2-Deoxy-α-C-Glycosides are a significant class of carbohydrates found in numerous bioactive molecules and medicines.Developing a concise strategy for the assembly of theseα-configured C-glycosides is crucial in the ...2-Deoxy-α-C-Glycosides are a significant class of carbohydrates found in numerous bioactive molecules and medicines.Developing a concise strategy for the assembly of theseα-configured C-glycosides is crucial in the field of carbohydrate chemistry.However,current methods are restricted to the utilization of glycosyl radical precursors,which are required for pre-syntheses.Herein,we present a novel approach for the synthesis of 2-deoxy-α-C-glycosides using a nickel-catalyzed stereoselective coupling reaction with commercially available glycals.Notably,this method circumvents the preparation for diverse glycosyl radical precursors.The developed protocol exhibits a broad substrate scope and remarkable stereoselectivity under mild reaction conditions.Furthermore,the raw materials required for this process are readily accessible,eliminating the necessity for pre-functionalization modifications of the glycosyl substrates and ensuring high atomic economy.展开更多
Two kinds of saponins have been investigated by negative electrospray ionization(NESI) mass spectrometry. Under ESI conditions, the - ions of saponins were observed which provide the molecular weights of saponins. The...Two kinds of saponins have been investigated by negative electrospray ionization(NESI) mass spectrometry. Under ESI conditions, the - ions of saponins were observed which provide the molecular weights of saponins. The fragment pathways of - ions of these two saponins depend on their structures. For steroidic saponins, - ion only produces the fragment ions by the losses of sugar units. For oleanolic saponins, - ion yields the cross ring ions as well as the fragment ions by the losses of sugar units. Moreover, the abundance of the former is higher than that of the latter. The characteristic fragments are used to provide the sequence and some linkage information of sugar moieties of saponins. Especially, their fragment difference strongly depends on the linkage between the aglycone and the sugar moieties.展开更多
基金supported by grants from the Fundamental Research Funds for Central Universities(No.2042021kf0190)。
文摘2-Deoxy-α-C-Glycosides are a significant class of carbohydrates found in numerous bioactive molecules and medicines.Developing a concise strategy for the assembly of theseα-configured C-glycosides is crucial in the field of carbohydrate chemistry.However,current methods are restricted to the utilization of glycosyl radical precursors,which are required for pre-syntheses.Herein,we present a novel approach for the synthesis of 2-deoxy-α-C-glycosides using a nickel-catalyzed stereoselective coupling reaction with commercially available glycals.Notably,this method circumvents the preparation for diverse glycosyl radical precursors.The developed protocol exhibits a broad substrate scope and remarkable stereoselectivity under mild reaction conditions.Furthermore,the raw materials required for this process are readily accessible,eliminating the necessity for pre-functionalization modifications of the glycosyl substrates and ensuring high atomic economy.
文摘Two kinds of saponins have been investigated by negative electrospray ionization(NESI) mass spectrometry. Under ESI conditions, the - ions of saponins were observed which provide the molecular weights of saponins. The fragment pathways of - ions of these two saponins depend on their structures. For steroidic saponins, - ion only produces the fragment ions by the losses of sugar units. For oleanolic saponins, - ion yields the cross ring ions as well as the fragment ions by the losses of sugar units. Moreover, the abundance of the former is higher than that of the latter. The characteristic fragments are used to provide the sequence and some linkage information of sugar moieties of saponins. Especially, their fragment difference strongly depends on the linkage between the aglycone and the sugar moieties.
