Dihydro-3-(triphenylphosphoranylidene)-2,5-thiophendione: A Convenient Synthon for the Preparation of Substituted 1,4-Thiazepin-5-ones and Piperidinones via the Intermediacy of Thioacids

Reaction of thiomaleic anhydride with triphenylphosphine gives the title compound, which undergoes reaction with a variety of aldehydes to give a range of alkylidene thiomaleic anhydrides (substituted monothioitaconic anhydrides). Subsequent treatment with tert-butoxycarbonylamino-substituted thiols, or under radical conditions with tert-butoxycarbonylamino-substituted alkyl halides results in a series of substituted monothiomaleic anhydrides, that on exposure to trifluoroacetic acid and then base lead to thiocarboxyl substituted 1,4-thiazepin-5-ones and piperidinones, respectively, that are ultimately trapped by reaction with 2,4-dinitrobenzenesulfonamides to give the corresponding amides.     

New heterocycles of 2,3‐diaryl‐substituted maleic hydrazides

2,3‐Diaryl‐substituted maleic anhydrides were prepared by a modified one‐pot synthesis of Perkin condensation using mixed sodium salts of arylglyoxylic acid and arylacetic acid with acetic anhydride in 1,4‐dioxane. The treatment of these anhydrides with ammonium bicarbonate, or methanolic hydrazine, offered the corresponding 2,3‐diaryl‐substituted maleimides and maleic hydrazides (4,5‐diaryl‐substituted 1,2‐dihydropyridazine‐3,6‐dione), respectively. Evidence obtained from NMR, UV, and mass spectra suggest that 2,3‐diaryl‐substituted maleic hydrazides do not exhibit monolactim forms. Ring contraction of the diaryl‐substituted maleic hydrazide by nitrosation led to the formation of the corresponding maleimide. Interconversion between the corresponding maleic hydrazide and maleimide was observed following equilibrium reaction. Our experiment proposes that the chemistry of 2,3‐diaryl‐substituted maleic hydrazides rarely involves the function of ethylene moiety and resembles that of succinic hydrazine. J. Heterocyclic Chem.,(2011).     

The preparation of 7-substituted norbornadiene-2,3-dicarboxylic anhydrides and an experimental and theoretical study of their reactivity

Four new substituted methano-bridged or heteroatom-bridged norbornadienomaleic anhydrides have been prepared and converted to sesquinorbornadiene anhydrides by reaction with cyclic 1,3-dienes. The versatility of parity reversal, in conjunction with N-substituent steric effects, has been used to produce all three possible stereoisomers of the N,O-sesquinorbornadiene anhydrides in separate, stereoselective cycloadditions. The anhydrides have been synthesized by cyclization of their diacids (in situ production) or by flash vacuum pyrolysis of their furan adducts (yielding crystalline products); further fragmentation occurs at these or higher temperatures to produce five-membered carbocyclic or heterocyclic anhydrides. Activation energies have been evaluated for the fragmentation and cycloaddition processes using DFT calculations (B3LYP/6-31G∗) and these calculations correctly predict, which reaction can be intercepted at the norbornadienomaleic anhydride stage and preferred stereochemistry of cycloadducts.     

Combinatorial synthesis of heterocycles: solid-phase synthesis of 2-amino-4(1H)-quinazolinone derivatives

A new solid-phase synthesis of various substituted 2-amino-4(1H)-quinazolinones from a resin bound amine component is described. The amine was readily converted to the corresponding polymer bound S-methylthiopseudourea. Condensation with different substituted isatoic anhydrides afforded 2-amino-4(1H)-quinazolinone derivatives. The method is amenable for combinatorial library generation.     

1,3-Dipolar cycloaddition-decarboxylation reactions of an azomethine ylide with isatoic anhydrides: formation of novel benzodiazepinones

A nonstabilized azomethine ylide reacts with a wide range of substituted isatoic anhydrides to afford novel 1,3-benzodiazepin-5-one derivatives, which are generally isolated in high yield. The transformations involve 1,3-dipolar cycloaddition reactions of the ylide with the anhydrides to give transient, and in a representative case spectroscopically observable, oxazolidine intermediates that undergo ring-opening-decarboxylation-ring-closing reaction cascades to yield the 1,3-benzodiazepin-5-one products.     

