Based on density functional theory and electronegativity equalization principle, a σπ model, which considers the structure of double bond for the first time, is developed. In this model the double bond is partitione...Based on density functional theory and electronegativity equalization principle, a σπ model, which considers the structure of double bond for the first time, is developed. In this model the double bond is partitioned into one σ bond region and four π bond regions. The atom bond electronegativity equalization method plus σπ model(ABEEM σπ ) is then proposed for the calculation of charge distribution and charge polarization in large molecules. It has been shown that the results of charge distribution in large molecules obtained by ABEEM σπ model agree with those obtained by ab initio method very well. In addition, the model can be used to explain the region selectivity of Diels Alder reaction successfully. All these indicate that ABEEM σπ model is reasonable and reliable.展开更多
A synthetic strategy toward the cyclic addition of 2,2＇-dihydroxybiphenyl to terminal alkynes has been developed using Lewis acid TICl4 as catalyst. The reactions generated dibenzo[d,f][1,3]dioxepines derivatives in ...A synthetic strategy toward the cyclic addition of 2,2＇-dihydroxybiphenyl to terminal alkynes has been developed using Lewis acid TICl4 as catalyst. The reactions generated dibenzo[d,f][1,3]dioxepines derivatives in good yields with excellent regio-selectivity in the presence of catalytic amount of TICl4 under mild reaction conditions.展开更多
Microbial transformation is a useful tool for structure modification of active natural products.Z-Butylidenephthalide is the main active constituent of Angelica sinensis.In the present work,a pair of new oxidized meta...Microbial transformation is a useful tool for structure modification of active natural products.Z-Butylidenephthalide is the main active constituent of Angelica sinensis.In the present work,a pair of new oxidized metabolites,namely(-)(11R)-(Z)-11-hydroxy-butylidenephthalide(1a)and(+)(11S)-(Z)-11-hydroxy-butylidenephthalide(1b),were obtained from microbial transformation for region-selective 11-hydroxylation of Z-butylidenephthalide by Aspergillus niger CGMCC 3.739.Their structures,including absolute configurations,were elucidated by extensive analysis of HR-ESI-MS,NMR spectra,and the modified Mosher’s method.This is the first study on the microbial transformation of Z-butylidenephthalide,and these findings offer a tool for region-selective 11-hydroxylation of Z-butylidenephthalide.展开更多
文摘Based on density functional theory and electronegativity equalization principle, a σπ model, which considers the structure of double bond for the first time, is developed. In this model the double bond is partitioned into one σ bond region and four π bond regions. The atom bond electronegativity equalization method plus σπ model(ABEEM σπ ) is then proposed for the calculation of charge distribution and charge polarization in large molecules. It has been shown that the results of charge distribution in large molecules obtained by ABEEM σπ model agree with those obtained by ab initio method very well. In addition, the model can be used to explain the region selectivity of Diels Alder reaction successfully. All these indicate that ABEEM σπ model is reasonable and reliable.
基金Project supported by the National Natural Science Foundation of China （No. 20972057）.
文摘A synthetic strategy toward the cyclic addition of 2,2＇-dihydroxybiphenyl to terminal alkynes has been developed using Lewis acid TICl4 as catalyst. The reactions generated dibenzo[d,f][1,3]dioxepines derivatives in good yields with excellent regio-selectivity in the presence of catalytic amount of TICl4 under mild reaction conditions.
基金This work was financially supported by grants from the National Key Research and Development Program of China(2018 YFA0903200/2018YFA0903201)the National Natural Science Foundation of China(81925037/31900284)+3 种基金Chang Jiang Scholars Program(Young Scholar)from the Ministry of Education of China(Hao Gao,2017)National High-level Personnel of Special Support Program(2017RA2259)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01Y036)K.C.Wong Education Foundation(Hao Gao,2016).
文摘Microbial transformation is a useful tool for structure modification of active natural products.Z-Butylidenephthalide is the main active constituent of Angelica sinensis.In the present work,a pair of new oxidized metabolites,namely(-)(11R)-(Z)-11-hydroxy-butylidenephthalide(1a)and(+)(11S)-(Z)-11-hydroxy-butylidenephthalide(1b),were obtained from microbial transformation for region-selective 11-hydroxylation of Z-butylidenephthalide by Aspergillus niger CGMCC 3.739.Their structures,including absolute configurations,were elucidated by extensive analysis of HR-ESI-MS,NMR spectra,and the modified Mosher’s method.This is the first study on the microbial transformation of Z-butylidenephthalide,and these findings offer a tool for region-selective 11-hydroxylation of Z-butylidenephthalide.
