A mild and facile synthesis of carboxylic anhydrides

Reaction of carboxylic acids with trimethylsilylethoxyacetylene in an inert solvent under mild conditions affords the corresponding carboxylic anhydrides in almost quantitative yields.     

Microwave-assisted Palladium Catalyzed Cross-coupling Reaction of Sodium Tetraphenylborate with Carboxylic Anhydrides

A rapid and efficient method for synthesis of unsymmetrical ketones under microwave irradiation is reported.     

Reaction of α-cyanomethylazaheterocycles with α-halo carboxylic acid chlorides and anhydrides

-Cyanomethylazaheterocycles (I) are acylated by -halo carboxylic acid chlorides and anhydrides at the methylene carbon atom to give hetaryl-containing halo ketones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1515–1517, November, 1977.     

Reaction of free radicals with unsymmetrical organomercury compounds

Russian Chemical Bulletin -     

Reaction of mixed carboxylic anhydrides with grignard reagents : Application to the preparation of keto esters; scope and limitations

The low-temperature Grignard reaction of mixed carboxylic anhydrides derived from acid chlorides and o-anisic acid to the general synthesis of keto esters is demonstrated for compounds 1–6, although, some limitations on substrate and Grignard reagent species are also encountered; attempts in the oxa series 2 are unsuccessful, and reaction with ω-phenylpropyl Grignard species for 1 and 4 shows a drastic decrease in yields of the keto esters for m-methoxy analogues. Anomalous behaviour may be associated with an alternative type of specific metal-coordination complex which includes the ether oxygen atom properly situated in the substrate or the reagent     

A new synthesis of carboxylic and carbonic acid anhydrides using phase transfer reactions

Acyl chlorides and alkylchloroformates smoothly reacted with one molar equivalent of sodium hydxoxide, using liquid-liquid phase transfer conditions to afford high yields of the corresponding symmtrical carboxylic and carbonic hemiester anhydrides. Unstable, anhydrides such as 4-nitrobenzoïc, 2-furoïc and methacrylic anhydrides, which are otherwise difficult to obtain, were easily prepared by this method. The reaction mechanism does not seem to involve intermediate hydrolysis of half the acid chloride into the corresponding sodium carboxylate.     

Palladium-catalyzed cross-coupling reactions of carboxylic anhydrides with organozinc reagents

[reaction: see text] Negishi-type cross-coupling reaction was effected by employing organozincs and anhydrides or mixed anhydrides that formed in situ from sodium salts of the corresponding acids and ethyl chloroformate under the catalysis of palladium(0). A general method for preparing symmetrical/unsymmetrical ketones was developed.     

Practical acid-catalyzed acylation of sulfonamides with carboxylic acid anhydrides

A highly efficient reaction between sterically and electronically diverse sulfonamides and carboxylic acid anhydrides to furnish monoacylated N-acylsulfonamides is described. This represents the first systematic disclosure of the scope of sulfuric acid-catalyzed acylation of sulfonamides.     

Reaction of acetyloxiranes with acetonitrile

2-Acetyloxiranes react with acetonitrile in the presence of equimolar amounts of Lewis acids. It was established that the use of boron trifluoride etherate or sulfuric acid as the catalyst leads to 2,7- and 3,6-diepoxy-1,5-dioxocanes, the use of aluminum trichloride, as well as stannic chloride, leads to the corresponding chlorohydrins, while the use of gaseous boron trifluoride leads to 2-oxazolines in satisfactory yields. It is shown that the reaction is regio- and stereospecific and that the resulting substituted 2-methyl-5-acetyl-2-oxazolines have a cis configuration.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No, 8, pp. 1022–1024, August, 1982.     

Zinc(0)/dimethylformamide-mediated synthesis of symmetrical carboxylic anhydrides from acid chlorides

The high yielding synthesis of symmetrical carboxylic anhydrides from acid chlorides mediated by zinc dust in the presence of dimethylformamide is presented. A mechanism involving the reductive insertion of zinc(0) into the C-Cl bond of a Vilsmeier-type iminium intermediate as the crucial step is also proposed.     

