共查询到20条相似文献,搜索用时 31 毫秒
1.
Dr. Yingle Mao Weijie Zhang Dr. Zunyun Fu Yanqiong Liu Lin Chen Xin Lian Dan Zhuo Prof. Jiewei Wu Prof. Mingyue Zheng Prof. Cangsong Liao 《Angewandte Chemie (International ed. in English)》2023,62(33):e202305250
C(sp3)−H oxyfunctionalization, the insertion of an O-atom into C(sp3)−H bonds, streamlines the synthesis of complex molecules from easily accessible precursors and represents one of the most challenging tasks in organic chemistry with regard to site and stereoselectivity. Biocatalytic C(sp3)−H oxyfunctionalization has the potential to overcome limitations inherent to small-molecule-mediated approaches by delivering catalyst-controlled selectivity. Through enzyme repurposing and activity profiling of natural variants, we have developed a subfamily of α-ketoglutarate-dependent iron dioxygenases that catalyze the site- and stereodivergent oxyfunctionalization of secondary and tertiary C(sp3)−H bonds, providing concise synthetic routes towards four types of 92 α- and β-hydroxy acids with high efficiency and selectivity. This method provides a biocatalytic approach for the production of valuable but synthetically challenging chiral hydroxy acid building blocks. 相似文献
2.
Nickel‐Catalyzed Insertion of Alkynes and Electron‐Deficient Olefins into Unactivated sp3 CH Bonds
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Arif Mahammad Earsad Avijit Hazra Prof. Debabrata Maiti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(32):11320-11324
Insertion of unsaturated systems such as alkynes and olefins into unactivated sp3 C?H bonds remains an unexplored problem. We herein address this issue by successfully incorporating a wide variety of functionalized alkynes and electron‐deficient olefins into the unactivated sp3 C?H bond of pivalic acid derivatives with excellent syn‐ and linear‐ selectivity. A strongly chelating 8‐aminoquinoline directing group proved beneficial for these insertion reactions, while an air‐stable and inexpensive NiII salt has been employed as the active catalyst. 相似文献
3.
A regioselective fluorocyclisation of β,γ-unsaturated oximes through I(I)/I(III) catalysis is disclosed to generate 5-fluoromethylated isoxazolines. The transformation leverages p-iodotoluene as an inexpensive catalyst, Selectfluor® as the terminal oxidant and an amine⋅HF complex (1 : 7.5) as both the fluoride and Brønsted acid source. The λ3-iodane p-TolIF2, which is generated in situ, engages the pendant alkene of the substrate to facilitate a cyclisation/fluorination sequence. A range of 5-fluoromethyl isoxazolines can be generated using this method, including aliphatic and aromatic systems (up to 56 % yield). Single crystal X-ray analysis of a representative example reveals a conformation that is consistent with the stereoelectronic gauche effect between the exocyclic C(sp3)−F bond and the C(sp3)−O of the isoxazoline (ϕOCCF=−62.0°). 相似文献
4.
Alessia Petti Matthew C. Leech Anthony D. Garcia Iain C. A. Goodall Adrian P. Dobbs Kevin Lam 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16261-16264
A new electrochemical methodology has been developed for the generation of oxycarbonyl radicals under mild and green conditions from readily available hemioxalate salts. Mono‐ and multi‐functionalised γ‐butyrolactones were synthesised through exo‐cyclisation of these oxycarbonyl radicals with an alkene, followed by the sp3–sp3 capture of the newly formed carbon‐centred radical. The synthesis of functionalised valerolactone derivatives was also achieved, demonstrating the versatility of the newly developed methodology. This represents a viable synthetic route towards pharmaceutically important fragments and further demonstrates the practicality of electrosynthesis as a green and economical method to activate small organic molecules. 相似文献
5.
Alessia Petti Matthew C. Leech Anthony D. Garcia Iain C. A. Goodall Adrian P. Dobbs Kevin Lam 《Angewandte Chemie (International ed. in English)》2019,58(45):16115-16118
A new electrochemical methodology has been developed for the generation of oxycarbonyl radicals under mild and green conditions from readily available hemioxalate salts. Mono‐ and multi‐functionalised γ‐butyrolactones were synthesised through exo‐cyclisation of these oxycarbonyl radicals with an alkene, followed by the sp3–sp3 capture of the newly formed carbon‐centred radical. The synthesis of functionalised valerolactone derivatives was also achieved, demonstrating the versatility of the newly developed methodology. This represents a viable synthetic route towards pharmaceutically important fragments and further demonstrates the practicality of electrosynthesis as a green and economical method to activate small organic molecules. 相似文献
6.
