Gold-Catalyzed Synthesis of Dihydrofuran-3-ones from Homopropargylic Alcohols

Significance

Reported is the gold-catalyzed synthesis of dihydrofuran-3-ones 3 from homo­propargylic alcohols 1. The reaction is tolerant to both alkyl- and aryl-substituted alcohols, although it was observed that more electron-rich substrates gave higher yields. Despite the mildly acidic nature of the reaction medium, both the OMOM and NHBoc groups survive. The reaction is proposed to proceed via oxidation of the terminal alkyne by the pyridine-N-oxide to give an α-oxo gold carbene intermediate 2, a mechanism which is supported by the isolation of minor byproducts arising from trapping of the carbene by MsOH or pyridine.