Reaction of unsymmetrical dienophiles with a key dienoid intermediate for aphidicolin synthesis

The Diels-Alder reactions of diene (6) with α-chloroacrylyl chloride and nitroethylene afford adducts (11) and (12), as proven by X-ray crystallographic analysis of a key transformation product (10), supplemented by appropriate correlation experiments. Formation of these adducts, rather than the less sterically congested isomers (7) and (9), can be rationalized using frontier molecular orbital theory.     

Reaction of cyclic sulfites with acetonitrile

A. V. Bogatskii Physicochemical Institute, Ukraine National Academy of Science, Odessa 270080. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, p. 25. February, 1995. Original article submitted January 15, 1995.     

A mild, clean, and simple synthesis of symmetrical carboxylic anhydrides from carboxylic acides using a polymer supported tosyl chloride

The use of polymeric reagents simplifies routine acylation of carboxylic acid because it eliminates the traditional purification. We describe the use of readily available cross-linked poly(4-vinylpyridine) supported tosyl chloride, [P₄VP].TsCl, in the suspended solution phase synthesis of symmetrical anhydrides from carboxylic acids in the presence of K₂CO₃ in high yields and purity. The products can be obtained by filtration and evaporation of the solvent.     

An effective method for the synthesis of carboxylic esters and lactones using substituted benzoic anhydrides with Lewis acid catalysts

An efficient mixed-anhydride method for the synthesis of carboxylic esters and lactones using benzoic anhydride having electron withdrawing substituent(s) is developed by the promotion of Lewis acid catalysts. In the presence of a catalytic amount of TiCl₂(ClO₄)₂, various carboxylic esters are prepared in high yields through the formation of the corresponding mixed-anhydrides from 3,5-bis(trifluoromethyl)benzoic anhydride and carboxylic acids. The combined catalyst consisting of TiCl₂(ClO₄)₂ together with chlorotrimethylsilane functions as an effective catalyst for the synthesis of carboxylic esters from free carboxylic acids and alcohols with 4-(trifluoromethyl)benzoic anhydride. Various macrolactones are prepared from the free ω-hydroxycarboxylic acids by the combined use of 4-(trifluoromethyl)benzoic anhydride and titanium(IV) catalysts together with chlorotrimethylsilane under mild reaction conditions. The lactonization of trimethylsilyl ω-(trimethylsiloxy)carboxylates using 4-(trifluoromethyl)benzoic anhydride is also promoted at room temperature in the presence of a catalytic amount of TiCl₂(ClO₄)₂. An 8-membered ring lactone, a synthetic intermediate of cephalosporolide D, is successfully synthesized according to this mixed-anhydride method using 4-(trifluoromethyl)benzoic anhydride by the promotion of a catalytic amount of Hf(OTf)₄.     

Reaction of [α-(trimethylsilyl)benzyl]ferrocenes with α-ferrocenylbenzyl cations

Although methanolysis of [α-(trimethylsilyl)benzyl]ferrocene (I) and [p-methyl-α-(trimethylsilyl)benzyl]ferrocene (II) in the presence of anhydrous ferric chloride merely gave α-ferrocenylbenzyl methyl ether (III) and p-methyl-α-ferrocenylbenzyl methyl ether (IV), respectively, acid-catalyzed methanolysis of (I) and (II) in the presence of an equimolar amount of (III) or (IV) afforded 1,2-diferrocenyl-l,2-diarylethanes. It is suggested that one electron oxidation of [α-(trimethylsilyl)benzyl]ferrocene by α-ferrocenylbenzyl cation generated from α-ferrocenylbenzyl methyl ether, and subsequent methanolysis of the resulting substituted ferricenium ion may occur to give the two species of α-ferrocenylbenzyl radical, which in turn undergo an approximately statistical coupling.