The mercury-mediated decarboxylation (Pesci reaction) of naphthoic anhydrides investigated by microwave synthesis

The mercury-mediated decarboxylation (Pesci reaction) of several substituted naphthoic anhydrides has been investigated by microwave synthesis. A laboratory microwave reactor was found to be ideal for small-scale preparations of this slow reaction, reducing reaction times from typically four days to less than 1 h for the three-step process. The ionic reaction medium rapidly heated to high temperatures under microwave heating and could be efficiently maintained by low microwave power settings. Generation of stoichiometric CO₂ was safely contained within the reaction tubes. A simplified reaction procedure has been developed. For substituted naphthoic anhydrides, ¹H NMR analysis of the naphthoate ester derivatives indicated no change in the regioisomer ratio compared to previously reported thermal values.     

Chemistry of 2,5-bis(trimethylsiloxy) furans. I: Preparation and diels-alder reactions

A number of substituted 2,5-bis (trimethylsioloxy) furans were prepared from the corresponding succinic anhydrides, and were found to be reactive dienes for the Diels-Alder reaction with electron - withdrawing dienophiles, giving p-quinones and hydroquinones.     

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.     

Synthesis and study of the luminescence properties of anhydrides and n-phenylimides of 4-(2-aryl-1,3,4-oxadiazol-5-yl)naphthalic acids

4-(2-Aryl-1,3,4-oxadiazol-5-yl)naphthalic anhydrides were obtained by condensation of 4-chlorocarbonylnaphthalic anhydride with monohydrazides of substituted benzoic acids and subsequent cyclodehydration; the corresponding N-phenylimides were obtained from the 4-(2-aryl-1,3,4-oxadiazol-5-yl)naphthalic anhydrides. The UV and luminescence spectra are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 461–463 April, 1974.     

Derivatives of 2-(3'-coumarinyl)-1, 3-indandione

The possibility of the direct preparation of 2-(3'-coumarinyl)-1,3-indandione and its derivatives by condensing phthalic and substituted phthalic anhydrides with 3-coumarinylacetic acid in acetic anhydride solution in the presence of triethylamine has been shown. The bromination and hydroxymethylation of 2-(3'coumarinyl)-1,3-indandione and its substituted derivatives have been performed.     

Room-temperature synthesis of pharmaceutically important carboxylic acids bearing the 1,2,4-oxadiazole moiety

An efficient and mild one-pot protocol has been developed for the synthesis of 1,2,4-oxadiazoles via the reaction of amidoximes with dicarboxylic acid anhydrides in a NaOH/DMSO medium. The method allows the synthesis of diversely substituted carboxylic acids bearing the 1,2,4-oxadiazole motif, – a popular building block for pharmaceutical research, in moderate to excellent yields. The reaction scope includes aromatic and heteroaromatic amidoximes as well as five-, six- and seven-membered anhydrides. The advantages of this procedure are proven gram-scalability and the use of inexpensive starting materials, which from a process chemistry point of view are essential for future industrial applications.     

Nickel-catalyzed cycloadditions of thiophthalic anhydrides with alkynes

Nickel-catalyzed cycloadditions have been developed where thiophthalic anhydrides react with alkynes to afford substituted sulfur-containing heterocyclic compounds. Selective formations of thioisocoumarins, benzothiophenes, and thiochromones were accomplished with three different reaction conditions.     

Chemistry of hetero analogs of isoflavones 26. Synthesis of 2-alkyl derivatives of 3-(thiazol-2-yl)-and 3-(benzothiazol-2-yl)chromones

Treatment of substituted 2-(2,4-dihydroxyphenacyl)thiazole and 2-(2,4-dihydroxyphenacyl)benzothiazole with propionic and isobutyric anhydrides gives the substituted 2-ethyl-and 2-isopropyl-7-acyloxychromones. The use of pivaloyl chloride gives 1-pivaloyloxy-2-hetarylstyrene derivatives. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 835–840, June, 2008.     

