Carboxylic acid fluorides pyridines

Barbituric Acid + Pyridine-4-carboxylic acid Fluoride Alizarin Fluorine blue + Lanthanum(III) ion... 

These reactions are most important for the preparation of acyl fluorides. " Acyl chlorides and anhydrides can be converted to acyl fluorides by treatment with polyhydrogen fluoride-pyridine solution" or with liquid HF at — 10°C. Formyl fluoride, which is a stable compound, was prepared by the latter procedure from the mixed anhydride of formic and acetic acids. Acyl fluorides can also be obtained by reaction of acyl chlorides with KF in acetic acid or with DAST. Carboxylic esters and anhydrides can be converted to acyl halides other than fluorides by the inorganic acid halides mentioned in 10-77, as well as with PhsPXa (X = Cl or but this is seldom done. Halide exchange can be carried out in a... 

Tertiary benzylic nitriles are useful synthetic intermediates, and have been used for the preparation of amidines, lactones, primary amines, pyridines, aldehydes, carboxylic acids, and esters. The general synthetic pathway to this class of compounds relies on the displacement of an activated benzylic alcohol or benzylic halide with a cyanide source followed by double alkylation under basic conditions. For instance, 2-(2-methoxyphenyl)-2-methylpropionitrile has been prepared by methylation of (2-methoxyphenyl)acetonitrile using sodium amide and iodomethane. In the course of the preparation of a drug candidate, the submitters discovered that the nucleophilic aromatic substitution of aryl fluorides with the anion of a secondary nitrile is an effective method for the preparation of these compounds. The reaction was studied using isobutyronitrile and 2-fluoroanisole. The submitters first showed that KHMDS was the superior base for the process when carried out in either THF or toluene (Table I). For example, they found that the preparation of 2-(2-methoxyphenyl)-2-methylpropionitrile could be accomplished h... 

The perfluoroorganozmc compounds have limited application in organic syn thesis because of their lack of reactivity However, heptafluoro 1 methylethylzinc iodide reacts with acyl fluorides or anhydrides of carboxylic acids in the presence of pyridine to give the corresponding ketones [38] (equations 28 and 29) In the presence of zinc fluoride, acyl chlorides can be used as substrates [33]... 

In most of their reactions, the pyridine- and azinecarboxylic acids and their derivatives behave as any other acid (cf. Scheme 86). However, some acid chlorides can be obtained only as hydrochlorides, and we must also consider decarboxylation. Esterification of pyridine carboxylic acids can be usefully achieved via in situ generation of the acid fluoride. For example, treatment of picolinic acid with a stoichiometric amount of N,N,N,A-tetramethylfluoroformami-dinium hexafluorophosphate (TFFH) in dichloromethane and triethylamine leads to generation of the acid fluoride, which reacts with (3-methyloxetan-3-yl)methanol to give the corresponding ester in 95% yield <2004S2485>. 

Good to excellent yields of jfc/M-difluoridcs are obtained from the reaction of ketoximes with NO BF4, (HF) /pyridine. The reactions are carried out under very mild conditions (rt, Nj atmosphere. 5 h) and the method is applicable to alkyl aryl (entry 7). diaryl (entry 8), and dialkyl ketoximes (entries 1 -6). In the ca.se of aldoximes. oxidation occurs and carboxylic acids are obtained. The concentration of the hydrogen fluoride in pyridine has an important effect on the yield of the reaction. The best results are obtained in the case of pyridinium poly(hydrogcn fluoride) with 60 wt % hydrogen fluoride. With lower concentrations, the major... 

Transesterification has been carried out with phase-transfer catalysts, without an added solvent. Nonionic superbases (see p. 365) of the type P(RNCH2CH2)3N catalyze the transesterification of carboxylic acid esters at 25°C. ° Silyl esters (R C02SiR3) have been converted to alkyl esters (R C02R) via reaction with alkyl halides and tetrabutylammonium fluoride. Thioesters are converted to phenolic esters by treatment with triphosgene-pyridine and then phenol. 

Acid anhydrides as activated derivatives of carboxylic acids have found little attention for the preparation of acid halides. Their use can be justified if they are obtained from other sources than from carboxylic acids, e.g. phthalic anhydride from the oxidation of naphthalene or o-xylene. It is, therefore, no surprise that there exist patents to convert phthalic anhydride to phthalic acid dichloride with carbonyl dichloride in the presence of catalysts. " However, there are some methods available thus a,a-di-chloromethyl methyl ether will convert acid anhydrides to acid chlorides and brenzcatechyl phosphorus tribromide will also achieve this transformation. Fluorides may be prepared similarly with the pyridine/HF mixture of 01ah. °... 

Hydrolysis of each acid fluoride fraction and redistillation of the carboxylic acids allowed separation of mono- from dicarboxylic acids (Table III). Thus, the 1 1 dicarboxylic acid and the monocarboxylic acid formed from three molecules of hexafluoropropylene epoxide were isolated from the 1 1 oligomer acid fluoride fraction shown in Table II. The acids were converted to acid chlorides in high yields (about 90%) by prolonged refluxing with thionyl chloride (Table IV). A trace of pyridine was added as a catalyst. 

Trifluoro-l,3,5-triazine (cyanuric fluoride) is a colorless liquid, which is used mainly in dye manufacturing. Cyanuric fluoride is a mild reagent that is suitable for the preparation of acyl fluorides even when unsaturated double bonds, hydroxyl groups, or aromatic rings are found in the molecule. Carboxylic acids were converted into the corresponding acyl fluorides by treatment with cyanuric fluoride in the presence of pyridine (Equation 56). 

Reactions with poly(hydrogen fluoride)-pyridine c(-Fluoro- from a-amino-carboxylic acids... 

Simple alcohols and aldehydes are efficiently oxidized to carboxylic acids using solid NaMn04-H20 yields around 70% are obtained. Rearrangement products are sometimes observed in the conversion of a-amino acids to a-fluoroacids using NaNOa in polyhydrogen fluoride-pyridine/ However, this problem is effectively suppressed by the use of 48 52 (w/w) hydrogen fluoride pyridine (Scheme 2). ... 

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