Synthesis of a Phosphate-Bridged Photoaffinity Labeling Probe via Transesterification of Phenols and Alcohols

We report a mild and versatile method for installing photoaffinity tags onto phenolic and alcoholic bioactive molecules. 4-Nitrophenyl phosphate and phosphoramidate based phosphoryl donors were designed to selectively modify phenol- and alcohol-containing drugs, respectively. The reactions proceeded with a broad substrate scope, good functional group tolerance, and compatibility with competing nucleophiles. In-gel fluorescence imaging demonstrated that the resulting phosphate-bridged photoaffinity probes are stable and effectively label cellular proteins, underscoring their utility for chemoproteomic applications, such as target identification.