The cratonization history of the North China Craton(NCC)and the nature of tectonothermal events are still highly controversial.Tonalite-trondhjemite-granodiorite(TTG)gneisses,as the dominant lithological assemblages i...The cratonization history of the North China Craton(NCC)and the nature of tectonothermal events are still highly controversial.Tonalite-trondhjemite-granodiorite(TTG)gneisses,as the dominant lithological assemblages in Archean metamorphic terranes,can provide significant clues to the magmatic and metamorphic evolution of Precambrian crust.This study presents zircon laser-ablation inductively-coupled-plasma mass spectrometry U–Pb ages,trace-element,and in-situ LA-MC-ICPMS zircon Hf isotope data for the TTG gneisses from the Bengbu-Wuhe area on the southeastern margin of the NCC.Cathodoluminescence images and trace elements indicated that magmatic zircons display the characteristics of euhedral-subhedral crystals with oscillatory growth zoning structures,high RREE contents,marked Ce positive anomalies,and Pr–Eu negative anomalies.The metamorphic zircons display the spherical-oval crystals with distinct core-rim structures,high and homogeneous luminescent intensity,lower RREE,Nb,Ta,Hf contents,relative flat REE patterns,weak Ce positive anomalies,and Pr-Eu negative anomalies.The Ti–in–zircon geothermometer data indicate that the crystallization temperature of the TTG gneiss ranged from 754 to 868℃.Zircon U–Pb ages indicate that the TTG gneisses formed at 2.79–2.77 Ga and 2.50 Ga and underwent metamorphism at 2.57–2.52 Ga.The Hf isotopic data indicate that the magmatic zircons exhibit high,positive eHf(t)values close to those of the coeval depleted mantle,whereas the metamorphic zircons exhibit negative or nil eHf(t)values.This implies that the TTG gneisses were derived from the partial melting of the~2.9–2.6 Ga juvenile crustal sources mixed with~3.0–2.8 Ga ancient crustal materials.Combined with the regional tectonic evolution,we propose that the metamorphic basement at the southeastern margin of the NCC underwent episodic crustal growth at~2.7 and~2.5 Ga and subsequently underwent crustal reworking or re-melting of the ancient crust during the Neoarchean.The Neoarchean TTG gneisses might have been derived from the partial melting of lower crustal materials related to plate subduction.展开更多
Dragocins A-C are structurally unique marine natural products featuring an uncommon tri-oxa-tricyclic[6.2.1]undecane moiety.However,their extremely low natural abundance has hindered extensive screening of their bioac...Dragocins A-C are structurally unique marine natural products featuring an uncommon tri-oxa-tricyclic[6.2.1]undecane moiety.However,their extremely low natural abundance has hindered extensive screening of their bioactivities.We hereby describe an efficient and modular approach to synthesizing dragocins A-C and their analogues using commercially available and inexpensive anisomycin and D-ribosyl thioglycoside derivative as the starting materials.A key feature of our synthesis is the construction of the uncommon tri-oxa-tricyclic[6.2.1]undecane skeleton.This challenging architecture is achieved by the stereocontrolled formation of theβ-ribofuranosidic bond and the DDQ(2,3-dichloro-5,6-dicyano-1,4-benzoquinone)-promoted intramolecular cross-dehydrogenative etherification at the benzylic position.Our synthesis is also characterized by the successful installation of a chlorine atom and a methoxy group at the tertiary C-4'position via a late-stage silver-catalyzed decarboxylative chlorination reaction and an electrophilic etherification reaction of the enol intermediate.Cytotoxicity evaluations of the synthesized compounds revealed demethyl dragocin A,the N-demethylated derivative of dragocin A,as a potential anticancer candidate due to its strong cytotoxicity against A549 lung,HCT116 colorectal and MCF7 breast cancer cell lines.This work also demonstrated the preliminary structure-activity relationship of this compound,setting a solid foundation for developing novel anticancer candidates.展开更多
