The following figure gives an overview of the design and synthesis of transporter caged ATP: a red-shifted clickable photocage installed on the γ-phosphate of ATP using P-amidite chemistry is subsequently modified with dendronized polyamines and polyguanidines. The synthesis of photocage 3 (Scheme 1A) was based on DEAC450 1 modification. 1 was obtained according to a previously reported synthesis (Scheme S1). Afterwards, an alkyne group was introduced to this photocage by peptide coupling to generate a clickable version of DEAC450 2 (Scheme 1A). Deprotection of the silyl group afforded alcohol 3, which reacted with phosphordiamidite 4, giving phosphoramidite 5 (Scheme 1B). Phosphoramidite 5 was utilized as a precursor for generating DEAC450 caged ATP 6 (Scheme 1B) ready for click chemistry. The synthesis strategy of coupling, oxidation and deprotection to obtain modified P-anhydrides has been previously described. One of its salient features is the possibility to run oligophosphate synthesis without protecting groups on the substrates, in this case ADP, and by extension a large variety of phosphorylated molecules.