N,N,N’,N’-Tetramethyl-S-(1-oxido-2-pyridyl)thiouronium Hexafluorophosphate is a reagent used in the preparation of hindered Barton esters from hindered carboxylic acid precursors. N,N,N’,N’-Tetramethyl-S-(1-oxido-2-pyridyl)thiouronium Hexafluorophosphate is also used as a coupling reagents for peptide bond formations and amidation reactions.