Reaction Steps
A solution of 16 (0.25 g, 0.5 mmol) in 10 mL of CH2Cl2 was treated with 70 μL (0.75 mmol) acetic anhydride followed by 140 μL (1.0 mmol) triethylamine. After stirring for 16 h, the mixture was washed with sodium bicarbonate solution, dried with sodium sulphate and purified by flash chromatography. Yield: 0.22 g (82%). Mp. (oxalate): foam. 1H NMR (CDCl3): δ 1.84 (m, 1H), 2.05 (m, 1H), 2.12 (s, 3H), 2.52 (dd, J 13.2, 5.2, 1H), 2.65 (m, 5H), 2.99 (s, 4H), 3.25 (dq, J 9.7, 5.00, 1H), 3.81 (dt, J 12.3, 5.7, 1H), 5.19 (m, 1H), 6.89 (dd, J 7.7, 1.8, 1H), 7.06-7.17 (m, 3H), 7.26 (ddd, J 6.1, 4.8, 2.44, 1H), 7.73-7.76 (m, 2H), 7.93 (d, J 8.6, 2H), 8.07 (d, J 8.6, 2H), 8.70 (td, J 4.83, 1.50, 1.50, 1H). 13C NMR (CDCl3): δ 21.0, 32.4, 36.1, 51.3, 53.7, 61.5, 69.6, 118.6, 120.8, 122.7, 124.5, 127.0, 127.4, 127.5, 133.9, 134.7, 136.9, 142.1, 149.8, 151.1, 156.2, 167.1, 171.5, Anal. (C26H30Cl2N4O3.1.5(COOH)2.H2O) C, H, N.
