(Method J9B) To the solution of 5-[[[4-(dimethylamino)-1-naphthalenyl]carbonyl]amino]-pentanoic acid methyl ester (3/62) (0.31 g, 0.94 mmol) and hydroxylamine hydrochloride (0.26 g, 3.8 mmol) in absolute methanol was added NaOMe solution made by dissolving Na (0.18 g, 8 mmol) in absolute methanol. A white precipitate immediately appeared. After 0.5 h the reaction was complete (TLC), and the reaction mixture was evaporated, suspended in 1M phosphate buffer (pH 4), and extracted with 3 portions of methylene chloride. The organic phase became turbid, therefore the solvent was removed, and the residue was dried under reduced pressure yielding the crude product (0.27 g). Recrystallisation from acetonitrile gave the title product (0.06 g, 19%) of acceptable purity. Rf 0.50 (CHCl3—MeOH 4:1). M.p. 129° C. 1H NMR (DMSO-d6, TMS) δ: 1.53-1.57 (4H, m), 1.97-2.01 (2H, m), 2.84 (6H, s), 3.32-3.33 (m, overlapped with a signal from DMSO), 7.08 (1H, d, J=8.2 Hz), 7.46-7.56 (3H, m), 8.14-8.24 (2H, m), 8.39 (1H, br t, J=5.2 Hz), 8.69 (1H, br s), 10.37 (1H, br s). HPLC analysis on Symmetry 18 column: impurities <1% (column size 3.9×150 mm; mobile phase acetonitrile −0.1M phosphate buffer (pH 2.5), 10:90; detector UV 220 nm; flow rate 1.3 ml/min). Anal. Calcd for C18H23N3O3: C, 65.63; H, 7.04; N, 12.76. Found: C, 65.50; H, 6.90; N, 12.73.
