Aminophenoxazinones as inhibitors of indoleamine 2,3-dioxygenase (IDO). Synthesis of exfoliazone and chandrananimycin A.

A range of 2-aminophenoxazin-3-ones has been prepared by oxidative cyclocondensation of 2-aminophenols, including the natural products exfoliazone and chandrananimycin A, both synthesized for the first time. The compounds were evaluated for their ability to inhibit indoleamine 2,3-dioxygenase. Compounds containing additional electron-withdrawing carboxylate groups, such as cinnabarinic acid, showed modest inhibitory activity with a dose response.