- Biological degradation of taxol by action of cultured cells on 7-acetyltaxol-2″-yl glucoside
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Biodegradation pathways of taxol in cultured cells of Synechocystis sp. PCC 6803, Synechococcus sp. PCC 7942, Marchantia polymorpha, Nicotiana tabacum, and Glycine max were investigated using a water-soluble taxol derivative, 7-ace-tyltaxol-2″-yl glucoside, as the substrate. Although cyanobacteria, Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7942, and a lower plant, M. polymorpha, catalyzed the epimerization at 7-position of taxol skeleton, no epimerization occurred with higher plants, N. tabacum and G. max. On the other hand, Synechocystis sp. PCC 6803, Synechococcus sp. PCC 7942, M. polymorpha, and N. tabacum catalyzed hydrolysis at 13-position of taxol to give baccatin III and 10-deacetyl baccatin III. Both cyanobacteria cells also deacetylated 7-epi-baccatin III at its 10-position. M. polymorpha and G. max deacetylated at 10-position of taxol. Copyright
- Shimoda, Kei,Mikuni, Katsuhiko,Nakajima, Kiyoshi,Hamada, Hatsuyuki,Hamada, Hiroki
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p. 362 - 363
(2008/09/20)
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- Acid catalyzed conversions of taxoids
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Treatment of 10-deacetylbaccatin-III and baccatin-III with dilute HCl affords 10-deacetylbaccatin-V and baccatin-V, respectively. 10-Deacetylbaccatin-V is also obtained when 10-deacetylbaccatin-III is treated with ZnCl2 or ZnBr2 in MeOH. These two Lewis acids convert baccatin-III to 10-deacetylbaccatin-III as well 10-deacetylbaccatin-V. BF3.OEt2 in CH2Cl2 opens the oxetane ring of 7,13-diacetylbaccatin-III to form two regioisomeric products while BBr3 in the same solvent leads to the contraction of its A-ring along with the oxetane cleavage. CF3COOH contracts the A-ring of 7-acetylbaccatin-III and 7,13-diacetylbaccatin-III.
- Das, Biswanath,Srinivas,Ravindranath,Ramesh,Venkataiah,Das, Ratna
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p. 667 - 670
(2007/10/03)
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- The chemistry of the taxane diterpene: Stereoselective reductions of taxanes
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Stereoselective reductions of taxanes are detailed. Chelation- controlled reductions employing SmI2 are described for the stereoselective reduction of the 9-keto functionality of the diterpene moiety of several taxanes. In all cases the 9β-hydr
- Georg, Gunda I.,Harriman, Geraldine C. B.,Datta, Apurba,Ali, Syed,Cheruvallath, Zacharia,Dutta, Dinah,Vander Velde, David G.,Himes, Richard H.
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p. 8926 - 8934
(2007/10/03)
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- Reactivity of baccatin III derivatives towards samarium II reagents
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A study of the reactivity of 10-deacetylbaccatin III (1) towards samarium II reagents in the presence of various proton donors led to efficient synthesis of 9β-dihydro-10-deacetylbaccatin III (7) and 2-debenzoyl-9β-dihydro-10-deacetyl-baccatin III (9).
- Py, Sandrine,Khuong-Huu, Francoise
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p. 1661 - 1664
(2007/10/02)
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- THE CHEMISTRY OF TAXANES: REACTIONS OF TAXOL AND BACCATIN DERIVATIVES WITH LEWIS ACIDS IN APROTIC AND PROTIC MEDIA
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Several Lewis acids were shown to cleanyl open the oxetane ring of taxol and baccatin derivatives.The reaction is shown to proceed via anchimeric assistance by the C-4 acetate group.Several minor products, including a novel derivative possessing a bridged C-ring, were also isolated.A mechanistric rationale is provides for all compounds formed.When taxol derivatives were treated with Lewis acids in methanol, ester cleavage reactions were observed.We provide conditions that are selective for C-10 acetate cleavage and for C-13 side-chain methanolysis.
- Chen, Shu-Hui,Huang, Stella,Wei, Jianmei,Farina, Vittorio
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p. 2805 - 2828
(2007/10/02)
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- New Oxetane-type Taxanes from Taxus wallichiani Zucc.
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The needles of Taxus wallichiani Zucc. gave the novel oxetane-type taxane diterpenoids 2 and 5, whose structures have been established on the basis of spectroscopic data and chemical reactions.The acid-catalysed rearrangement of 10-deacetylbaccatin III ha
- Appendino, Giovanni,Oezen, Hasan Cetin,Gariboldi, Pierluigi,Torregiani, Elisabetta,Gabetta, Bruno,et al.
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p. 1563 - 1566
(2007/10/02)
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- Anitleukemic Alkaloids from Taxus wallichiana Zucc.
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A new antileukemic taxane alkaloid, cephalomannine (1a), has been isolated from leaves, stems, and roots of Taxus wallichiana Zucc.Cephalomannine is closely related to taxol (1b), a previously characterized antileukemic alkaloid, which also occurs in T. wallichiana but in lesser amounts than cephalomannine.The new alkaloid and its hydrolysis products were characterized by nuclear magnetic resonance, mass spetroscopy, and X-ray crystallography; taxol and two cytotoxic taxane congeners were also identified.
- Miller, Roger W.,Powell, Richard G.,Smith, Cecil R.
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p. 1469 - 1474
(2007/10/02)
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