Lanthanoid(III) Trichloride-Tin(II) Chloride mediated Cycloaddition Reaction of α,α'-Dibromo Ketones with 1,3-Dienes or Enamines

Article abstract of DOI:10.1246/bcsj.62.2348

The reaction of α,α'-dibromo ketones with 1,3-dienes in the presence of CeCl3-SnCl2 in tetrahydrofuran is found to give the corresponding <3+4> cycloadduct in fair to good yields under mild conditions.Furan and cyclopentadiene serve as highly efficient receptors of the oxallyl intermediate to give bicyclic cycloadducts.The reaction of 2,4-dibromo-3-pentanone with isoprene gives both <3+4> and <3+2> cycloadducts. <3+2> Cycloaddition proceeds similarly with enamines to afford 2-cyclopenten-1-ones after treatment with 3percent ethanolic NaOH solution.