Evaluation of paclitaxel rearrangement involving opening of the oxetane ring and migration of acetyl and benzoyl groups

Pyo, Sang‐Hyun; Jinsuk, Cho; Choi, Ho-Joon; Han, Byung-Hee

doi:10.1016/j.jpba.2006.08.026

Cited by 10 publications

(5 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hydrolysis of 15 under basic conditions and then with TiCl 3 /NH 4 OAc gave 3-one-16-β-ol 16. The nascent 16-β-OH and 23-OH were firstly protected with acetyl groups; however, subsequent reduction of the 3-ketone with NaBH 4 led to a mixture, due to acetyl group migration under basic conditions [35,36]. Thus, diol 16 was masked with the bulkier pivaloyl groups and then the carbonyl was reduced with NaBH 4 to afford the desired aglycone derivative 17 (80%) [37].…”

Section: Resultsmentioning

confidence: 99%

Facile Synthesis of Saikosaponins

Wang

Bian

et al. 2021

Molecules

View full text Add to dashboard Cite

Saikosaponin A (SSa) and D (SSd) are typical oleanane-type saponins featuring a unique 13,28-epoxy-ether moiety at D ring of the aglycones, which exhibit a wide range of biological and pharmacological activities. Herein, we report the first synthesis of saikosaponin A/D (1–2) and their natural congeners, including prosaikosaponin F (3), G (4), saikosaponin Y (5), prosaikogenin (6), and clinoposaponin I (7). The present synthesis features ready preparation of the aglycones of high oxidation state from oleanolic acid, regioselective glycosylation to construct the β-(1→3)-linked disaccharide fragment, and efficient gold(I)-catalyzed glycosylation to install the glycans on to the aglycones.

show abstract

Section: Resultsmentioning

confidence: 99%

Facile Synthesis of Saikosaponins

Wang

Bian

et al. 2021

Molecules

View full text Add to dashboard Cite

show abstract

“…By opening the oxetane ring, oxygen might appear outside the region, enabling hydrogen bond to Thr276. Three seco derivatives ( Figure 18 , 63 – 65 ) only possess poor activity [ 72 ]. All these analogues, however, are not acetylated at O-4 and all have wrong stereochemistry at C-5 [ 69 , 72 ].…”

Section: The Taxus Diterpenesmentioning

confidence: 99%

“…Three seco derivatives ( Figure 18 , 63 – 65 ) only possess poor activity [ 72 ]. All these analogues, however, are not acetylated at O-4 and all have wrong stereochemistry at C-5 [ 69 , 72 ]. Other analogues such as ( 66 ) have a higher affinity for tubulin but a much lower cytotoxicity [ 65 ]…”

Section: The Taxus Diterpenesmentioning

confidence: 99%

See 1 more Smart Citation

Drugs That Changed Society: Microtubule-Targeting Agents Belonging to Taxanoids, Macrolides and Non-Ribosomal Peptides

Christensen

2022

Molecules

View full text Add to dashboard Cite

During a screening performed by the National Cancer Institute in the 1960s, the terpenoid paclitaxel was discovered. Paclitaxel expanded the treatment options for breast, lung, prostate and ovarian cancer. Paclitaxel is only present in minute amounts in the bark of Taxia brevifolia. A sustainable supply was ensured with a culture developed from Taxus chinensis, or with semi-synthesis from other taxanes. Paclitaxel is marketed under the name Taxol. An intermediate from the semi-synthesis docetaxel is also used as a drug and marketed as Taxotere. O-Methylated docetaxel is used for treatment of some paclitaxel-resistant cancer forms as cabazitaxel. The solubility problems of paclitaxel have been overcome by formulation of a nanoparticle albumin-bound paclitaxel (NAB-paclitaxel, Abraxane). The mechanism of action is affinity towards microtubules, which prevents proliferation and consequently the drug would be expected primarily to be active towards cancer cells proliferating faster than benign cells. The activity against slowly growing tumors such as solid tumors suggests that other effects such as oncogenic signaling or cellular trafficking are involved. In addition to terpenoids, recently discovered microtubule-targeting polyketide macrolides and non-ribosomal peptides have been discovered and marketed as drugs. The revolutionary improvements for treatment of cancer diseases targeting microtubules have led to an intensive search for other compounds with the same target. Several polyketide macrolides, terpenoids and non-ribosomal peptides have been investigated and a few marketed.

show abstract

“…Later on, taxol was known to be extractable from other Taxus species of Yew trees including the Chinese yew Hong Dou Shan (Taxus chinensis) grows in china (Siow et al, 2005). Upon the selection of taxol as a development candidate in 1977 and the approval as anticancer drug by U.S. Food and Drug Administration in 1992, efforts were non-stopped to explore methods to enhance its production and synthesis, although the current yielding has achieved over 90% of pure paclitaxel (Khosroushahi et al, 2006;Pyo et al, 2007). The drug is nowadays the first-line treatment for advanced ovarian and breast cancer, the second-line treatment for AIDSrelated Kaposi's sarcoma, and used in combination with cisplatin for treating nonsmall-cell lung carcinoma (Siow et al, 2005), however, intensive studies are still underway for its anticancer mechanisms (Varbiro et al, 2001) as well as its toxic side effects (Atas et al, 2006;Rabah, 2010).…”

Section: The Transition Of Herbs Into Pure Chemicalsmentioning

confidence: 99%