Synthesis and Characterization of Cell‐Permeable Caged Phosphates that Can Be Photolyzed by Visible Light or 800 nm Two‐Photon Photolysis

We report the synthesis and photolytic properties of caged inorganic phosphates (Pi compounds) based on the 2‐(4′‐{bis[2‐(2‐methoxyethoxy)ethyl]amino}‐4‐nitro‐[1,1′‐biphenyl]‐3‐yl)propan‐1‐ol (EANBP) and 7‐(diethylamino)coumarin‐4‐yl]methyl (DEACM) protecting groups. The EANBP‐Pi showed unprecedented photolysis efficiency at 405 nm, with 95 % release of free phosphate and a quantum yield of 0.28. Thanks to the high two‐photon sensitivity of the EANBP chromophore, Pi release through two‐photon photolysis is also possible, with an action cross section of 20.5 GM at 800 nm. Two bioactivatable acetoxymethyl protection groups were added to the “caged‐Pi” compounds. The resulting triesters of phosphoric acid were able to diffuse through the cellular membranes of plant cells. Once inside a cell, the cleavage of these biocleavable motifs by intracellular esterases allows intracellular accumulation of EANBP‐Pi. Bis(AM)‐EANBP‐Pi therefore represents a very attractive tool for study of the Pi signal transduction cascade in living cells.