Through-space interactions of pi orbiatl and sigma orbital in molecule tricycle 4,2,2,2,dodecadiene -1.5 were studied by means of DV-X alpha SVF method using a model molecule that consists of two ethylenes with interd...Through-space interactions of pi orbiatl and sigma orbital in molecule tricycle 4,2,2,2,dodecadiene -1.5 were studied by means of DV-X alpha SVF method using a model molecule that consists of two ethylenes with interdeck distance D. The results show the through-space interactions of the title molecule decrease with the increasing of D,the through-space interactions of pi orbital are larger than that of sigma orbital. Furthermore, through-bond interactions of the pi orbtial and sigma orbital were analyzed basing on the calculations of the electronic structure of the title molecule. Both through-space and through-bond interactions are Large and,the net interactions are small. The calculated ionization potential energies of the title molecule which were obtained by transition-state procedure are in good agreement with the PE spectroscopy.展开更多
A neolignan codonopiloneolignanin A（1） with a novel 2,9：20,9：7,70-tricyclo-8,90-neolignane skeleton was isolated from an aqueous extract of the Codonopsis pilosula roots. Its structure including the absolute confi...A neolignan codonopiloneolignanin A（1） with a novel 2,9：20,9：7,70-tricyclo-8,90-neolignane skeleton was isolated from an aqueous extract of the Codonopsis pilosula roots. Its structure including the absolute configuration was elucidated by extensive spectroscopic analysis, including 2D NMR and electronic circular dichroism calculation. The proposed biosynthetic pathway of compound 1 is also discussed.展开更多
Gambogic acid （GA, 1）, the most prominent member of Garcinia natural products, has been reported to be a promising anti-tumor agent. Previous studies have suggested that the planar B ring and the unique 4-oxa-tricyc...Gambogic acid （GA, 1）, the most prominent member of Garcinia natural products, has been reported to be a promising anti-tumor agent. Previous studies have suggested that the planar B ring and the unique 4-oxa-tricyclo- [4.3.1.03.7]dec-2-one caged motif were essential for anti-tumor activity. To further explore the structure-activity relationship （SAR） of caged Garcinia xanthones, two new series of B-ring modified caged GA analogues 13a-13e and 15a-lge were synthesized utilizing a Claisen/Diel-Alder cascade reaction. Subsequently, these compounds were evaluated for their in vitro antitumor activities against A549, MCF-7, SMMC-7721 and BGC-823 cancer cell lines by MTT assay. Among them, 13b-13e exhibited micromolar inhibition against several cancer cell lines, being approximately 2-4 fold less potent in comparison to GA. SAR analysis revealed that the peripheral gem-dimethyl groups are essential for maintaining antitumor activity and substituent group on C1 position of B-ring has a significant effect on potency, while modifications at C-2, C-3 and C-4 positions are relatively tolerated. These findings will enhance our understanding of the SAR of Garcinia xanthones and lead to the development of simplified analogues as potential anti-tumor agents.展开更多
Two novel constituents were isolated from the roots of Chinese medicinal herbs, Salvia miltiorrhiza. Their structures were determined by spectroscopic technique. The compounds were named 13,14-dihydroxy-15-methyl-benz...Two novel constituents were isolated from the roots of Chinese medicinal herbs, Salvia miltiorrhiza. Their structures were determined by spectroscopic technique. The compounds were named 13,14-dihydroxy-15-methyl-benzo[2,3-a]-7,7-dimethyl-12-oxa-tricyclo[4,4,21.4,0]dodecane(1) and 16-methyl-tropono[2,3-c]-7,7-dimethyl-12-oxa-tricyclo[4,4,21.4,0]dodecane(2).展开更多
The unusual tricyclo[6.4.0.0^4,9]dodecane framework was constructed in eight linear steps in 13%overall yield.An innovative strategy accessing the framework from bicyclo[3.3.1]nonanes was employed.The key steps involv...The unusual tricyclo[6.4.0.0^4,9]dodecane framework was constructed in eight linear steps in 13%overall yield.An innovative strategy accessing the framework from bicyclo[3.3.1]nonanes was employed.The key steps involve a Robinson annulation,a base induced decarboxylation and epimerization in a single step,and an intramolecular alkylation.展开更多
Asymmetric syntheses of both enantiomerically pure (+) and (-) 5-oxo-endo-tricyclo [5.2.1.0.^(2,6)] deca-3, 8-diene 1 was described. The key step is the use of enzyme-catalyzed hydrolysis of meso-diacetate 5.
