Optically active 1-(p-methoxybenzyl)-1,2,3,4,5,6,7,8-octahydroisoquinoline having the formula (I) is prepared by asymmetric hydrogenation of the corresponding 3,4,5,6,7,8-hexahydro-compound or of the new 1-(p-methoxybenzyl)-3,4,5,6,7,8-hexahydroisoquinoline dihydrogenated phosphate in the present of chiral iridium-phosphine complexes. This product is an intermediate product in the synthesis of cough-relieving dextromethorphanne and analgesic levorphanol. ##STR1##
