A simple and efficient procedure for the synthesis of substituted benzothiazoles through condensation of 2-aminothiophenol with aromatic aldehydes in the presence of H2O2/HCl system in ethanol at room temperature is d...A simple and efficient procedure for the synthesis of substituted benzothiazoles through condensation of 2-aminothiophenol with aromatic aldehydes in the presence of H2O2/HCl system in ethanol at room temperature is described. The target compounds have been characterized by ^1H NMR, ^13C NMR, IR and MS. Short reaction time, easy and quick isolation of the products, and excellent yields are the main advantages of this procedure.展开更多
Asymmetric hydrogenation of tetrasubstituted alkenes is an important but challenging research topic.Herein,we report an efficient iridium-catalyzed asymmetric hydrogenation of tetrasubstituted α,β-unsaturated ketone...Asymmetric hydrogenation of tetrasubstituted alkenes is an important but challenging research topic.Herein,we report an efficient iridium-catalyzed asymmetric hydrogenation of tetrasubstituted α,β-unsaturated ketones for the synthesis of chiral 2-substituted cyclopentyl aryl ketones,an important chiral structural motif for the preparation of chiral pharmaceuticals and bioactive molecules.The reaction proceeded very well with good functional group compatibility and delivered the hydrogenated products in high yields and stereoselectivities(up to 99% yield,>20:1 dr and 99%ee).In addition,the reaction could be carried out on a gram-scale,and all four stereoisomers of the hydrogenated products bearing two contiguous stereocenters were obtained.Furthermore,the hydrogenated product can be transformed into the ERβ agonist Erteberel,and the reaction pathway was also studied via deuterium-labelling experiments.展开更多
An efficient synthesis of 2-substituted benzoxazoles through RuCl3·3H2O catalyzed, air oxidized tandem reactions of 2-aminophenols and aldehydes in [bmim]BF4 was developed. This synthetic strategy has such advant...An efficient synthesis of 2-substituted benzoxazoles through RuCl3·3H2O catalyzed, air oxidized tandem reactions of 2-aminophenols and aldehydes in [bmim]BF4 was developed. This synthetic strategy has such advantages as mild reaction conditions, cost-free oxidant, readily available starting materials, and recyclable catalyst and solvent. As an application, it was successfully used in the synthesis of the unreported 5-（benzoxazol-2-yl）-2＇-deoxyuridines with potential biological activities.展开更多
Ga（ClO4）3-catalyzed reaction of 1,2-aryldiamines and α-bromoketones to afford 2-substituted quinoxalines in good yields is described.The reaction proceeded via grinding process with 10%（molar fraction） catalyst u...Ga（ClO4）3-catalyzed reaction of 1,2-aryldiamines and α-bromoketones to afford 2-substituted quinoxalines in good yields is described.The reaction proceeded via grinding process with 10%（molar fraction） catalyst under solvent-free conditions at room temperature.For unsymmetrical o-phenylenediamines bearing electron-withdrawing groups,regio-selective quinoxalines were obtained.展开更多
Simple and efficient stereo-selective synthesis of exo-5-norbornene-2-carboxylic acid (NBCA) is reported. Preliminary studies on base promoted isomerization of methyl 5-norbornene-2-carboxylate (MNBC) revealed that ra...Simple and efficient stereo-selective synthesis of exo-5-norbornene-2-carboxylic acid (NBCA) is reported. Preliminary studies on base promoted isomerization of methyl 5-norbornene-2-carboxylate (MNBC) revealed that rapid isomerization was accomplished with sodium tert-butoxide (tBuONa), and the exo-content at the equilibrium was ca. 60%. The hydrolyses of endo-rich MNBC (endo/exo = 80/20) under various conditions were carried out. The exo selectivity for resulting NBCA was improved when the hydrolysis was conducted with equimolar water at room temperature in the presence of the stronger base (tBuONa) (endo/exo: 18/82). Whereas the use of excess amount of water led to rapid and non-selective hydrolysis affording high endo content of the product. The plausible reaction mechanism involving rapid equilibrium of thermodynamic isomerization and kinetically preferred hydrolysis of exo ester is proposed.展开更多
