Transition-Metal-Free Synthesis of Carbonyl-Containing Oxindoles from N-Arylacrylamides and α-Diketones via TBHP- or Oxone-Mediated Oxidative Cleavage of C(sp2)-C(sp2) Bonds

Carbonyl-containing oxindoles can be prepared from N-arylacrylamides and alpha-diketones by TBHP- or oxone (KHSO5)-mediated C(sp(2))-C(sp(2)) bond cleavage and new C(sp(2))-C(sp(3)) bond formation. This methodology is characterized by its simple and transition-metal-free conditions and good functional group compatibility utilizing inexpensive and readily available reagents, thus providing a practical and efficient approach to an important class of 3-(2-oxoethyl)indolin-2-ones which are highly valued synthetic intermediates of biologically active molecules. In this transformation, alkylcarbonyl-containing oxindoles were obtained in majority when N-arylacrylamides reacted with asymmetric aliphatic/aromatic alpha-diketones. On the basis of the preliminary experiments, a plausible mechanism of this transformation is disclosed.