Acyl fluorides Alcohols

Pd salts and CC14 in the presence of K2CO3,362 or (3) RuH PPluV363 Primary alcohols RCH2OH can be directly oxidized to acyl fluorides RCOF with cesium fluoroxysulfate.364 Lactones can be prepared by oxidizing diols in which at least one OH is primary.365... 

Standard solid-phase peptide synthesis requires the first (C-terminal) amino acid to be esterified with a polymeric alcohol. Partial racemization can occur during the esterification of N-protected amino acids with Wang resin or hydroxymethyl polystyrene [200,201]. /V-Fmoc amino acids are particularly problematic because the bases required to catalyze the acylation of alcohols can also lead to deprotection. A comparative study of various esterification methods for the attachment of Fmoc amino acids to Wang resin [202] showed that the highest loadings with minimal racemization can be achieved under Mitsunobu conditions or by activation with 2,6-dichloroben-zoyl chloride (Experimental Procedure 13.5). iV-Fmoc amino acid fluorides in the presence of DMAP also proved suitable for the racemization-free esterification of Wang resin (Entry 1, Table 13.13). The most extensive racemization was observed when DMF or THF was used as solvent, whereas little or no racemization occurred in toluene or DCM [203]. 

Addition of allyl alcohol to perfluoro(2-mcthy1propene) in the absence of a catalyst gave ally ether 2 and rearranged ester 4, presumably formed by alcoholysis of the intermediate acyl fluoride 3. 

Methyl perfluoromethacrylate reacts with allyl and propargyl alcohols to give the Michael addition products 19 and 20, respectively these eliminate hydrogen fluoride in the presence of the boron trifluoride-triethylamine complex and rearrange to acyl fluorides 21 and 22. Hydrolysis of the acyl fluorides with base results in decarboxylation to give the 2-(trifluoromethyl) esters 23 and 24.11... 

Tetrafluoroethene has been used as a 2-carbon difluoroacetic acid equivalent, methodology developed by Normanl and co-workers, in the synthesis of inhibitors of Cobra venom phospholipase A2.13 Conversion of the allyl alcohols into the 2,2-difluoropent-4-enoic acids 32 is performed in one pot. The crude acids 32 are then converted into the methyl esters 33. Although esters 33 can be obtained directly from the acyl fluorides 29, as originally described by Normant and co-workers,10 a two-step procedure facilitates the workup after the Claisen rearrangement. 

Being an oxidizing agent, CsS04F was used to transform primary alcohols as well as aromatic aldehydes to the corresponding acyl fluorides (equation 180)309. Various N-substituted uracils and barbituric acid derivatives form, in contact with this reagent, 5-fluoro-6-alkoxyuracils accompanied by some 5,5-difluoro derivatives (equation 181)310. 

Fontana [4] prepared the free radical pro-initiator perfluoroethyether acyl fluoride, (V), by florination of the precursor alcohol having a Mj, of roughly 460 daltons with CsF. 

After reaction with SF4, all OH groups are converted to F groups [9]. The reactions of carboxylic acids with SF4 give acyl fluorides, and alcohols and hydroperoxides give alkyl fluorides. SF4 treatment carried out on a pre-photooxidized film leads to a decrease in absorption in the carbonyl vibration region (1698, 1710, 1732 and 1753 cm-1) and to the formation of two new bands at 1813 and 1841 cm-1 (Figure 30.2). 

Yamada, M., Yashiro, S., Yamano, T., Nakatani, Y., Ouhsson, G. Efficient acylation of alcohols with acylthiazolidine-2-thiones and cesium fluoride. Bull. Soc. Chim. Fr. 1990, 824-829. 

For the preparation, see Acyl fluorides. The reagent formylates aromatic hydrocarbons, alcohols, and phenols. ... 

Synthesis of trifluoromethylated compounds 152 has been achieved via ester-enolate [2,3]-Wittig and [3,3]-lreland-Claisen rearrangements. Perfluorocyclo-butane phosphonium ylides, e.g. 153, have been used as a masked fluoride anion source in their reactions with alcohols and carboxylic acids which lead to alkyl-and acyl-fluorides. Ylides 153 are also reported to cleave Si-C and Si-O bonds, cause dimerisation of fluoro-olefins, and also react with acid chlorides or other activated aromatic compounds under halogen exchange. ... 

Alkenyl and arylfluorides (F—C=C) are reactive and so one can imagine that the moiety of (F—C=X) (X=0, NR) should also be reactive. Acyl fluorides have greater stability than the corresponding chlorides toward neutral oxygen nucleophiles such as water and methanol, but appear to be equal reactivity toward anionic nucleophiles and amines [ 1 ]. Cyanuric fluoride 2 is a mild reagent for the preparation of acyl fluorides [2]. The protected amino acids can be transformed into the corresponding amino alcohols without racemization by the reduction of acyl fluorides 3 [3]. 

Acyl fluorides. Primary alcohols are directly oxidized to RCOF at slightly below... 

The intermediate acyl fluoride, (XVII), can be converted using classical chemical reactions to acids, alcohols, vinyl ethers, and iodides that in turn may be used as surfactants and intermediates for monomers and polymers. These are the same reactions that have been exploited in the chemistry of HFPO oligomers. 

Acetylenedicarbonyl fluoride reacts with alcohols and amines to furnish esters and amides, respectively. On the other hand, ethanethiol adds to the triple bond of the substrate despite the extremely high reactivity of the acyl fluoride carbonyl (62). Aromatic amines undergo both Michael addition and amida-tion (63). 

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