共查询到20条相似文献,搜索用时 15 毫秒
1.
Sean R. Gitter Dr. Wei Pin Teh Dr. Xuejin Yang Alexander F. Dohoda Prof. Dr. Forrest E. Michael Prof. Dr. Andrew J. Boydston 《Angewandte Chemie (International ed. in English)》2023,62(23):e202303174
Post-polymerization modification (PPM) via direct C−H functionalization is a powerful synthetic strategy to convert polymer feed-stocks into value-added products. We found that a metal-free, Se-catalyzed allylic C−H amination provided an efficient method for PPM of polynorbornenes (PNBs) produced via ring-opening metathesis polymerization. Inherent to the mechanism of the allylic amination, PPM on PNBs preserved the alkene functional groups along the polymer backbone, while also avoiding transposition of the double bonds. Amination using a series of aryl sulfonamides led to good control over the degree of functionalization, access to a range of functionalities, and tunable thermal properties from the resulting polymers. 相似文献
2.
Zhong-Sheng Nong Xin-Ran Chen Prof. Pu-Sheng Wang Prof. Xin Hong Prof. Liu-Zhu Gong 《Angewandte Chemie (International ed. in English)》2023,62(46):e202312547
Enantioconvergent catalysis enables the conversion of racemic molecules into a single enantiomer in perfect yield and is considered an ideal approach for asymmetric synthesis. Despite remarkable advances in this field, enantioconvergent transformations of inert tertiary C−H bonds remain largely unexplored due to the high bond dissociation energy and the surrounding steric repulsion that pose unparalleled constraints on bond cleavage and formation. Here, we report an enantioconvergent Pd-catalyzed alkylation of racemic tertiary allylic C−H bonds of α-alkenes, providing a unique approach to access a broad range of enantioenriched γ,δ-unsaturated carbonyl compounds featuring quaternary carbon stereocenters. Mechanistic studies reveal that a stereoablative event occurs through the rate-limiting cleavage of tertiary allylic C−H bonds to generate σ-allyl-Pd species, and the achieved E/Z-selectivity of σ-allyl-Pd species effectively regulates the diastereoselectivity via a nucleophile coordination-enabled SN2′-allylation pathway. 相似文献
3.
ZW Jiao SY Zhang C He YQ Tu SH Wang FM Zhang YQ Zhang H Li 《Angewandte Chemie (International ed. in English)》2012,51(35):8811-8815
Spiro compounds: An organocatalytic asymmetric method for the C?sp?3?H functionalization of the α?position of racemic cyclic ethers has been developed. The transformation, mediated by catalytic amounts of an imidazolidinone and strong acid, involves a tandem 1,5-hydride transfer/cyclization and provides access to a structurally diverse series of chiral spiroethers with high levels of enantioselectivity. 相似文献
4.
Remote C-H bond functionalization of arenes with precise control is a recognized extraordinary challenge in organic synthesis. Recently, Yu and Houk et al. developed an elegant strategy to distinguish and functionalize remote Csp2-H bonds of (hetero)arenes within one-bond distance by the interplay of a remote directing template and a transient norbornene-type mediator. A wide range of medicinally important benzoazines are well compatible with this method. The chemistry significantly expands the toolbox for site-selective functionalization of remote Csp2-H bond of (hetero)arenes. This work has been published in Nature Chemistry in March, 2020. 相似文献
5.
Dr. Jin Xie Dr. Matthias Rudolph Dr. Frank Rominger Prof. Dr. A. Stephen K. Hashmi 《Angewandte Chemie (International ed. in English)》2017,56(25):7266-7270
A controllable mono- and di-multifluoroarylation of acyclic and cyclic N-aryl amines with aryl fluorides by photocatalyzed dual C(sp3)−H/C(sp2)−F functionalization has been developed, providing new access to a wide array of valuable α-fluoroarylated amines. In addition, the one-pot consecutive hetero-di-multifluoroarylation of N-aryl pyrrolidines and N,N-dimethylanilines was achieved with high to excellent diastereoselectivity. This new defluorinative C(sp3)−C(sp2) coupling is distinguished by a broad scope, good regioselectivity, and mild conditions as well as gram-scale and late-stage applicability, and thus constitutes a significant advance in the arylation of unactivated C(sp3)−H bonds with aryl fluorides. 相似文献
6.
Lvqi Jiang Jinlong Qian Wenbin Yi Guoping Lu Chun Cai Wei Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(49):15178-15182
A new method for CF3SO2Na‐based direct trifluoromethylthiolation of C(sp2) H bonds has been developed. CF3SSCF3 is generated in situ from cheap and easy‐to‐handle CF3SO2Na, and in the presence of CuCl can be used for electrophilic trifluoromethylthiolation of indoles, pyrroles, and enamines. The method has been extended to perfluoroalkylthiolation reactions using RfSO2Na. 相似文献
7.
