(1R,8aα,9S)-6β-[(Dimethylamino)methyl]-1,5a,6,7,8,8a-hexahydro-5aα-methyl-9-isopropyl-1,4α-methano-2H-cyclopent[d]oxepine-2,5(4H)-dione

Present in Dendrobiurn nobile, this alkaloid forms colourless crystals from MeOH. It yields a crystalline hydrochloride, m.p. 206-8°C and the methiodide, m.p. 275-6°C. Treatment of the free base with alcoholic KOH followed by HCI gives isonobiline hydrochloride, m.p. l83-5°C. LiAIH4 furnishes an amorphous tril whereas NaBH4 in tetrahydrofuran gives the amorphous hydroxynobiline which is converted into hydroxyisonobiline, m.p. 217 -9°C under the same conditions as given above for the alkaloid. Hofmann degradation of nobiline methiodide yields trimethylamine and deaminonobiline, m.p. l79-183°C. The structure given above for the alkaloid has been suggested on the basis of these chemical reactions and spectroscopic evidence.

Yamamura, Hirata., Tetrahedron Lett., 79 (1964)