Chemistry and occurrence of taxane derivatives. Part 16. Rearranged taxoids from Taxus×media Rehd. cv Hicksii. X-Ray molecular structure of 9-O-benzoyl-9,10-dide-O-acetyl-11(15 → 1)abeo-baccatin VI

Abstract

The roots of Taxus×media Rehd. cv Hicksii gave four new taxoids of the abeo 11(15 → 1)-type (2–5). Structures were elucidated by spectroscopic techniques, including X-ray analysis for compound 4. Compound 2 is conformationally fixed, whereas compounds 3–5 exist in solution as a mixture of rotamers, whose interconversion was investigated by variable-temperature NMR spectroscopy. Compound 2 has a C-13, C-15 oxygen bridge, and is the first natural taxoid with a β-oxygen function at C-13.