Addition of a Silyl Ketene Acetal to α,β-Unsaturated Cyclic Anhydrides

Addition of [1-methoxy-2 methyl-1-propenyl)-oxy] trimethylsilane (MTS) to unsymmetrical α,β-unsaturated cyclic anhydrides (namely, itaconic anhydride and citraconic anhydride) as well as symmetrical anhydrides (namely, maleic anhydride and 2,3-dimethylmaleic anhydride) was investigated. Itaconic anhydride isomerizes to citraconic anhydride in the presence of MTS. In the presence of Lewis acid catalysts (Yb(OTf)₃/CH₂Cl₂), MTS adds to itaconic anhydride at room temperature in a 1,4-fashion. 1,2-Addition is the preferred pathway with both 2,3-dimethyl maleic anhydride and citraconic anhydride.     

The synthesis of biscitraconimides and polybiscitraconimides

A series of N-alkylene biscitraconimides was synthesized from the corresponding N-alkylene-biscitraconamic acids or directly from itaconic anhydride and a homologous series of aliphatic diamines, H₂N(CH₂)_nNH₂, where n = 2 through 12. The biscitraconamic acids were synthesized from the α,ω-diamino-alkanes and itaconic anhydride. Isomerization of itaconic anhydride to citraconic anhydride occurs in the presence of the diamines to yield biscitraconamic acids instead of bisitaconamic acids expected and observed in similar studies. The intermediate biscitraconamic acids or the biscitraconimides were polymerized thermally between 175 and 225°C to tough ambered-colored films of polybiscitraconimides that exhibit good thermal stability.     

Thermolysis of 7-phenyl-2,3,7-triazabicyclo[3.3.0]oct-2-ene-6,8-dione

Thermolysis of the title compound in boiling xylene (138°) produces a 7.7/10.1/1.0 mixture of the N-phenylimides of cis-1,2-cyclopropanedicarboxylic acid, citraconic acid, and itaconic acid. The imides of citraconic and itaconic acids are produced by hydrogen shifts. A completely concerted mechanism involving simultaneous hydrogen shift and cleavage of both C-N bonds is unlikely in the present case because both hydrideshift products are formed and because the optimal arrangement for the hydrogen shift requires deformation of the imide ring and loss of imide resonance. The C? N bond strengths in the title compound should be quite different. The products can arise either from two parallel pathways involving nitrogen-containing dipoles or from a single nitrogen-free trimethylene fragment.     

Chemoselective and Regiospecific Synthesis of Iminospiro‐γ‐lactones from Maleic Anhydride or Citraconic Anhydride and Alkyl Isocyanides with Dialkyl Acetylenedicarboxylates

Isocyanides, dialkyl acetylenedicarboxylates (=dialkyl but‐2‐ynedioates), and anhydrides such as maleic anhydride (=furan‐2,3‐dione) or citraconic anhydride (=3‐methylfuran‐2,3‐dione) react in one pot to afford novel iminospiro‐γ‐lactones in fairly good yields at room temperature (Schemes 1 and 3).     

Reaction of 2-(phenylamino)benzoic and 2-(phenylamino)- and 2-methyl-6-phenylpyridine-3-carboxylic acid hydrazides with succininc anhydride

Reactions of 2-(phenylamino)benzoic and 2-(phenylamino)- and 2-methyl-6-phenylpyridine-3-carboxylic acid hydrazides with succinic anhydride in organic solvents at room temperature gave the corresponding 4-(2-aroylhydrazinyl)-4-oxobutanoic acids. The reactions in boiling acetic acid afforded N-(2,5-dioxopyrrolidin-1-yl)benzamide or N-(2,5-dioxopyrrolidin-1-yl)pyridine-3-carboxamide.     

Solid-state polymerization of N-carboxy-L-leucine anhydride crystals in n-hexane

4-Isobutyloxazolidinedione, L -leucine N-carboxy anhydride, was polymerized to produce high molecular weight polymer with triethylamine in n-hexane which is not a solvent for the N-carboxy anhydride and poly-L -leucine. It was found that as the crystal size became smaller, the total surface area was increased, the initial rate of polymerization was increased, and inherent viscosity of the formed polymer was decreased.     

