Palladium-catalyzed non-directed C-H functionalization provides an efficient approach for direct functionalization of arenes, but it usually suffers from poor site selectivity, limiting its wide application.Herein, it...Palladium-catalyzed non-directed C-H functionalization provides an efficient approach for direct functionalization of arenes, but it usually suffers from poor site selectivity, limiting its wide application.Herein, it is reported for the first time that the carboxylic acid ligand of 3,5-dimethyladamantane-1-carboxylic acid(1-DMAd CO_(2)H) can affect the site selectivity during the C-H activation step in palladiumcatalyzed non-directed C-H functionalization, leading to highly para-selective C-H olefination of TIPSprotected phenols. This transformation displayed good generality in realizing various other para-selective C-H functionalization reactions such as halogenation, and allylation reactions. A wide variety of phenol derivatives including bioactive molecules of triclosan, thymol, and propofol, were compatible substrates,leading to the corresponding para-selective products in moderate to good yields. A preliminary mechanism study revealed that the spatial repulsion factor between carboxylic acid ligand and bulky protecting group resulted in the selective C-H activation at the less sterically hindered para-position. This new model non-directed para-selective C-H functionalization can provide a straightforward route for remote site-selective C-H activations.展开更多
A Ru(Ⅱ)-catalyzed para-difluoroalkylation of aro matic alde hydes and ketones with a tra nsient directing group has been developed.It utilizes less expensive ruthenium catalysts and allows facile access to challengin...A Ru(Ⅱ)-catalyzed para-difluoroalkylation of aro matic alde hydes and ketones with a tra nsient directing group has been developed.It utilizes less expensive ruthenium catalysts and allows facile access to challenging difluoroalkylated aldehydes.The mechanism studies suggest that the distinct coordination mode of ruthenium complex with imine moieties is responsible for para-selectivity.展开更多
Friedel-Crafts reaction and transition-metal catalysis represent primary methodologies for arene acylation;however,suffer from certain limitations,such as electronic effect-dependent reactivity,regioselectivity issues...Friedel-Crafts reaction and transition-metal catalysis represent primary methodologies for arene acylation;however,suffer from certain limitations,such as electronic effect-dependent reactivity,regioselectivity issues,the necessity of directing group,and relatively exceptionally limited exploration in meta-and para-acylations.N-heterocyclic carbene(NHC)catalysis has recently emerged as a promising alternative strategy for arene acylation,offering distinct regioselectivity profiles that are challenging to achieve through known methods.Herein,an NHC-mediated photo-catalytic para-selective C-H acylation of aryl alcohols is disclosed.The reaction employs a remote radical-induced temporary spiro cyclization strategy,proceeding via tandem radical dearomatization,radical acylation,rearomatization processes.Combined experimental and computational mechanistic studies support the proposed reaction pathway and observe an exclusive para-selectivity regardless of the nature of the substituents on the substrates.Despite the less satisfactory yields,the current method exhibits non-electronic nature-based reactivity and regioselectivity,enabling quick access to acylated arenes that are difficult or impossible for reported methods.展开更多
Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we ...Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution,the hydrothermal synthesis time,and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core–shell catalysts.The ZS core–shell catalysts were characterized by X-ray diffraction (XRD),N_2 adsorption,and NH_3 temperature-programmed desorption (NH_3-TPD) techniques.The highest PX selectivity of 95.5%was obtained for the ZS(Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2 TPAOH:1TEOS:250H_2O at 175°C and 10 r·min^(-1) for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.展开更多
Visible-light-mediated para-C-H difluoroalkylation of anilides via combination of steric effects and Lewis acid activation strategies has been developed. The addition of(C_6H_5O)_(2)P(O)OH and Ag_(2)CO_(3) properly tu...Visible-light-mediated para-C-H difluoroalkylation of anilides via combination of steric effects and Lewis acid activation strategies has been developed. The addition of(C_6H_5O)_(2)P(O)OH and Ag_(2)CO_(3) properly tune the redox potential of ruthenium catalyst and leads to mild reaction conditions. The protocol exhibits broad functional group tolerance and allows the late-stage functionalization of complex bioactive molecules.展开更多
基金supported by the National Natural Science Foundation of China(No.21772139)the Jiangsu Province Natural Science Found for Distinguished Young Scholars(No.BK20180041)+1 种基金the PAPD Projectsupported by the Open Research Fund of the School of Chemistry and Chemical Engineering,Henan Normal University。
文摘Palladium-catalyzed non-directed C-H functionalization provides an efficient approach for direct functionalization of arenes, but it usually suffers from poor site selectivity, limiting its wide application.Herein, it is reported for the first time that the carboxylic acid ligand of 3,5-dimethyladamantane-1-carboxylic acid(1-DMAd CO_(2)H) can affect the site selectivity during the C-H activation step in palladiumcatalyzed non-directed C-H functionalization, leading to highly para-selective C-H olefination of TIPSprotected phenols. This transformation displayed good generality in realizing various other para-selective C-H functionalization reactions such as halogenation, and allylation reactions. A wide variety of phenol derivatives including bioactive molecules of triclosan, thymol, and propofol, were compatible substrates,leading to the corresponding para-selective products in moderate to good yields. A preliminary mechanism study revealed that the spatial repulsion factor between carboxylic acid ligand and bulky protecting group resulted in the selective C-H activation at the less sterically hindered para-position. This new model non-directed para-selective C-H functionalization can provide a straightforward route for remote site-selective C-H activations.
