(2S-cis)-3-(Bromomethyl)-2-methyl-2-(4-methyl-3-pentenyl)oxirane is an intermediate used in the synthesis of Juvenile Hormone B 3 (J211205), which is a sesquiterpenoid produced by the larval ring gland and adult corpus allatum (CA) of Drosophila melanogaster. Juvenile hormones regulate development, reproduction, diapause, and polyphenisms.