Chemoselective halogenation of 2-hydroperfluoroalkyl aldehydes

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• 作者：Donald A. Wiebe ; Donald J. Burton ; ^{donald-burton@uiowa.edu} ; ^{mburton105@gmail.com}
• 关键词：Fluorinated vinyl ethers ; 2-Hydroperfluoroalkylaldehydes ; 2-Hydroperfluoroacyl halides ; 2-Haloperfluoroaldehydes ; 2-Hydro-branched perfluorocarboxylic acids ; Chemoselective halogenation ; Perfluoroalkyl effect ; Free-radical halogenation of 2-hydroaldehydes
• 刊名：Journal of Fluorine Chemistry
• 出版年：2012
• 期刊代码：52_00221139
• 类别：ch
• 出版时间：July, 2012
• 卷：139
• 期：Complete
• 页码：4-11
• 文件大小：418 K

摘要

2-Hydroaldehydes, R_fCH(R)CHO, where R_f = CF₃, C₂F₅, n-C₃F₇ and R = CF₃, C₂F₅, n-C₃F₇, Ph, H, were prepared via acid hydrolysis of the corresponding vinyl ethers, R_fC(R) = CHOCH₃, which can be readily prepared by reaction of with the corresponding ketone. The 2-hydroaldehydes can be chemoselectively converted to the acyl halide, R_fCH(R)C(O)X (X = Cl, Br), via free-radical halogenation. The perfluoroalkyl group deactivates the 2-position toward radical abstraction of the 2-hydrogen, and halogenation occurs exclusively at the formyl hydrogen. However, halogenations of the 2-hydroaldehydes in glacial acetic acid chemoselectively gives the 2-haloaldehydes, R_fCX(R)CHO, X = Cl, Br. Hydrolysis of the 2-hydroperfluoroacyl halides provides a useful route to 2-hydroperfluoroalkyl branched carboxylic acids, useful ketene precursors. This route avoids the use of toxic fluoroolefins, such as perfluoroisobutylene.