Dr. Kristína Plevová Dr. Péter Kisszékelyi Dr. Denisa Vargová Samuel Andrejčák Viktor Tóth Lukáš Fertáľ Dr. Erik Rakovský Dr. Juraj Filo Prof. Dr. Radovan Šebesta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(62):15501-15507
Diastereoselective double C−H heteroarylation of chiral ferrocenes provides valuable compounds with multiple functionalities using mild reaction conditions and simple reagents. Pd-Complexes with chiral mono-protected amino acids afforded corresponding heteroarylated ferrocenyl amines in good yields and high diastereomeric purities. In this way, a variety of indole, thiophene, pyrrole, or furan substituents were introduced to the ferrocene moiety. Furthermore, a range of relevant functional groups, for example ketone, ester, chloro, nitro, or silyl, are tolerated by this method. An alternative combination of amino acid and ferrocenyl amine configurations was leveraged to provide the complementary diastereomeric products. The products of C−H heteroarylation can be transformed into corresponding phosphines. Absolute configurations of CH-activation products were confirmed by the combination of X-ray crystallographic analysis and CD spectroscopy. 19F NMR kinetic study and DFT calculations provided insights into the reaction mechanism and reasons governing stereoinduction. 相似文献
8.
Jiani Ye Dongsheng Zhang Sofia Salli Yajiao Li Feiyu Han Yuanqiang Mai Prof. Dr. Federico Rosei Prof. Dr. Yongwang Li Prof. Dr. Yong Yang Prof. Dr. Flemming Besenbacher Prof. Dr. Hans Niemantsverdriet Dr. Emma Richards Prof. Dr. Ren Su 《Angewandte Chemie (International ed. in English)》2023,62(23):e202302994
Environmental-friendly halogenation of C−H bonds using abundant, non-toxic halogen salts is in high demand in various chemical industries, yet the efficiency and selectivity of laboratory available protocols are far behind the conventional photolytic halogenation process which uses hazardous halogen sources. Here we report an FeX2 (X=Br, Cl) coupled semiconductor system for efficient, selective, and continuous photocatalytic halogenation using NaX as halogen source under mild conditions. Herein, FeX2 catalyzes the reduction of molecular oxygen and the consumption of generated oxygen radicals, thus boosting the generation of halogen radicals and elemental halogen for direct halogenation and indirect halogenation via the formation of FeX3. Recycling of FeX2 and FeX3 during the photocatalytic process enables the halogenation of a wide range of hydrocarbons in a continuous flow, rendering it a promising method for applications. 相似文献
9.
Yan Gao Rui Xiao Shangbiao Zhang Dr. Yanan Wang Dr. Zheliang Yuan 《European journal of organic chemistry》2023,26(38):e202300668
Due to their high lipophilicity and strong electron-withdrawing property, more and more attention has been paid to introducing trifluoromethylseleno and fluoroalkylseleno moieties into organic molecules. In this short review, we categorize the synthesis of compounds that combine selenium and fluorinated moieties into two main types: trifluoromethylselenolation (CF3Se) and fluoroalkylselenolation (RfSe, except CF3Se). This review aims to provide a summary of the recent advances in direct C−H trifluoromethylselenolation and fluoroalkylselenolation from the synthesis of trifluoromethylselenolation and fluoroalkylselenolation reagents to their application. Based on the method of how the RfSe group was introduced, the main content is divided into three parts: transition-metal-free reactions, transition-metal-mediated/catalyzed reactions and photo-catalyzed reactions. The general substrate scope, mechanism and limitations would also be discussed so that we hope the review will serve as an inspiration for further research in this appealing research field. 相似文献
10.
Dr. Qinhua Zhang Dr. Bo An Dr. Yu Lei Zhixiao Gao Dr. Haonan Zhang Prof. Sheng Xue Prof. Xin Jin Prof. Wengang Xu Zihan Wu Prof. Mingbo Wu Prof. Xin Yang Prof. Wenting Wu 《Angewandte Chemie (International ed. in English)》2023,62(36):e202304699
Developing new reactive pathway to activate inert C(sp3)−H bonds for valuable oxygenated products remains a challenge. We prepared a series of triazine conjugated organic polymers to photoactivate C−H into aldehyde/ketone via O2→H2O2→⋅OH→Cl⋅→Cl2⋅−. Experiment results showed Cl2⋅− could successively activate C(sp3)−H more effectively than Cl⋅ to generate unstable dichlorinated intermediates, increasing the kinetic rate ratio of dichlorination to monochlorination by a factor of 2,000 and thus breaking traditional dichlorination kinetic constraints. These active intermediates were hydrolyzed into aldehydes or ketones easily, when compared with typical stable dichlorinated complexes, avoiding chlorinated by-product generation. Moreover, an integrated two-phase system in an acid solution strengthened the Cl2⋅− mediated process and inhibited product overoxidation, where the conversion rate of toluene reached 16.94 mmol/g/h and the selectivity of benzaldehyde was 99.5 %. This work presents a facile and efficient approach for selective conversion of inert C(sp3)−H bonds using Cl2⋅−. 相似文献
11.
