Synthesis of ¹⁴C labelled acrylic derivatives: Diethyl [3‐¹⁴C] methylidenemalonate and isobutyl [3‐¹⁴C] cyanoacrylate

Abstract

Abstract Isobutyl [3‐ 14 C] cyanoacrylate and diethyl [3‐ 14 C] methylidenemalonate were synthesized by the intermediate of their protective Diels‐Alder adduct with anthracene. These adducts ( 2a‐b ) were obtained in a one‐pot procedure by Knoevenagel condensation of [ 14 C] paraformaldehyde with isobutyl cyanoacetate and diethyl malonate respectively in the presence of a basic catalyst and anthracene. The adducts are stable crystalline compounds easily purified by recrystallization. The olefinic target coumpounds ( 1a‐b ) were obtained in high chemical and radiochemical purity (>99%) by thermolysis at 220 °C in mineral oil in the presence of maleic anhydride.