2 research outputs found
Radical Reactions of Alkyl 2‑Bromo-2,2-difluoroacetates with Vinyl Ethers: “Omitted” Examples and Application for the Synthesis of 3,3-Difluoro-GABA
Addition reactions of perfluoroalkyl
radicals to ordinary or polyfluorinated
alkenes have been frequently used to synthesize perfluoroalkylated
organic compounds. Here ethyl/methyl 2-bromo-2,2-difluoroacetate,
diethyl (bromodifluoromethyl)phosphonate, [(bromodifluoromethyl)sulfonyl]benzene,
and ethyl 2-bromo-2-fluoroacetate were involved in Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub>-mediated radical additions to vinyl ethers in
the presence of alcohols to give difluoro or monofluoroacetyl-substituted
acetals or corresponding difluoromethylphosphonate- and (difluoromethylphenyl)sulfonyl-substituted
alkyl acetals. This methodology has also been applied as a key step
in the synthesis of hitherto unknown 3,3-difluoro-GABA, completing
the series of isomeric difluoro GABAs. Comparison of the p<i>K</i><sub>a</sub> values of 3-fluoro- and 3,3-difluoro-GABA
with that of the fluorine free parent compound showed that introduction
of each fluorine lead to acidification of both the amino and the carboxyl
functions by approximately one unit
Radical Reactions of Alkyl 2‑Bromo-2,2-difluoroacetates with Vinyl Ethers: “Omitted” Examples and Application for the Synthesis of 3,3-Difluoro-GABA
Addition reactions of perfluoroalkyl
radicals to ordinary or polyfluorinated
alkenes have been frequently used to synthesize perfluoroalkylated
organic compounds. Here ethyl/methyl 2-bromo-2,2-difluoroacetate,
diethyl (bromodifluoromethyl)phosphonate, [(bromodifluoromethyl)sulfonyl]benzene,
and ethyl 2-bromo-2-fluoroacetate were involved in Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub>-mediated radical additions to vinyl ethers in
the presence of alcohols to give difluoro or monofluoroacetyl-substituted
acetals or corresponding difluoromethylphosphonate- and (difluoromethylphenyl)sulfonyl-substituted
alkyl acetals. This methodology has also been applied as a key step
in the synthesis of hitherto unknown 3,3-difluoro-GABA, completing
the series of isomeric difluoro GABAs. Comparison of the p<i>K</i><sub>a</sub> values of 3-fluoro- and 3,3-difluoro-GABA
with that of the fluorine free parent compound showed that introduction
of each fluorine lead to acidification of both the amino and the carboxyl
functions by approximately one unit