Modular Stereoselective Synthesis of (1→2)‐C‐Glycosides based on the sp2–sp3 Suzuki–Miyaura Reaction
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Beata Oroszova Jan Choutka Dr. Radek Pohl Dr. Kamil Parkan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7043-7047
This work reports a modular and rapid approach to the stereoselective synthesis of a variety of α‐ and β‐(1→2)‐linked C‐disaccharides. The key step is a Ni‐catalyzed cross‐coupling reaction of D ‐glucal pinacol boronate with alkyl halide glycoside easily prepared from commercially available D ‐glucal. The products of this sp2–sp3 cross‐coupling reaction can be converted to glucopyranosyl, mannopyranosyl, or 2‐deoxy‐glucopyranosyl C‐mannopyranosides by one‐ or two‐step stereoselective oxidative–reductive transformations. To the best of our knowledge, we demonstrated the first synthetic application of a challenging sp2–sp3 Suzuki‐Miyaura cross‐coupling reaction in carbohydrate chemistry. 相似文献
7.
Han Seul Park Dr. Zhoulong Fan Dr. Ru-Yi Zhu Prof. Dr. Jin-Quan Yu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12953-12959
Reported herein is the distal γ-C(sp3)−H olefination of ketone derivatives and free carboxylic acids. Fine tuning of a previously reported imino-acid directing group and using the ligand combination of a mono-N-protected amino acid (MPAA) and an electron-deficient 2-pyridone were critical for the γ-C(sp3)−H olefination of ketone substrates. In addition, MPAAs enabled the γ-C(sp3)−H olefination of free carboxylic acids to form diverse six-membered lactones. Besides alkyl carboxylic acids, benzylic C(sp3)−H bonds also could be functionalized to form 3,4-dihydroisocoumarin structures in a single step from 2-methyl benzoic acid derivatives. The utility of these protocols was demonstrated in large scale reactions and diversification of the γ-C(sp3)−H olefinated products. 相似文献
8.
Longkun Chen Mingshuai Zhang Zhuoyuan Liu Donghan Liu Yulin Sun Prof. Yongchao Wang Prof. Fuchao Yu 《European journal of organic chemistry》2023,26(32):e202300653
The divergent synthesis of dihydropyrimidouracil and pyrimidouracil derivatives from N-uracil amidines and tertiaryamines by an oxidative C(sp3)−N cleavage cascade cyclization reaction is first described. This transformation enables the formation of new C(sp3)−N and C(sp2)−N bonds via the selection of different oxidation conditions. The features of this method include tunable product selectivity, excellent chemoselectivity, readily available starting materials, broad substrate scope, good tolerance of functional groups, and moderate to high yields. 相似文献
9.
Zhiyang Yan Bin Sun Xun Zhang Xiaohui Zhuang Jin Yang Weike Su Can Jin 《化学:亚洲杂志》2019,14(19):3344-3349
A novel visible‐light‐driven decarboxylative coupling of alkyl N‐hydroxyphthalimide esters (NHP esters) with quinoxalin‐2(1H)‐ones has been developed. This C(sp2)?C(sp3) bond‐forming transformation exhibits excellent substrate generality with respect to both the coupling partners. Of note, a series of 3‐primary alkyl‐substituted quinoxalin‐2(1H)‐ones that were difficult to synthesize by previous methods could be obtained in moderate to excellent yields. Additionally, the mild conditions, easy availability of substrates, wide functional group tolerance and operational simplicity make this protocol practical in the synthesis of 3‐alkylated quinoxalin‐2(1H)‐ones. 相似文献
10.
