Multi-conformers caused by conformational change of A-ring in the C₁₈- and C₁₉-N-dealkyl diterpenoid alkaloids

Abstract

This paper describes a rare phenomenon of multi-conformers caused by conformational change of A-ring in the C₁₈- and C₁₉- N-dealkyl diterpenoid alkaloids. The possible reasons for the generation of multiple conformational isomers are complex, which could be affected by the substituents at C-1, C-3, C-13, C-14, and C-15, pH, solvents, the intramolecular hydrogen bond between 1α-OCH₃/1α-OH and N-H groups, acid-base treatment, preparation methods, and work-up procedures.

Graphical Abstract

Keywords:

• Diterpenoid alkaloid
• conformation
• N-dealkylation

Acknowledgements

We gratefully acknowledge Professor Ming Zhao (College of Pharmacy, Capital University, Beijing) for measuring ¹H-¹⁵N HMBC spectra. We also thank Hao Yisheng Pharmaceutical Company for providing the sample of 3,14,15-triacetyl-N-deethylaconine (21a).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The research was supported by the National Natural Science Foundation of China (U21A20278).