Grandiflorenic acid(1),possessing potent contragestational activity,is an ent-kauranediterpenoid.It has been isolated from Mexical medicinal plant zoapatle(Montanoa tomento)In connection with our synthetic work on ent...Grandiflorenic acid(1),possessing potent contragestational activity,is an ent-kauranediterpenoid.It has been isolated from Mexical medicinal plant zoapatle(Montanoa tomento)In connection with our synthetic work on ent-kaurane diterpenoids,we are interested in theconversion of stevioside(2)occurred abundantly in Stevia rebaudiana into grandiflorenic acid展开更多
Two new tetracyclic taxane diterpenoids----yunnanxol(1) and yunnanxamine(2)have been isolated from the bark of Taxus yunnanensis Cheng et L.K.Fu.Their structures have been established from the spectral data,mainly fro...Two new tetracyclic taxane diterpenoids----yunnanxol(1) and yunnanxamine(2)have been isolated from the bark of Taxus yunnanensis Cheng et L.K.Fu.Their structures have been established from the spectral data,mainly from MS,highfield ~1H NMR,~1H-~1H COSY, ^(13)C NMR,^(13)C-~1H COSY and ^(13)C-~1H COLOC spectroscopies.展开更多
The key intermediate 5 for synthesis of the contragestationally active diterpenoid grandiflorenic acid(1)and its analogues 2 and 3 was prepared and an acetyl transposition reaction occurred in the SeO_2 oxida- tion of 8.
Devonian cutinitic liptobiolith is a special type of coal formed during the early evolutionary stage of land plants.The Baishaping and Damaidi Devonian coals are notable for their distinct papery,sheet-like texture,an...Devonian cutinitic liptobiolith is a special type of coal formed during the early evolutionary stage of land plants.The Baishaping and Damaidi Devonian coals are notable for their distinct papery,sheet-like texture,and unusually high cutinite content(>50%),belonging to typical cutinitic liptobiolith.They are bituminous coals and have a suppressed vitrinite reflectance.Compared with typical typeⅢkerogen,these liptobioliths are characterized by extremely high yields of volatile matter and high hydrogen contents owing to their enhanced cutinite contents.As indicated by pyrolysis and elemental analysis results,the Devonian cutinitic liptobioliths are dominated by typeⅠ-Ⅱkerogens and have an excellent potential to generate liquid hydrocarbons.The Baishaping cutinitic liptobioliths are mainly composed of ribbon-like thick-walled cutinites,with small amounts of thin-walled type.Vitrinite is only present in trace amounts and is dominated by telinite.Meanwhile,the Damaidi Devonian coals are primarily composed of ribbon-like thin-walled cutinites,followed by collotelinites which are usually sandwiched by cutinites.The different petrological characteristics of the Baishaping and Damaidi liptobioliths might indicate a structural variation in the coal-forming plant cuticles and two distinct coal-forming conditions.The molecular bio markers in the Devonian coals are mainly composed of C_(18)-C_(20)tetracyclic diterpenoids,which are assumed to be the dominant soluble constituent of the Devonian land-plant cuticles and might have played an important role in early land plant radiation.Other molecules include aromatic tetracyclic diterpenoids,3-5 ring polycyclic aromatic hydrocarbons and their methylated counterparts,and C_(16)-and C_(18)-monocarboxylic acids.n-Alkanes are present only in small amounts.The molecular composition of the cutinite-rich coals is unexpected,because cuticular waxes are one of the most important sources of n-alkanes.In general,the petrology and geochemistry of the Devonian cutinitic liptobiolith indicate a distinct structure and composition for the early land-plant cuticles,which is significantly different from that of the plant cuticles since Carboniferous.Devonian cutinitic liptobioliths are of great interest because of their unique petrography,geochemistry,coal-forming plants,and oil-prone potential.Studies on this unique coal type provide a better understanding of coal-forming plants,paleoenvironment,paleoclimate,and early land-plant evolution in the Devonian.展开更多
文摘Grandiflorenic acid(1),possessing potent contragestational activity,is an ent-kauranediterpenoid.It has been isolated from Mexical medicinal plant zoapatle(Montanoa tomento)In connection with our synthetic work on ent-kaurane diterpenoids,we are interested in theconversion of stevioside(2)occurred abundantly in Stevia rebaudiana into grandiflorenic acid
文摘Two new tetracyclic taxane diterpenoids----yunnanxol(1) and yunnanxamine(2)have been isolated from the bark of Taxus yunnanensis Cheng et L.K.Fu.Their structures have been established from the spectral data,mainly from MS,highfield ~1H NMR,~1H-~1H COSY, ^(13)C NMR,^(13)C-~1H COSY and ^(13)C-~1H COLOC spectroscopies.
文摘The key intermediate 5 for synthesis of the contragestationally active diterpenoid grandiflorenic acid(1)and its analogues 2 and 3 was prepared and an acetyl transposition reaction occurred in the SeO_2 oxida- tion of 8.
基金founded by the National Natural Science Foundation of China(Grant No.42073069)。
文摘Devonian cutinitic liptobiolith is a special type of coal formed during the early evolutionary stage of land plants.The Baishaping and Damaidi Devonian coals are notable for their distinct papery,sheet-like texture,and unusually high cutinite content(>50%),belonging to typical cutinitic liptobiolith.They are bituminous coals and have a suppressed vitrinite reflectance.Compared with typical typeⅢkerogen,these liptobioliths are characterized by extremely high yields of volatile matter and high hydrogen contents owing to their enhanced cutinite contents.As indicated by pyrolysis and elemental analysis results,the Devonian cutinitic liptobioliths are dominated by typeⅠ-Ⅱkerogens and have an excellent potential to generate liquid hydrocarbons.The Baishaping cutinitic liptobioliths are mainly composed of ribbon-like thick-walled cutinites,with small amounts of thin-walled type.Vitrinite is only present in trace amounts and is dominated by telinite.Meanwhile,the Damaidi Devonian coals are primarily composed of ribbon-like thin-walled cutinites,followed by collotelinites which are usually sandwiched by cutinites.The different petrological characteristics of the Baishaping and Damaidi liptobioliths might indicate a structural variation in the coal-forming plant cuticles and two distinct coal-forming conditions.The molecular bio markers in the Devonian coals are mainly composed of C_(18)-C_(20)tetracyclic diterpenoids,which are assumed to be the dominant soluble constituent of the Devonian land-plant cuticles and might have played an important role in early land plant radiation.Other molecules include aromatic tetracyclic diterpenoids,3-5 ring polycyclic aromatic hydrocarbons and their methylated counterparts,and C_(16)-and C_(18)-monocarboxylic acids.n-Alkanes are present only in small amounts.The molecular composition of the cutinite-rich coals is unexpected,because cuticular waxes are one of the most important sources of n-alkanes.In general,the petrology and geochemistry of the Devonian cutinitic liptobiolith indicate a distinct structure and composition for the early land-plant cuticles,which is significantly different from that of the plant cuticles since Carboniferous.Devonian cutinitic liptobioliths are of great interest because of their unique petrography,geochemistry,coal-forming plants,and oil-prone potential.Studies on this unique coal type provide a better understanding of coal-forming plants,paleoenvironment,paleoclimate,and early land-plant evolution in the Devonian.
