In the presence of tetra-butylammonium fluoride and molecular sieve (MS) 4? in DMF, an efficient auto-oxidation reaction of 2-oxindoles with ketones under air at room temperature has been developed. This approach may provide a green, practical, and metal-free protocol for a wide range of biologically important 3-hydroxy-3-(2-oxo-alkyl)-2-oxindoles.

Chemistry - A European Journal, 2015