(3aR,4S,7R,7aS)-rel-3a,4,7,7a-Tetrahydro-4-methyl-4,7-epoxyisobenzofuran-1,3-dione is an intermediate in the synthesis of 2-Amino-1,6-dimethylfuro[3,2-e]imidazo[4,5-b]pyridine (A605070), a heterocyclic aromatic amines (HAAs) as potential human carcinogen.