An efficient synthesis of iminoquinones by a chemoselective domino ortho-hydroxylation/oxidation/imidation sequence of 2-aminoaryl ketones.

An efficient chemoselective domino oxidative homocoupling of 2-aminoaryl ketones in the presence of 2-iodoxybenzoic acid (IBX) for the synthesis of iminoquinone has been developed. The domino reaction proceeds via three consecutive steps, such as domino ortho-hydroxylation of 2-aminoaryl ketones, oxidation of a phenol derivative to benzoquinone and dimerization through imine formation to yield iminoquinone. Importantly, this reaction allows the recycling of the oxidant IBX by recovering the by-product iodosobenzoic acid (IBA) and oxidizing it back to IBX. A four step domino strategy for the synthesis of iminoquinone through in situ generation of 2-amino benzophenone from (2-amino phenyl)(phenyl)methanol was also developed.

An efficient route to synthesize isatins by metal-free, iodine-catalyzed sequential C(sp(3))-H oxidation and intramolecular C-N bond formation of 2'-aminoacetophenones.

A novel molecular I2-catalyzed synthesis of isatins through C(sp(3))-H oxidation and intramolecular C-N bond formation of 2'-aminoacetophenones with excellent yields up to 97% under transition metal, base, additive, peroxide and ligand free conditions is described. The present protocol is suitable for gram scale synthesis of isatins and retained its high yield. Further, the synthetic utility of this present reaction towards synthesis of bioactive 3-hydroxy-2-oxindoles and oxindoles is demonstrated.