Synthesis of 3‐Acetoxyoxindole Derivatives by Metal‐Free PhI(OAc)2‐Mediated Oxidation of 3‐Substituted Indoles

A new metal-free PhI(OAc)2-mediated oxidation for the synthesis of 3-acetoxyoxindole derivatives using easily available indoles as starting materials has been developed. This protocol allows efficient access to various densely functionalized 3-acetoxyoxindoles in moderate to good yields. The experimental results demonstrate that both the electronic properties of the N-protecting groups of the indoles and also the acidic reaction medium play important roles in this process.