Regioselective nucleophilic 1,4-trifluoromethylation of 2-polyfluoroalkylchromones with (trifluoromethyl)trimethylsilane. Synthesis of fluorinated analogs of natural 2,2-dimethylchroman-4-ones and 2,2-dimethylchromenes

J Org Chem. 2003 Oct 3;68(20):7747-54. doi: 10.1021/jo034591y.

Abstract

Reactions of 2-polyfluoroalkylchromones with (perfluoroalkyl)trimethylsilanes proceed as a 1,4-nucleophilic perfluoroalkylation to give 2,2-bis(polyfluoroalkyl)chroman-4-ones with high regioselectivity and good yields after acid hydrolysis. Oxidation of 6-methyl-2,2-bis(trifluoromethyl)chroman-4-one with a mixture of K2S2O8 and CuSO4 in aqueous acetonitrile leads to fluorinated analogues of natural lactarochromal and the corresponding acid. Reduction of substituted 2,2-bis(trifluoromethyl)chroman-4-one with sodium borohydride in methanol and subsequent dehydration of chromanols in refluxing xylene in the presence of p-toluene sulfonic acid gives 2,2-bis(trifluoromethyl)chromenes, which are fluorinated analogues of natural precocenes.

MeSH terms

  • Benzopyrans / chemical synthesis*
  • Benzopyrans / chemistry
  • Chromones / chemistry*
  • Hydrocarbons, Fluorinated / chemistry*
  • Methylation
  • Stereoisomerism
  • Trimethylsilyl Compounds / chemistry*

Substances

  • Benzopyrans
  • Chromones
  • Hydrocarbons, Fluorinated
  • Trimethylsilyl Compounds