Description
Amino-PEG3-t-butyl ester is a PEG linker containing an amino group with a t-butyl protected carboxyl group. The hydrophilic PEG spacer increases solubility in aqueous media. 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
The general procedure for the synthesis of tert-butyl 12-amino-4,7,10-trioxa-dodecanoate from tert-butyl 3-(2-(2-(2-azidoethoxy)ethoxy)ethoxy)propionate was as follows: Raney-Ni (7.5 g, suspended in water) was washed sequentially with water (three times) and isopropanol (three times), and was subsequently mixed with tert-butyl 3-(2-(2-(2- azidoethoxy)ethoxy ) ethoxy)propionic acid tert-butyl ester (5.0 g, 16.5 mmol) in isopropanol. The reaction mixture was stirred at room temperature under hydrogen atmosphere for 16 hours. After completion of the reaction, the reaction mixture was filtered through a diatomaceous earth pad and the pad was washed with isopropanol. The filtrate was concentrated and purified by column chromatography (eluent: 5-25% methanol/dichloromethane) to afford the light yellow oily product tert-butyl 12-amino-4,7,10-trioxa-dodecanoate (2.60 g, 57% yield). Mass spectrometry (ESI) m/z calculated value C13H28NO5 [M+H]+ 279.19; measured value: 279.19.
References
[1] Organic and Biomolecular Chemistry, 2015, vol. 13, # 1, p. 81 - 97
[2] Journal of the American Chemical Society, 2018, vol. 140, # 38, p. 12189 - 12199
[3] Patent: WO2016/59622, 2016, A2. Location in patent: Page/Page column 102-103
[4] Patent: WO2017/46658, 2017, A1. Location in patent: Page/Page column 148
[5] Patent: WO2018/86139, 2018, A1. Location in patent: Page/Page column 151
