Structural revision of franchetine and vilmorisine, two norditerpenoid alkaloids from the roots of Aconitum spp.

Four New Diterpenoid Alkaloids from the Roots of Aconitum carmichaelii

“…In consequence, it was supposed that 2 was a franchetine-type C 19 -diterpenoid alkaloid. [13] Besides, the signals at d(C) 92.6 (d) and d(H) 4.38 (s) characteristic for N,O-mixed acetal moiety further confirmed that parent skeleton. [14] [15] The correlations between signals of d(H) 3.37 (s), 3.33 (s), and 3.29 (s) and C(1) (d(C) 86.9 (d)), C(16) (93.9 (d)), and Figure 2) revealed that three methoxy groups were located at C(1), C(16), and C(18), respectively.…”

“…Its NMR spectra exhibited the presence of four methoxy groups, an acetoxy group, a benzoyl group (Table 1), and an imine (N=C-) moiety (d(H) 7.33 (1H, s); d(C) 165.8 (d)). Besides, there was a close resemblance between 4 and known ouvrardianine A (18; Figure 1) [18] in 13 C-NMR spectrum apart from one additional O-bearing C-atom signal at d(C) 78. 8 (d).…”

“…Seven O‐bearing C‐atom signals ( δ (C) 86.9 (d), 74.6 (d), 78.8 (d), 73.4 (d), 93.9 (d), 92.6 (d), 79.1 (t)) were found in 13 C‐NMR spectrum, with the exception of four ones connected to the above‐mentioned O‐containing groups, an oxygen bridge and a hydroxy group were formed to afford the remaining three ones. In consequence, it was supposed that 2 was a franchetine‐type C 19 ‐diterpenoid alkaloid . Besides, the signals at δ (C) 92.6 (d) and δ (H) 4.38 (s) characteristic for N , O ‐mixed acetal moiety further confirmed that parent skeleton.…”

“…The proton signals of two hydroxy groups (d(H) 3.90 (s) and 4.28 (d)) showed HMBCs with C(13) (d(C) 74.2 (s)) and C(15) (78.9 (d)), which led to the hydroxy groups at C(13) and C(15), respectively. Then, according to the remained C-atom and N-atom in molecular formula and the signal at d(C) 118.8 (s) in 13 C-NMR, a cyano group (CN) was considered to exist. [11] Comparing the 13 C-NMR data of 1 with that of hypaconitine (13), [4] the changes in the chemical shifts of C(3) and C(4) and the disappearance of methylene carbon signal characteristic for C (19) illustrated that the cyano moiety was located at this position, which was further supported by the key HMBC ( Figure 2) between H-C(19) (d(H) 3.80 (1H, s)) and CN (d(C) 118.8 (s)).…”

“…Known compounds were identified as songorine (5), [19] songoramine (6), [20] sachaconitine (7), [21] talatisamine (8), [22] chasmanine (9), [23] 14-acetyltalatisamine (10), [24] 3-deoxyhokbusine A (11), [25] 14-benzoylaconine (12), [26] hypaconitine (13), mesaconitine (14), [4] aconitine (15), [27] and beiwutine (16) [28] by comparison of their spectroscopic data with those reported in the literature.…”