Synthesis of the optical isomers of (+)-methyl 6,7-dimethyl-3',4'-dideoxynorlaudanosoline-l-carboxylate ((k)-Z) was accomplished by reaction of (+)-2 with (+)-(R)-1-phenylethyl isocyanate, separation of the urea diastereoisomers (-)-4A and (+)-48, and alcoholysis of the ureas in refluxing BuOH. Optically active isoquinolinecarboxylates ZA, B and hydantoins 8A,B isolated were characterized. The absolute configuration of the reaction products was established by X-ray analysis of the optically active hydantoin (+)-8A. Hydrolysis of the methyl isoquinolinecarboxylates 2A, B with 48 % HBr soh. at reflux afforded the desired optically active 3',4'-dideoxynorlaudanosoline-1 -carboxylic acids 1 A, B required for enzyme-inhibition studies. Details of the X-ray diffraction analysis of (+)-methyl salsoline-I-carboxylate hydrobromide ((+)-1lA. HBr) prepared earlier are included. CD spectra of (+)-(S)-methyl 6,7-dimethyl-3',4-dideoxynorlaudanosoline-l-carboxylate hydrobromide ((+)-2A. HBr) and (-)-(R)-methyl salsoline-1-carboxylate hydrochloride ((-)-llB' HCI) confirmed the assignment of their (S)and (R)-configurations, respectively. ') Salsoline and norlaudanosoline are well known alkaloids, and these names will be used in the General Part (for systematic names, see Exper. Part). The systematic name for salsoline is l-methyl-7-methoxy-l,2,3,4-tetrahydroisoquinolin-6-01 and that for norlaudanosoline, also named tetrahydropapaveroline, is 1-(3',4'-dihy-droxybenzy1)-1,2,3,4-tetrahydroisoquinoline-6,7-diol.