Unexpected formation of N,N-disubstituted formamidines from aromatic amines, formamides and trifluoroacetic anhydride

An intriguing selectivity towards the formation of the formamidine was observed upon the reaction of an amine with sodium hydride and trifluoroacetic anhydride in dimethyl formamide. Various aromatic amines were reacted with a series of N,N-disubstituted formamides as a solvent under the influence of trifluoroacetic anhydride to thoroughly probe this behaviour. A trend in selectivity is discussed and a proposed mechanism for the reaction is also presented.     

Regioselectivity in the Addition of 1,3-Dipolarophiles to 6-Aryl-1,5-diazabicyclo[3.1.0]hexanes

Thermolysis of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes in the presence of 1,3-dipolarophiles having an unsymmetrically substituted double C=C bond (such as N-arylimides derived from 2-aryl-substituted maleic, citraconic, and itaconic acids, ethyl propynoate, aryl isocyanates, and aryl isothiocyanates) leads to formation of the corresponding 1,3-dipolar cycloaddition products. The reaction is regioselective, and in most cases only one regioisomer is obtained. The addition direction depends on the 1,3-dipolarophile structure, i.e., electronic and steric factors determining the most effective orbital interaction upon approach of the reagent to substrate.     

Kinetic Study of the Bromine-Catalyzed Isomerization of Methyl- and Chloro-Maleic Acids in Aqueous Ce(IV)-Br -H2SO4 Medium

Methylmaleic (citraconic, CTA) acid and methylfumaric (measaconic, MSA) acid in aqueous sulfuric acid solution undergo bromine-catalyzed reversible cis-trans isomerization in the presence of ceric and bromide ions. The positional isomerization of CTA or MSA to itaconic acid (ITA) is not observed. The method of high performance liquid chromatography (HPLC) was applied to study the kinetics of this catalyzed isomerization. The major catalytic species is best expressed as the Br^?₂ · radical anion. Under suitable catalytic conditions, there is a tendency for the [MSA]/[CTA] ratio to reach an equilibrium value of 4.10 at 25° for the CTA+Br^?₂ · ? MSA+Br^?₂ · reaction. Chloromaleic (CMA) and chlorofumaric (CFA) acids undergo similar isomerization with an equilibrium [CFA]/[CMA] ratio of 10.3 at 25°. The isomerization of maleic acid (MA) to fumaric acid (FA) is essentially irreversible with 50 as the lower limit of the equilibrium [FA]/[MA] ratio. The substituent has an important effect on the reversibility of this catalyzed isomerization of butenedicarboxylic acids. The thermodynamic parameters ΔH° and ΔS° at 25° for the CTA+Br^?₂ · ? MSA+Br^?₂ · reaction were found to be ?5.1±0.7 kj/mol and ?6.0±3.3 J/mol K, respectively. The present method gives a plausible way to measure the differences in enthalpy and entropy between the trans- and cis-isomers of butenedicarboxylic acids (CRCO₂H=CR'CO₂H) in aqueous solution.     

Syntheses and reactions of functional polymers. XLII. Preparation and use of polymers having N-hydroxy-succinimide unit in the chain

Styrene-maleic anhydride alternating copolymer was converted to N-hydroxymaleimide-styrene copolymer by reaction with hydroxylamine in pyridine at room temperature. The conversion was more than 90%. From this copolymer, N-acetoxy- or N-benzoyloxymaleimide-styrene copolymers were derived by action of acetic anhydride or benzoyl chloride in dimethylformamide at room temperature. Acylation of several primary amines was carried out effectively by use of these N-acyloxyimide-styrene copolymers. The reaction of the acetylated copolymer with diethylamine at room temperature afforded N-hydroxyimide copolymer.     

