The structure of (5H)-2-Amino-3-hydroxy-5-phenyl-furan-4-one (lb) was determined by NMR-spectroscopy in solution and in the solid state. The structure of its oxidation product, 3,4-Dihydro-3,3,4,4-tetrahydroxy-5-phenyl-furan-2(5H)-one (7), given in the literature as 5-Phenyl-2,3,4-(5H)-furan-trione, was determined by NMR spectroscopy and crystal structure analysis. The solid state NMR spectrum of 7 was compared to the spectrum of dehydroascorbic acid
Atropisomerism in 2-(2,2-Dicyano-1-methylethenyl)benzoic Acid and 3-(2,2-Dicyano-1-methylethenyl)thiophene-2-carboxylic Acid Studied by Solid-State 13C NMR Spectroscopy and X-Ray Crystallography.