CHEMISTRY AND OCCURRENCE OF TAXANE DERIVATIVES .16. REARRANGED TAXOIDS FROM TAXUS X MEDIA REHD CV HICKSII - X-RAY MOLECULAR-STRUCTURE OF -BENZOYL-9,10-DIDE-O-ACETYL-11(15-]1)ABEO-BACCATIN VI

The roots of Taxus x media Rehd. cv Hicksii gave four new taxoids of t he abeo 11(15-->1)-type (2-5). Structures were elucidated by spectrosc opic techniques, including X-ray analysis for compound 4. Compound 2 i s conformationally fixed, whereas compounds 3-5 exist in solution as a mixture of rotamers, whose interconversion was investigated by variab le-temperature NMR spectroscopy. Compound 2 has a C-13. C-15 oxygen br idge, and is the first natural taxoid with a beta-oxygen function at C -13.