Description
N-Boc-PEG4-alcohol is a PEG linker containing a hydroxyl group and Boc-protected amino group. The hydrophilic PEG spacer increases solubility in aqueous media. The hydroxyl group enables further derivatization or replacement with other reactive functional groups. The Boc group can be deprotected under mild acidic conditions to form the free amine.
Synthesis
Example 5: Synthesis of tert-butyl (2-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)ethyl) carbamate
Step 1: Synthesis of S9
In a round bottom flask, 1-amino-3,6,9-trioxa-11-undecanol (2.9 g, 15 mmol) was dissolved in 10 mL of ethanol. Another di-tert-butyl dicarbonate (3.6 g, 16.5 mmol) was dissolved in 10 mL of ethanol and added to the above solution slowly and dropwise over 10 minutes. The reaction mixture was stirred at room temperature for 2 hours. After completion of the reaction, the solvent was removed by rotary evaporator and the residue was purified by column chromatography using dichloromethane/methanol system to give S9 as a colorless oil (3.69 g, 80% yield).
1H NMR (400 MHz, CDCl3) δ (ppm): 5.49 (s, 1H), 3.46-3.25 (m, 14H), 3.02 (s, 2H), 1.18 (s, 9H); ESI-MS calculated value C13H27NNaO4 [M + Na]+ = 316.17, measured value: 316.18.
