Three novel bicyclic taxane diterpenoids with the rare 6/12-membered rings wereisolated from the need ies of Taxus chinensis var. mairei. The structures were established with the help of 1D and 2D NMR spectral analysis.
A new taxane diterpenoid, named 7-deacetoxy taxinine J, together with ten knowncompounds were isolated from the needles of Taxus × media Hickiii. The structures of allcompounds were elucidated and identified by s...A new taxane diterpenoid, named 7-deacetoxy taxinine J, together with ten knowncompounds were isolated from the needles of Taxus × media Hickiii. The structures of allcompounds were elucidated and identified by spectroscopic methods. T’he structure of 7-deacetoxytaxinine J was further confirmed by X-ray crystallographic analysis. The structure of the knowncompound, taxinine E, was also revised.展开更多
-An oxetane ring can be constructed from 5 α-acyloxy-Δ4(20) -taxoids with osmylation as the first step in the usual manner. The innovation reported here is the use of an intramolecularly available acyl group for the...-An oxetane ring can be constructed from 5 α-acyloxy-Δ4(20) -taxoids with osmylation as the first step in the usual manner. The innovation reported here is the use of an intramolecularly available acyl group for the protection of 20-OH by an unexpected 5-to 20-migration under slightly basic conditions.展开更多
Microbial trdrisformation of taxoids was inveStigared: taxoid 2 was transformed into 1β and 14β hydroxylated derivahves 3 and 4, unnatural taxoid 6 was transformed into 1β-hydroxy derivative 7 and 11(15-1) abeotaxa...Microbial trdrisformation of taxoids was inveStigared: taxoid 2 was transformed into 1β and 14β hydroxylated derivahves 3 and 4, unnatural taxoid 6 was transformed into 1β-hydroxy derivative 7 and 11(15-1) abeotaxane 8. Taxoids with an oxetane ring, 11-13 were synthesized from 1 via chemical reachons.展开更多
We have studied the fragmentation behavior of positive and negative ions of taxoi and 6/8/6 type taxoids, the influence of different substituents on fragmentation, and the correlativity between fragmentation patterns ...We have studied the fragmentation behavior of positive and negative ions of taxoi and 6/8/6 type taxoids, the influence of different substituents on fragmentation, and the correlativity between fragmentation patterns and structure by MS/MS technique with different ionization methods such as FAB-MS, ESI-MS, ete. We have also investigated in detail the fragmentation of various molecular-related ions, such as [M+H]+, [M+Na]+ and [M-H] ions, and the formation pathways of characteristic fragment ions. It has been found that there exists some competing reaction between the loss of C-13 side chain and decomposition by loss of acetic acid. In addition, by comparing CID spectra obtained with low- and high-energy collision, it is seen that CID-MS/MS with low-energy collision is more suitable for the study of the structural analysis of small molecules and drug metabolites. The experimental results demonstrate that MS/MS spectra can reflect more effectively the slight difference of structure between the related展开更多
An oxetane ring can be constructed from 5α-acyloxy-Δ4(20)-taxoids. Hie facile intramolecular acyl migration from 5- to 20-position under slightly basic conditions enabled the construction of the oxetane ring in a co...An oxetane ring can be constructed from 5α-acyloxy-Δ4(20)-taxoids. Hie facile intramolecular acyl migration from 5- to 20-position under slightly basic conditions enabled the construction of the oxetane ring in a convenient short cut, whereas the acyl migration from 2- to 20-position left the 2-hydroxyl accessible to a later benzoylation. An unexpected five-mem-bered 4-O, 20- O sulfite ring was formed in the attempted construction of the oxetane ring with 5α-triflate as a leaving group. After the construction of the oxetane ring, treatment with strong base LiHMDS and acetyl chloride gave the expected 4-O-acetate while treatment with acetic anhydride and DMAP gave a 4-O-acetoacetate.展开更多
1-Hydroxyl acetylation of 10-deacetylbaccatin Ⅲ was achieved by removing the neighboring bulky 2-benzoyl group and oxidizing 2-hydroxyl group to a ketone function, but attempted reductive cleavage of 1-acetoxy gave r...1-Hydroxyl acetylation of 10-deacetylbaccatin Ⅲ was achieved by removing the neighboring bulky 2-benzoyl group and oxidizing 2-hydroxyl group to a ketone function, but attempted reductive cleavage of 1-acetoxy gave rearranged products under different conditions with or without proton source.展开更多
