First synthesis of 1,10-phenanthroline-2,9-diamine dioxides, a novel family of phenanthroline-based ligands

Oxidation of 2,9-dialkylamino-1,10-phenanthrolines with mCPBA affords the corresponding N,N'-dioxides at the aliphatic amino substituents in up to 99% yield. The stability of these compounds can be improved by their conversion into dihydrochlorides at the remaining aromatic nitrogen atoms. The mercury-assisted Meisenheimer rearrangement of the prepared compounds is described.