Efficient Synthesis of α-Allylbutenolides from Allyl Ynoates via Tandem Ligand-Enabled Au(I) Catalysis and the Claisen Rearrangement

A facile construction of α-allylbutenolides from readily available allyl ynoates has been developed via tandem gold-catalyzed alkyne isomerization to allene and cycloisomerization, the Claisen rearrangement and a double bond migration. The gold catalysis is enabled by a bifunctional phosphine ligand featuring a critical remote tertiary amino group, and the reaction tolerates a range of substituents and exhibits yields up to 96%.