1-(2′-Anilinyl)prop-2-yn-1-ol rearrangement for oxindole synthesis

A synthetic method that relies on NIS (N-iodosuccinimide)-mediated cycloisomerization reactions of 1-(2′-anilinyl)prop-2-yn-1-ols to gem-3-(diiodomethyl)indolin-2-ones and 2-(iodomethylene)indolin-3-ones has been developed. The reactions were shown to be chemoselective, with secondary and tertiary alcoholic substrates exclusively giving the 3- and 2-oxindole products, respectively. In the case of the latter, the transformation features an unprecedented double 1,2-OH and 1,2-alkyl migration relay. Density functional theory (DFT) calculations based on proposed iodoaminocyclization species provide insight into this unique divergence in product selectivity.