New Regio- and Stereoselective <i>O</i>-Deacetylated and Epoxy Products of Taxanes Isolated from <i>Taxus </i><i>m</i><i>airei</i>
作者:Ya-Ching Shen、Chin-Lien Ko、Yuan-bin Cheng、Michael Y. Chiang、Ashraf Taha Khalil
DOI:10.1021/np040152y
日期:2004.12.1
Deacylation of a taxoid mixture isolated from the roots of Taxus mairei followed by chromatographic fractionation resulted in the isolation of three new taxoid derivatives, 2alpha,9alpha,10beta-triacetoxy-5alpha,14beta-dihydroxy-4(20),11(12)-taxadiene (1), 9alpha,10beta-diacetoxy-2alpha,5alpha,14beta-trihydroxy-4(20),11(12)-taxadiene (2), and 9alpha,10beta-diacetoxy-2alpha,5alpha,14beta-trihydroxy-4,20-epoxy,11(12)-taxene (3). Epoxidation of 2 afforded 9alpha,10beta-diacetoxy-2alpha,5alpha-,14beta-trihydroxy-4,20:11,12-diepoxytaxane (6), while epoxidation of 4 yielded 9alpha,10beta-diacetoxy-5alpha,13alpha-dihydroxy-4,20-epoxy,11(12)-taxene (7) and 9alpha,10beta-diacetoxy-5alpha,13alpha-dihydroxy-4,20:11,12-diepoxytaxane (8). The structures were elucidated by detailed analysis of their NMR spectra. The structure and relative stereochemistry of 7 was confirmed by X-ray crystallography.