Use of polymers as protecting groups: Interaction of the reactive sites in highly crosslinked macroporous derivatives of glycidyl methacrylate-ethylene dimethacrylate resins

Diol-containing resins derived from a 60:40 co-polymer of glycidyl methacrylate and ethylene dimethacrylate were used as protecting groups for an aldehydic function of terephthalaldehyde through the formation of acetal linkages. The polymer with pendant aldehyde groups was then modified in the solid phase by reaction with hydroxylamine or sodium borohydride to yield the corresponding polymer-bound oximes or alcohols. Cleavage of the acetal links to the polymer support resulted in the liberation of terephthalaldehyde mono-oxime or p-hydroxybenzaldehyde, as well as large amounts of terephthalaldehyde. These results indicate that although the starting polymer is highly crosslinked, extensive interaction of the reactive sites occur during the slow formation of the acetal links to the polymer support. Fourier transform infrared difference spectroscopy proved extremely valuable in the monitoring of the various chemical transformations on the solid support.