基金support from the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(No.UNPYSCT-2017124)。
文摘A Ru(Ⅱ)-catalyzed para-difluoroalkylation of aro matic alde hydes and ketones with a tra nsient directing group has been developed.It utilizes less expensive ruthenium catalysts and allows facile access to challenging difluoroalkylated aldehydes.The mechanism studies suggest that the distinct coordination mode of ruthenium complex with imine moieties is responsible for para-selectivity.
基金supported by the National Natural Science Foundation of China(22371058,21961006,32172459,22371057,22071036)National Key Research and Development Program of China(2022YFD1700300)+9 种基金National Natural Science Fund for Excellent Young Scientists Fund Program(Overseas),starting grant of Guizhou University[(2023)29]Science and Technology Department of Guizhou Province(Qiankehejichu-ZK[2024]Key009,Qiankehejichu-ZK[2021]Key033)Program of Introducing Talents of Discipline to Universities of China(111 Program,D20023)at Guizhou UniversityFrontiers Science Center for Asymmetric Synthesis and Medicinal Molecules,Department of Education,Guizhou Province[Qianjiaohe KY(2020)004]Guizhou University(China),Central Government Guides Local Science and Technology Development Fund Projects[Qiankehezhongyindi(2024)007]Singapore National Research Foundation under its NRF Investigatorship(NRFNRFI2016-06,U23A20201)Competitive Research Program(NRFCRP22-2019-0002),Ministry of Education,Singapore,under its MOE AcRF Tier 1 Award(RG7/20,RG70/21),MOE AcRF Tier 2(MOE2019-T22-117),and MOE AcRF Tier 3 Award(MOE2018-T3-1-003),a Chair Professorship GrantNanyang Technological Universitythe funding support from the Chinese University of Hong Kong(CUHK)under the Vice-Chancellor Early Career Professorship Scheme Research Startup Fund(Project Code 4933634)Research Startup Matching Support(Project Code 5501779)。
文摘Friedel-Crafts reaction and transition-metal catalysis represent primary methodologies for arene acylation;however,suffer from certain limitations,such as electronic effect-dependent reactivity,regioselectivity issues,the necessity of directing group,and relatively exceptionally limited exploration in meta-and para-acylations.N-heterocyclic carbene(NHC)catalysis has recently emerged as a promising alternative strategy for arene acylation,offering distinct regioselectivity profiles that are challenging to achieve through known methods.Herein,an NHC-mediated photo-catalytic para-selective C-H acylation of aryl alcohols is disclosed.The reaction employs a remote radical-induced temporary spiro cyclization strategy,proceeding via tandem radical dearomatization,radical acylation,rearomatization processes.Combined experimental and computational mechanistic studies support the proposed reaction pathway and observe an exclusive para-selectivity regardless of the nature of the substituents on the substrates.Despite the less satisfactory yields,the current method exhibits non-electronic nature-based reactivity and regioselectivity,enabling quick access to acylated arenes that are difficult or impossible for reported methods.
基金Supported by the National Natural Science Foundation of China(21676238)
文摘Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution,the hydrothermal synthesis time,and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core–shell catalysts.The ZS core–shell catalysts were characterized by X-ray diffraction (XRD),N_2 adsorption,and NH_3 temperature-programmed desorption (NH_3-TPD) techniques.The highest PX selectivity of 95.5%was obtained for the ZS(Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2 TPAOH:1TEOS:250H_2O at 175°C and 10 r·min^(-1) for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.
基金support from the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(No.UNPYSCT-2017124)。
文摘Visible-light-mediated para-C-H difluoroalkylation of anilides via combination of steric effects and Lewis acid activation strategies has been developed. The addition of(C_6H_5O)_(2)P(O)OH and Ag_(2)CO_(3) properly tune the redox potential of ruthenium catalyst and leads to mild reaction conditions. The protocol exhibits broad functional group tolerance and allows the late-stage functionalization of complex bioactive molecules.
