Structure and Synthesis of the Anhalonium Alkaloids

Degradation experiments disproved Spath s first assumption that the other bases in mescal buttons, were structurally similar to the then known mescaline. Spath, therefore, gathered experimental evidence for their structure, mainly of synthetic nature, working on the hypothesis that their structures were of the isoquinolinic pattern (2). Starting from N-acetylmes-caline the following route was followed  

The quaternary iodide obtained was shown to be identical with 0-methyl-pellotine methiodide. Pellotine and anhalonidine yield, on complete methylation, the same product, and, since anhalonidine is a secondary base, pellotine must be A -methylanhalonidine. 

In a further study Spath (19) described the synthesis of anhalonidine and pellotine. Treatment of the 0, A -diacetyl derivative of the 5-hydroxy- 

4-dimethyoxyphenethylamine with phosphorus pentoxide, and reduction of the resultant dihydroisoquinoline followed by hydrolysis of the 0-acetyl group afforded anhalonidine. However, the position of the free hydroxyl group in anhalonidine (and pellotine) had still to be determined two different structures were possible, since the ring closure might have taken place either in the ortho (I) or para position (II) to the hydroxy group  

The correct anhalonidine structure (I) was proved by Spath and Passl 

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