Synthesis of cis -3-acyl-4-alkenylpyrrolidines via Gold(I)-catalyzed cycloisomerization reaction of (Z)-8-aryl-5-tosyl-5-azaoct-2-en-7-yn-1-ols

(Z)-8-Aryl-5-tosyl-5-azaoct-2-en-7-yn-1-ols were cycloisomerized to the corresponding cis-3-acyl-4-alkenylpyrrolidines when treated with a catalytic amount of Ph₃PAuCl/AgOTf in CH₂Cl₂. The reaction proceeded via attack of the hydroxyl group onto the gold-activated alkynes followed by [3,3]-sigmatropic rearrangement to generate cis-3-acyl-4-alkenylpyrrolidines in good yields. This transformation can be applied to the synthesis of cis- and trans-3-acyl-4-alkenylcyclopentanes from (Z)- and (E)-8-aryloct-2-en-7-yn-1-ols, respectively.