Tolterodine Lactone Impurity Racemate

6-Methyl-4-phenyl-3,4-dihydro-1-benzopyran-2-one|6-Methyl-4-phenyl-3,4-dihydro-1-benzopyran-2-one ;|6-methyl-4-phenylchroman-2-one;|Tolterodine Lactone Impurity Racemate ;