Nucleophilic fluorinations, tetrabutylammonium fluoride

In a comparative study of fluorination of l,2 3,4-di-0-isopropyli-dene-6-O-p-tolylsulfonyl-a-D-galactopyranose with tetrabutylammonium fluoride in a variety of dipolar, aprotic solvents (as well as 1,2-eth-anediol, in which no reaction was observed), acetonitrile was found to give the highest proportion of substitution of the sulfonic esters relative to their elimination.106 Elimination is the major, competing reaction in these nucleophilic-substitution reactions, because of the high basicity and low nucleophilicity of the fluoride ion or, in terms of the... 

Further examples are found in references 196 and 197. Tetrabutylammonium fluoride (TBAF) has found many applications in synthesizing several fluoro derivatives via nucleophilic substitution on the appropriate substrates. Organo-fluorine compounds are not only interesting as medicinal drugs, but they are also useful as technical products. 

Albanese, D., Landini, D., Penso, M. Hydrated Tetrabutylammonium Fluoride as a Powerful Nucleophilic Fluorinating Agent. J. Org. Chem. 

Enolphosphate phosphonates derived from perfluoroalkanoylphosphonates have a number of synthetic uses. Reactions of such compounds with nucleophiles such as amines or alcohols in the presence of catalytic amounts of tetrabutylammonium fluoride (tbaf) gave a,j5-unsaturated perfluorocarboxylic acid derivatives, presumably via a ketene type intermediate (equation 94) When a primary amine was employed as the nucleophile a,j -unsaturated amides were formed, which could be converted into fluorinated pyrimidi-nones by treatment with urea. On the other hand, butylcopper(I) reagent reduces such... 

Tetrabutylammonium fluoride (TBAF) is one of the most efficient reagents in the nucleophilic fluorination reactions. It was demonstrated that TBAF can be successfully used to substitute nitro group in pyridines 60 (Scheme 6.21). The developed technique allows direct synthesis of 2-fluoropyridines from 2-nitropyridines. 

Thus, beyond the seminal contributions on deaminations, side reactions were found to most frequently occur in attempted sulfonate displacements when poor nucleophiles, especially fluoride, or the conditions of solvolysis were applied. In this way, impetus for the development of better LGs, represented by trifiuoro-methanesulfonates (triflates) and imidazolesulfonates (imidazylates), as well as more powerful nucleophiles, e.g., tetraalkylammonium salts, was added. In the case of intended fluorinations, the classical sulfonate/fluoride tandem [usually triflate/tetrabutylammonium fluoride (TBAF) or triflate/tris(dimethylamino)... 

The addition of tin(II) chloride or tin(II) fluoride, as low-redox-polential reductants, in the dediazoniation slop of the fluorination of arylamines with polar groups, using hydrogen fluoride in the presence of a nucleophilic fluoride source (e.g., tetrabutylammonium dihydrogen trifluoride), not only improves the yield of the fluoroaromalic, but also allows the fluorodediazoni-ation process to be performed under milder reaction conditions.46... 

---