The diazotisation of 6,7-dimethoxy- and 7-ethoxy-6-methoxy-1-(2-amino-4,5-methylenedioxybenzyl)-1,2,3,4-tetrahydro-2-methylisoquinoline (XII) and (XV), followed by thermal decomposition, gave amurine (Ib), as a result of which Döpke's structure for the alkaloid was proved to be correct.