Nitration of 1,8-naphthalic anhydride (I) in sulfuric acid at 60 C for 1 h gives 3,6-dinitro-1,8-naphthalic anhydride (II) in 80% yield (m.p. 209-211 C from toluene; NMR: in CDCl3 a 9.22, 9.27, 2 singlet aromatic H), which, on treatment with unsym-N,N-dimethylethylenediamine at room temperature for 30 min, followed by azeotropical removal of water at 140 C for 2 h in refluxing toluene solution and salt conversion with HCl, yields the monohydrochloride salt of dinimide in 62% yield.

Nitration of 1,8-naphthalic anhydride (I) in sulfuric acid at 60 C for 1 h gives 3,6-dinitro-1,8-naphthalic anhydride (II) in 80% yield (m.p. 209-211 C from toluene; NMR: in CDCl3 a 9.22, 9.27, 2 singlet aromatic H), which, on treatment with unsym-N,N-dimethylethylenediamine at room temperature for 30 min, followed by azeotropical removal of water at 140 C for 2 h in refluxing toluene solution and salt conversion with HCl, yields the monohydrochloride salt of dinimide in 62% yield.

This compound can be obtained by two related ways: 1) The reduction of 3-nitronaphthalene-1,8-dicarboxylic acid anhydride (I) with H2 over Pd/C in DMF gives the corresponding 3-amino-anhydride (II), which is then treated with N,N-dimethylethylenediamine in refluxing toluene or ethanol. (2,3) 2) The reaction of anhydride (I) with N,N-dimethylethylenediamine as before gives 2-[2-(dimethylamino)ethyl]-5-nitro-1H-benz[d,e]isoquinoline-1,3 (2H)-dione (III), which is reduced with H2 or HCOONH4 (4) over Pd/C , or with Sn-HCl at 90-100 C. (1)

Nitration of 1,8-naphthalic anhydride (I) in sulfuric acid at 60 C for 1 h gives 3,6-dinitro-1,8-naphthalic anhydride (II) in 80% yield (m.p. 209-211 C from toluene; NMR: in CDCl3 a 9.22, 9.27, 2 singlet aromatic H), which, on treatment with unsym-N,N-dimethylethylenediamine at room temperature for 30 min, followed by azeotropical removal of water at 140 C for 2 h in refluxing toluene solution and salt conversion with HCl, yields the monohydrochloride salt of dinimide in 62% yield.