New aliphatic boronate ligands for affinity chromatography

Abstract

Aliphatic boronates have not been used as ligands in boronate affinity chromatography, possibly because of their low stability. To fill this void, we have prepared three different boronate esters: 1-chloro-5-(3-dimethylaminophenoxy)pentane-1-boronate, 1-thiourea-5-(3-dimethylaminophenoxy)pentane-1-boronate and 1-acetamido-5-(3-dimethylaminophenoxy)pentane-1-boronate, the latter two of which have a hetero atom coordinated with the boron, creating a tetrahedral boronate. These were coupled to the hydroxylic matrix and their ability to interact with various catechols was tested. Chloroboronate gel bound a number of catechol derivatives, except dl-DOPA, quantitatively, but was rather unstable. Thiourea-boronate gel, on the other hand, was relatively stable, although chromatography using it failed. Acetamido-boronate gel did not bind catechol derivatives quantitatively, but did retard them differentially, a property which could be used for their separation. Acetamido-boronate gel was also more stable than chloro-boronate gel, although it was not stable enough for unlimited application. © 1992.