Han Seul Park Zhoulong Fan Ru‐Yi Zhu Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2020,59(31):12853-12859
Reported herein is the distal γ‐C(sp3)?H olefination of ketone derivatives and free carboxylic acids. Fine tuning of a previously reported imino‐acid directing group and using the ligand combination of a mono‐N‐protected amino acid (MPAA) and an electron‐deficient 2‐pyridone were critical for the γ‐C(sp3)?H olefination of ketone substrates. In addition, MPAAs enabled the γ‐C(sp3)?H olefination of free carboxylic acids to form diverse six‐membered lactones. Besides alkyl carboxylic acids, benzylic C(sp3)?H bonds also could be functionalized to form 3,4‐dihydroisocoumarin structures in a single step from 2‐methyl benzoic acid derivatives. The utility of these protocols was demonstrated in large scale reactions and diversification of the γ‐C(sp3)?H olefinated products. 相似文献
11.
Dr. Yuxiang Zhu Matthew J. S. Smith Wenbin Tu Prof. John F. Bower 《Angewandte Chemie (International ed. in English)》2023,62(16):e202301262
TFA promoted deprotection of O−Ts activated N-Boc hydroxylamines triggers aminofunctionalization-based polycyclizations of tethered alkenes. The processes involve intramolecular stereospecific aza-Prilezhaev alkene aziridination in advance of stereospecific C−N cleavage by a pendant nucleophile. Using this approach, a wide range of fully intramolecular alkene anti-1,2-difunctionalizations can be achieved, including diaminations, amino-oxygenations and amino-arylations. Trends associated with the regioselectivity of the C−N cleavage step are outlined. The method provides a broad and predictable platform for accessing diverse C(sp3)-rich polyheterocycles of relevance to medicinal chemistry. 相似文献
12.
A metal-free one-pot two-step reductive coupling reaction of benzocyclonone, tosylhydrazide, and arylboronic acid was developed for the formation of a C(sp3)–C(sp2) bond, which enabled the efficient synthesis of 1-aryl-benzocycloalkane compounds in moderate to good yields on a multi-gram scale. Moreover, five- and six-membered benzocyclic ketones are also suitable substrates for this reaction. Notably, this protocol was also found to be suitable for synthesizing 3-(3,4-dichlorophenyl)-2,3-dihydro-1H-inden-1-one, an important intermediate in the synthesis of indatraline. 相似文献
13.
Kanako Nozawa-Kumada Satoshi Saga Yuta Matsuzawa Masahito Hayashi Masanori Shigeno Yoshinori Kondo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(20):4496-4499
β-Lactams are important structural motifs because of their ubiquity in natural products and pharmaceuticals. We report herein a Cu-catalyzed intramolecular oxidative C(sp3)−H amidation for the synthesis of β-lactams using tBuOOtBu. This method is based on Kharasch–Sosnovsky amidation and does not require prefunctionalization of C(sp3)−H bonds or the installation of a directing group, thereby allowing for the straightforward synthesis of β-lactams. Our intramolecular functionalization protocol can be extended to diverse benzylic C(sp3)−H bonds and shows excellent functional-group tolerance. 相似文献
14.
Yong Zhang Min Yang Chengli Jia Prof. Min Ji 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(60):13709-13713
A method for the synthesis of novel fused four-ring quinoxaline skeleton has been described by an I2 promoted sp3 C−H functionalization between 1,2,3,3-tetramethyl-3H-indolium iodides and 1,2-diamines. This transformation proceeds smoothly under metal- and peroxide-free conditions through a sequential iodination, oxidation, annulation and rearrangement. Moreover, 8,9-dichloro-5,12,12-trimethyl-2-(trifluoromethyl)-5,12-dihydroquinolino[2,3-b]quinoxaline showed good photophysical properties and was used in live cell imaging, indicating the potential value of this skeleton as a fluorophore in probes. 相似文献
15.
《Surface and interface analysis : SIA》2018,50(4):441-447
The influence of a post‐annealing treatment on the chemical structure of a diamondlike carbon (DLC) film was clarified by Raman spectroscopy. The DLC films were synthesized by ionized deposition. The structures were elucidated via Raman analysis in conjunction with the sp2 cluster model. The as‐prepared DLC film consisted of a dielectric matrix including sp3 carbon, where sp2 clusters were floating. When the post‐annealing treatment commenced, especially between 450 and 600°C, carbon─hydrogen bonds were cleaved, and the hydrogen atoms were desorbed from the film, creating defects or dangling bonds. The defects were reactive in growing sp2 clusters that were strained with numerous defects because of the restricted degrees of freedom in the solid. As the post‐annealing temperature further increased, the clusters became dominant and the strain was gradually dissolved. 相似文献
16.
