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1.
Jian He Toshihiko Shigenari Jin‐Quan Yu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(22):6645-6649
An intermolecular C(sp3) H amination using a Pd0/PAr3 catalyst was developed. The reaction begins with oxidative addition of R2N OBz to a Pd0/PAr3 catalyst and subsequent cleavage of a C(sp3) H bond by the generated Pd NR2 intermediate. The catalytic cycle proceeds without the need for external oxidants in a similar manner to the extensively studied palladium(0)‐catalyzed C H arylation reactions. The electron‐deficient triarylphosphine ligand is crucial for this C(sp3) H amination reaction to occur. 相似文献
2.
Prof. Dr. Daniel Solé Francesco Mariani Prof. Dr. M.‐Lluïsa Bennasar Dr. Israel Fernández 《Angewandte Chemie (International ed. in English)》2016,55(22):6467-6470
A palladium‐catalyzed carbene insertion into C(sp3)?H bonds leading to pyrrolidines was developed. The coupling reaction can be catalyzed by both Pd0 and PdII, is regioselective, and shows a broad functional group tolerance. This reaction is the first example of palladium‐catalyzed C(sp3)?C(sp3) bond assembly starting from diazocarbonyl compounds. DFT calculations revealed that this direct C(sp3)?H bond functionalization reaction involves an unprecedented concerted metalation–deprotonation step. 相似文献
3.
Quan Gou Gang Liu Zi‐Ning Liu Prof. Dr. Jun Qin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(44):15491-15495
PdII‐catalyzed intermolecular amination of unactivated C(sp3)?H bonds has been successfully developed for the first time. This method provides a new way to achieve the challenging intermolecular amination of unactivated C(sp3)?H bonds, producing a variety of unnatural β2‐amino carboxylic acid analogues. This C(sp3)?H amination protocol is demonstrated with a broad substrate scope, good functional‐group tolerance, and chemoselectivity. It is operated without use of phosphine ligand or external oxidant. 相似文献
4.
Julia Pedroni Michele Boghi Dr. Tanguy Saget Prof. Dr. Nicolai Cramer 《Angewandte Chemie (International ed. in English)》2014,53(34):9064-9067
β‐Lactams are very important structural motifs because of their broad biological activities as well as their propensity to engage in ring‐opening reactions. Transition‐metal‐catalyzed C? H functionalizations have emerged as strategy enabling yet uncommon highly efficient disconnections. In contrast to the significant progress of Pd0‐catalyzed C? H functionalization for aryl–aryl couplings, related reactions involving the formation of saturated C(sp3)? C(sp3) bonds are elusive. Reported here is an asymmetric C? H functionalization approach to β‐lactams using readily accessible chloroacetamide substrates. Important aspects of this transformation are challenging C(sp3)? C(sp3) and strain‐building reductive eliminations to for the four‐membered ring. In general, the β‐lactams are formed in excellent yields and enantioselectivities using a bulky taddol phosphoramidite ligand in combination with adamantyl carboxylic acid as cocatalyst. 相似文献
5.
N‐Heterocyclic Carbene Ligand‐Enabled C(sp3)−H Arylation of Piperidine and Tetrahydropyran Derivatives
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Dr. Shengqing Ye Dr. Weibo Yang Timothy Coon Dewey Fanning Tim Neubert Dean Stamos Prof. Dr. Jin‐Quan Yu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4748-4752
PdII‐catalyzed C(sp3)?H arylation of saturated heterocycles with a wide range of aryl iodides is enabled by an N‐heterocyclic carbene (NHC) ligand. A C(sp3)?H insertion step by the PdII/NHC complex in the absence of ArI is demonstrated experimentally for the first time. Experimental data suggests that the previously established NHC‐mediated Pd0/PdII catalytic manifold does not operate in this reaction. This transformation provides a new approach for diversifying pharmaceutically relevant piperidine and tetrahydropyran ring systems. 相似文献
6.
Intermolecular Amination of Unactivated C(sp3)−H Bonds with Cyclic Alkylamines: Formation of C(sp3)−N Bonds through Copper/Oxygen‐Mediated C(sp3)−H/N−H Activation
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Quan Gou Yu‐Wen Yang Zi‐Ning Liu Prof. Jun Qin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16057-16061
The first example of intermolecular amination of unactivated C(sp3)?H bonds by cyclic alkylamines mediated by Cu(OAc)2/O2 is reported. This method avoids the use of benzoyloxyamines as the aminating reagent, which are normally prepared from alkylamines in extra steps. A variety of unnatural β2, 2‐amino acid analogues are synthesized by this simple and efficient procedure. This approach offers a solution to the previous unmet challenge of C(sp3)?H/N?H activation for the formation of C(sp3)?N bonds. 相似文献
7.
