Target-directed organocatalysis: a direct asymmetric catalytic approach to chiral propargylic and allylic fluorides

J Am Chem Soc. 2009 May 27;131(20):7153-7. doi: 10.1021/ja901459z.

Abstract

A simple, direct one-pot organocatalytic approach to the formation of optically active propargylic fluorides is presented. The approach is based on organocatalytic alpha-fluorination of aldehydes and trapping and homologation of the intermediate providing optically active propargylic fluorides in good yields and enantioselectivities up to 99% ee. The procedure takes place by addition of NFSI, in the presence of 2-[bis(3,5-bis-trifluoromethylphenyl)trimethylsilyloxymethyl]pyrrolidine (as low as 0.25 mol %) as the catalyst, to aldehydes in combination with dimethyl 2-oxopropylphosphonate and 4-acetamidobenzenesulfonyl azide. The scope of the reaction is demonstrated by the formation of a number of optically active propargylic fluorides. It is also shown that optically active fluoro-containing triazoles can be obtained in one-pot procedures from aldehydes using click-chemistry. Furthermore, important coupling and multicomponent reactions of the optically active propargylic fluorides can be performed without affecting the enantiomeric excess. The direct one-pot formation of optically active allylic fluorides from aldehydes is also demonstrated. Finally, the mechanisms for both the formation of the propargylic and allylic fluorides are outlined.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehydes / chemistry*
  • Alkynes / chemical synthesis
  • Allyl Compounds / chemical synthesis*
  • Catalysis
  • Hydrocarbons, Fluorinated / chemical synthesis*
  • Pyrrolidines / chemistry
  • Stereoisomerism
  • Sulfonamides / chemistry

Substances

  • Aldehydes
  • Alkynes
  • Allyl Compounds
  • Hydrocarbons, Fluorinated
  • Pyrrolidines
  • Sulfonamides
  • fluorodi(phenylsulfonyl)amine