tert-butyl N-[2-[2-[2-(2-aminoethoxy)ethoxy]ethoxy]ethyl]carbamate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To (S)-4-(((9H-fluoren-9-yl)methoxy)carbonylamino)-5-tert-butoxy-5-oxopentanoic acid (721 mg, 1.69 mmol), tert-butyl 2-(2-(2-(2-aminoethoxy)ethoxy)ethoxy)ethylcarbamate (595 mg, 2.04 mmol), and N,N-diisopropylethylamine (0.9 mL, 5.2 mmol) in THF (20 mL), N,N,N′,N′-tetramethyl-O-(1H-benzotriazol-1-yl)uroniumhexafluorophosphate (1.29 g, 3.40 mmol) was added in one portion. The reaction was stirred 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 hexanes to ethyl acetate to afford (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 (1.17 g, 99%) as an off-white solid: 1H NMR (300 MHz, CDCl3) δ 7.77 (d, J=7.5 Hz, 2H), 7.62-7.59 (m, 2H), 7.44-7.38 (m, 2H), 7.36-7.26 (m, 2H), 6.78 (bs, 1H), 6.07 (bs, 2H), 5.77 (bs, 1H), 4.42-4.38 (m, 2H), 4.27-4.17 (m, 2H), 3.80-3.70 (m, 2H), 3.68-3.46 (m, 9H), 3.31-3.12 (m, 4H), 2.37-2.13 (m, 3H), 2.00-1.87 (m, 1H), 1.47 (s, 9H), 1.45 (s, 9H); ESI MS m/z=700 [M+H]+. After this time, the reaction was dry purified by silica gel column chromatography eluting with hexanes to ethyl acetate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To (S)-4-(((9H-fluoren-9-yl)methoxy)carbonylamino)-5-tert-butoxy-5-oxopentanoic acid (721 mg, 1.69 mmol), tert-butyl 2-(2-(2-(2-aminoethoxy)ethoxy)ethoxy)ethylcarbamate (595 mg, 2.04 mmol), and N,N-diisopropylethylamine (0.9 mL, 5.2 mmol) in THF (20 mL), N,N,N′,N′-tetramethyl-O-(1H-benzotriazol-1-yl)uroniumhexafluorophosphate (1.29 g, 3.40 mmol) was added in one portion. The reaction was stirred 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 hexanes to ethyl acetate to afford (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 (1.17 g, 99%) as an off-white solid: 1H NMR (300 MHz, CDCl3) δ 7.77 (d, J=7.5 Hz, 2H), 7.62-7.59 (m, 2H), 7.44-7.38 (m, 2H), 7.36-7.26 (m, 2H), 6.78 (bs, 1H), 6.07 (bs, 2H), 5.77 (bs, 1H), 4.42-4.38 (m, 2H), 4.27-4.17 (m, 2H), 3.80-3.70 (m, 2H), 3.68-3.46 (m, 9H), 3.31-3.12 (m, 4H), 2.37-2.13 (m, 3H), 2.00-1.87 (m, 1H), 1.47 (s, 9H), 1.45 (s, 9H); ESI MS m/z=700 [M+H]+. After this time, the reaction was dry purified by silica gel column chromatography eluting with hexanes to ethyl acetate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To (S)-4-(((9H-fluoren-9-yl)methoxy)carbonylamino)-5-tert-butoxy-5-oxopentanoic acid (721 mg, 1.69 mmol), tert-butyl 2-(2-(2-(2-aminoethoxy)ethoxy)ethoxy)ethylcarbamate (595 mg, 2.04 mmol), and N,N-diisopropylethylamine (0.9 mL, 5.2 mmol) in THF (20 mL), N,N,N′,N′-tetramethyl-O-(1H-benzotriazol-1-yl)uroniumhexafluorophosphate (1.29 g, 3.40 mmol) was added in one portion. The reaction was stirred 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 hexanes to ethyl acetate to afford (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 (1.17 g, 99%) as an off-white solid: 1H NMR (300 MHz, CDCl3) δ 7.77 (d, J=7.5 Hz, 2H), 7.62-7.59 (m, 2H), 7.44-7.38 (m, 2H), 7.36-7.26 (m, 2H), 6.78 (bs, 1H), 6.07 (bs, 2H), 5.77 (bs, 1H), 4.42-4.38 (m, 2H), 4.27-4.17 (m, 2H), 3.80-3.70 (m, 2H), 3.68-3.46 (m, 9H), 3.31-3.12 (m, 4H), 2.37-2.13 (m, 3H), 2.00-1.87 (m, 1H), 1.47 (s, 9H), 1.45 (s, 9H); ESI MS m/z=700 [M+H]+. After this time, the reaction was dry purified by silica gel column chromatography eluting with hexanes to ethyl acetate