Fluoride-catalyzed addition of PhSCF2SiMe3 to N-substituted cyclic imides followed by radical cyclization: general synthetic strategy of gem-difluoromethylenated 1-azabicyclic compounds

J Org Chem. 2009 May 15;74(10):3798-805. doi: 10.1021/jo802794u.

Abstract

PhSCF(2)SiMe(3) (1) was found, for the first time, to undergo fluoride-catalyzed nucleophilic difluoro(phenylsulfanyl)methylation reaction to cyclic imides 2, affording the corresponding adducts 3 in moderate to good yields. Reductive cleavage of the phenylsulfanyl group of N-alkylated adducts 3 with Bu(3)SnH/AIBN yielded gem-difluoromethylated products 4. Under the same reduction conditions, N-alkenylated and N-alkynylated adducts 3 afforded the corresponding gem-difluoromethylenated 1-azabicyclic compounds 5 and 6 with trans stereoselectivity. These compounds were employed as precursors for preparing substituted gem-difluoromethylenated pyrrolizidinones and indolizidinones 7 and 8 by treatment with Et(3)SiH/BF(3) x OEt(2), and compounds 9 and 10 by nucleophilic displacement of the hydroxyl group, using organosilanes in the presence of BF(3) x OEt(2). The synthesis of highly substituted gem-difluoromethylenated pyrrolizidines 13 and 14 was also demonstrated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Azabicyclo Compounds / chemical synthesis*
  • Azabicyclo Compounds / chemistry
  • Catalysis
  • Cyclization
  • Fluorides / chemistry*
  • Hydroxides / chemistry
  • Imides / chemistry*
  • Organosilicon Compounds / chemistry*
  • Oxidation-Reduction
  • Stereoisomerism

Substances

  • Azabicyclo Compounds
  • Hydroxides
  • Imides
  • Organosilicon Compounds
  • hydroxide ion
  • Fluorides