title: New regio- and stereoselective O-deacetylated and epoxy products of taxanes isolated from Taxus mairei.
abstract: 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.
authors.affiliation: Institute of Marine Resources, National Sun Yat-sen University, 70 Lien-Hai Road, Kaohsiung, Taiwan 80424, Republic of China. ycshen@mail.nsysu.edu.tw
authors.forename: Ya-Ching
authors.initials: YC
authors.lastname: Shen
authors.forename: Chin-Lien
authors.initials: CL
authors.lastname: Ko
authors.forename: Yuan-Bin
authors.initials: YB
authors.lastname: Cheng
authors.forename: Michael Y
authors.initials: MY
authors.lastname: Chiang
authors.forename: Ashraf Taha
authors.initials: AT
authors.lastname: Khalil
mesh_terms: D018360:Crystallography, X-Ray; D004852:Epoxy Compounds / Q000737:chemistry* / Q000302:isolation & purification*; D008968:Molecular Conformation; D015394:Molecular Structure; D010946:Plants, Medicinal / Q000737:chemistry*; D013237:Stereoisomerism; D013624:Taiwan; D043823:Taxoids / Q000737:chemistry* / Q000302:isolation & purification*; D020946:Taxus / Q000737:chemistry*
chemical_list: D004852:Epoxy Compounds; D043823:Taxoids