Iron-catalyzed oxidative sp3 carbon-hydrogen bond functionalization of 3,4-dihydro-1,4-benzoxazin-2-ones.

A novel and efficient iron-catalyzed sp3 carbon-hydrogen bond functionalization of benzoxazinone derivatives has been developed. For the first time, benzoxazin-2-ones were used as substrates in an oxidative dehydrogenative coupling reaction. The experiments were performed under mild reaction conditions to construct alkyl-aryl C(sp3)-C(sp2) bonds. The application of this method to the gram-scale synthesis of natural product cephalandole A has been accomplished in a 3-step sequence. A plausible one electron oxidation involved mechanism is proposed.