Preparation of substituted cinnamic acids labelled with deuterium and tritium at the ring positions

Abstract

A series of substituted cinnamic acids labelled at the ring positions with deuterium or tritium has been easily obtained via the Doebner modification of Knoevenagel condensation reaction between labelled benzaldehyde derivatives and malonic acid in pyridine. The substituted benzaldehyde precursors were synthesized by isotope exchange method in deuterated or tritiated water at 80 °C in acidic medium. Ring-tritiated substituted cinnamic acids with specific activity ranging from 207 GBq /5.6 Ci/ mol−1 to 4366 GBq /118 Ci/ mol−1 was obtained using ca. 37 GBq /1 Ci/ of HTO.