The Use of Polymer Supports in Organic Synthesis. III. Selective Chemical Reactions on One Aldehyde Group of Symmetrical Dialdehydes

Abstract

An insoluble polymer support system incorporating a diol functional group was prepared. The symmetrical dialdehydes, terephthalaldehyde and isophthalaldehyde, were attached to the polymer through acetal formation, constituting a unique method of blocking one aldehyde group of symmetrical dialdehydes. The free aldehyde group was reacted with hydroxylamine to give the mono-oximes of the terephthalaldehyde and isophthalaldehyde upon acid cleavage from the polymer. Similarly, the polymer bound aldehydes were reacted with Wittig reagents to give p- and m-formylstilbenes and 1-p- and -m-formyl-phenyl-4-phenyl-1,3-butadienes. The crossed aldol condensation of acetophenone with the symmetrical dialdehydes gave the 3-p- and -m-formylphenyl-1-phenyl-2-propene-1-ones (formylchalcones) in high yield. The Grignard reaction of phenylmagnesium bromide on the polymer bound aldehyde gave(p- and m-formylphenyl)phenylcarbinol in quantitative yield. Reduction of the polymer bound free aldehydes with sodium bis(2-methoxyethoxy)-aluminum hydride gave p- and m-hydroxymethylbenzaldehydes. Similarly the mixed benzoin condensation of polymer bound terephthalaldehyde and isophthalaldehyde gave p- and m-formylbenzils.