Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often pla-gued by the lack of alkene s...Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often pla-gued by the lack of alkene selectivity. In this work, the reaction system can be significantly improved through enhancing the performance of Lewis acid catalysts in the dehydration of activated alcohols by combining with a Lewis base. Observations of the reaction mechanism revealed that the Lewis base component might have changed the reaction rate order. Although both the principal and side reaction rates decreased, the effect was markedly more observed on the latter reaction. Therefore, the selectivity of the dehydration reaction was improved. On the basis of this observation, a new route to synthesize 2-cinnamyl-1,3-dicarbonyl compounds was developed by using 2-aryl-3,4- di-hydropyran as a starting substrate in the presence of a Lewis acid/Lewis base combined catalyst system.展开更多
Oxathioacetalyzation of carbonyl compounds with 2-mercaptoethanol and deprotection of the obtained 1,3-oxathiolanes is easily performed in the presence of silica sulfuric acid （SSA）. All reactions were performed und...Oxathioacetalyzation of carbonyl compounds with 2-mercaptoethanol and deprotection of the obtained 1,3-oxathiolanes is easily performed in the presence of silica sulfuric acid （SSA）. All reactions were performed under mild and completely heterogeneous reaction conditions in good to high yields.展开更多
A one-pot synthesis of Hantzsch pyridines was achieved through NH4I-promoted condensation of 1,3-dicarbonyl compounds with DMSO and NH4OAc, in which the C4 of the pyridine rings was derived from DMSO and the nitrogen ...A one-pot synthesis of Hantzsch pyridines was achieved through NH4I-promoted condensation of 1,3-dicarbonyl compounds with DMSO and NH4OAc, in which the C4 of the pyridine rings was derived from DMSO and the nitrogen atom resulted from NH4OAc and NH4I. The target product could be obtained in moderate to excellent yields.展开更多
The asymmetric α-amination of 1,3-dicarbonyl compounds with dialkyl azodicarboxylates has been achieved by C2-symmetric BINOL-squaramide bearing multiple hydrogen bond donors to provide the desired products in excell...The asymmetric α-amination of 1,3-dicarbonyl compounds with dialkyl azodicarboxylates has been achieved by C2-symmetric BINOL-squaramide bearing multiple hydrogen bond donors to provide the desired products in excellent yields and enantioselectivities （up to 99% yield and 98% ee）.展开更多
Silica-supported tin chloride and titanium tetrachloride were prepared by the reaction of tin chloride and titanium tetrachloride with activated silica gel in refluxing toluene.These solid acids have been employed as ...Silica-supported tin chloride and titanium tetrachloride were prepared by the reaction of tin chloride and titanium tetrachloride with activated silica gel in refluxing toluene.These solid acids have been employed as the catalysts for the synthesis of bisdihydropyrimidin -2(1H)-ones from aromatic dialdehydes,1,3-dicarbonyl compounds and urea at 90℃under solvent-free conditions.展开更多
基金supported by the National Natural Science Foundation of China (21173089 and 21373093)the Fundamental Research Funds for the Central Universities of China (2014ZZGH019)the Cooperative Innovation Center of Hubei Province
文摘Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often pla-gued by the lack of alkene selectivity. In this work, the reaction system can be significantly improved through enhancing the performance of Lewis acid catalysts in the dehydration of activated alcohols by combining with a Lewis base. Observations of the reaction mechanism revealed that the Lewis base component might have changed the reaction rate order. Although both the principal and side reaction rates decreased, the effect was markedly more observed on the latter reaction. Therefore, the selectivity of the dehydration reaction was improved. On the basis of this observation, a new route to synthesize 2-cinnamyl-1,3-dicarbonyl compounds was developed by using 2-aryl-3,4- di-hydropyran as a starting substrate in the presence of a Lewis acid/Lewis base combined catalyst system.
基金国家重点研发项目(2022YFA1503200,2021YFC2101901)国家自然科学基金(22122103,21971108,21971111,22271144)+1 种基金中央高校基本科研业务费(020514380304,020514380252 and 020514380272)江苏省研究生科研与实践创新计划项目(KYCX22_0100).
文摘Oxathioacetalyzation of carbonyl compounds with 2-mercaptoethanol and deprotection of the obtained 1,3-oxathiolanes is easily performed in the presence of silica sulfuric acid （SSA）. All reactions were performed under mild and completely heterogeneous reaction conditions in good to high yields.
基金We are grateful to the National Natural Science Foundation of China （Nos. 21572070 and 21172079）.
文摘A one-pot synthesis of Hantzsch pyridines was achieved through NH4I-promoted condensation of 1,3-dicarbonyl compounds with DMSO and NH4OAc, in which the C4 of the pyridine rings was derived from DMSO and the nitrogen atom resulted from NH4OAc and NH4I. The target product could be obtained in moderate to excellent yields.
基金the Fundamental Research Funds for the Central Universities (No.2042014kf0248) for support of this research
文摘The asymmetric α-amination of 1,3-dicarbonyl compounds with dialkyl azodicarboxylates has been achieved by C2-symmetric BINOL-squaramide bearing multiple hydrogen bond donors to provide the desired products in excellent yields and enantioselectivities （up to 99% yield and 98% ee）.
文摘Silica-supported tin chloride and titanium tetrachloride were prepared by the reaction of tin chloride and titanium tetrachloride with activated silica gel in refluxing toluene.These solid acids have been employed as the catalysts for the synthesis of bisdihydropyrimidin -2(1H)-ones from aromatic dialdehydes,1,3-dicarbonyl compounds and urea at 90℃under solvent-free conditions.
