19436-54-5 2H-Thiopyran-5-carboxylic acid, 3-benzyl-4-hydroxy-2-oxo-6-phenyl- 3-Benzyl-4-hydroxy-2-oxo-6-phenyl-2H-thiopyran-5-carboxylic acid 3-Benzyl-4-hydroxy-5-karboxy-6-phenyl-thia-alpha-pyron [German]