ACETOGENIC ISOQUINOLINE ALKALOIDS .50. THE SYNTHESIS OF ALL POSSIBLE ISOMERIC 6,8-DIOXYGENATED 1,3-DIMETHYL-1,2,3,4-TETRAHYDROISOQUINOLINE METHYL ETHERS - USEFUL CHIRAL BUILDING-BLOCKS FOR NAPHTHYLISOQUINOLINEALKALOIDS

The practicable synthesis of all imaginable isomeric heterocyclic moie ties 8-11 and ent-8-ent-11 of the naphthylisoquinoline alkaloids is de scribed. The stereoinformation at C-3 is induced by asymmetric reducti ve amination, using 1-phenylethylamines of either enantiomeric series as chiral auxiliaries. The key step of the stereocontrolled constructi on of the stereocenter at C-1 is the diastereoselective reduction of t he corresponding dihydroisoquinolines, as obtained by Bischler-Napiera lski synthesis, or the regio- and stereoselective Pictet-Spengler reac tion of arylisopropylamines with acetaldehyde, respectively,