2-Hydroxy-6-(3-methylbut-2-en-1-yl)cyclohexa-2,5-diene-1,4-dione is an intermediate used in the synthesis of Endophenazine B (E555485), which is a new phenazine antibiotic isolated from the arthropod associated endosymbiont Streptomyces anulatus and shows antimicrobial activities against Gram-positive bacteria and some filamentous fungi, and herbicidal activity against Lemna minor (duckweed).