The diamide (IX) was prepared by Schotten-Baumann reaction of 2-(3-methoxy-4-hydroxyphenyl) ethylamine with the diacid chloride (V), followed by ethoxycarbonylation. Cyclization gave the bisdihydroisoquinoline (XI), the dimethiodide of which, on reduction, gave a stereoisomeric mixture of magnoline or berbamunine (I).

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A synthesis of rac-dihydrorotundine (I) was described. Methylsuccinic anhydride was condensed with ethyl 3, 4-dimethoxyphenethylaminoacetate to yield a single methyl-succinamic acid (XI), having the methyl substituent β to the amido group. This was esterified, cyclized, and reduced, and thus the tetrahydroisoquinoline base (XIII) was obtained. Dieckmann cyclization of the latter by means of sodium hydride in boiling toluene gave a fair yield of the keto-ester (XV), but its ketonic fission proceeded with difficulty and thus the ketone (XVI) was produced only in a low yield. When dimethyl ketal (XVII) of (XVI) was submitted to distillation in vacuo a loss of one molecule of methanol took place and rac-dihydrorotundine (I) was collected as a viscous distillate, which was characterized as its crystalline methiodide. rac-Dihydro-norrotundine (X) was also prepared as a model substance and its behavior towards catalytic hydrogenation was studied.

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A synthesis of9, 10-dimethoxy-1, 2, 3, 4, 6, 7-hexahydro-2, 6-methano-11bH-benzo [a]-quinolizine having a new ring system was described. Thus, dl-N-benzyl-3-(3, 4-dimethoxyphenyl) alanine ester (VI) was condensed with succinic anhydride followed by esterification to give amido-ester (IX), which on being cyclized with phosphoryl chloride under reflux furnished the corresponding dihydroisoquinoline derivative (X) isolated as iodide. When the latter was reduced with sodium borohydride-methanol, there were obtained α-and β-isomers of tetrahydroisoquinoline derivative (XI)ca. in a ratio 5 : 1. On being cyclized with sodium hydride-toluene they gave one and the same cyclic β-ketoester (XII), which was condensed with ethyl bromoacetate followed by ketone fission to yieldγ-ketoester (XV). An alternative route XV was also discribed. XV was then reduced with sodium borohydride and the resultant alcohol (XVIII) was chlorinated to give the chloride (XIX), which was reduced with lithium aluminum hydride-tetrahydrofuran. The reduction product was directly tosylated and worked up properly furnishing the cyclized product, which was characterized as perchlorate. On being reduced catalytically the latter furnished the ultimate product (I). A smaller quantity of by-product was also obtained in the final cyclization step, to which structure (I-B) was postulated.

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