Synthesis and Biological Activity of <i>N</i>-Sulfonylphosphoramidates:  Probing the Electrostatic Preferences of Alkaline Phosphatase

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