A novel and efficient approach to the synthesis of 2-substituted benzimidazoles has been developed via CuI/DMEDA-catalyzed coupling reaction and post-cyclization with glacial acetic acid from readily available 2-iodoa...A novel and efficient approach to the synthesis of 2-substituted benzimidazoles has been developed via CuI/DMEDA-catalyzed coupling reaction and post-cyclization with glacial acetic acid from readily available 2-iodoanilines and amides. This method is suitable for the construction of a variety of benzimidazoles in moderate to good yields under short reaction times.展开更多
cis-1,2-Disubstituted cyclododecanes 2 were synthesized by sodium borohydride reduction of 2-monosubstituted cyclododecanones and their structures were confirmed by 1HNMR, ^13C NMR and elemental analysis. The higher c...cis-1,2-Disubstituted cyclododecanes 2 were synthesized by sodium borohydride reduction of 2-monosubstituted cyclododecanones and their structures were confirmed by 1HNMR, ^13C NMR and elemental analysis. The higher cis-selectivity of NaBH4 reduction of 2- monosubstituted cyclododecanones was rationalized by the mode of ＂corner position carbonyl participation＂. Crystal data for 2c： Mr = 263.21, monoclinic, space group P21/c, a = 1.11140（7）, b = 2.62590（17）, c = 0.91360（6） nm, β= 106.1840（10）°, V = 2.5606（3） nm^3, Dc = 1.366 g/cm^3, Z = 8, F（000） = 1104, μ（MoKα= 3.182 mm^-1, S = 0.837, the final R = 0.0460 and wR = 0.1033. Crystal X-ray diffraction analysis for 2c showed that its ring skeleton adopts [3333] conformation, in which the OH group presents at the side-exo position and the other one at the corner carbon. The 1H NMR data of 2 showed that 1-corner-R-2-side-exo-OH [3333] and 1-corner-OH-2-side-exo-R [3333] conformations coexist in dynamic equilibrium in the solution, but only the former presents in the crystal.展开更多
基金Education Department of Zhejiang Province(No.20060811) for the financial support of this work.
文摘A simple and efficient procedure for the synthesis of substituted benzothiazoles through condensation of 2-aminothiophenol with aromatic aldehydes in the presence of H2O2/HCl system in ethanol at room temperature is described. The target compounds have been characterized by ^1H NMR, ^13C NMR, IR and MS. Short reaction time, easy and quick isolation of the products, and excellent yields are the main advantages of this procedure.
基金supported by the National Key R&D Program of China(No.2018YFE0126800)the National Natural Science Foundation of China(Nos.21991112 and 22001164)the Shanghai Pujiang Program(20PJ1406400).
文摘Asymmetric hydrogenation of tetrasubstituted alkenes is an important but challenging research topic.Herein,we report an efficient iridium-catalyzed asymmetric hydrogenation of tetrasubstituted α,β-unsaturated ketones for the synthesis of chiral 2-substituted cyclopentyl aryl ketones,an important chiral structural motif for the preparation of chiral pharmaceuticals and bioactive molecules.The reaction proceeded very well with good functional group compatibility and delivered the hydrogenated products in high yields and stereoselectivities(up to 99% yield,>20:1 dr and 99%ee).In addition,the reaction could be carried out on a gram-scale,and all four stereoisomers of the hydrogenated products bearing two contiguous stereocenters were obtained.Furthermore,the hydrogenated product can be transformed into the ERβ agonist Erteberel,and the reaction pathway was also studied via deuterium-labelling experiments.
基金Project supported by the National Natural Science Foundation of China （Nos. 20772025, 20972042）, Innovation Scientists and Technicians Troop Construction Projects of Henan Province （No. 104100510019）, and the Natural Science Foundation of Henan Province （No. 092300410237）.
