Fluoroacetic anhydride

Perfluoroalkanoyl chlorides and anhydrides are also acylating agents Tri-fluoroacetic anhydride acylates a number of pyrroles, thiophenes, and furans without a catalyst [37, 38, 39] AzuUne can be diacylated without a catalyst in 12 h [40] (equation 26). 

Anhydrous peroxytrifluoroacetic acid is not easy to handle, but the procedure has recently been revised.121 Namely, reaction of urea-hydrogen peroxide complex (UHP) with tri-fluoroacetic anhydride in acetonitrile at 0 °C gives solutions of peroxytrifluoroacetic acid, which oxidize aldoximes to nitroalkanes in good yields (Eqs. 2.58 and 2.59). Ketoximes fail to react under these conditions, the parent ketone being recovered. 

The formation of iminium ions of 20-epipandoline occurred only under Polo-novski-Potier conditions. Thus on treatment of the TV-oxide of 165 with tri-fluoroacetic anhydride followed by an aqueous solution of KCN, the iminium ion 329 was obtained, readily isolated as the corresponding a-amino nitrile 331 (Scheme 17). The reaction was completely regioselective and no traces of the enamine 332 could be obtained. This made the synthesis of spiroketone 333... 

Fluoroacetic anhydride, which was readily prepared by the action of fluoroacetyl chloride on sodium fluoroacetate, is a mobile liquid of b.p. 89°/12 mm. It is a useful fluoroacetylating substance. It was rather more toxic by inhalation than M.F.A. (weight for weight). 

As with the Henry nitro-aldol condensation, the modified Dakin-West acylation is primarily used for synthesis of trifluoromethyl ketones, although there are several examples of its use in the synthesis of fluoromethyl ketones (Table 3).[31314 The modified Dakin-West reaction utilizes fluoroacetic anhydride (or other appropriate anhydrides) to form an anhydride, which then undergoes cyclization, activation of the a-carbon, and acylation at the a-carbon the precise details of this method will be discussed in Section 15.1.4.3.1. 

A typical example of such heterocyclization is the interaction of 3-phenyl-5-met-hoxy-l,2,4-triazine 182 with urea or A,A -dimethylurea in acetic or, better, in tri-fluoroacetic anhydride. The role of anhydride consists in converting starting molecule into a more electrophilic triazinium salt 183, which then reacts with a bifunctional nucleophile to form imidazotriazinone 184 (Scheme 54) (00MC58, 01JHC901). 

Aqueous H202 (30% 0.40 mL) was slowly added (Caution exothermic reaction) dropwise to a vigorously stirred mixture of SnO (0.50 g), TFAH (3 mL), and tri-fluoroacetic anhydride (4mL). This mixture was stirred at room temperature for 2 days until the dark solids (SnO) had all dissolved. The resulting white opaque solution was evaporated under N2 and the residue was treated first with trifluoro-... 

The piperazine moiety of 9-(l-piperazinyl)-7-oxo-2,3-dihydro-7//-pyrido[l,2,3-de]-l,4-benzothiazine-6-carboxylate was N-acylated with tri-fluoroacetic anhydride under reflux for 2 h (87JMC465). 

Chloropyrimidine-4,.5-diamine gives 8-(trinuoromethyl)purin-6-ol (5) under reflux with tri-fluoroacetic anhydride. ... 

Bobbitt, J. M., Periodate Oxidation of Carbohydrates, 11, 1-41 BOeseken, j., Tbe Use of Boric Acid for the Determination of the Configuration of Carbohydrates, 4, 189-210 Bonner, T. G., Applications of Tri-fluoroacetic Anhydride in Carbohydrate Chemistry, 15, 59-84 Bonner, William A., Friedel-Crafts and Grignard Processes in the Carbohydrate Series, 5, 251-289 Bourne, E. J., and Peat, Stanley, The Methyl Ethers of D-Glucose, 5, 145-190... 

Preparation. A solution of N-hydroxysuccinimide and a slight excess of tri-fluoroacetic anhydride in benzene is refluxed for 5 hrs.1... 

Preparation.1 The salt is prepared in methylene chloride solution from tri-fluoroacetic anhydride (1 mmole) and trimethylamine oxide (1 mmole) at 0°. It... 

Pyrroles. Enamines of an a-amino acid such as (1) react rapidly with tri-fluoroacetic anhydride at 0° to form pyrrole derivatives (2). ... 

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