Iodide-Mediated Synthesis of Spirooxindolo Dihydrofurans from Iodonium Ylides and 3-Alkylidene-2-oxindoles.

An iodide-mediated reaction between cyclic iodonium ylides of 1,3-dicarbonyls and 3-alkylidene-2-oxindoles results in 3H-spiro[furan-2,3'-indolin]-2'-ones. The reaction was tolerant to substitutions on both the alkylidene and ylide substrates and provided access to 19 new, densely functionalized polycyclic spirocycles in typically high yield.