Hua-Jie Jiang Xiu-Mei Zhong Zi-Ye Liu Rui-Long Geng Yang-Yang Li Prof. Dr. Yun-Dong Wu Prof. Dr. Xinhao Zhang Prof. Dr. Liu-Zhu Gong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12874-12878
A hybrid palladium catalyst assembled from a chiral phosphoric acid (CPA) and thioamide enables a highly efficient and enantioselective β-C(sp3)−H functionalization of thioamides (up to 99 % yield, 97 % ee). A kinetic resolution of unsymmetrical thioamides by intermolecular C(sp3)−H arylation can be achieved with high s-factors. Mechanistic investigations have revealed that stereocontrol is achieved by embedding the substrate in a robust chiral cavity defined by the bulky CPA and a neutral thioamide ligand. 相似文献
17.
A high‐efficient and stereo‐specific approach for the preparation of biologically important (E)‐2‐styryl‐tetrahydrobenzo[d]thiazoles has been developed via TMSCl promoted direct sp3 C‐H alkenylation of 2‐methyl‐5,6‐dihydrobenzo[d]thiazol‐7(4H)‐one under metal‐free conditions. Seventeen target compounds were synthesized in excellent yields of 82% –98% under the optimal conditions of 300 mol% TMSCl at 110°C for 2 h, and their chemical structures were elucidated by IR, NMR, ESI‐MS, elemental analyses and X‐ray crystallography analysis. A plausible mechanism was also proposed, and this method provided a good functional group conversion for the sp3 C‐H substrates. 相似文献
18.
Dr. Jørn Eivind Tungen Dr. Lisa Gerstmann Prof. Dr. Anders Vik Roberta De Matteis Dr. Romain Alexandre Colas Prof. Dr. Jesmond Dalli Prof. Dr. Nan Chiang Prof. Dr. Charles Nicholas Serhan Prof. Dr. Markus Kalesse Prof. Dr. Trond Vidar Hansen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(6):1476-1480
New drugs that can resolve inflammation without immunosuppressive effects are at the medicinal chemistry frontier. Pro-resolving endogenously formed small molecules, that is, the resolvins, are excellent candidates displaying such bioactions. The first total synthesis of the specialized pro-resolving mediator RvD1n−3 DPA has been achieved using the underutilized sp3–sp3 Negishi cross coupling reaction and an alkyne hydrosilylation–protodesilylation protocol. Biological evaluations revealed that this novel mediator displays low nanomolar pro-resolving properties and potently activates the human DRV1/GPR32 receptor. As such, this endogenous natural product is a lead compound for the development of novel immunoresolvents. 相似文献
19.
Hua‐Jie Jiang Xiu‐Mei Zhong Zi‐Ye Liu Rui‐Long Geng Yang‐Yang Li Yun‐Dong Wu Xinhao Zhang Liu‐Zhu Gong 《Angewandte Chemie (International ed. in English)》2020,59(31):12774-12778
A hybrid palladium catalyst assembled from a chiral phosphoric acid (CPA) and thioamide enables a highly efficient and enantioselective β‐C(sp3)?H functionalization of thioamides (up to 99 % yield, 97 % ee). A kinetic resolution of unsymmetrical thioamides by intermolecular C(sp3)?H arylation can be achieved with high s‐factors. Mechanistic investigations have revealed that stereocontrol is achieved by embedding the substrate in a robust chiral cavity defined by the bulky CPA and a neutral thioamide ligand. 相似文献
20.
By condensation of the chlorides of the three 9-oxo-fluorene-2-, -3-, and -4-carboxylic acids with 4-bromo-1,2-xylene on one side, and of the chlorides of o-bromobenzoic acid, 2-bromo-4-methyl-benzoic acid and 2-bromo-4,5-dimethyl-benzoic acid with fluorene, 2-methylfluorene and 3-methylfluorene on the other side, followed by direct or indirect cyclisation and by final reduction, several new methyl derivatives of the indenofluorenes I, II and IV are synthesized. 相似文献