Gold(I)-Catalyzed Intermolecular Rearrangement Reaction of Glycosyl Alkynoic β-Ketoesters for the Synthesis of 4--Glycosylated 2-Pyrones.

A new gold(I)-catalyzed rearrangement reaction with glycosyl alkynoic β-ketoesters as substrates is developed. The rearrangement reactions under the catalysis of PPhAuOTf proceeded smoothly to afford a range of 4--glycosylated 2-pyrones. Based on the isolation of the 4-hydroxy-2-pyrone derivative generated from the departure of the leaving group and the competitive reaction, a plausible mechanism of the gold(I)-catalyzed intermolecular rearrangement reactions is proposed.