Novel taxanes from the needles of Taxus canadensis

Nineteen taxanes were characterized for the first time in the needles of the Canadian yew. Four of these metabolites are novel: taxinine-11, 12-oxide (1), 7-acetoxytaxuspine C (2), 5-cinnamoyltaxin B (3), and 7, 9-deacetyltaxinine B (4). Compound 1 is the second 11,12-epoxy-taxane known and 7-oxygenated-3, 11-cyclotaxane structures are unique to Taxus canadensis. In addition, taxinine and taxinine E were found to be major taxanes in the Canadian yew. The structures of all the taxanes were rigorously established by spectroscopic methods.