HIGHLY SUBSTRATE SELECTIVE NUCLEOPHILIC AMINATION OF NITROSUBSTITUTED4-(2-HYDROXYETHYLAMINO)PHTHALAZIN-1(2H)-ONES

An unexpected selectivity was observed in the aromatic displacement re action of 4-(2-hydroxyethylamino)phthalazinones (1) under bar-(3) unde r bar and (7) under bar, (8) under bar differently substituted with th e leaving nitro group on the condensed benzene ring. On treatment with a series of amine and hydrazine nucleophiles, the 8-nitro isomers (1) under bar-(3) under bar were readily transformed into the correspondi ng aromatic amine ((4) under bar-(6) under bar), while the substrates carrying the nitro group at position 6 or 7 ((7) under bar and (8) und er bar) remained unchanged on prolonged treatment with any of the reag ents used. Application of pyridine or DMF as a solvent proved to be in dispensable to successful conversions even of the 8-nitro derivatives (1) under bar-(3) under bar.