Tetramethylmagnolamine (-, -) (XI) was synthesized by the Ullmann reaction of l-6′-bromolaudanosine (IX) and l-armepavine (X), and it was proved that this synthesized base is the optical antipode of the natural tetramethylmagnolamine (+, +). It was thereby established that the structure of magnolamine itself and the optical rotation of its two asymmetric centers are represented by the structural formula (XII).
