Strategies for Expanding Structural Diversity Available from Olefin Isomerization−Claisen Rearrangement Reactions

Boron-substituted di(allyl) ethers provide an efficient conduit for expanding the structural diversity available from olefin isomerization−Claisen rearrangement (ICR) reactions. Easily prepared allyl propargyl ethers undergo chemoselective Zr(IV)-catalyzed hydroboration to afford the boron-substituted ICR substrates. The boron-substituted allyl residue undergoes chemoselective Ir(I)-catalyzed olefin isomerization and in situ Claisen rearrangement to afford stereodefined β-boryl aldehyde products. Functionalization of the C−B linkage by oxidation or Suzuki cross-coupling provides a route to Claisen adducts previously inaccessible from the ICR methodology.