The absolute configuration of (+)-10-hydroxy-1, 2, 3, 3a, 11b, 11c-hexahydroaporphine A and B (IVa and IVb), which were obtained as by-products on the cyclization of (+)-1-(4-methoxybenzyl)-2-methyl-1, 2, 3, 4, 5, 6, 7, 8-octahydroisoquinoline (I) to (+)-3-hydroxy-N-methylmorphinan (II) was established by degradation reaction to 3-alkyl cyclohexane-1, 2-dicarboxylic acids.
