Metal-free oxidative spirocyclization of hydroxymethylacrylamide with 1,3-dicarbonyl compounds: a new route to spirooxindoles.

A metal-free oxidative spirocyclization of hydroxymethylacrylamide with 1,3-dicarbonyl compounds is described. The reaction proceeds through tandem dual C-H functionalization and intramolecular dehydration, in which two new C-C bonds and one C-O bond were formed. This method affords a novel and straightforward access to various spirooxindoles under mild conditions.