Thioureas 2-5 were prepared from homocalycotomine and isocyanates. When 2 and 3 were treated with methyl iodide and then with alkaline, 9,10-dimethoxy-4-arylimino-1,6,7,11b-tetrahydro-2H,4H-1,3-oxazino[4,3-a] isoquinoline, 6 and 7 were formed. The corresponding 9,10-dimethoxy-4-arylimino- 1,6,7,11b-tetrahydro-2H,4H-1,3-thiazino [4,3-a]isoquinolines 8 and 9 were synthesized from 4 and 5 treatment with hydrogen chloride. The predominant conformations and the conformational equilibria were studied by means of NMR spectroscopy and molecular modelling calculations. The 1,3-X,N heterocyclic ring attains a flattened twist conformation, due to the orbital interaction between the bridgehead nitrogen lone pair and the C=N double bond.
|Number of pages||7|
|Publication status||Published - Dec 1 2001|
ASJC Scopus subject areas
- Organic Chemistry