Adsorption and reaction of CO and CO2 were studied on oxygen-covered Au（997） surfaces by means of temperature- programmed desorption/reaction spectroscopy. Oxygen atoms （O（a）） on Au（997） enhances the CO2 adsor...Adsorption and reaction of CO and CO2 were studied on oxygen-covered Au（997） surfaces by means of temperature- programmed desorption/reaction spectroscopy. Oxygen atoms （O（a）） on Au（997） enhances the CO2 adsorption and stabilizes the adsorbed COe（a）, and the stabilization effect also depends on the CO2（a） coverage and involved Au sites. CO2（a） desorp- tion is the rate-limiting step for the CO＋O（a） reaction to produce CO2 on Au（997） at 105 K and exhibits complex behaviors, including the desorption of CO2（a） upon CO exposures at 105 K and the desorption of O（a）-stabilized CO2（a） at elevated temperatures. The desorption of CO2（a） from the surface upon CO exposures at 105 K to produce gaseous CO2 depends on the surface reaction extent and involves the reaction heat-driven CO2（a） desorption channel. CO＋O（a） reaction proceeds more easily with weakly-bound oxygen adatoms at the （111） terraces than strongly-bound oxygen adatoms at the （111） steps. These re- sults reveal complex rate-limiting COe（a） desorption behaviors during CO＋O（a） reaction on Au surfaces at low temperatures which provide novel information on the fundamental understanding of Au catalysis.展开更多
A direct strategy toward the synthesis of functionalized abietane-type diterpenes and related polycyclic molecules was developed through an Au-catalyzed 1,3-acyloxy migration/cyclization/electrophilic aromatic substit...A direct strategy toward the synthesis of functionalized abietane-type diterpenes and related polycyclic molecules was developed through an Au-catalyzed 1,3-acyloxy migration/cyclization/electrophilic aromatic substitution cascade.Unlike the known polyene-type cyclization strategies for the construction of abietane-type diterpene skeletons,propargylic ester groups were used for the cyclization process,which can readily lead to the key skeleton with C2 and C3 functionalization.As a demonstration of the potential application of this tandem reaction,a collective total synthesis of(±)-2-ketoferruginol,(±)-fleuryinol B,(±)-salviol,(±)-2β-acetoxyferruginol,and(±)-2β-acetoxysugiyl methyl ether was achieved.Among these molecules,(±)-fleuryinol B and(±)-2β-acetoxyferruginol were synthesized for the first time.展开更多
Comprehensive Summary Sepositoside A(1)is a prototypical cyclic steroid glycoside bearing a hybrid 16-membered ring composed of the steroid skeleton and a 1,2-trans-linked trisaccharide.Herein,we report an expedient a...Comprehensive Summary Sepositoside A(1)is a prototypical cyclic steroid glycoside bearing a hybrid 16-membered ring composed of the steroid skeleton and a 1,2-trans-linked trisaccharide.Herein,we report an expedient access toward two simplified analogues,in which the strained 16-membered ring is constructed via Au(I)-catalyzed intramolecular addition of alcohol to epoxide.A similar macroetherification in relevant steroid trisaccharides has been intensively examined,however,failed to furnish the macrocyclic skeleton of Sepositoside A.展开更多
基金supported by the National Basic Research Program of China (2013CB933104)National Natural Science Foundation of China (20973161, 21373192)+1 种基金Ministry of Education Fundamental Research Funds for the Central Universities (WK2060030017)Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘Adsorption and reaction of CO and CO2 were studied on oxygen-covered Au（997） surfaces by means of temperature- programmed desorption/reaction spectroscopy. Oxygen atoms （O（a）） on Au（997） enhances the CO2 adsorption and stabilizes the adsorbed COe（a）, and the stabilization effect also depends on the CO2（a） coverage and involved Au sites. CO2（a） desorp- tion is the rate-limiting step for the CO＋O（a） reaction to produce CO2 on Au（997） at 105 K and exhibits complex behaviors, including the desorption of CO2（a） upon CO exposures at 105 K and the desorption of O（a）-stabilized CO2（a） at elevated temperatures. The desorption of CO2（a） from the surface upon CO exposures at 105 K to produce gaseous CO2 depends on the surface reaction extent and involves the reaction heat-driven CO2（a） desorption channel. CO＋O（a） reaction proceeds more easily with weakly-bound oxygen adatoms at the （111） terraces than strongly-bound oxygen adatoms at the （111） steps. These re- sults reveal complex rate-limiting COe（a） desorption behaviors during CO＋O（a） reaction on Au surfaces at low temperatures which provide novel information on the fundamental understanding of Au catalysis.
基金supported by the National Natural Science Foundation of China(nos.21472077 and 21772071)Department of Education of Guangdong Province(nos.2017KTSCX185,2017KSYS010,2016KCXTD005,and 2019KZDXM035).
文摘A direct strategy toward the synthesis of functionalized abietane-type diterpenes and related polycyclic molecules was developed through an Au-catalyzed 1,3-acyloxy migration/cyclization/electrophilic aromatic substitution cascade.Unlike the known polyene-type cyclization strategies for the construction of abietane-type diterpene skeletons,propargylic ester groups were used for the cyclization process,which can readily lead to the key skeleton with C2 and C3 functionalization.As a demonstration of the potential application of this tandem reaction,a collective total synthesis of(±)-2-ketoferruginol,(±)-fleuryinol B,(±)-salviol,(±)-2β-acetoxyferruginol,and(±)-2β-acetoxysugiyl methyl ether was achieved.Among these molecules,(±)-fleuryinol B and(±)-2β-acetoxyferruginol were synthesized for the first time.
基金the National Natural Science Foundation of China(21901251)Shanghai Sailing Program(19YF1458400)+1 种基金Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology(LMDBKF201803)is acknowledged.The CAS Pioneer Hundred Talents Program(No.2017-128)the starting up funding of Kunming Institute of Botany are greatly thanked.
文摘Comprehensive Summary Sepositoside A(1)is a prototypical cyclic steroid glycoside bearing a hybrid 16-membered ring composed of the steroid skeleton and a 1,2-trans-linked trisaccharide.Herein,we report an expedient access toward two simplified analogues,in which the strained 16-membered ring is constructed via Au(I)-catalyzed intramolecular addition of alcohol to epoxide.A similar macroetherification in relevant steroid trisaccharides has been intensively examined,however,failed to furnish the macrocyclic skeleton of Sepositoside A.
