Bis[2‐(methylsulfonyl)ethyl] phosphochloridate, a new phosphorylating agent

This communication describes the application of the 2‐(methylsulfonyl)ethyl group (Mse) as a base‐labile protecting group for the two hydroxyl functions in phosphoric acid monoesters. Due to its perfect stability towards acids, the Mse group can function as a stable protecting group in a phosphochloridate, providing a suitable phosphorylating agent. Some model phosphorylations are presented, and the reaction is applied to the synthesis of bis[2‐(methylsulfonyl)ethyl] tyrosine phosphate. Removal of the Mse functions is achieved effectively and extremely rapidly in alkaline media. The estimation of the minimum conditions necessary for the removal of one or both Mse functions from bis[2‐(methylsulfonyl)ethyl] p‐nitrophenyl phosphate and from a tyrosine derivative is described.