Synthesis of a linear polymer with triacylmethane fragments and study of keto-enole tautomerism in the polymer backbone

The C-acylation reaction of Na-derivatives of β-ketoesters was used for the first time and a polymer containing triacylmethane groups was obtained. The results of 1 H and 13 C NMR measurements showed that a repeating unit of the polymer has a structure similar to dibenzoylacetic ester and exists in three tautomeric forms, including a ketone and two enole forms. The latter forms have intramolecular hydrogen bonds between the enole benzoyl group and the ester group (main tautomer) or between the two enole benzoyl groups. The proportion of enole forms decreases upon going from a solid polymer to solutions.