基金supported by the National Natural Science Foundation of China(Nos.41303041 and41763005)Open Fund(Nos.Z1909,Z1912,RGET1804,15LCD08)of the State Key Laboratory of Nuclear Resources and Environment+1 种基金Fundamental Science on Radioactive Geology and Exploration Technology LaboratoryState Key Laboratory of Continental Dynamics。
文摘The cratonization history of the North China Craton(NCC)and the nature of tectonothermal events are still highly controversial.Tonalite-trondhjemite-granodiorite(TTG)gneisses,as the dominant lithological assemblages in Archean metamorphic terranes,can provide significant clues to the magmatic and metamorphic evolution of Precambrian crust.This study presents zircon laser-ablation inductively-coupled-plasma mass spectrometry U–Pb ages,trace-element,and in-situ LA-MC-ICPMS zircon Hf isotope data for the TTG gneisses from the Bengbu-Wuhe area on the southeastern margin of the NCC.Cathodoluminescence images and trace elements indicated that magmatic zircons display the characteristics of euhedral-subhedral crystals with oscillatory growth zoning structures,high RREE contents,marked Ce positive anomalies,and Pr–Eu negative anomalies.The metamorphic zircons display the spherical-oval crystals with distinct core-rim structures,high and homogeneous luminescent intensity,lower RREE,Nb,Ta,Hf contents,relative flat REE patterns,weak Ce positive anomalies,and Pr-Eu negative anomalies.The Ti–in–zircon geothermometer data indicate that the crystallization temperature of the TTG gneiss ranged from 754 to 868℃.Zircon U–Pb ages indicate that the TTG gneisses formed at 2.79–2.77 Ga and 2.50 Ga and underwent metamorphism at 2.57–2.52 Ga.The Hf isotopic data indicate that the magmatic zircons exhibit high,positive eHf(t)values close to those of the coeval depleted mantle,whereas the metamorphic zircons exhibit negative or nil eHf(t)values.This implies that the TTG gneisses were derived from the partial melting of the~2.9–2.6 Ga juvenile crustal sources mixed with~3.0–2.8 Ga ancient crustal materials.Combined with the regional tectonic evolution,we propose that the metamorphic basement at the southeastern margin of the NCC underwent episodic crustal growth at~2.7 and~2.5 Ga and subsequently underwent crustal reworking or re-melting of the ancient crust during the Neoarchean.The Neoarchean TTG gneisses might have been derived from the partial melting of lower crustal materials related to plate subduction.
基金the Marine S&T Fund of Shandong Province for Qingdao Marine Science and Technology Center(Qingdao)(No.2022QNLM030003-2)the National Natural Science Foundation of China(No 22377114).
文摘Dragocins A-C are structurally unique marine natural products featuring an uncommon tri-oxa-tricyclic[6.2.1]undecane moiety.However,their extremely low natural abundance has hindered extensive screening of their bioactivities.We hereby describe an efficient and modular approach to synthesizing dragocins A-C and their analogues using commercially available and inexpensive anisomycin and D-ribosyl thioglycoside derivative as the starting materials.A key feature of our synthesis is the construction of the uncommon tri-oxa-tricyclic[6.2.1]undecane skeleton.This challenging architecture is achieved by the stereocontrolled formation of theβ-ribofuranosidic bond and the DDQ(2,3-dichloro-5,6-dicyano-1,4-benzoquinone)-promoted intramolecular cross-dehydrogenative etherification at the benzylic position.Our synthesis is also characterized by the successful installation of a chlorine atom and a methoxy group at the tertiary C-4'position via a late-stage silver-catalyzed decarboxylative chlorination reaction and an electrophilic etherification reaction of the enol intermediate.Cytotoxicity evaluations of the synthesized compounds revealed demethyl dragocin A,the N-demethylated derivative of dragocin A,as a potential anticancer candidate due to its strong cytotoxicity against A549 lung,HCT116 colorectal and MCF7 breast cancer cell lines.This work also demonstrated the preliminary structure-activity relationship of this compound,setting a solid foundation for developing novel anticancer candidates.