Fei Wang Shannon S. Stahl 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6451-6456
Direct amination of C(sp3)?H bonds is of broad interest in the realm of C?H functionalization because of the prevalence of nitrogen heterocycles and amines in pharmaceuticals and natural products. Reported here is a combined electrochemical/photochemical method for dehydrogenative C(sp3)?H/N?H coupling that exhibits good reactivity with both sp2 and sp3 N?H bonds. The results show how use of iodide as an electrochemical mediator, in combination with light‐induced cleavage of intermediate N?I bonds, enables the electrochemical process to proceed at low electrode potentials. This approach significantly improves the functional‐group compatibility of electrochemical C?H amination, for example, tolerating electron‐rich aromatic groups that undergo deleterious side reactions in the presence of high electrode potentials. 相似文献
8.
Easily Accessible Auxiliary for Palladium‐Catalyzed Intramolecular Amination of C(sp2)H and C(sp3)H Bonds at δ‐ and ε‐Positions
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Chao Wang Changpeng Chen Jingyu Zhang Jian Han Qian Wang Kun Guo Pei Liu Mingyu Guan Dr. Yingming Yao Prof. Dr. Yingsheng Zhao 《Angewandte Chemie (International ed. in English)》2014,53(37):9884-9888
An easily synthesized and accessible N,O‐bidentate auxiliary has been developed for selective C? H activation under palladium catalysis. The novel auxiliary showed its first powerful application in C? H functionalization of remote positions. Both C(sp2)? H and C(sp3)? H bonds at δ‐ and ε‐positions were effectively activated, thus giving tetrahydroquinolines, benzomorpholines, pyrrolidines, and indolines in moderate to excellent yields by palladium‐catalyzed intramolecular C? H amination. 相似文献
9.
Practical Synthesis of anti‐β‐Hydroxy‐α‐Amino Acids by PdII‐Catalyzed Sequential C(sp3)H Functionalization
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Kai Chen Shuo‐Qing Zhang Huai‐Zhi Jiang Jing‐Wen Xu Prof. Dr. Bing‐Feng Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3264-3270
An improved and practical procedure for the stereoselective synthesis of anti‐β‐hydroxy‐α‐amino acids (anti‐βhAAs), by palladium‐catalyzed sequential C(sp3)?H functionalization directed by 8‐aminoquinoline auxiliary, is described. followed by a previously established monoarylation and/or alkylation of the β‐methyl C(sp3)?H of alanine derivative, β‐acetoxylation of both alkylic and benzylic methylene C(sp3)?H bonds affords various anti‐β‐hydroxy‐α‐amino acid derivatives. As an example, the synthesis of β‐mercapto‐α‐amino acids, which are highly important to the extension of native chemical ligation chemistry beyond cysteine, is described. The synthetic potential of this protocol is further demonstrated by the synthesis of diverse β‐branched α‐amino acids. The observed diastereoselectivities are strongly influenced by electronic effects of aromatic AAs and steric effects of the linear side‐chain AAs, which could be explained by the competition of intramolecular C?OAc bond reductive elimination from PdIV intermediates vs. intermolecular attack by an external nucleophile (AcO?) in an SN2‐type process. 相似文献
10.
Zijun Zhou Shuming Chen Jie Qin Xin Nie Xingwen Zheng Klaus Harms Radostan Riedel K. N. Houk Eric Meggers 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(4):1100-1105
An enantioselective ring‐closing C(sp3)?H amination of 2‐azidoacetamides is catalyzed by a chiral‐at‐metal ruthenium complex and provides chiral imidazolidin‐4‐ones in 31–95 % yield, with enantioselectivities of up to 95 % ee, and at catalyst loadings down to 0.1 mol % (turnover number (TON)=740). To our knowledge, this is the first example of a highly enantioselective C(sp3)?H amination with aliphatic azides. Mechanistic experiments reveal the importance of the amide group, which presumably enables initial bidentate coordination of the 2‐azidoacetamides to the catalyst. DFT calculations show that the transition state leading to the major enantiomer features a better steric fit and favorable π–π stacking between the substrate and the catalyst framework. 相似文献
11.
