Alkaloids ofDelphinium speciosum
On separating the total alkaloids we isolated methyllycaconitine, lycoctonine, anthranoyllycoctonine, and gigactonine, which were identified on the basis of an analysis of spectral characteristics and a comparison of the I~C NMR spectra. In addition to these, a base was isolated with mp 180-182°C (acetone), composition C22H35N05 (I). The NMR spectrum of (I) had the signals of tertiary C-methyl group (0.97 ppm, 3 H, singlet), of a N-ethyl group (1.04 ppm, 3 H, triplet, J = 7 Hz), and of a methoxy group (3.82 ppm, 3 H, singlet), and also one-proton signals at 4.12 ppm (triplet, J = 5 Hz) and 4.6 ppm (doublet, J = 7 Hz), The IR spectrum showed the absorption bands of hydroxy groups at 3400-3600 cm -: and of ether bonds at ii00 cm -~. The mass spectrum of (I) was characteristic for alkaloids with the lycoctonine skeleton and was close to the spectrum of karakoline [2, 3]. The maximum peak in the mass spectrum of (I) was the peak of the M +17 ion, showing the presence of the hydroxy group at C-I [2], Acetylation of the alkaloid with acetic anhydride in the presence of pyridine yielded the triacetate (II) with mp 162-164°C (acetone), showing the presence of three secondary hydroxy groups. Its mass spectrum contained the peak of the molecular ion M + 519 (8%), and also the peaks of ions with m/z 476 (8%), 460 (100%), 416 (15%) and 400 (12%), The PMR spectrum contained the signals of a N-ethyl, a tertiary C-methyl, and of three acetoxy groups, and also one-proton signals at 4.68 ppm (triplet, J = 5 Hz), 4.75 ppm (quartet, ABX system, JAX = i0 Hz, JBX = 7 Hz) and 5.22 ppm (doublet, J = 7 Hz), showing the presence of hydroxy groups at C-14, C-I, and C-6 [3, 4]. The acetylation of (I) with acetyl chloride gave the tetraacetate (III). Its mass spectra contained the peak of the molecular ion M + 561 (1%), and also the peaks of ions with m/z 502 (77%), 442 (33%), 400 (100%), and 372 (33%), According to these results, the fourth hydroxy group must be located at C-8, The information obtained indicated that (I) was alkaloid B, isolated previously from Delphinium bicolor Nutt, [4-7]. A direct comparison with alkaloid B kindly supplied by Prof, M. N, Benn showed their identity.
The alkaloids of nutt.
The structures of alkaloid- and - were established via X-ray crystallography of the former as its HI salt, and its chemical conversion to the latter.
The diterpene alkaloids: the structure and stereochemistry of heteratisine
Abstract Chemical and spectroscopic studies have shown that heteratisine (C 22 H 33 NO 5 ), a diterpene lactone alkaloid occurring as a monobenzoyl ester in the roots of Aconitum heterophyllum Wall, has stereostructure 1 . Heteratisine thus bears a closer structural relationship to the highly toxic and polyoxygenated alkaloids of the lycoctonine-aconitine type than to its companion bases of A. heterophyllum , atisine, atidine and hetisine. An unusual cleavage reaction occurring when 19-oxodehydroheteratisine ( 28 ) is treated with strong base is described.