1865-01-6Relevant articles and documents
Effect of Solvation on β-Values of Formyl Acetyl, and Pivaloyl Transfer between Sulfur and Oxygen Nucleophiles
Pohl, Eric R.,Wu, Dorothy,Hupe, D.J.
, p. 2759 - 2763 (1980)
Second-order rate constants were measured in aqueous solution for the reaction of a series of oxy anions and thiol anions with the formate and pivalate esters of p-nitrophenol and p-nitrothiophenol.These data, along with literature data provide a picture of the effect of alkyl substitution on the rates of uncatalyzed acyl transfer between sulphur and oxygen nucleophiles.Evidence is provided in support of the proposal that β values for oxy anions are altered by solvation, whereas those for thiol anions are not.The change of rate-determining step from formation to breakdown of tetrahedral intermediate occurs for formate and pivalate esters in the same manner that this occurs for acetate esters.The greater kinetic reactivity of formate esters compared to acetate esters is not a function of the entering or leaving nucleophile but is an inherent difference in the esters reflecting the relative ease of formation of the tetrahedral intermediates.
Three step procedure for the preparation of aromatic and aliphatic difluoromethyl ethers from phenols and alcohols using a chlorine/fluorine exchange methodology
Dolbier Jr., William R.,Wang, Fei,Tang, Xiaojun,Thomoson, Charles S.,Wang, Linhua
, p. 72 - 76 (2014/03/21)
Difluoromethyl ethers are prepared from phenols in three steps via their respective formate ester derivatives. The formates are first converted to dichloromethyl ethers by treatment with PCl5. These ethers are then induced to undergo chlorine/fluorine exchange to form the respective difluoromethyl ethers. The chlorine/fluorine exchange is carried out by either a room temperature, solvolytic process using THF-5HF or Et3N-3HF as exchange medium, where HF is the ultimate source of fluorine, or by a direct displacement process in sulfolane at 125 C, where KF is the source of fluorine. By one or another of these processes, virtually all phenols, electron-rich and electron-poor, can be converted to their respective difluoromethyl ethers in good yields. Aliphatic alcohols are also able to be converted to their difluoromethyl ether derivatives using the Et3N-3HF exchange medium.
Genetic expression of an amyloid peptide fragment and analysis of formylated products
Cheng,Krasel,Zhou,Chappell,Hamley
supporting information; experimental part, p. 2572 - 2575 (2011/07/08)
The model amyloid peptide AAKLVFF was expressed as a His-tagged fusion protein with the immunoglobulin-binding domain B1 of streptococcal protein G (GB1), a small (56 residues), stable, single-domain protein. It is shown that expression of this model amyloid peptide is possible and is not hindered by aggregation. Formylation side reactions during the CNBr cleavage are investigated via synthesis of selectively formylated peptides.
