11-Dehydrokobusine — A new alkaloid from Aconitum thalassicum

II-DEHYDROKOBUSINE - A NEW ALKALOID FROM Aconitum thalassicum UDC 547/945 A. A. Nishanov, M. N. Sultankhodzhaev, and M. S. Yunusov Continuing the separation of the total alkaloids of the epigeal part of the plant Acontium thalassicum M. Pop., when the mixture obtained from fraction (II) [i] was chromatographed on silica gel 0.01 g of a base with the composition C2QH2~NO 2 (I), mp 239-241°C (acetone), was isolated. The base was readily soluble in methanol and chloroform and sparingly soluble in ether and hexane. Its IR spectrum (vmax, KBr cm -l) had absorption bands of hydroxy groups (3080) and of a carbonyl group in a five-membered ring (1725). The PMR spectrum (i00 MHz, CDCI3) showed the signals of a C-methyl group (0.93 ppm, 3 H, s, CH3-18) and of a terminal methylene group (5.07 and 5.15 ppm, i H each, br.s, =CH 2) and of a proton at C-15 (4.07 ppm, br.s, 1 H). In the mass spectrum there were the peaks of the molecular ion, M + 317 (87%) and also of the ions M + - 28 (100%) and M + - 45 (38%). A comparison of the developed formulas of the base and the alkaloid kobusine showed the presence of a carbonyl in (I) in place of a hydroxyl in (II), while the absence from the PMR spectrum of (I) of the signal of a proton at C-II gave grounds for assuming that the alkaloid isolated was ll-dehydrokobusine. To confirm this, we obtained ll-dehydrokobusine from kobusine [2] and found it to be identical with (I) by a mixed melting point, TLC, and spectral characteristics (IR, PMR, and mass spectra). Consequently, the alkaloid was ll-dehydrokobusine, and this is the first time that it has been isolated from plants. R#, R~~'CH2 I. RI* R2=O ~. R4=OH,R~=H ;,\ v LITERATURE CITED lo 0 A. A° Nishanov, B° Tashkhodzhaev, M. N. Sultankhodzhaev, B. T. Ibragimov, and M. S. Yunusov, Khimo Prir. Soedin., 39 (1989). So Sakai, I. Yamamoto, K. Yamaguchi, H. Takayama, M° Ito, and T. Okamoto, Chem. Pharm° Bull., 30, 4579 (1982). Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, Vol. 6, p. 857, November-December, 1989. Original article submitted February 21, 1989. 728 0009-3130/89/2506-0728512.50 ©1990 Plenum Publishing Corporation  (...truncated)