Synthesis of 2,5-Disubstituted Dihydrofuran-3(2H)-ones via [2,3]-Sigmatropic Rearrangement of Oxonium Ylides Generated from α-Oxo Gold Carbenes

Novel [2,3]-sigmatropic rearrangements of oxonium ylides generated from α-oxo gold carbenes were discovered. An ­efficient synthetic method of 2,5-disubstituted dihydrofuran-3(2H)-ones via gold-catalyzed intermolecular oxidation of the allyl homopropargyl ethers with N-oxide was developed. And the synthetic utility of the current method has been proved by concise formal synthesis of (±)-kumausallene.