Anthranil: An Aminating Reagent Leading to Bifunctionality for Both C(sp3)−H and C(sp2)−H under Rhodium(III) Catalysis
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Dr. Songjie Yu Guodong Tang Yingzi Li Xukai Zhou Prof. Yu Lan Prof. Xingwei Li 《Angewandte Chemie (International ed. in English)》2016,55(30):8696-8700
Previous direct C?H nitrogenation suffered from simple amidation/amination with limited atom‐economy and is mostly limited to C(sp2)?H substrates. In this work, anthranil was designed as a novel bifunctional aminating reagent for both C(sp2)?H and C(sp3)?H bonds under rhodium(III) catalysis, thus affording a nucleophilic aniline tethered to an electrophilic carbonyl. A tridendate rhodium(III) complex has been isolated as the resting state of the catalyst, and DFT studies established the intermediacy of a nitrene species. 相似文献
12.
Chemoselective Amination of Propargylic C(sp3)H Bonds by Cobalt(II)‐Based Metalloradical Catalysis
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Prof. Dr. Hongjian Lu Dr. Chaoqun Li Dr. Huiling Jiang Christopher L. Lizardi Prof. Dr. X. Peter Zhang 《Angewandte Chemie (International ed. in English)》2014,53(27):7028-7032
Highly chemoselective intramolecular amination of propargylic C(sp3)? H bonds has been demonstrated for N‐bishomopropargylic sulfamoyl azides through cobalt(II)‐based metalloradical catalysis. Supported by D2h‐symmetric amidoporphyrin ligand 3,5‐DitBu‐IbuPhyrin, the cobalt(II)‐catalyzed C? H amination proceeds effectively under neutral and nonoxidative conditions without the need of any additives, and generates N2 as the only byproduct. The metalloradical amination is suitable for both secondary and tertiary propargylic C? H substrates with an unusually high degree of functional‐group tolerance, thus providing a direct method for high‐yielding synthesis of functionalized propargylamine derivatives. 相似文献
13.
Ethan A. Wappes Stacy C. Fosu Trevor C. Chopko Prof. Dr. David A. Nagib 《Angewandte Chemie (International ed. in English)》2016,55(34):9974-9978
The Cδ?H amination of unactivated, secondary C?H bonds to form a broad range of functionalized pyrrolidines has been developed by a triiodide (I3?)‐mediated strategy. By in situ 1) oxidation of sodium iodide and 2) sequestration of the transiently generated iodine (I2) as I3?, this approach precludes undesired I2‐mediated decomposition which can otherwise limit synthetic utility to only weak C(sp3)?H bonds. The mechanism of this triiodide‐mediated cyclization of unbiased, secondary C(sp3)?H bonds, by either thermal or photolytic initiation, is supported by NMR and UV/Vis data, as well as intercepted intermediates. 相似文献
14.
A Preliminary Study of Diastereoselectivity in the PdII‐Catalyzed C(sp3)‐H Alkoxylation of Cyclic Systems
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Xinglin Yang Tian‐Yu Sun Prof. Yu Rao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3273-3277
Primary mechanism of a PdII‐catalyzed 8‐aminoquinoline‐directed C?H alkoxylation was investigated. It was understood that the PdII‐catalyzed C(sp3)?O bond formation proceeded through a concerted reductive elimination from the PdIV intermediate in the cyclic system. Deuteration experiments and related computational studies elucidate that intrinsic conformation determined the diastereoselectivity of the PdII‐catalyzed C?H alkoxylation of cyclic carboxylic acids. 相似文献
15.
Eric Tan Margherita Zanini Antonio M. Echavarren 《Angewandte Chemie (International ed. in English)》2020,59(26):10470-10473
An Ir‐catalyzed C(sp3)?H alkynylation of aliphatic ketones, aldehydes, and alcohols was achieved by using the corresponding oxime derivatives and a IrIII catalyst. This general reaction is selective towards primary C(sp3)?H bonds and can be used for the late‐stage C?H alkynylation of complex molecules. 相似文献
16.
