PhI(OAc)2-Mediated Intramolecular Oxidative Aryl-Aldehyde Csp2-Csp2 Bond Formation: Metal-Free Synthesis of Acridone Derivatives

A metal-free protocol for direct aryl-aldehyde Csp(2)-Csp(2) bond formation via a PhI(OAc)(2)-mediated intramolecular cross-dehydrogenative coupling (CDC) of various 2-(N-arylamino)aldehydes was developed. The novel methodology requires no need of preactivation of the aldehyde group, is applicable to a large variety of functionalized substrates, and most of all provides a convenient approach to the construction of biologically important acridone derivatives.