Rui Liu Meng-Lan Shen Lian-Feng Fan Xiao-Le Zhou Pu-Sheng Wang Liu-Zhu Gong 《Angewandte Chemie (International ed. in English)》2023,62(4):e202211631
Allylamines are important building blocks in the synthesis of bioactive compounds. The direct coupling of allylic C−H bonds and commonly available amines is a major synthetic challenge. An allylic C−H amination of 1,4-dienes has been accomplished by palladium catalysis. With aromatic amines, branch-selective allylic aminations are favored to generate thermodynamically unstable Z-allylamines. In addition, more basic aliphatic cyclic amines can also engage in the reaction, but linear dienyl allylic amines are the major products. 相似文献
12.
Xiao-Li Lai Xiao-Min Shu Dr. Jinshuai Song Prof. Dr. Hai-Chao Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(26):10713-10719
Decarboxylative C−H functionalization reactions are highly attractive methods for forging carbon–carbon bonds considering their inherent step- and atom-economical features and the pervasiveness of carboxylic acids and C−H bonds. An ideal approach to achieve these dehydrogenative transformations is through hydrogen evolution without using any chemical oxidants. However, effective couplings by decarboxylative carbon–carbon bond formation with proton reduction remain an unsolved challenge. Herein, we report an electrophotocatalytic approach that merges organic electrochemistry with photocatalysis to achieve the efficient direct decarboxylative C−H alkylation and carbamoylation of heteroaromatic compounds through hydrogen evolution. This electrophotocatalytic method, which combines the high efficiency and selectivity of photocatalysis in promoting decarboxylation with the superiority of electrochemistry in effecting proton reduction, enables the efficient coupling of a wide range of heteroaromatic bases with a variety of carboxylic acids and oxamic acids. Advantageously, this method is scalable to decagram amounts, and applicable to the late-stage functionalization of drug molecules. 相似文献
13.
Fen Su Dr. Juan Zou Xiaokang Lv Fengfei Lu Yijie Long Kun Tang Benpeng Li Prof. Dr. Huifang Chai Prof. Xingxing Wu Prof. Dr. Yonggui Robin Chi 《Angewandte Chemie (International ed. in English)》2023,62(23):e202303388
The development of catalyst-controlled methods for direct functionalization of two distinct C−H bonds represents an appealing approach for C−C formations in synthetic chemistry. Herein, we describe an organocatalytic approach for straightforward acylation of C(sp3)−H bonds employing readily available aldehyde as “acyl source” involving dehydrogenative coupling of aldehydes with ether, amine, or benzylic C(sp3)−H bonds. The developed method affords a broad range of ketones under mild conditions. Mechanistically, simple ortho-cyanoiodobenzene is essential in the oxidative radical N-heterocyclic carbene catalysis to give a ketyl radical and C(sp3) radical through a rarely explored intermolecular hydrogen atom transfer pathway, rendering the acylative C−C formations in high efficiency under a metal- and light-free catalytic conditions. Moreover, the prepared products show promising anti-bacterial activities that shall encourage further investigations on novel agrochemical development. 相似文献
14.
Zhiwei Zhao Yin Liu Siyi Wang Shunyao Tang Dengke Ma Zile Zhu Chengcheng Guo Prof. Dr. Youai Qiu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202214710
Herein, a direct, metal-free, and site-selective electrochemical C−H carboxylation of arenes by reductive activation using CO2 as the economic and abundant carboxylic source was reported. The electrocarboxylation was carried out in an operationally simple manner with high chemo- and regioselectivity, setting the stage for the challenging site-selective C−H carboxylation of unactivated (hetero)arenes. The robust nature of the electrochemical strategy was reflected by a broad scope of substrates with excellent atom economy and unique selectivity. Notably, the direct and selective C−H carboxylation of various challenging arenes worked well in this approach, including electron-deficient naphthalenes, pyridines, simple phenyl derivatives, and substituted quinolines. The method benefits from being externally catalyst-free, metal-free and base-free, which makes it extremely attractive for potential applications. 相似文献
15.
Jianyi Shi Xia Chen Jingyun Huang Yantong Lu Zhendong Yang Mingli Zhong Dr. Zhongzhi Zhu Dr. Xiuwen Chen 《European journal of organic chemistry》2023,26(3):e202201231
The efficient three-component cascade coupling reaction of 3-haloisoquinolines, haloalkanes, and sp3-carbon nucleophiles (acetophenone or nitromethane) led to a series of structurally novel 1,2-disubstituted-3-isoquinolinones through the formation of C(sp3)−C(sp2), C−N, and C=O bonds. The NaOAc-promoted reaction described in this work is simple to operate, environment friendly, and highly selective. 相似文献
16.
