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The Steglich Rearrangement of 2‐Oxindole Derivatives Promoted by Anion‐based Nucleophilic Catalysis

The first small anion‐triggered Steglich rearrangements are reported. Tetrabutylammonium carboxylates‐, cyanide‐ and fluoride promote the O‐ to C‐acyl transfer of a range of O‐acylated oxindoles to form 3,3‐disubstituted oxindole products with new quaternary stereocentres. DFT calculations on the TBAF‐mediated reaction strongly support a nucleophilic catalysis mechanism involving initial attack of fluoride on the O‐acyl group to give an enolate and an acyl fluoride in the rate determining step.