A new taxane diterpenoid with a rearranged 5/7/6-membered ring system was isolated from the seeds of the Chinese yew. Taxus yunnanensis. Its structure was established as 9αacetoxy-5α-cinnamoyl-11(15 →1 )-abeotaxa-4...A new taxane diterpenoid with a rearranged 5/7/6-membered ring system was isolated from the seeds of the Chinese yew. Taxus yunnanensis. Its structure was established as 9αacetoxy-5α-cinnamoyl-11(15 →1 )-abeotaxa-4(20), 11-dienc-10β, 13α, 15-triol on the basis of spectroscopic analysis. its relative stereochemistry is proposed from the results of a NOESY experment.展开更多
A series of 94 taxol analogues exhibiting antitumor activity were investigated using comparative molecular ficld analsis (CoMFA) method. The most optimal CoMFA from 80 compounds selected randomly . yielded a two-compo...A series of 94 taxol analogues exhibiting antitumor activity were investigated using comparative molecular ficld analsis (CoMFA) method. The most optimal CoMFA from 80 compounds selected randomly . yielded a two-components model, with siginficant cross-validation r cv of 0.640 and conventional r of 0.868. The robustness of the CoMFA model was further validatal by prediedon Of 14 test set componds. The CoMFA model explained present SAR and prtcularly the importance of the hydroxyl group at C-2’ position and the stereochemistry at C-2’ and C-3’展开更多
An α-4(20)-epoxy-5α-hydroxytaxinine B 1, when treated with diethylaluminum chloride, underwent reactions involving intramolecular substitution along with deacetylation or addition leading to new rings. Two novel 1-d...An α-4(20)-epoxy-5α-hydroxytaxinine B 1, when treated with diethylaluminum chloride, underwent reactions involving intramolecular substitution along with deacetylation or addition leading to new rings. Two novel 1-deoxy compounds 2 and 3 were isolated and fully characterized.展开更多
Compound 2 with 14β-hydroxyl group was successfully converted into its epimerized α-counterpart via oxidation - reduction.The elimination product (6) was auto-oxidized to epoxide 8,even in the solid
A new taxoid taxa-4(20), 11-diene-2α, 5β, 10β, 14β-tetraol-2α, 14β-diacetate (sinenxan H) (1) was obtained by biotransformation of taxa-4(20), 11-diene-2α, 5α, 10β, 14β-tetraol-2α, 5α, 10β, 14β-tetraacet...A new taxoid taxa-4(20), 11-diene-2α, 5β, 10β, 14β-tetraol-2α, 14β-diacetate (sinenxan H) (1) was obtained by biotransformation of taxa-4(20), 11-diene-2α, 5α, 10β, 14β-tetraol-2α, 5α, 10β, 14β-tetraacetate (2) with a fungus isolated from Taxus yunnanensis. Its structure was determined based on spectral展开更多
A new taxoid with 5/716 taxane skeleton, named taxamedin A (1) was isolated from the needles of Taxus x media Hicksii. Its structure was elucidated by spectal
Two new taxane diterpenoids, 2-deacetoxy-7, 9-dideacetyltaxinine J (1) and 2 -deacctoxytaxinine B (3), were isolated from the barks of Taxus chinensis. Their smicfures were elucidated by spectroscopic methods.
文摘Three novel bicyclic taxane diterpenoids with the rare 6/12-membered rings wereisolated from the need ies of Taxus chinensis var. mairei. The structures were established with the help of 1D and 2D NMR spectral analysis.
文摘A new taxane diterpenoid, named 7-deacetoxy taxinine J, together with ten knowncompounds were isolated from the needles of Taxus × media Hickiii. The structures of allcompounds were elucidated and identified by spectroscopic methods. T’he structure of 7-deacetoxytaxinine J was further confirmed by X-ray crystallographic analysis. The structure of the knowncompound, taxinine E, was also revised.
文摘-An oxetane ring can be constructed from 5 α-acyloxy-Δ4(20) -taxoids with osmylation as the first step in the usual manner. The innovation reported here is the use of an intramolecularly available acyl group for the protection of 20-OH by an unexpected 5-to 20-migration under slightly basic conditions.
文摘Microbial trdrisformation of taxoids was inveStigared: taxoid 2 was transformed into 1β and 14β hydroxylated derivahves 3 and 4, unnatural taxoid 6 was transformed into 1β-hydroxy derivative 7 and 11(15-1) abeotaxane 8. Taxoids with an oxetane ring, 11-13 were synthesized from 1 via chemical reachons.
