Propargyl-PEG3-1-o-b-cyanoethyl-NN-diisopropylphosphoramidite is a PEG-based PROTAC linker that can be used in the synthesis of PROTACs. Propargyl-PEG3-1-o-(b-cyanoethyl-N,N-diisopropyl)phosphoramidite is a click chemistry reagent, it contains an Alkyne group and can undergo copper-catalyzed azide-alkyne cycloaddition (CuAAc) with molecules containing Azide groups.