Of 7-hydroxy-6-methoxy-1 methylisoquinoline

Recently, Gozler et al. (123) proposed the stereostructure 1,4-ci s-l,2,3,4-tetrahydro-4,6-dihydroxy-7-methoxy-l-(3,4-dimethoxyben-zyl)-2-methylisoquinoline (446) for (-l-)-roemecarine. However, the stereostructure was revised to 449 based on the synthesis of 446 (124). Namely, two epimeric acetates, ( )-l,4-(ij- and ( )-l,4-/r zi.v-4-acetoxy-l,2,3,4-tetrahydro-6-hydroxy-7-methoxy-1 -(3,4-dimethoxybenzyl)-2-methyliso -quinolines (447 and 448), previously prepared via a thermal isomerization of the corresponding o-quinol acetates (19), were used for synthesis of ( )-roemecarine and its epimer (Scheme 60). Hydrolysis of 447 and 448 with 5% methanolic potassium hydroxide proceeded with retention of the configuration at C-4 to give the authentic ( )-1,4-c/.v- and ( )-i,4-tran.s-diols 446 and 449. As a result, structure 446 was inconsistent with natural roemecarine on the basis of H-NMR spectral comparison, while 449 was identical with the alkaloid with respect to spectroscopic data. 

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