One-pot, three-component reaction of isocyanides, dialkyl acetylenedicarboxylates, and non-cyclic anhydrides: synthesis of 2,5-diaminofuran derivatives and dialkyl (E)-2-[(N-acyl-N-alkylamino)carbonyl]-2-butenedioates

Abstract  

Isocyanides, dialkyl acetylenedicarboxylates, and non-cyclic anhydrides, for example acetic anhydride or benzoic anhydride, react in one-pot to afford 2,5-diaminofuran derivatives and dialkyl (E)-2-[(N-acyl-N-alkylamino)carbonyl]-2-butenedioates in fairly good yields at room temperature.     

Preparation of N‐alkylpyridinium aryl ketone derivatives via the surfactant promoted cross‐coupling reaction of N‐alkylpyridiniumboronic acids with carboxylic anhydride in water at room temperature

The palladium (II) chloride catalyzed coupling reaction of N‐alkylpyridiniumboronic acids with benzoic anhydride was carried out smoothly in water to give high yields of ketones without the use of a phosphine ligand. The reaction was conducted under mild conditions at room temperature. In this article, by focusing on the Suzuki reaction, it is shown how this method can impact modern synthetic chemistry, making reactions faster, easier and cleaner. Copyright © 2009 John Wiley & Sons, Ltd.     

Amine/anhydride reaction versus amide/anhydride reaction in polyamide/anhydride carriers

Polyamide 6 (PA6) and poly(metaxylene adipamide) (PAmXD6) were blended in a batch mixer with anhydrides such as phthalic anhydride, n-octadecyl succinic anhydride, and anhydride-grafted ethylene propylene rubber. The melt viscosity, the solution viscosity, and chain end concentration were studied during the mixing. PA was first mixed 5 min to get an homogeneous melt prior to the anhydride addition. The introduction of the anhydride to the molten polyamide resulted in large decreases of melt and solution viscosities and of amine chain end concentrations. The anhydride units react with amine chain ends to form imide groups. The resulting low amine chain end concentration causes hydrolysis reaction to maintain the condensation equilibrium. As a consequence an increased carboxylic chain end concentration is observed. The imide concentration was studied by IR. It was shown that when most of the amine chain ends are consumed, the remaining anhydride reacts with amino groups formed by polyamide hydrolysis. © 1995 John Wiley & Sons, Inc.     

A macroporous polymer-supported cyclic anhydride for efficient sequestration of amines

The efficient removal of primary and secondary amines from organic solutions using a macroporous polymer-supported anhydride is described. The sequestering of primary amines by the anhydride via polymer-bound amide formation is completed within 2-4 h at room temperature. Secondary amines require typically 4 h for complete sequestration.     

Copolymerization of N-carboxy Nϵ-carbobenzoxy L-lysine anhydride with N-carboxy β-benzyl L-aspartate anhydride in acetonitrile

Copolymerization of N-carboxy N^?-carbobenzoxy L -lysine anydride with N-carboxy β-benzyl L -aspartate anhydride was initiated with n-butylamine in acetonitrile. The copolymerization proceeded almost homogeneously except for the initial stage, when the proportion of N-carboxy anhydride (NCA) in the polymerization mixture varied from 25 to 75 mol %. This was due to the fact that the copolypeptides formed were soluble or highly swollen in the solvent, in contrast to the homopolymerization of NCAs such as N^?-carbobenzoxy L -lysine NCA and β-benzyl L -aspartate NCA in acetonitrile, which proceeds heterogeneously. The compositions of the copolymers obtained were, within experimental error, the same as their monomer feed compositions. The initial rates of copolymerization were almost the same as the rate of homopolymerization of β-benzyl L -aspartate NCA, which propagates with a nonhelical polypeptide, but were slower than the rate of homopolymerization of N^?-carbobenzoxy L -lysine NCA, which propagates with a helical polypeptide.     

