A Synthesis of 2-(6, 7-Dimethoxy-1, 2, 3, 4-tetrahydro-1-isoquinolylmethyl)-9, 10-dimethoxy-1, 2, 3, 4, 6, 7-hexahydro-11bH-benzo [a] quinolizine (rac-c-Bisnoremetine)

A new synthesis of rac-c-bisnoremetine was described, in which 4-acetylpyridine was one of the starting materials. Ethyleneketal of this compound was quaternized with 3, 4-dimethoxy-phenethyl bromide and the product (II) was subjected to oxidation with alkaline potassium ferricyanide to furnish 1-(3, 4-dimethoxyphenethyl)-4-acetyl-2 (1H)-pyridone in a good yield after acid hydrolysis. The latter ketone (IV) underwent a smooth Willgerodt reaction to give the corresponding acetic acid (VI) from which the key intermediate (XIII) was prepared by several different routes. The structure of the final product (XV) was proved by converting the penultimate compound (XIV) into a well defined crystalline rac-c-bisnorrubremetinium bromide (XVI).