5-O-Demethyl-5-O-[(2-propen-1-yloxy)carbonyl]avermectin A1a is an intermediate used in the synthesis of Emamectin-D3 (E520402), which is deuterium labeled emamectin, a soluble derivative of avermectin and used asparasiticide and insecticide.Emamectinactivates glutamate-gated chloride channels.