Structure of neoline, chasmanine, and homochasmanine

Abstract

Neoline (C24H39NO6), mp 161 °, was first isolated from amorphous aconitine by Freudenberg and Rogers.1 Careful studies led Wiesner, et al.,2 to assign structure 1, with a C-l -hydroxyl, to the alkaloid. Marion, et al.,2 subsequently correlated neoline with chasmanine, an alkaloid re-ported4•5 to have structure 3, and, on this basis, assigned structure 4, with a C-l 0-hydroxyl, to neoline.

The 1α-hydroxy-A-rings of norditerpenoid alkaloids are twisted-boat conformers

“…aconitine (1), lycoctonine (2), and chasmanine (4). [14][15][16][17][18][19][20] Solution conformation studies can provide detail of the bioactive conformations in biological uids of these pharmacologically important norditerpenoid alkaloids. Specically, we are studying the effects of the C1-a-oxygenated substituents on the A-rings in four selected norditerpenoid alkaloids (5)(6)(7)(8).…”

Carbon-13 nuclear magnetic resonance: aconitine-type diterpenoid alkaloids from Aconitum and Delphinium species

“…3•4 Even "identical ir spectra and x-ray powder patterns" have been shown to be unsafe for the establishment of identity of compounds (e.g., lycoctonine-browniine-chasmanine-neoline). 4 Similarly, small amounts of impurities may strongly influence ir spectra, leading to the incorrect conclusion about the identity of compounds (e.g., aconitinehypaconitine).5 13C NMR is a more powerful tool than proton NMR and ir since most of the carbon atoms in diterpenoid alkaloids give rise to separate signals. For example, 24 separate signals were resolved in the spectrum of natural neoline (16) (C24H39NO6) and showed identity (±0.05 ppm) with the 13C spectrum of a sample of neoline derived from the alkaloid delphisine.…”

“…For example, 24 separate signals were resolved in the spectrum of natural neoline (16) (C24H39NO6) and showed identity (±0.05 ppm) with the 13C spectrum of a sample of neoline derived from the alkaloid delphisine. 4 On the basis of this observation we revised the structure of neoline. This work concerns the application of 13C spectroscopy to diterpene alkaloids (43.2 ppm) and 2 (43.5 ppm) as a result of the /3-hydroxy effect.…”

The synthesis of chasmanine: aromatic intermediate

“…All the steps of this process proceeded under mild conditions and in high yield and we felt that they could be applied without major modification to compound I11 with a suitably blocked nitrogen. This would lead very simply to the fully substituted, naturally occurring delphinium alkaloid chasmanine IV (2).…”