Liriodenine (III) is recognised to be a representative of a new class of isoquinoline alkaloid belonging to the aporphine subgroup. A synthetic procedure for this type of alkaloid is developed and applied to the specific case of liriodenine, the key step being the Pschorr cyclization of 1-2′-aminobenzoyl-6,7-methylenedioxyisoquinoline. © 1961.