Zhen Wang Jizhi Ni Prof. Dr. Yoichiro Kuninobu Prof. Dr. Motomu Kanai 《Angewandte Chemie (International ed. in English)》2014,53(13):3496-3499
The first copper‐catalyzed intramolecular C(sp3)? H and C(sp2)? H oxidative amidation has been developed. Using a Cu(OAc)2 catalyst and an Ag2CO3 oxidant in dichloroethane solvent, C(sp3)? H amidation proceeded at a terminal methyl group, as well as at the internal benzylic position of an alkyl chain. This reaction has a broad substrate scope, and various β‐lactams were obtained in excellent yield, even on gram scale. Use of CuCl2 and Ag2CO3 under an O2 atmosphere in dimethyl sulfoxide, however, leads to 2‐indolinone selectively by C(sp2)? H amidation. Kinetic isotope effect (KIE) studies indicated that C? H bond activation is the rate‐determining step. The 5‐methoxyquinolyl directing group could be removed by oxidation. 相似文献
17.
Ali Nasrallah Vincent Boquet Alexandra Hecker Pascal Retailleau Benjamin Darses Philippe Dauban 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(24):8276-8280
A practical general method for asymmetric intermolecular benzylic C(sp3)?H amination has been developed by combining the pentafluorobenzyl sulfamate PfbsNH2 with the chiral rhodium(II) catalyst Rh2(S‐tfptad)4. Various substrates can be used as limiting components and converted to benzylic amines with excellent yields and high levels of enantioselectivity. Additional key features for the reaction are the low catalyst loading and the ability to remove the Pfbs group under mild conditions to give NH‐free benzylic amines. 相似文献
18.
Li‐Jun Xiao Kai Hong Fan Luo Liang Hu William R. Ewing Kap‐Sun Yeung Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2020,59(24):9594-9600
The use of chiral transient directing groups (TDGs) is a promising approach for developing PdII‐catalyzed enantioselective C(sp3)?H activation reactions. However, this strategy is challenging because the stereogenic center on the TDG is often far from the C?H bond, and both TDG covalently attached to the substrate and free TDG are capable of coordinating to PdII centers, which can result in a mixture of reactive complexes. We report a PdII‐catalyzed enantioselective β‐C(sp3)?H arylation reaction of aliphatic ketones using a chiral TDG. A chiral trisubstituted cyclobutane was efficiently synthesized from a mono‐substituted cyclobutane through sequential C?H arylation reactions, thus demonstrating the utility of this method for accessing structurally complex products from simple starting materials. The use of an electron‐deficient pyridone ligand is crucial for the observed enantioselectivity. Interestingly, employing different silver salts can reverse the enantioselectivity. 相似文献
19.
Site‐Selective δ‐C(sp3)−H Alkylation of Amino Acids and Peptides with Maleimides via a Six‐Membered Palladacycle
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Bei‐Bei Zhan Ya Li Jing‐Wen Xu Xing‐Liang Nie Dr. Jun Fan Liang Jin Prof. Dr. Bing‐Feng Shi 《Angewandte Chemie (International ed. in English)》2018,57(20):5858-5862
The site‐selective functionalization of unactivated C(sp3)?H bonds remains one of the greatest challenges in organic synthesis. Herein, we report on the site‐selective δ‐C(sp3)?H alkylation of amino acids and peptides with maleimides via a kinetically less favored six‐membered palladacycle in the presence of more accessible γ‐C(sp3)?H bonds. Experimental studies revealed that C?H bond cleavage occurs reversibly and preferentially at γ‐methyl over δ‐methyl C?H bonds while the subsequent alkylation proceeds exclusively at the six‐membered palladacycle that is generated by δ‐C?H activation. The selectivity can be explained by the Curtin–Hammett principle. The exceptional compatibility of this alkylation with various oligopeptides renders this procedure valuable for late‐stage peptide modifications. Notably, this process is also the first palladium(II)‐catalyzed Michael‐type alkylation reaction that proceeds through C(sp3)?H activation. 相似文献
20.
Ronan Rocaboy Ioannis Anastasiou Olivier Baudoin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14767-14770
The intramolecular coupling of two C(sp3)?H bonds to forge a C(sp3)?C(sp3) bond is enabled by 1,4‐Pd shift from a trisubstituted aryl bromide. Contrary to most C(sp3)?C(sp3) cross‐dehydrogenative couplings, this reaction operates under redox‐neutral conditions, with the C?Br bond acting as an internal oxidant. Furthermore, it allows the coupling between two moderately acidic primary or secondary C?H bonds, which are adjacent to an oxygen or nitrogen atom on one side, and benzylic or adjacent to a carbonyl group on the other side. A variety of valuable fused heterocycles were obtained from easily accessible ortho‐bromophenol and aniline precursors. The second C?H bond cleavage was successfully replaced with carbonyl insertion to generate other types of C(sp3)‐C(sp3) bonds. 相似文献