4H,8H-Benzo(1,2-b:3,4-b')dipyran-2-carboxylic acid, 5-methoxy-8,8-dimethyl-4-oxo- 5-Methoxy-8,8-dimethyl-4-oxo-4H,8H-benzo(1,2-b:3,4-b')dipyran-2-carboxylic acid 94736-67-1 Perforatic acid