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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.

A new franchetine-type (leueandine 1) and two new lycoctonine-type [potanisines F (3) and G (5)] C19-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.

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]