To a solution of N-[2-(2-Nitro-benzenesulfonylamino)-ethyl]-N-[(thymin-1-yl)-acetyl]-glycine ethyl ester (1.00 g, 2.0 mmol) in THF (10 ml,) was added a solution of lithium hydroxide (210 mg, 5 mmol) in water (10 mL) at 10° C. After stirring for 1.5 h, the reaction mixture was acidified to pH=2˜3 by adding 1 N HCl solution. The precipitated solid was filtered off, washed with water, and dried in vacuo to give the tilted product as a white solid (896 mg, 95%). 1H-NMR (500 MHz; DMSO-d6) δ 11.30 (s, 0.6H), 11.27 (s, 0.4H), 8.22˜7.85 (m, 5H), 7.31 (d, 0.6H), 7.23 (d, 0.4H), 4.63 (s, 1.2H), 4.45 (s, 0.8H), 4.19 (s, 0.8H), 4.16 (q. 0.8H), 3.93 (s, 1.2H), 3.47 (t, 1.2H), 3.34 (t, 0.8H), 3.20 (q, 1.2H), 3.04 (q. 0.8H), 1.75 (s, 3H).
