An attempt to enlarge the B ring of maoecrystal B, an ent-kaurane-type diterpene

Abstract

An attempt to enlarge the B ring of maoecrystal B (6), an ent-kaurane-type diterpene from Isodon eriocalyx (Labiatae), to obtain the desired compound 23 via six steps, led to the novel rearranged diterpene compound 22.

Keywords:

• Isodon eriocalyx
• ent-Kauranoid
• Diterpene
• Maoecrystal B
• Rearrangement

Acknowledgements

Financial support for this project was provided by the National Natural Science Foundation of China (No. 0040505401008). We also acknowledged with thanks the help of Professor Sun Han-Dong, Kunming Institute of Botany, Chinese Academy of Sciences, for the collection and extraction of the plant materials.