N-Boc-Azido-tris(ethylenoxy)-L-alanin has a Boc protected L-alanine residue and an azido group. The free amine can under further conjugation with carboxylic acid bearing molecules to form amide bond. The azide group can react with alkyne, BCN, DBCO via Click Chemistry to afford a stable triazole linkage.
AxisPharm offers 4000+ PEG Linkers with high purity. Different kinds of PEG Reagents may be available by custom synthesis.