Clean catalytic oxidation has a broad prospect in the modern chemical engineering and energy chemistry fields.However,unexpected over-oxidation and disruptive degradation are frequently induced by excessive reactive o...Clean catalytic oxidation has a broad prospect in the modern chemical engineering and energy chemistry fields.However,unexpected over-oxidation and disruptive degradation are frequently induced by excessive reactive oxygen species(ROS).Herein,we reported a new ROS-free approach to effectively drive O_(2) to be activated into highly reactive surface peroxo species through enzyme-mimicking mechanism.Benefiting from the dual-metal synergy effect between Cu and Co active sites,ROS(H_(2)O_(2) and OH•)is generated in situ while further scavenged completely into surface peroxo species,which gives rise to very high selectivity and extremely high carbon balance.For example,the CuCo/N-C catalyst affords>99.8%conversion and 94.5%selectivity to 2,5-furanedicarboxylic acid at 25℃ for 6 h in the aerobic oxidation of biomass platform 5-hydroxymethylfurfural.Moreover,it achieved exceptional performance in the oxidation of a variety of hydroxyl compounds to organic acids with high yields(89.9%–99.5%)at a mild temperature(25–40℃).This exploration introduces an innovative clue for emulating enzyme catalysts,thereby enriching our comprehension and advancement of biologically inspired catalytic oxidations.展开更多
Mangiferin is a natural plant polyphenol with a structure of xanthone C-glycoside and it displays a wide spectrum of pharmacological activities. Investigation of the metabolites of mangiferin is valuable in studying t...Mangiferin is a natural plant polyphenol with a structure of xanthone C-glycoside and it displays a wide spectrum of pharmacological activities. Investigation of the metabolites of mangiferin is valuable in studying the mechanisms of its various pharmacological properties and developing novel drugs from the mangiferin derivatives. Among the metabolites of mangiferin, mangiferin-7-O-β-D-glucuronide has been reported as the phase Ⅱ metabolite of mangiferin. Herein we described the first semi-synthesis of mangiferin-7-O-β-D-glucuronide with the natural product mangiferin as the starting material. In this work, we adopted several regioselective protection procedures to distinguish the different hydroxyl groups in the structure of mangiferin, and we accomplished the glycosylation under the phase-transfer catalysis conditions. In this method, we efficiently synthesized the glucuronide derivative of mangiferin in 10 steps with highly regioselective protection.展开更多
A visible light-mediated approach for the preparation of α-bromo-α,β-unsaturated ketones and aldehydes was developed. In comparison to traditional methods that generally take two steps to afford the above compounds...A visible light-mediated approach for the preparation of α-bromo-α,β-unsaturated ketones and aldehydes was developed. In comparison to traditional methods that generally take two steps to afford the above compounds, this protocol was highlighted by its operational simplicity, avoiding using hazardous bromine and mild reaction conditions.展开更多
文摘Clean catalytic oxidation has a broad prospect in the modern chemical engineering and energy chemistry fields.However,unexpected over-oxidation and disruptive degradation are frequently induced by excessive reactive oxygen species(ROS).Herein,we reported a new ROS-free approach to effectively drive O_(2) to be activated into highly reactive surface peroxo species through enzyme-mimicking mechanism.Benefiting from the dual-metal synergy effect between Cu and Co active sites,ROS(H_(2)O_(2) and OH•)is generated in situ while further scavenged completely into surface peroxo species,which gives rise to very high selectivity and extremely high carbon balance.For example,the CuCo/N-C catalyst affords>99.8%conversion and 94.5%selectivity to 2,5-furanedicarboxylic acid at 25℃ for 6 h in the aerobic oxidation of biomass platform 5-hydroxymethylfurfural.Moreover,it achieved exceptional performance in the oxidation of a variety of hydroxyl compounds to organic acids with high yields(89.9%–99.5%)at a mild temperature(25–40℃).This exploration introduces an innovative clue for emulating enzyme catalysts,thereby enriching our comprehension and advancement of biologically inspired catalytic oxidations.
基金The National Research Foundation for the Doctoral Program of Higher Education of China(Grant No.20130001110058)
文摘Mangiferin is a natural plant polyphenol with a structure of xanthone C-glycoside and it displays a wide spectrum of pharmacological activities. Investigation of the metabolites of mangiferin is valuable in studying the mechanisms of its various pharmacological properties and developing novel drugs from the mangiferin derivatives. Among the metabolites of mangiferin, mangiferin-7-O-β-D-glucuronide has been reported as the phase Ⅱ metabolite of mangiferin. Herein we described the first semi-synthesis of mangiferin-7-O-β-D-glucuronide with the natural product mangiferin as the starting material. In this work, we adopted several regioselective protection procedures to distinguish the different hydroxyl groups in the structure of mangiferin, and we accomplished the glycosylation under the phase-transfer catalysis conditions. In this method, we efficiently synthesized the glucuronide derivative of mangiferin in 10 steps with highly regioselective protection.
基金supported by the National Natural Science Foundation of China(2100201821072038+3 种基金2147203021302029)the State Key Laboratory of Urban Water Resource and Environment(2015DX01)the Fundamental Research Funds for the Central Universities(HIT.BRETIV.201310)
文摘A visible light-mediated approach for the preparation of α-bromo-α,β-unsaturated ketones and aldehydes was developed. In comparison to traditional methods that generally take two steps to afford the above compounds, this protocol was highlighted by its operational simplicity, avoiding using hazardous bromine and mild reaction conditions.
