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Structural Studies on Related Argemone Alkaloids

1961; Elsevier BV; Volume: 50; Issue: 4 Linguagem: Inglês

10.1002/jps.2600500410

1520-6017

Lemont B. Kier, Taito O. Soine,

Advanced Synthetic Organic Chemistry

The alkaloids argemonine, C16H10(OCH3)4NCH3; norargemonine, C16H10(OCH3)3-(OH)NCH3; and bisnorargemonine, C16H10(OCH3)2(OH)2NCH3 are considered to be tetrahydroisoquinolines based on oxidation products and the inability to hydrogenate argemonine further. The benzoylation reaction of bisnorargemonine is typical of aporphine alkaloids. Oxidation studies indicate that the hydroxyl group of norargemonine is in ring D while the two hydroxyl groups of bisnorargemonine are in rings A and D. The Hofmann degradation of argemonine yielded successively a vinyl dihydrophenanthrene methine and an unexpected pyran. Oxidation of the pyran gave an expected tricarboxylic acid. Hydrogenation of the methine followed by the Hofmann degradation gave the expected ethyl phenanthrene. It is tentatively proposed that argemonine has a 6,7 placement of methoxyl groups in ring A and of the three possible vicinal placements of methoxyl groups in ring D, the 2,3 positions appear to be the most likely.