Novel alkaloids, paxdaphnines A and B with unprecedented skeletons from the seeds of Daphniphyllum paxianum

Abstract

Two novel Daphniphyllum alkaloids with unprecedented skeletons, namely paxdaphnines A ( 1) and B ( 2), have been isolated from the seeds of Daphniphyllum paxianum. Paxdaphnine A ( 1) is a 19-nor- Daphniphyllum alkaloid with highly caged skeleton, and paxdaphnine B ( 2) is the first 1,19-bisnor- Daphniphyllum alkaloid. The relative structures of 1 and 2 were elucidated by spectral methods, and their unique biosynthetic pathway postulated. The absolute structure of 1 was determined by X-ray diffraction of the iodide derivative ( 1a) of 1, and the absolute stereochemistry of 2 was proposed by correlation with the biosynthetic pathway for 1.