基金The project is supported by National Nature Scrence Funds of China.
文摘Through-space interactions of pi orbiatl and sigma orbital in molecule tricycle 4,2,2,2,dodecadiene -1.5 were studied by means of DV-X alpha SVF method using a model molecule that consists of two ethylenes with interdeck distance D. The results show the through-space interactions of the title molecule decrease with the increasing of D,the through-space interactions of pi orbital are larger than that of sigma orbital. Furthermore, through-bond interactions of the pi orbtial and sigma orbital were analyzed basing on the calculations of the electronic structure of the title molecule. Both through-space and through-bond interactions are Large and,the net interactions are small. The calculated ionization potential energies of the title molecule which were obtained by transition-state procedure are in good agreement with the PE spectroscopy.
基金Financial support from the National Natural Science Foundation of China (Nos. 30825044, 21132009)the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT, No. IRT1007)the National Science and Technology Project of China (Nos. 2012ZX09301002-002, 2011ZX0 9307-002-01) are acknowledged
文摘A neolignan codonopiloneolignanin A（1） with a novel 2,9：20,9：7,70-tricyclo-8,90-neolignane skeleton was isolated from an aqueous extract of the Codonopsis pilosula roots. Its structure including the absolute configuration was elucidated by extensive spectroscopic analysis, including 2D NMR and electronic circular dichroism calculation. The proposed biosynthetic pathway of compound 1 is also discussed.
基金This work was supported by 90713038 and 21072231 of National Natural Science Foundation of China （Key Program）, 2008ZX09401-001, 2009ZX09501-003 and 2010ZX09401-401 of National Major Science and Technology Project of China （Innovation and Development of New Drugs）.
文摘Gambogic acid （GA, 1）, the most prominent member of Garcinia natural products, has been reported to be a promising anti-tumor agent. Previous studies have suggested that the planar B ring and the unique 4-oxa-tricyclo- [4.3.1.03.7]dec-2-one caged motif were essential for anti-tumor activity. To further explore the structure-activity relationship （SAR） of caged Garcinia xanthones, two new series of B-ring modified caged GA analogues 13a-13e and 15a-lge were synthesized utilizing a Claisen/Diel-Alder cascade reaction. Subsequently, these compounds were evaluated for their in vitro antitumor activities against A549, MCF-7, SMMC-7721 and BGC-823 cancer cell lines by MTT assay. Among them, 13b-13e exhibited micromolar inhibition against several cancer cell lines, being approximately 2-4 fold less potent in comparison to GA. SAR analysis revealed that the peripheral gem-dimethyl groups are essential for maintaining antitumor activity and substituent group on C1 position of B-ring has a significant effect on potency, while modifications at C-2, C-3 and C-4 positions are relatively tolerated. These findings will enhance our understanding of the SAR of Garcinia xanthones and lead to the development of simplified analogues as potential anti-tumor agents.
文摘Two novel constituents were isolated from the roots of Chinese medicinal herbs, Salvia miltiorrhiza. Their structures were determined by spectroscopic technique. The compounds were named 13,14-dihydroxy-15-methyl-benzo[2,3-a]-7,7-dimethyl-12-oxa-tricyclo[4,4,21.4,0]dodecane(1) and 16-methyl-tropono[2,3-c]-7,7-dimethyl-12-oxa-tricyclo[4,4,21.4,0]dodecane(2).
基金Financial support from TianJin Municipal Science and Technology Commission(No.11ZCKFSY06200) is greatly acknowledged
文摘The unusual tricyclo[6.4.0.0^4,9]dodecane framework was constructed in eight linear steps in 13%overall yield.An innovative strategy accessing the framework from bicyclo[3.3.1]nonanes was employed.The key steps involve a Robinson annulation,a base induced decarboxylation and epimerization in a single step,and an intramolecular alkylation.
文摘Asymmetric syntheses of both enantiomerically pure (+) and (-) 5-oxo-endo-tricyclo [5.2.1.0.^(2,6)] deca-3, 8-diene 1 was described. The key step is the use of enzyme-catalyzed hydrolysis of meso-diacetate 5.
