CDI (0.188 g, 1.16 mmol) was added to a solution of (10) (0.76 g, 1.09 mmol) in dry CH2Cl2 (45 mL). The solution was cooled to 0° C. after 1 hour and (6) (free amine, 0.240 g, 1.15 mmol) was added by cannula in CH2Cl2 (60 mL) over 5 minutes. The reaction was stirred at 0° C. to room temperature for 24 hours. Solvent was removed in vacuo and dilute brine (100 mL) was added to the residue. Extraction was carried out with EtOAc (5×75 mL), followed by washing with 50 mL of cold 0.5M citric acid, 5% NaHCO3, water and brine. Solvent removal gave 0.87 g (90% ) of (11) which was used directly in the next reaction: NMR δ 1.1-1.8 (m+s, 27 H) , 2.3-3.7 (m, 20 H), 4.5 (br s, 1 H), 4.67 (s, 2 H), 4.82 (s, 4 H), 6.2 (br s, 1 H), 7.2-7.4 (m, 15 H). An analytical sample of (11) was obtained from silica gel column chromatography, eluting with 5% MeOH/CHCl3. Anal. calcd. for C49H72N6O9 : C, 66.19; H, 8.16; N, 9.45. Found: C, 66.18; H, 8.17; N, 9.42.
