Two novel aconane-type diterpenes derived from C-nor-C19-diterpenoid alkaloid

A new C20-diterpenoid alkaloid from Aconitum soongaricum var. pubescens

“…The 13 C NMR and DEPT spectra of 1 exhibited the presence of six methylenes (δ C 23.5, 24.6, 24.7, 29.7, 35.8 and 45.7), nine methines (δ C 38.3, 38.6, 45.8, 49.4, 68.3, 70.4, 71.1, 76.8 and 94.4) and four quaternary carbons (δ C 37.7, 45.3, 49.7 and 64.1). The above-mentioned data suggested that compound 1 is a denudatine-type C 20 -diterpenoid alkaloid (Shen et al 2009). Selected 1 H and 13 C NMR resonances of 1 indicated the characteristic pattern of an epoxy group (δ H 3.10, 2.42, ABq, J = 5.4 Hz; δ C 64.1 s, 45.7 t) instead of a typical exocyclic double bond in C 20 -diterpenoid alkaloids.…”

Synthesis of Taxane ABC Tricyclic Skeleton from Lycoctonine

“…Finally, we achieved the conversional synthesis of the desired taxane-like compounds, which possess the 6/8/6 tricyclic ABC ring system of paclitaxel and docetaxel, using deltaline (1) as starting material [20,21]. During the course of this investigation, we have recently observed by chance that treatment of imine A, the aconitine-type C 19 -diterpenoid alkaloids, with NaNO 2 -HBr-Br 2 can form compound B with a 6/8/7 tricyclic ring system via ring B enlargement reaction [22,23]. Inspired by this reaction, we envisioned a new strategy towards the conversional synthesis of the A/B/C tricyclic core of taxane-like compounds.…”

“…We started with the exploration on whether the ring B enlargement reaction [22,23] is also applicable to the imines of lycoctonine-type C 19 -diterpenoid alkaloids. Consequently, 18-acetyllycoctonine (7), prepared from lycoctonine (2) by acetylation, was used as the first substrate.…”