A synthetic method to prepare cis-cyclohepta-4,8-diene-fused pyrrolidines efficiently from Au(I)-catalyzed cycloisomerization of 1,6,8-dienyne carbonates and esters at a low catalyst loading of 2 mol % is reported. The cyclization process was found to proceed through two distinctly different mechanistic pathways, either 1,2-acyloxy migration/cyclopropanation followed by Cope rearrangement or 1,3-acyloxy migration/[4C+3C] cycloadditon, depending on the substitution pattern on the distal alkene moiety of the substrate. However, product selectivity was shown to be independent of whether the transformation was initiated by [2,3]- or [3,3]- sigmatropic rearrangement. This provided a rare example in the field of homogenous gold catalysis where the initial rearrangement did not influence product selectivity.

Gold-catalyzed cycloisomerization of 1,6,8-dienyne carbonates and esters to cis-cyclohepta-4,8-diene-fused pyrrolidines

248th National Meeting (2014)

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