The major products of carbonium cyclization of 1 are 2 and 3;2 is unstable and undergoes aerial oxidation to give 4.A similar product(6)from 5 is somehow stabilized by the extra ben- zoyloxy group(or OH)and can be sto...The major products of carbonium cyclization of 1 are 2 and 3;2 is unstable and undergoes aerial oxidation to give 4.A similar product(6)from 5 is somehow stabilized by the extra ben- zoyloxy group(or OH)and can be stored without deterioration.展开更多
Schisandrin(1)under the Ritter reaction conditions (conc.H_2SO_4/CH_3CN)gave trace amounts of the expected acetamido derivatives(2a,2b).The main product is 5a,from intramolecular car- bonium cyclization.
Isovaleroyl oxokadsurane,a novel dibenzocyclooctadiene lignan pos- sessing a spirobenzofuranoid skeleton was isolated from the stems of Kadsura coccinea.Its structure and relative configuration were determined by X-ra...Isovaleroyl oxokadsurane,a novel dibenzocyclooctadiene lignan pos- sessing a spirobenzofuranoid skeleton was isolated from the stems of Kadsura coccinea.Its structure and relative configuration were determined by X-ray diffraction analysis.展开更多
The stereochemistry of two 6, 9-oxygen bridge dibenzocyclooctadiene lignans from Kadsura coccinea, are difficult to separate and very unstable. The present study was designed to develop a high-performance liquid chrom...The stereochemistry of two 6, 9-oxygen bridge dibenzocyclooctadiene lignans from Kadsura coccinea, are difficult to separate and very unstable. The present study was designed to develop a high-performance liquid chromatography using circular dichroism detection for the analysis of the stereochemistry. A new 6, 9-oxygen bridge dibenzocyclooctadiene lignans named Kadsulignan Q was firstly found with an S-biphenyl configuration. The other compound was identified as Kadsulignan L with an R- biphenyl configuration. In order to obtain kinetic data on their reversible interconversion, the stability was measured at different deuterated solvents such as deuterated methanol, deuterated chloroform and deuterated dimethylsulfoxide. The lignans were more unstable and converted more easily in deuterated methanol than in deuterated chloroform and deuterated dimethylsulfoxide.展开更多
The reaction of schisandrin(1)under Ritter reaction conditions(conc.sulfuric acid/aceto- nitrile)was studied.Besides trace amounts of normal products(7α-and 7β-acetamido derivatives 2a and 2b),the main product was a...The reaction of schisandrin(1)under Ritter reaction conditions(conc.sulfuric acid/aceto- nitrile)was studied.Besides trace amounts of normal products(7α-and 7β-acetamido derivatives 2a and 2b),the main product was a carbonium cyclization compound(3a).展开更多
Negative thermal expansion(NTE) behavior has roused wide interest for the control of thermomechanical properties of functional materials.Although NTE behaviors have been found in kinds of compounds,it remains challeng...Negative thermal expansion(NTE) behavior has roused wide interest for the control of thermomechanical properties of functional materials.Although NTE behaviors have been found in kinds of compounds,it remains challenging for polymers to achieve intrinsic NTE property.In this work,we systematically studied the conformational change of dibenzocyclooctadiene(DBCOD) derivatives between chair(C) and twist-boat(TB) forms based on density-functional theo ry(DFT) calculations,and found clear evidence of the relationship between the structure of DBCOD units and the thermal contraction behavior of the related polymers.In order to obtain the polymer with NTE property,two conditions should be met for the thermal contracting DBCOD related units as follows:(i) the TB conformation can turn into C conformation as the temperature increases,and(ii) the volume of C conformation is smaller than that of TB conformation.This rule should offer a guidance to exploration of the new intrinsic NTE polymers in the future.展开更多
文摘The major products of carbonium cyclization of 1 are 2 and 3;2 is unstable and undergoes aerial oxidation to give 4.A similar product(6)from 5 is somehow stabilized by the extra ben- zoyloxy group(or OH)and can be stored without deterioration.
文摘Schisandrin(1)under the Ritter reaction conditions (conc.H_2SO_4/CH_3CN)gave trace amounts of the expected acetamido derivatives(2a,2b).The main product is 5a,from intramolecular car- bonium cyclization.
文摘Isovaleroyl oxokadsurane,a novel dibenzocyclooctadiene lignan pos- sessing a spirobenzofuranoid skeleton was isolated from the stems of Kadsura coccinea.Its structure and relative configuration were determined by X-ray diffraction analysis.
基金supported by the PAPD(Priority Academic Program Development)of Jiangsu Higher Education Institutions,University Science Research Project of Jiangsu Province(No.09KJB350002)National Key Technology R&D Program(No.2012BAI30B02),National Natural Science Foundation of China(No.30901853)Hepatic Fibrosis Innovative Medicine-Research and Development of Fructus Schisandrae capsule(No.F12-157-9-00)
文摘The stereochemistry of two 6, 9-oxygen bridge dibenzocyclooctadiene lignans from Kadsura coccinea, are difficult to separate and very unstable. The present study was designed to develop a high-performance liquid chromatography using circular dichroism detection for the analysis of the stereochemistry. A new 6, 9-oxygen bridge dibenzocyclooctadiene lignans named Kadsulignan Q was firstly found with an S-biphenyl configuration. The other compound was identified as Kadsulignan L with an R- biphenyl configuration. In order to obtain kinetic data on their reversible interconversion, the stability was measured at different deuterated solvents such as deuterated methanol, deuterated chloroform and deuterated dimethylsulfoxide. The lignans were more unstable and converted more easily in deuterated methanol than in deuterated chloroform and deuterated dimethylsulfoxide.
文摘The reaction of schisandrin(1)under Ritter reaction conditions(conc.sulfuric acid/aceto- nitrile)was studied.Besides trace amounts of normal products(7α-and 7β-acetamido derivatives 2a and 2b),the main product was a carbonium cyclization compound(3a).
基金supported by the National Natural Science Foundation of China (Nos.51633001,51721002 and 51873040)National Key R&D Program of China (No.2016YFC1100300)。
文摘Negative thermal expansion(NTE) behavior has roused wide interest for the control of thermomechanical properties of functional materials.Although NTE behaviors have been found in kinds of compounds,it remains challenging for polymers to achieve intrinsic NTE property.In this work,we systematically studied the conformational change of dibenzocyclooctadiene(DBCOD) derivatives between chair(C) and twist-boat(TB) forms based on density-functional theo ry(DFT) calculations,and found clear evidence of the relationship between the structure of DBCOD units and the thermal contraction behavior of the related polymers.In order to obtain the polymer with NTE property,two conditions should be met for the thermal contracting DBCOD related units as follows:(i) the TB conformation can turn into C conformation as the temperature increases,and(ii) the volume of C conformation is smaller than that of TB conformation.This rule should offer a guidance to exploration of the new intrinsic NTE polymers in the future.
