Carboxylic acid fluorides ketones

The acylation of alkenes can also be similarly effected with SbFs [32], For example, a,/3-unsaturated carboxylic acid fluorides react with perfluoroalkenes to form a,/3-unsaturated ketones (Eq. 16) [32b]. 

In hydrogen fluoride containing antimony pentafluoride, aliphatic hydrocarbons are converted by carbon monoxide at atmospheric pressure and 0-20° into carboxylic acids or ketones 163... 

Alcohols, carboxylic acids, aldehydes, ketones, ethers and amines are further examples of basic substances in the liquid hydrogen fluoride solvent system. 

Ketones from carboxylic acid fluorides s. 11, 896 Alkylthiomethyl compounds s.ll, 897... 

Acylation of alkenes can also be similarly effected with SbFs. Reaction of acetyl fluoride with trifluoroethylene produces 1,1,1,2-tetrafluorohexane-3,5-dione in 40% yield. When antimony pentafluoride is used in excess (more than 6 molar equivalents), 1,1,1,2-tetrafluorobutan-3-one is formed as a side product. Benzoyl fluoride reacts with dilluoroethy lene to form the expected ketone in 39% yield. a, 3-Unsaturated carboxylic acid fluorides have also been used in reactions with perfluoroalkenes. In these cases, a,p-unsaturated ketones are obtained (eq 17). Enol acetates of perfluoroisopropyl methyl ketone and perfluoro-f-butyl methyl ketone react with acetyl fluoride to provide the corresponding p-diketones (eq IS). ... 

The recent discovery of a convenient synthesis of sulfur tetrafluoride from sulfur dichloride and sodium fluoride in acetonitrile invited the application of this reagent in fluorination reactions. Hasek, Smith and Engelhardt showed that carboxylic acids and their derivatives can be converted into trifluoromethyl derivatives and that aldehydes and ketones are converted into 5 em-difluoro compounds. They also observed that the reaction was acid... 

Theperfluoroorganozmc compounds have limited application in organic syn thesis because of their lack of reactivity However, heptafluoro I methylethylzinc iodide reacts with acyl fluorides or anhydrides of carboxylic acids in the presence of pyndine to give the corresponding ketones [7S] (equations 28 and 29) In the presence of zinc fluoride, acyl chlorides can be used as substrates [7d]... 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

Many aldehydes and ketones have been converted to g m-difluoro compounds with sulfur tetrafluoride (SF4), " including quinones, which give 1,1,4,4-tetra-fluorocyclohexadiene derivatives. With ketones, yields can be raised and the reaction temperature lowered, by the addition of anhydrous HF. Carboxylic acids, acyl chlorides, and amides react with SF4 to give 1,1,1-trifluorides. In these cases the first product is the acyl fluoride, which then undergoes the ge i-difluorination reaction ... 

Alternative paths for decomposition of the metal carboxylate can lead to ketones, acid anhydrides, esters, acid fluorides (1,11,22,68,77,78), and various coupling products (21,77,78), and aspects of these reactions have been reviewed (1,11). Competition from these routes is often substantial when thermal decomposition is carried out in the absence of a solvent (Section III,D), and their formation is attributable to homolytic pathways (11,21,77,78). Other alternative paths are reductive elimination rather than metal-carbon bond formation [Eq. (36)] (Section III,B) and formation of metal-oxygen rather than metal-carbon bonded compounds [e.g., Eqs. (107) (119) and (108) (120). Reactions (36) and (108) are reversible, and C02 activation (116) is involved in the reverse reactions (48,120). 

The nucleophilic addition of a trifluoromethyl anion or its equivalent to an activated carboxylic acid derivative is another potential method for the synthesis of trifluoromethyl ketones (Scheme 8). Due to the well-known instability of the trifluoromethyl anion, the organometallic approach (Section 15.1.4.3.3) is often difficult to utilize. However, a trifluoromethyl anion equivalent, (trifluoromethyl)trimethylsilane (CF3TMS), was developed in 1984 by Ruppert and co-workers.[30] This reagent, known as Ruppert s reagent, is stable and does not undergo fluoride elimination like other equivalent trifluoromethyl anions. An obvious limitation to this method is that it is only useful for the synthesis of a-amino trifluoromethyl ketones unless other fluoroalkyl analogues of Ruppert s reagent are developed. 

Silylation of acidic compounds.2 The combination of ethyl trimethylsilylacetate and 2-5 mole % of tetra-n-butylammonium fluoride (TBAF) is a markedly efficient reagent for transfer of trimethylsilyl groups to relatively acidic substrates such as ketones, alcohols, thiols, phenols, and carboxylic acids, and even 1-alkynes. KOCH3/ (18-crown-6) and Triton B are also effective catalysts. 

The lower fluoride, SF4, has recently become important as a reagent in organic synthesis, for it has been found that this compound converts ketones and carboxylic acids to fluoro derivatives with great ease ... 

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