2(1H)-one ( 19 , CMBI) have been studied. Out of a series of fluorescent fused lactams 9-11, 13-15 and 17 , benzindolone 17 was selected and transformed via hydroxymethylbenzin-dolone 18 into CMBI 19. CMBI reacts with CA, diCA and alcohols respectively to yield strongly fluorescent benz[c,d]indol-1-ylmethyl esters 20, 21 (BIM esters) and BIM ethers 22. Phenobarbital is transformed by action of CMBI into fluorescent 1,3-bisBIM phenobarbital 25. Studies on the applicability of the derivatization reactions to the fluorodensitometric determination of CA, alcohols and imides showed that CA with more than 3 carbon atoms can be determined via BIM esters down to the low picomole range. In the case of alcohols and imides the results were not satisfying. The ir, uv, fluorescence, nmr and mass spectra of the prepared benzindole derivatives are also presented.     

The synthesis of bisitaconamic acids and isomeric bisimide monomers

Members of a series of N,N′-alkylene bisitaconamic acids were synthesized from the reaction between itaconic anhydride and a homologous group of aliphatic diamines with the general formula H₂N (CH₂)_n NH₂, where n = 4–12. Cyclodehydration of the acids in toluene gave the isomeric imides: bisitaconimide, biscitraconimide, and citra-itaconimide. The isomeric imides were isolated, purified, and characterized for each diaminoalkane studied.     

Polyimides derived from bismethylolimides. I. Polyamide–imides from bismethylolimides and dinitriles

New polyamide–imides were synthesized from bismethylolimides and dinitriles. The bismethylolimides, N,N′-bismethylolpyromellitdiimide and N,N′-bismethylolbenzophenonete-tracarboxylic diimide, were prepared by the hydroxymethylation of the corresponding diimides with formaldehyde. The polymerization reaction was carried out in either concentrated sulfuric acid or poly(phosphoric acid), and the former was found to be superior to the latter. The polyamide–imides had inherent viscosities in the 0.08–0.41 dl/g range. Most of these polymers were soluble in m-cresol and dichloroacetic acid. The thermal stability of the polymers was examined by thermogravimetric analysis, and they were found to start to decompose at 275–350°C in air.     

The reaction of lithium phenylacetylide and phenyllithium with N-(ω-Bromoalkyl)phthalimides

Lithium phenylacetylide reacted with short-chain N-(ω-bromoalkyl)phthalimides 1b and 1c to give tricyclic products 2b and 2c in moderate yields. Likewise, tricyclic products 3a-c were obtained when short-chain imides 1a-c were treated with phenyllithium. When longer-chain imides 1d-f in this series were treated with lithium phenylacetylide only tertiary alcohols 4d-f could be isolated. Partial hydrogenation of 2b and 2c yielded the corresponding alkenes 5b and 5c , products which corroborated the structural assignment of 2b and 2c .     

A ONE-STEP PROTOCOL FOR THE N-CHLOROMETHYLATION OF HETEROCYCLIC IMIDES

A convenient single step methodology for the N-chloromethylation of heterocyclic imides using a mixture of formaldehyde sodium bisulfite adduct and thionyl chloride is described.     

Synthesis and properties of alternating copolyamide‐imides based on 2,6‐bis(4‐aminophenoxy)naphthalene and comparison with its related isomeric polymers

A series of novel polyamide‐imides III containing 2,6‐bis(phenoxy)naphthalene units were synthesized by 2,6‐bis(4‐aminophenoxy)naphthalene and various bis(trimellitimide)s in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents through direct polycondensation. The polymers were obtained in quantitative yield with inherent viscosities up to 1.53 dL/g. Most of the polymers showed good solubility in NMP, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide and could be solution‐cast into transparent, flexible, and tough films. The films had tensile strengths of 84–111 MPa, elongations at break of 8–33%, and initial moduli of 2.2–2.8 GPa. Wide‐angle X‐ray diffraction revealed that most polymers III were amorphous. The glass‐transition temperatures of some of the polymers could be determined by differential scanning calorimetry traces, recorded at 247–290 °C. The polyamide‐imides exhibited excellent thermal stabilities and had 10% weight loss at temperatures in the range of 501–575 °C under nitrogen atmosphere. They left more than 57% residue even at 800 °C in nitrogen. A comparative study of some corresponding polyamide‐imides is also presented. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2591–2601, 2001     

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.     

微波辐射下氧化N-烷基酰胺合成二酰亚胺

二酰亚胺是一个很有用的官能团, 它广泛存在于天然产物和有药物活性的分子中. 通过微波辐射条件合成它吸引了很多化学家的注意. 极性反应物可以吸收微波辐射, 化学家将微波应用于一些化学反应中. N-烷基酰胺(NH邻位有一个亚甲基CH₂)和N上没有取代的内酰胺可以被过氧化物和过渡金属盐氧化成二酰亚胺. 报道了在乙酸乙酯中过氧叔丁醇和乙酰丙酮锰(III)在微波条件(90 W, 5 min)下, 酰胺迅速、高选择性地、高产率地转变为二酰亚胺的方法.