Synthesis of chromeno[2,3-b]indol-11(6H)-one via PhI(OAc)2-mediated intramolecular oxidative C(sp(2))–N(H2) bond formation.

Various chromeno[2,3-b]indol-11(6H)-ones were conveniently constructed via phenyliodine(III) diacetate (PIDA)-mediated intramolecular oxidative annulation. This method, while realizing a direct oxidative C–N bond formation between an aromatic ring and a pendent free-NH2 moiety, features a metal-free protocol, mild reaction conditions, simple workup, and the ready availability of the starting substrates.