Tadalafil Spiro-urethane Impurity (EP Impurity F)

(6’R,8a’R)-6′-(benzo[d][1,3]dioxol-5-yl)-2′-methyl-2′,3′,8′,8a’-tetrahydro-1’H-spiro[benzo[d][1,3]oxazine-4,7′-pyrrolo[1,2-a]pyrazine]-1′,2,4′(1H,6’H)-trione