文摘We have studied the fragmentation behavior of positive and negative ions of taxoi and 6/8/6 type taxoids, the influence of different substituents on fragmentation, and the correlativity between fragmentation patterns and structure by MS/MS technique with different ionization methods such as FAB-MS, ESI-MS, ete. We have also investigated in detail the fragmentation of various molecular-related ions, such as [M+H]+, [M+Na]+ and [M-H] ions, and the formation pathways of characteristic fragment ions. It has been found that there exists some competing reaction between the loss of C-13 side chain and decomposition by loss of acetic acid. In addition, by comparing CID spectra obtained with low- and high-energy collision, it is seen that CID-MS/MS with low-energy collision is more suitable for the study of the structural analysis of small molecules and drug metabolites. The experimental results demonstrate that MS/MS spectra can reflect more effectively the slight difference of structure between the related
基金Project supported by Chinese Academy of Medical Science Researeh Grant and Taisho Pharmaceutical Co. Ltd.
文摘An oxetane ring can be constructed from 5α-acyloxy-Δ4(20)-taxoids. Hie facile intramolecular acyl migration from 5- to 20-position under slightly basic conditions enabled the construction of the oxetane ring in a convenient short cut, whereas the acyl migration from 2- to 20-position left the 2-hydroxyl accessible to a later benzoylation. An unexpected five-mem-bered 4-O, 20- O sulfite ring was formed in the attempted construction of the oxetane ring with 5α-triflate as a leaving group. After the construction of the oxetane ring, treatment with strong base LiHMDS and acetyl chloride gave the expected 4-O-acetate while treatment with acetic anhydride and DMAP gave a 4-O-acetoacetate.
文摘1-Hydroxyl acetylation of 10-deacetylbaccatin Ⅲ was achieved by removing the neighboring bulky 2-benzoyl group and oxidizing 2-hydroxyl group to a ketone function, but attempted reductive cleavage of 1-acetoxy gave rearranged products under different conditions with or without proton source.
基金described here comes from the Ministry of Education, Scienceports, and Culture of japan through a grant-in-aid for scientifi
文摘A new taxane diterpenoid with a rearranged 5/7/6-membered ring system was isolated from the seeds of the Chinese yew. Taxus yunnanensis. Its structure was established as 9αacetoxy-5α-cinnamoyl-11(15 →1 )-abeotaxa-4(20), 11-dienc-10β, 13α, 15-triol on the basis of spectroscopic analysis. its relative stereochemistry is proposed from the results of a NOESY experment.
文摘A series of 94 taxol analogues exhibiting antitumor activity were investigated using comparative molecular ficld analsis (CoMFA) method. The most optimal CoMFA from 80 compounds selected randomly . yielded a two-components model, with siginficant cross-validation r cv of 0.640 and conventional r of 0.868. The robustness of the CoMFA model was further validatal by prediedon Of 14 test set componds. The CoMFA model explained present SAR and prtcularly the importance of the hydroxyl group at C-2’ position and the stereochemistry at C-2’ and C-3’
基金Giant-in-Aid for scientific reserch from the Ministry of Education, Science and Culture of JapanJSPS fellowship to DL Q. Che
文摘An α-4(20)-epoxy-5α-hydroxytaxinine B 1, when treated with diethylaluminum chloride, underwent reactions involving intramolecular substitution along with deacetylation or addition leading to new rings. Two novel 1-deoxy compounds 2 and 3 were isolated and fully characterized.
文摘Compound 2 with 14β-hydroxyl group was successfully converted into its epimerized α-counterpart via oxidation - reduction.The elimination product (6) was auto-oxidized to epoxide 8,even in the solid
文摘A new taxoid taxa-4(20), 11-diene-2α, 5β, 10β, 14β-tetraol-2α, 14β-diacetate (sinenxan H) (1) was obtained by biotransformation of taxa-4(20), 11-diene-2α, 5α, 10β, 14β-tetraol-2α, 5α, 10β, 14β-tetraacetate (2) with a fungus isolated from Taxus yunnanensis. Its structure was determined based on spectral
文摘A new taxoid with 5/716 taxane skeleton, named taxamedin A (1) was isolated from the needles of Taxus x media Hicksii. Its structure was elucidated by spectal
文摘Two new taxane diterpenoids, 2-deacetoxy-7, 9-dideacetyltaxinine J (1) and 2 -deacctoxytaxinine B (3), were isolated from the barks of Taxus chinensis. Their smicfures were elucidated by spectroscopic methods.
