Hydrochloric Acid → 12-(Methanesulfonyl)-3-methoxy-5,8,8a,9,10,11,12,12a,13,13a-decahydro-6H-isoquinolino[2,1-g][1,6]naphthyridine--hydrogen chloride (1/1)

Excess 3% hydrogen chloride in methanol is added to a solution of (8aR,12aS,13aS)-3-methoxy-12-methanesulfonyl-5,6,8a,9,10,11,12,12a,13,13a-decahydro-8H-isoquino[2,1-g][1,6]naphthyridine in 20 ml methanol. Diethyl ether is added until precipitation is complete. The product is filtered, washed with ether, air dried and recrystallized from methanol/acetone to yield (8aR,12aS,13aS)-3-methoxy-12-methanesulfonyl-5,6,8a,9,10,11,12,12a,13,13a-decahydro-8H-isoquino[2,1-g][1,6]naphthyridine hydrochloride.