英文别名Tadalafil Impurity 20; Tadalafil Spiro-oxindole Impurity (EP Impurity I); Spiro[3H-indole-3,7'(6'H)-pyrrolo[1,2-a]pyrazine]-1',2,4'(1H)-trione, 6'-(1,3-benzodioxol-5-yl)-2',3',8',8'a-tetrahydro-2'-methyl-, (6'R,8'aR)-rel-; Tadalafil Impurity 20 (Tadalafil EP Impurity I); (8a′R)-6′-(1,3-Benzodioxol-5-yl)-2′-methyl-2′,3′,8′,8a′-tetrahydro-6′H-spiro[indole-3,7′-pyrrolo[1,2-a]pyrazine]-1′,2,4′(1H)-trione; rel-(6'R,8a'R)-6'-(Benzo[d][1,3]dioxol-5-yl)-2'-methyl-2',3',8',8a'-tetrahydro-1'H-spiro[indoline-3,7'-pyrrolo[1,2-a]pyrazine]-1',2,4'(6'H)-trione; Tadalafil Impurity 6; Tadalafil Impurity N98; (6'R,8'aR)-6'-(1,3-benzodioxol-5-yl)-2'-methylspiro[1H-indole-3,7'-3,6,8,8a-tetrahydropyrrolo[1,2-a]pyrazine]-1',2,4'-trione 