文摘An efficient synthesis of 2-substituted benzoxazoles through RuCl3·3H2O catalyzed, air oxidized tandem reactions of 2-aminophenols and aldehydes in [bmim]BF4 was developed. This synthetic strategy has such advantages as mild reaction conditions, cost-free oxidant, readily available starting materials, and recyclable catalyst and solvent. As an application, it was successfully used in the synthesis of the unreported 5-（benzoxazol-2-yl）-2＇-deoxyuridines with potential biological activities.
基金Supported by the National Natural Science Foundation of China(Nos.20772088,21172163)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(No.JSSYSXK2010007)
文摘Ga（ClO4）3-catalyzed reaction of 1,2-aryldiamines and α-bromoketones to afford 2-substituted quinoxalines in good yields is described.The reaction proceeded via grinding process with 10%（molar fraction） catalyst under solvent-free conditions at room temperature.For unsymmetrical o-phenylenediamines bearing electron-withdrawing groups,regio-selective quinoxalines were obtained.
文摘Simple and efficient stereo-selective synthesis of exo-5-norbornene-2-carboxylic acid (NBCA) is reported. Preliminary studies on base promoted isomerization of methyl 5-norbornene-2-carboxylate (MNBC) revealed that rapid isomerization was accomplished with sodium tert-butoxide (tBuONa), and the exo-content at the equilibrium was ca. 60%. The hydrolyses of endo-rich MNBC (endo/exo = 80/20) under various conditions were carried out. The exo selectivity for resulting NBCA was improved when the hydrolysis was conducted with equimolar water at room temperature in the presence of the stronger base (tBuONa) (endo/exo: 18/82). Whereas the use of excess amount of water led to rapid and non-selective hydrolysis affording high endo content of the product. The plausible reaction mechanism involving rapid equilibrium of thermodynamic isomerization and kinetically preferred hydrolysis of exo ester is proposed.
基金Acknowledgement We are grateful for support of this project by the National Natural Science Foundation of China （No. J1103307） and the project of Science Foundation of Gansu Province （No. 1208RJZA266）.
文摘A novel and efficient approach to the synthesis of 2-substituted benzimidazoles has been developed via CuI/DMEDA-catalyzed coupling reaction and post-cyclization with glacial acetic acid from readily available 2-iodoanilines and amides. This method is suitable for the construction of a variety of benzimidazoles in moderate to good yields under short reaction times.
基金Presented in part at the Third National Symposium of the Chinese Chemical Society on Organic Chemistry, Lanzhou, China, August, 2004 (for abstract, see Chin. J. Org. Chem., 2004, Suppl. 365)This project was supported by the National Natural Science Foundation of China (No. 20072053)
文摘cis-1,2-Disubstituted cyclododecanes 2 were synthesized by sodium borohydride reduction of 2-monosubstituted cyclododecanones and their structures were confirmed by 1HNMR, ^13C NMR and elemental analysis. The higher cis-selectivity of NaBH4 reduction of 2- monosubstituted cyclododecanones was rationalized by the mode of ＂corner position carbonyl participation＂. Crystal data for 2c： Mr = 263.21, monoclinic, space group P21/c, a = 1.11140（7）, b = 2.62590（17）, c = 0.91360（6） nm, β= 106.1840（10）°, V = 2.5606（3） nm^3, Dc = 1.366 g/cm^3, Z = 8, F（000） = 1104, μ（MoKα= 3.182 mm^-1, S = 0.837, the final R = 0.0460 and wR = 0.1033. Crystal X-ray diffraction analysis for 2c showed that its ring skeleton adopts [3333] conformation, in which the OH group presents at the side-exo position and the other one at the corner carbon. The 1H NMR data of 2 showed that 1-corner-R-2-side-exo-OH [3333] and 1-corner-OH-2-side-exo-R [3333] conformations coexist in dynamic equilibrium in the solution, but only the former presents in the crystal.
