A gold-catalyzed synthesis of an important building block, 1-(furan-3-yl)-1,2-diones, from easily available starting materials under mild reaction conditions was reported. Preliminary mechanistic investigation indicated that water was involved as a reactant in the reaction serving as an oxygen source.

The metal-free reactions of 1,4-diynes and 1-en-4-yn-3-ones with isoquinoline and quinoline N-oxides are developed, resulting in the formation of 3,4-dihydro-2H-pyrido[2,1-a]isoquinolines and 2,3-dihydro-1H-pyrido[1,2-a]quinolines via cascade C═O/C═C/C–N bond formation. It is the first report in which in the alkyne oxidation by N-oxides both the oxygen atom of N-oxides and the nitrogen atom are involved in a second C–heteroatom bond formation. The reactions showed a broad substrate scope and functional group tolerance. Furthermore, the products were found to display green-blue fluorescence in DMSO with fluorescence quantum yields up to 0.59.

A gold(I)-catalyzed formal [4 + 1] cycloaddition of α-diazoesters and propargyl alcohols is disclosed, offering access to a variety of 2,5-dihydrofurans. The reaction shows a broad substrate scope and functional group tolerance. Preliminary mechanistic investigation indicates that this reaction most likely occurs through a 5-endo-dig cyclization of an α-hydroxy allene intermediate.