6,17-Bis(benzyloxy)-7,10-dioxo-6,11,17-triazaheptadecane-nitrile (9) was synthesized by slowly adding trifluoroacetic acid (TFA, 40 mL) to (8) (6.00 g, 10.1 mmol) in CH2Cl2 (100 mL). The solution was stirred at 0° C. for 15 minutes and at room temperature for 30 minutes. Solvents were removed by rotary evaporation, aqueous NaHCO3 was added and the product was extracted into CHCl3. Column chromatography on silica gel, eluting with 5% CH3OH/CHCl3, afforded 4.3 g (87%) of (9): NMR δ 1.2-1.8 (m, 10 H), 2.2-3.3 (m, 10 H), 3.62 (t, 2 H, J=7), 4.63 (s, 2 H), 4.82 (s, 2 H), 5.5 (br s, 1 H), 5.87 (br s, 1 H), 7.15-7.35 (m, 10 H). Anal. calcd. for C28H38N4O4 : C, 67.99; H, 7.74; N, 11.33. Found: C, 67.82; R, 7.79; N, 11.29 [Bergeron at al, Tetrahedron (1989), supra].
