USING NPS CHROMATOGRAPHY TO MONITOR MESYLATION REACTIONS

Abstract

Using nonporous silica (NPS) chromatography, mesylation reactions with unhindered and hindered amines were studied as proton scavengers. During reaction monitoring it is important to conduct sensitive and fast analyses. To optimally control the reaction quick feedback is necessary. The NPS proved to be highly suitable. When unhindered amines are used to remove the proton, the S_N2 mesylate reaction was observed to take place, followed by the S_N1 reaction to form the quaternary salt. The S_N1 reaction did not occur when the sterically hindered dicyclohexylamine was used. Liquid chromatography/mass spectrometry confirmed this process and was used to identify the final products when various amines were used as proton scavengers. This study confirmed that dicyclohexylamine is the preferred proton scavenger if one desires to obtain a stoichiometric amount of mesylate.

Acknowledgments