Description
Amino-PEG2-t-butyl ester is a PEG linker containing an amino group with a t-butyl protected carboxyl group (Boc).The amino group is reactive with carboxylic acids, activated NHS esters, carbonyls (ketone, aldehyde) etc. The t-butyl protected carboxyl group can be deprotected under acidic conditions.
Synthesis
General procedure for the synthesis of tert-butyl 9-amino-4,7-dioxanonanoate from the compound (CAS: 1629676-61-4): 5% Pd/C (JM US 2.14 g) was added to a solution of dibenzylamine 27 (35.0 g, 85 mmol) in methanol (420 mL), and the mixture was placed in an Atlantis reactor and subjected to a hydrogenation reaction at 40 °C and 15 psi hydrogen pressure for the hydrogenation reaction. After 2 h of reaction, the catalyst was removed by filtration and the filtrate was concentrated to yield 18.90 g (96% yield) of amine 7 as a turbid oil, which was used directly in the next step of the reaction without further purification.IR (ATR cells): 2977, 2868, 1727, 1456, 1393, 1367, 1254, 1157, 1113, 847, 755, 589, 564, 547, 536 cm^-1. ^1H NMR (400 MHz, CDCl3): δ = 1.30 (s, 9H), 2.36 (t, J = 6.43 Hz, 2H), 2.71 (t, J = 5.19 Hz, 2H), 3.36 (t, J = 5.19 Hz, 2H), 3.43-3.50 (m, 4H) , 3.57 (t, J = 6.64 Hz, 2H). ^13C NMR (100 MHz, CDCl3): δ = 28.18, 36.36, 41.92, 66.98, 70.32, 70.44, 73.58, 80.52, 170.92. HRMS (ESI): m/z [M + H]^+ Calculated value for C11H24NO4: 234.16998; measured value: 234.17009.
References
[1] Synthesis (Germany), 2014, vol. 46, # 10, p. 1399 - 1406
[2] Patent: WO2016/59622, 2016, A2. Location in patent: Page/Page column 104
[3] Patent: WO2017/46658, 2017, A1. Location in patent: Page/Page column 144
[4] Patent: WO2018/86139, 2018, A1. Location in patent: Page/Page column 152