Daphniphyllum alkaloids, elaborated by plants of the genus Daphniphyllum (Daphniphyllaceae), are a family of structurally diverse natural products with complex polycyclic skeletons. Their unique structural features have attracted great interest as challenging projects for total synthesis and biosynthetic research for several decades.

Previous studies conducted in HAO Xiaojiang’s group by ZHANG Yu et al. have resulted in the isolation of two novel yuzurimine-type Daphniphyllum alkaloids (Organic Letters, 2009, 11, 5414-5417). To further search for structurally unique Daphniphyllum alkaloids, two new yuzurine-type alkaloids of the rare 14R, 15S series, daphmaleninesA (1) and B (2), with an unusual penta- or tetra- ring system, respectively, were isolated from the leaves of Daphniphyllum himalense by HAO Xiaojiang’s Group. Their structures and absolute configurations were elucidated by a combination of spectroscopic data, X-ray crystallographic, and computational methods. A plausible biosynthetic pathway of 1and 2 was also proposed. The above studies have been published in European Journal of Organic Chemistry, 2011, 2011, 4103-4107. http://onlinelibrary.wiley.com/doi/10.1002/ejoc.201100414/full

The findings of daphmalenines A (1) and B (2) enriched the biogenetic pathway of Daphniphyllum alkaloids especially the stereochemistry during the formation of C-C bond. It also sheds light on the total synthesis and biosynthetic research of Daphniphyllum alkaloids. Moreover, the two compounds were selected into “Hot off the Press” of Natural Products Reports after they were reported.

The Structures of alkaloids 1 and 2 and the hypothetical biosynthetic pathway of 1-3. (Image by ZHANG Yu)