MISC

1998年1月1日

Generation and carbonyl addition reactions of dibromofluoromethyllithium derived from tribromofluoromethane as applied to the stereoselective synthesis of fluoro olefins and 2-bromo-2-fluoro-1,3-alkanediols

Bulletin of the Chemical Society of Japan
  • Masaki Shimizu
  • ,
  • Nobuko Yamada
  • ,
  • Yoko Takebe
  • ,
  • Takeshi Hata
  • ,
  • Manabu Kuroboshi
  • ,
  • Tamejiro Hiyama

71
12
開始ページ
2903
終了ページ
2921
記述言語
英語
掲載種別
DOI
10.1246/bcsj.71.2903
出版者・発行元
Chemical Society of Japan

The treatment of tribromofluoromethane with BuLi in THF-Et2O (2: 1) at - 130°C generated dibromofluoromethyllithium, which was allowed to react smoothly with a coexisting aldehyde or ketone (RR'C=O) to give fluorinated alcohol RR'C(OH)CFBr2 (3) in good yield. Alcohol 3 was converted stereoselectively to (E)-1-bromo-1,2-difluoro olefin 5 via fluorination with Et2NSF3, followed by dehydrobromination with lithium 2,2,6,6- tetramethylpiperidide, while (E)-1-bromo-1-fluoro olefin was obtained with high selectivity by acetylation of 3, followed by reductive elimination using EtMgBr/(i-Pr)2NH. Difluoro olefin 5 underwent a cross-coupling reaction with an aryl, alkenyl, or alkynylmetal reagent to afford the corresponding fluoro olefin with retention of configuration. On the other hand, the treatment of RCH[OCH2O(CH2)2OCH3]CFBr2 with BuLi at -130°C in the presence of 4- heptanone gave the corresponding adduct diastereoselectively. The stereochemical outcome is explained in terms of chelation between lithium and oxygen atoms of the (2-methoxyethoxy)methyl group. Starting with 2- phenylpropanal, a product is obtained highly selectively containing three contiguous stereocenters including a -CFBr-moiety.

リンク情報
DOI
https://doi.org/10.1246/bcsj.71.2903
ID情報
  • DOI : 10.1246/bcsj.71.2903
  • ISSN : 0009-2673
  • SCOPUS ID : 0032442654

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