Cocatalyst-controlled divergent cascade cycloaddition reaction of arylalkynols and dioxopyrrolidienes: access to spiroketals and oxa-bridged eight-membered cyclic ethers

A cocatalyst-controlled divergent cascade cycloaddition reaction was developed for the synthesis of two different complex oxygen-containing heterocyclic compounds from arylalkynols and dioxopyrrolidienes in the presence of Au(i) catalyst. Using two different cocatalysts, Ni(OTf)(2)and (rac)-phosphoric acid, two completely different products, spiroketals andoxa-bridged eight-membered cyclic ethers, were precisely constructed with high yields and good stereoselectivities, respectively. These methods feature simple and high efficiency, good chemoselectivity and mild conditions in one-pot.