Baptiste Neil Lamine Saadi Prof. Dr. Louis Fensterbank Dr. Clément Chauvier 《Angewandte Chemie (International ed. in English)》2023,62(31):e202306115
Benzylsilanes have found increasing applications in organic synthesis as bench-stable synthetic intermediates, yet are mostly produced by stoichiometric procedures. Catalytic alternatives based on the atom-economical silylation of benzylic C(sp3)−H bonds remain scarcely available as specialized directing groups and catalytic systems are needed to outcompete the kinetically-favored silylation of C(sp2)−H bonds. Herein, we describe the first general and catalytic-in-metal undirected silylation of benzylic C(sp3)−H bonds under ambient, transition metal-free conditions using stable tert-butyl-substituted silyldiazenes (tBu−N=N−SiR3) as silicon source. The high activity and selectivity of the catalytic system, exemplified by the preparation of various mono- or gem-bis benzyl(di)silanes, originates from the facile generation of organopotassium reagents, including tert-butylpotassium. 相似文献
17.
Yong Yang Shaopeng Liu Shuang Li Dr. Zhaohong Liu Dr. Peiqiu Liao Paramasivam Sivaguru Ying Lu Jiaojiao Gao Prof. Xihe Bi 《Angewandte Chemie (International ed. in English)》2023,62(4):e202214519
The construction of allylic quaternary sp3-carbon centers has long been a formidable challenge in transition-metal-catalyzed alkyl-allyl coupling reactions due to the severe steric hindrance. Herein, we report an effective carbene strategy that employs well-defined vinyl-N-triftosylhydrazones as a versatile allylating reagent to enable direct assembly of these medicinally desirable structural elements from low-cost alkane feedstocks. The reaction exhibited excellent site selectivity for tertiary C−H bonds, broad scope (>60 examples and >20 : 1:0 r. r.) and good efficiency, even on a gram-scale, making it a convenient alternative to the well-known Trost–Tsuji allylation reaction for the formation of alkyl–allyl bonds. Combined experimental and computational studies were employed to unravel the mechanism and origin of site- and chemoselectivity of the reaction. 相似文献
18.
In this study, we present a straightforward and environmentally friendly electrochemical approach for achieving selective halogenation of N-heteroarenes, including indoles, diazoles, pyrroles, quinolinone, and naphthols. Our method utilizes commercially available and affordable ammonium halides as halogen source. A library of valuable halogenated N-heteroarenes can be synthesized in moderate to excellent yields under mild conditions (transition-metal-free, oxidant-free, ethanol as solvent, atmospheric environment). The approach demonstrates a broad substrate scope, excellent tolerance towards various functional groups, and scalability. 相似文献
19.
Dr. Nikolaos Kaplaneris Alejandro Puet Felix Kallert Julia Pöhlmann Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2023,62(9):e202216661
Bioorthogonal late-stage diversification of structurally complex peptides bears enormous potential for drug discovery and molecular imaging, among other applications. Herein, we report on a palladium-catalyzed C−H arylation of tryptophan-containing peptides with readily accessible and modular arylthianthrenium salts. Under exceedingly mild reaction conditions, the late-stage diversification of structurally complex peptides was accomplished. The tunability and ease of preparation of arylthianthrenium salts allowed the expedient stitching of tryptophan-containing peptides with drug, natural product, and peptidic scaffolds by forging sterically congested biaryl linkages. The robustness of the palladium catalysis regime was reflected by the full tolerance of a plethora of sensitive and coordinating functional groups. Hence, our manifold enabled efficient access to highly decorated, labelled, conjugated, and ligated linear and cyclic peptides. 相似文献
20.
Dr. Liu Ye Yu Tian Xiang Meng Dr. Qiang-Shuai Gu Prof. Dr. Xin-Yuan Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(3):1145-1149
Radical-involved enantioselective oxidative C−H bond functionalization by a hydrogen-atom transfer (HAT) process has emerged as a promising method for accessing functionally diverse enantioenriched products, while asymmetric C(sp3)−H bond amination remains a formidable challenge. To address this problem, described herein is a dual CuI/chiral phosphoric acid (CPA) catalytic system for radical-involved enantioselective intramolecular C(sp3)−H amination of not only allylic positions but also benzylic positions with broad substrate scope. The use of 4-methoxy-NHPI (NHPI=N-hydroxyphthalimide) as a stable and chemoselective HAT mediator precursor is crucial for the fulfillment of this transformation. Preliminary mechanistic studies indicate that a crucial allylic or benzylic radical intermediate resulting from a HAT process is involved. 相似文献