Condensation of 1,8-naphthalic anhydride (I) with ethylenediamine (II) provides the N-aminoethyl naphthalimide (III). Amine (III) is subsequently condensed with 2-chloroethyl isocyanate (IV) to afford urea (V). Finally, nitrosation of (V) by means of NaNO2 and formic acid leads to the title N-nitrosourea.