Acetylation of alcohols with acetic anhydride promoted by N,N,N-trimethylanilinium tribromide

A wide variety of alcohols were reacted with acetic anhydride at room temperature in the presence of a catalytic amount of N,N,N-trimethylanilinium tribromide to produce the corresponding alkyl acetates in good to excellent yields. Following this procedure, acetylation of primary, secondary, and tertiary alcohols has been performed under neutral conditions.     

Preparation of Silica‐bonded Propyl‐diethylene‐triamine‐N‐sulfamic Acid as a Recyclable Catalyst for Chemoselective Synthesis of 1,1‐Diacetates

A simple and efficient procedure for the preparation of silica‐bonded propyl‐diethylene‐triamine‐N‐sulfamic acid (SPDTSA) by reaction of 3‐diethylenetriamine‐propylsilica (DTPS) and chlorosulfonic acid in chloroform is described. Silica‐bonded propyl‐diethylene‐triamine‐N‐sulfamic acid is employed as a recyclable catalyst for the synthesis of 1,1‐diacetates from aromatic aldehydes and acetic anhydride under mild and solvent‐free conditions at room temperature. Catalyst could be recycled for several times without any additional treatment.     

Synthesis of aromatic polyamide-imides from N,N′-bis(trimethylsilyl)-substituted aromatic diamines and 4-chloroformylphthalic anhydride

The polymerization of N,N′-bis(trimethylsilyl)-substituted aromatic diamines with 4-chloroformylphthalic anhydride in various solvents at a temperature range between 10 and 70°C afforded polyamide-amic acid trimethylsilyl esters having inherent viscosities of 0.8–1.4 dL/g. Transparent and flexible films of the silylated precursor polymers were obtained by casting directly from the polymer solutions. Desilylation of the silylated polymers with methanol resulted in the formation of the corresponding polyamide-amic acids. Subsequent thermal imidization of the silylated precursor polymers with the elimination of trimethylsilanol afforded yellow, transparent, and tough films of the aromatic polyamide-imides. The thermal conversion of the silylated precursor polymer to polyamide-imide proceeded almost as rapidly as that of the corresponding polyamide-amic acid prepared by a conventional method from the parent aromatic diamine and 4-chloroformylphthalic anhydride.     

Novel synthesis of steryl esteryl esters from β-sitosterol and N-phosphoryl amino acid under microwave irradiation

Ten novel N-phosphoryl amino acids β-sitosterol esters were synthesized by coupling the N-phosphoryl amino acids with β-sitosterol under microwave irradiation, and their structures were elucidated by IR, NMR, and HR MS. Various reaction conditions including the catalyst, solvent, temperature and time were investigated. Under the optimal conditions, the reaction was finished in 20 min with 60–87% yields by employing DCC/DMAP as a catalyst system at room temperature.     

Synthesis of coruscanones A and B,metabolites of <Emphasis Type="Italic">Piper coruscans</Emphasis>, and related compounds

Base-catalyzed rearrangements of both individual 4-(acylmethylidene)butenolides and their mixtures prepared by condensation of citraconic anhydride with various phosphoranes occur successfully only in the presence of 5.2% MeONa in MeOH (molar ratio MeONa: substrate ≤ 10: 1, room temperature, 1–2 h). Under these conditions, the yields of 2-cinnamoyl-4-methylcyclopent-4-ene-1,3-dione (coruscanone B) and 2-acetyl-4-methylcyclopent-4-ene-1,3-dione are 56 and 65%, respectively. With a considerable increase in the reaction temperature or the molar ratio MeONa: substrate, formal addition of MeOH to the C(4)=C(5) double bond of these triketones becomes an appreciable (or predominant) process. A reaction of coruscanone B with CH₂N₂ in ether gives coruscanone A as a ~3: 2 mixture of (Z)- and (E)-methyl enolates (43%); other products (10%) result from the expansion and aromatization of the five-membered ring of the triketone. The simplest analog of coruscanone B, 2-acetyl-4-methylcyclopent-4-ene-1,3-dione, reacts with CH₂N₂ in a similar way.