Gold(i)-catalyzed C-glycosylation of glycosyl ortho-alkynylbenzoates: the role of the moisture sequestered by molecular sieves.

C-Glycosylation of glycosyl ortho-hexynylbenzoates with allyltrimethylsilane or silyl enol ethers could proceed smoothly under the catalysis of Ph3PAuNTf2 to provide the corresponding C-glycosides in high yields and stereoselectivity, wherein the moisture sequestered by the molecular sieves was disclosed to play a critical role in the gold(i)-catalytic cycle.