Solifenacin Impurity 2

(S)-4-Nitrophenyl 1-Phenyl-d5-3,4-dihydroisoquinoline-2(1H)-carboxylate is the labeled analog of (S)-4-Nitrophenyl 1-Phenyl-3,4-dihydroisoquinoline-2(1H)-carboxylate (N504490), a reactant in the synthesis of solifenacin succinate, an antimuscarinic agent.