C-Alkylation of Various Carbonucleophiles with Secondary Alcohols under CoIII-Catalysis

Oxindoles have been successfully alpha-alkylated under Cp*Co-III catalysis by a vast array of secondary alcohols, including cyclic, acyclic, symmetrical, and unsymmetrical, to produce C-alkylated oxindoles. This protocol was also extended to the alpha-alkylation of N,N-dimethyl barbituric acid and benzyl cyanides. The kinetic profile and other preliminary mechanistic investigations suggest a first-order reaction rate in oxindoles and catalysts. A plausible catalytic cycle is proposed on the basis of the kinetic profile, of other preliminary mechanistic investigations, and of previous mechanistic studies on similar transformations, whereas density functional theory calculations provide insight into the nature of the active species.