The constitution of the alkaloid anonaine has been investigated. The following structural formula was suggested: It is based chiefly on the following experimental results: 1. Empirical formula for anonaine C17H15O2N. 2. Proof a methylenedioxy and a secondary amino-group. 3. Negative tests for methoxy, carbonyl, phenolic and alcoholic hydroxy groups. 4. The details of the Hofmann degradation as well as the effect of chloroethylcarbonate upon N. methyl-anonaine proved the isoquinoline structure of anonaine. 5. The formation of phthalic acid in the oxydation of anonaine proved that anonaine does not possess a papaverine structure. It showed further, that ring C is unsubstituted. By analogy the methylenedioxy group was assumed to be in position 5,6. The correctness of the suggested formula was proved by the synthesis of the alkaloid. d,1-anonaine and also d,1-N-methyl-anonaine were synthesised. These synthetic alkaloids were deprived of their asymmetric centres by a Hofmann degradationand the products thus obtained were proved to be identical with the corresponding degradation compounds of natural anonaine
