Synthesis of γ-Fluoro-α, β-unsaturated Carboxylic Esters from Saturated α-Fluoro Aldehydes
摘要:
gamma-Fluoro-alpha,beta-unsaturated carboxylic esters 7a, 7b and 7d and 4-fluoro-4-phenylbut-3-enoic ester (8) are obtained by two alternative pathways from 2-fluoro aldehydes 5a-d, either by Horner-Wadsworth-Emmons reaction or by Wittig reaction. The aldehydes 5a-d are prepared by Swern oxidation of the corresponding fluorohydrins 4a-d. These are available from alpha-olefins by bromofluorination, bromine-by-acetate replacement and subsequent hydrolysis.
Selective Halofluorination of Alkenes with Tetrabutylphosphonium Dihydrogentrifluoride in Combination with<i>N</i>-Halosuccinimide or 1,3-Dibromo-5,5-dimethylhydantoin
Alkenes and their functionalized derivatives were readily converted to the corresponding halofluorides with tetrabutylphosphonium dihydrogentrifluoride as combined with N-halosuccinimides or 1,3-dibromo-5,5-dimethylhydantoin in highly regio-, stereo-, and chemoselective manners. In particular, alkenes having a oxirane or primary hydroxyl group also underwent halofluorination selectively in good yields
It was found that potassium fluoride-poly(hydrogen fluoride) salts are useful fluorine sources for halofluorination of alkenes. The reaction proceeded with these salts and N-halosuccinimides or 1,3-dibromo-5,5-dimethylhydantoin in a regio- and stereoselective manner.
Selective bromofluorination of alkenes with 1,3-dibromo-5,5-dimethylhydantoin and silicon tetrafluoride
作者:Makoto Shimizu、Yuko Nakahara、Hirosuke Yoshioka
DOI:10.1039/c39890001881
日期:——
Alkenes have been converted into the corresponding bromofluorides by reaction with 1,3-dibromo-5,5-dimethylhydantoin (DBH) and silicontetrafluoride in 1,4-dioxane in a highly regio-, stereo-, and chemo-selective manner.
Poly-4-vinylpyridinium Poly(Hydrogen Fluoride): A Solid Hydrogen Fluoride Equivalent Reagent
作者:George A. Olah、Xing-Ya Li、Qi Wang、G. K. Surya Prakash
DOI:10.1055/s-1993-25924
日期:——
Poly-4-vinylpyridinium poly(hydrogen fluoride) (PVPHF), containing 35-60% hydrogen fluoride by weight, was prepared as a solid hydrogen fluoride equivalent reagent. PVPHF with 60% hydrogen fluoride by weight was found to be a versatile fluorinating agent for the hydrofluorination and bromofluorination of alkenes and alkynes, fluorination of alcohols as well as other fluorination reactions. Low hydrogen fluoride content PVPHF (3 equivalents of hydrogen fluoride to 1 equivalent of 4-vinylpyridine unit) was also found to be an efficient reagent for bromofluorination of alkenes in the presence of 1,3-dibromo-5,5-dimethylhydantoin. Fluorosulfonic acid-modified PVPHF showed enhanced reactivities for the fluorination of secondary alcohols.
Fluorination process using hydrogen fluoride-containing fluorinating
申请人:AlliedSignal Inc.
公开号:US05705717A1
公开(公告)日:1998-01-06
Fluorination processes using hydrogen fluoride-containing fluorinating agents that are safely and easily handled, transported, and stored and that also exhibit good reactivity are provided. More particularly, the invention provides processes for producing fluorinated products using fluorinating agents comprising hydrogen fluoride and a carrier that may be an acid salt or a water-soluble polymer.