2-Ethyl-2,5-dihydro-4-hydroxy-3-methyl-5-oxo-2-furancarboxylic Acid Methyl Ester is an by-product intermediate formed during the synthesis of 4,5-Dimethyl-3-hydroxy-2(5H)-furanone (D473600), a fragrant compound that is a key indicator of maple syrup urine disease, a disorder affecting newborn children that is the result of its inability to properly metabolize Valine (V094205), Leucine (L330110) and Isoleucine (I820175). 4,5-Dimethyl-3-hydroxy-2(5H)-furanone is naturally found in fenugreek seeds, and is an odourant present in sherry wines.