Gold(I)-catalyzed propargyl Claisen rearrangement.
Homoallenic alcohols are prepared from propargyl vinyl ethers using a trinuclear gold(I)-oxo complex, [(Ph3PAu)3O]BF4, as a catalyst for propargyl Claisen rearrangement at room temperature. The gold(I)-catalyzed reaction is effective for a diverse collection of propargyl vinyl ethers, including substrates containing aryl and alkyl groups at the propargylic position, and hydrogen, aryl, and alkyl substituents at the alkyne terminus. Tertiary propargyl vinyl ethers can be employed in the reaction, at slightly elevated temperatures, to afford tetrasubstituted allenes. Importantly, the rearrangement of 1,2-disubstituted vinyl ethers proceeds with excellent diastereoselectivity, and the rearrangement of chiral nonracemic propargyl vinyl ethers proceeds with excellent chirality transfer to furnish enantioenriched allenes.
Sherry
Benjamin D
BD
Center for New Directions in Organic Synthesis, Department of Chemistry, University of California, Berkeley, California 94720, USA.
Toste
F Dean
FD