Synthesis and Biological Activity of N-Sulfonylphosphoramidates:  Probing the Electrostatic Preferences of Alkaline Phosphatase

N-Sulfonylphosphoramidates have been synthesized to investigate the electrostatic requirements for binding to alkaline phosphatase. Alkyl- and aryl N-benzylated sulfonamides were phosphorylated with bromophosphates or synthesized via phosphoramidite chemistry in moderate yields (44−77%.) The resulting tribenzylated N-sulfonylphosphoramidates may be deprotected in one step to give the free acids in quantitative yields. Physical data of N-sulfonylphosphoramidates, including pK_a's and stability toward hydrolysis, were determined. Inhibition data suggests that AP does not bind trianionic N-sulfonylphosphoramidates better than dianionic N-sulfonylphosphoramidates, although N-sulfonylphosphoramidates are bound tighter than N-phenylphosphoramidate. k_cat for the hydrolysis of N-sulfonylphosphoramidates by bovine and E. coli alkaline phosphatases is 10−60% that of p-nitrophenyl phosphate.