摘要：

PURPOSE:To obtain cotarnine useful as a raw material for tritoqualine which is an antiallergic agent without forming isomers, by dehydrogenating a specific tetrahydroisoquinoline compound to give dihydroisoquinoline and subjecting the resultant dihydroisoquinoline to methylation and hydrolysis one after another. CONSTITUTION:8-Methoxy-6, 6-methylenedioxy-1, 2, 3, 4-tetrahydroisoquinoline expressed by formula I is dehydrogenated with a hypohalogenous acid or a salt thereof, etc., in a molar amount of preferably 0.5-2 times based on the compound expressed by formula I in a solvent, e.g. methanol, preferably at 0-100 deg.C to give a dihydroisoquinoline expressed by formula II, which is then methylated with a methylating agent, e.g. dimethyl sulfate, in a molar amount of preferably 0.8-10 times based on the compound expressed by formula II at 0-100 deg.C. The resultant compound is then hydrolyzed in the presence of preferably a base, e.g. NaOH, normally in a solvent, e.g. water or alcohol, at -20-+100 deg.C to afford the aimed cotarnine.

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