an Entity references as follows:
Macrophomic acid is a fungal metabolite isolated from the fungus . The enzyme converts 5-acetyl-4-methoxy-6-methyl-2-pyrone to 4-acetyl-3-methoxy-5-methyl-benzoic acid (macrophomic acid) through an unusual intermolecular Diels-Alder reaction (Scheme 1). The pathway to formation of macrophomic acid suggests that the enzyme is a natural Diels-Alderase. Formation of this type of aromatic ring compound normally proceeds via the shikimate and polyketide pathways; however, the production of macrophomic acid by macrophomate synthase proceeds totally differently. Learning about the production of macrophomic acid by a possible natural Diels-Alderase enzyme is important in understanding enzyme catalytic mechanisms. This knowledge can then be applied to organic synthesis.