Bismuth compounds in organic synthesis. Bismuth nitrate catalyzed chemoselective synthesis of acylals from aromatic aldehydes

Aromatic aldehydes are smoothly converted into the corresponding acylals in good yields in the presence of 3-10 mol% Bi(NO₃)₃·5H₂O. Ketones are not affected under the reaction conditions. The relatively non-toxic nature of the catalyst, its ease of handling, easy availability and low cost make this procedure especially attractive for large-scale synthesis.     

Synthèse en une étape de N-méthoxyindolinones, de N-méthoxymaléimides et d’anhydrides maléiques à partir d’acides hydroxamiques α-halogénés

α-Halo hydroxamic acids were used in the synthesis of N-methoxyindolinones, symmetric and dissymmetric N-methoxymaleimides in good yields. The hydrolysis of N-methoxymaleimides constitues a new and good route to maleic anhydrides.     

Ethenolate Transfer Reactions: A Facile Synthesis of Vinyl Esters

A simple and efficient metal‐free ethenolate transfer reaction has been elaborated in moderate‐to‐high yields from vinyl acetate. This reaction was accomplished by generation of potassium ethenolate, which was then reacted with homo and mixed anhydrides of aliphatic, aryl and heteroaryl acids, to yield the corresponding vinyl esters. The utility of thus generated vinyl esters was then probed by carrying out intramolecular Heck reactions to give isobenzofuran‐1(3H)‐one derivatives in excellent yields.     

Organic reactions in water: an efficient method for the synthesis of 1,2,4-oxadiazoles in water

A simple and efficient process has been developed for the synthesis of 1,2,4-oxadiazoles in good yields through the reaction of amidoximes with anhydrides under catalyst-free conditions in water.     

Anhydride-functionalized fullerene: a versatile precursor for fullerene-based materials

Soluble phthalic anhydride-functionalized fullerene was generated via simple pyrolysis of the corresponding di-t-butyl phthalate precursor at 200 °C for 120 min. This non-chemical method for generating electrophilic fullerene may be advantageous for the preparation of various fullerene-containing materials. The utility of the resulting fullerene anhydride was demonstrated by solution coupling reaction with PEG-amine, surface reaction with amine-functionalized glass, and hydrolysis reaction to form amphiphilic fullerene.     

Dabco/SOCl 2 , Mild,and Convenient Reagent for the Preparation of Symmetrical Carboxylic Acid Anhydrides

Various types of carboxylic acids undergo rapid dehydration with 1,4-diazabicyclo[2.2.2]octane, dabco/thionyl chloride, under mild reaction conditions to afford symmetrical acid anhydrides in high isolated yields.     

Study on the chemical modification of epoxy/anhydride thermosets using a hydroxyl terminated hyperbranched polymer

Mixtures of diglycidylether of bisphenol A (DGEBA) resin and commercially available hyperbranched polyester (HBP) Boltorn H30 were cured by anhydride to covalently bond the hydroxyl end groups in HBP with the epoxy resin. The curing mixtures were investigated by Differential Scanning Calorimetry (DSC) to study the curing evolution and to evaluate the kinetic parameters. DSC studies suggested that HBP could increase the curing rate of epoxy/anhydride systems at low conversions, but it produced a decelerative effect in the last stages of the curing. The influence of the HBP content and the proportion of anhydride on the curing conversions were discussed in detail. The addition of a tertiary amine was proved to decrease the curing temperatures. By Fourier Transform Infrared Spectroscopy (FTIR) the reaction of hydroxyl groups during the whole process was confirmed. By the determination of the conversion at the gelation, we could prove that it increased on increasing the proportion of HBP in the reactive mixture. By Thermomechanical Analysis (TMA) we could determine a reduction of the shrinkage after gelation.     

A new odorless one-pot synthesis of thioesters and selenoesters promoted by Rongalite

Rongalite^® promotes cleavage of diaryl disulfides generating chalcogenolate anions that then undergo facile acylation with anhydrides in the presence of CsF to afford thioesters (3) with good to excellent yields. By using the present protocol, 5-arylthio-5-oxopentanoic acid (4) can be facilely prepared. The important features of the methodology are broad substrate scope, simple operation, and no requirement for metal catalysts. It is noteworthy that acylations of diphenyl diselane with anhydrides are also conducted smoothly to afford selenoesters (5) in good yields under the standard conditions.     

The Internal Steric Push-Effect: Its Consequences on the Reactivity of Carbonyl Functions in 3-Substituted Phthalic Anhydrides

The enhanced reactivity of the meta carbonyl function vis-a-vis nucleophiles in 3-substituted phthalic anhydrides is interpreted in terms of an internal steric effect. A through-space interaction between the substituent and the carbonyl function causes a displacement of electrons in the C=O bond from the oxygen to the carbon atom with simultaneous deactivation of the carbon atom toward nucleophilic attack and the oxygen atom toward complexation with a counter ion.     

One-pot synthesis of 3-hydroxymaleic anhydrides by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride

Functionalized 3-hydroxymaleic anhydrides were prepared by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride.