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The first biomimetic conversion from the aconitine-type C(19)-diterpenoid alkaloids to the corresponding alkaloids of lactone-type C(19)-diterpenoid alkaloid has been achieved. Chasmanine was used as starting material with Baeyer-Villiger oxidation as a key reaction. It was also observed that the oxygenated group at C-16 did not change the relative migration tendencies of C-13 and C-9 during the oxidation. Meantime, a novel D-ring fragmented compound was obtained during the course of the present investigation. The plausible mechanism of the formation of this compound was also proposed.

The O-acyl group at C-1 of two C₁₉-diterpenoid alkaloids 2 and 5 was transferred to the secondary amine nitrogen to form amides 3 and 6 in the basic condition. This kind of O-to-N intramolecular acyl migration could be caused by the near distance between the nucleophilic nitrogen atom and the carbonyl group of the ester at C-1 in the C₁₉-diterpenoid alkaloids, which is consistent with the conformation of rings A and E in the C₁₉-diterpenoid alkaloids.

Four novel taxoid analogs were conversionally synthesized from the C(19)-diterpenoid alkaloid deltaline, and their cytotoxic activities were evaluated against a small panel of cancer cell lines.

The conversional synthesis of taxoids by the BAC sequence from the C(19)-diterpenoid alkaloids, 14-acetyltalatisamine (1), yunaconitine (12), and 14-acetylchasmanine (19), was designed and explored. Two aconane-type diterpenes 17 and 28, the advanced intermediates for our conversional synthesis, were synthesized. The key steps include the rupture of the C(7)-C(17) bond, the formation of imine, and the denitrogenation.

In the title study, the synthesis of the vital intermediate C-nor-aconanone (3) from 4 was completed through 11 steps, mainly including semipinacol rearrangement, formation of the imines by the treatment of 10 or 20 with NBS, the cleavage of N-C19 bonds in 11 or 21 by treatment with m-CPBA and subsequently with LTA, as well as the rupture of the N-C17 bonds in 22 by a modified Nef reaction (NaH/t-BuOH --> KMnO4/H2O). One-pot procedure was successfully developed starting from 11 or 21 to afford the N,19-seco-C-nor product 15 or 22, respectively, in reasonably good yields.

Treatment of some C(19)-diterpenoid alkaloids (3, 6, 10 and 12) with anhydrous DMSO at 100-170 degrees C for 3-7 h led to the formation of the corresponding imines (4, 7/8, 11, 13/14) in 65-83% yield, respectively. This is a new simpler formation of the imines of the C(19)-diterpenoid alkaloids.

Two new C19-diterpenoid alkaloids, kongboentine A (1) and kongboentine B (3), were isolated from the roots of Aconitum kongboense Lauener and their structures were elucidated by spectral data.

Three new C19-diterpenoid alkaloids, umbrosumines A-C (1-3), and 11 known compounds (4-14) were isolated from the roots of Delphinium umbrosum. Their structures were elucidated on the basis of the spectroscopic data interpretation. [ABSTRACT FROM AUTHOR]

Two new C 19 -diterpenoid alkaloids, kongboentine A ( 1 ) and kongboentine B ( 3 ), were isolated from the roots of Aconitum kongboense Lauener and their structures were elucidated by spectral data. [ABSTRACT FROM AUTHOR]

A new franchetine-type (leueandine 1 ) and two new lycoctonine-type [potanisines F ( 3 ) and G ( 5 )] C 19 -diterpenoid alkaloids have been isolated from the roots of Aconitum hemsleyanum var. leueanthus and Delphinium potaninii , respectively, and their structures were established on the basis of spectral data. [ABSTRACT FROM AUTHOR]