Ammonia hydroxide → (5)-Tert-butyl 21-amino-2,2-dimethyl-4,18-dioxo-3,8,11,14-tetraoxa-5,17-diazadocosan-22-oate

Participants

Reaction Conditions

Reaction Steps

To (S)-tert-butyl 1-(9H-fluoren-9-yl)-24,24-dimethyl-3,8,22-trioxo-2,12,15,18,23-pentaoxa-4,9,21-triazapentacosane-5-carboxylate (1.18 g, 1.69 mmol), in 1,4-dioxane (45 mL) chilled to 0° C. concentrated ammonia hydroxide (9.5 mL, 133 mmol) was added dropwise over 15 minutes. The reaction was stirred at 0° C. for 2 hours and then at ambient temperature for 16 hours. After this time, the reaction was dry loaded onto silica and purified by silica gel column chromatography eluting with methylene chloride to 3:17 methanol/methylene chloride to afford (S)-tert-butyl 21-amino-2,2-dimethyl-4,18-dioxo-3,8,11,14-tetraoxa-5,17-diazadocosan-22-oate (802 mg, 99%) as an off-white solid: 1H NMR (300 MHz, CDCl3) δ 6.92 (bs, 1H), 5.14 (bs, 3H), 3.90-3.85 (m, 1H), 3.80-3.54 (m, 9H), 3.49-3.45 (m, 2H), 3.34-3.29 (m, 2H), 3.23-3.15 (m, 3H), 2.61-2.41 (m, 2H), 2.33-2.23 (m, 1H), 2.15-2.03 (m, 1H), 1.48 (s, 9H), 1.46 (s, 9H); ESI MS m/z=478 [M+H]+.

Provenance & Evidence