Catalytic Asymmetric Tamura Cycloadditions

In the presence of a novel, tert‐butyl‐substituted squaramide‐based catalyst, enolizable anhydrides react with alkylidene oxindoles to generate spirooxindole products of significant synthetic interest with excellent enantio‐ and diastereocontrol. The methodology is of wide scope and encompasses both homophthalic and glutaconic anhydride derivatives, which lead to structurally diverse products. Glutaconic acid‐derived anhydrides undergo a clean post‐cyclization decarboxylation process which is not a feature of reactions involving homophthalic acid‐derived anhydrides. The unusual influence of reaction temperature on diastereocontrol has been probed, with reactions occurring at 30 °C and ?30 °C delivering products epimeric at one stereocenter only, in near optical purity.     

Photochemical and thermal transformations of carboxylic dithiocarbamic anhydrides and acyl xanthates

The reaction of diphenylchloroacetyl chloride with different dithiocarbamates gave the corresponding dithiocarbamic anhydrides. Under analogous conditions, dithiocarbamyl phenylacetic acids and dithiocarbamyl acetic acids were formed from the reaction of dithiocarbamates with phenylchloroacetyl chloride and chloroacetyl chloride, respectively. O-Ethyl S-acyl xanthates were formed from the reaction of potassium O-ethyl xanthate with diphenylacetyl chloride, diphenylchloroacetyl chloride, cyclopentylphenylacetyl chloride and triphenylacetyl chloride. Photolysis of dithiocarbamic anhydrides gave a mixture of products consisting of 1,2-dichlorotetraphenylethane, carbon monoxide and the corresponding thiocarbamoyl sulfides. Acyl xanthates, on the other hand, gave carbon monoxide and the corresponding substituted ethane derivatives. When dithiocarbamic anhydrides were refluxed in hydroxylic solvents such as methanol, ethanol and n-propanol, the corresponding dithiocarbamyl acetates were formed. Thermal decomposition of acyl xanthates gave carbon disulfide and the corresponding esters.     

An expeditious synthesis of natural and unnatural disubstituted maleic anhydrides

A facile entry to the synthesis of natural and unnatural substituted maleic anhydrides based on the Barton radical decarboxylation is described. The radicals, generated by the photolysis of N-hydroxy-2-thiopyridone esters derived from succinic and alkyl acids reacted, respectively, with electron deficient olefin phenyl maleimide by a consecutive two-step radical addition, afforded the corresponding disubstituted maleic anhydrides 1a-f.     

Reaction of di(bromomagnesio)alkanes with unsymmetrically substituted cyclic anhydrides

Alkylated γ-spirolactones were prepared in one-step reactions in high yields from butane-1,4-diyl and pentane-1,5 diyldimagnesium dibromides and substituted cyclic anhydrides in tetrahydrofuran. In the light of experimental findings electronic and steric factors influence the regiospecificity of this reaction.     

Envirocats,as Novel Solid‐Supported Catalysts for Friedel‐Crafts Acylation

The Friedel‐Crafts acylation reactions of substituted benzenes with acid chloride or anhydrides proceeded smoothly in the presence of a catalytic amount of novel solid‐supported reagents such as EPZG, EPZ10, EPIC and EPZE. These catalysts are reusable and environmentally friendly.     

Homophthalic anhydrides and their application to the synthesis of heterocyclic compounds (review)

This review covers the reactions of homophthalic anhydrides and their related C-H-acid anhydrides with compounds containing carbon-oxygen or carbon-nitrogen double bonds, which yield compounds with a substituted or condensed -pyrone or -pyri-done ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1587–1599, December, 1984.     

Selective esterifications of alcohols and phenols through carbodiimide couplings

Esterification of carboxylic acids capable of forming ketene intermediates upon treatment with carbodiimides permits the selective acylation of alcohols in the presence of phenols lacking strong electron-withdrawing groups. The selectivity of acylations involving highly acidic phenols could be reversed through the addition of catalytic amount of acid. Esterification of other carboxylic acids was found to proceed through the formation of symmetric anhydrides and provide the opposite chemoselectivity. In both cases the relative acylation rates of substituted phenols are consistent with a reaction mechanism involving an attack of phenolate anions on electrophilic intermediates such as ketenes and symmetric anhydrides, with the carbodiimides serving both as an activating reagent and as a basic catalyst.