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1.
《中国化学》2018,36(3):213-216
Transition‐metal catalyzed C—H functionalization of benzaldehydes is of great interest in organic synthesis. Herein, we developed a transient directing group assisted amidation of benzaldehydes catalyzed by rhodium catalyst. With the employment of 10 mol% of 4‐trifluoromethyl aniline, the in situ generated imine groups as the directing group efficiently enable this transformation. By using this protocol, a wide range of benzaldehydes were efficiently converted into the corresponding N‐(2‐formylphenyl)benzamides utilizing dioxazolones as the nitrogen source. 相似文献
2.
Jompol Thongpaen Romane Manguin Olivier Basl 《Angewandte Chemie (International ed. in English)》2020,59(26):10242-10251
The asymmetric functionalization of C?H bond is a particularly valuable approach for the production of enantioenriched chiral organic compounds. Chiral N‐heterocyclic carbene (NHC) ligands have become ubiquitous in enantioselective transition‐metal catalysis. Conversely, the use of chiral NHC ligands in metal‐catalyzed asymmetric C?H bond functionalization is still at an early stage. This minireview highlights all the developments and the new advances in this rapidly evolving research area. 相似文献
3.
An efficient NaBArF4‐catalyzed oxidative cyclization of readily available 1,5‐ and 1,6‐diynes has been developed. Importantly, this transition metal‐free oxidative catalysis proceeds via a presumable Lewis acid‐catalyzed SN2’ pathway, which is distinct from the relevant oxidative rhodium and gold catalysis. This method leads to the facile and practical construction of a diverse range of synthetically useful γ‐ and δ‐lactams in mostly good to excellent yields with broad substrate scope. 相似文献
4.
Rhodium(III)‐Catalyzed Alkenylation–Annulation of closo‐Dodecaborate Anions through Double B−H Activation at Room Temperature
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Yuanbin Zhang Yuji Sun Furong Lin Jiyong Liu Dr. Simon Duttwyler 《Angewandte Chemie (International ed. in English)》2016,55(50):15609-15614
1,2,3‐Trisubstituted closo‐dodecaborates with B?O, B?N, and B?C bonds as well as a fused borane oxazole ring have been synthesized by rhodium‐catalyzed direct cage B?H alkenylation and annulation of ureido boranes in the first reported example of regioselective B?H bond functionalization of the [B12H12]2? cage by transition‐metal catalysis. This reaction proceeded at room temperature under ambient conditions and exhibited excellent selectivity for efficient monoalkenylation with good functional‐group tolerance. The urea moiety enabled B?H activation by acting as a directing group, was incorporated in the oxazole ring in situ, and also avoided multiple alkenylation. A possible mechanism is proposed on the basis of the isolation of a rhodium agostic intermediate and control experiments. 相似文献
5.
Chloride‐Bridged Dinuclear Rhodium(III) Complexes Bearing Chiral Diphosphine Ligands: Catalyst Precursors for Asymmetric Hydrogenation of Simple Olefins
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Dr. Yusuke Kita Shoji Hida Kenya Higashihara Dr. Himanshu Sekhar Jena Kosuke Higashida Prof. Dr. Kazushi Mashima 《Angewandte Chemie (International ed. in English)》2016,55(29):8299-8303
Efficient rhodium(III) catalysts were developed for asymmetric hydrogenation of simple olefins. A new series of chloride‐bridged dinuclear rhodium(III) complexes 1 were synthesized from the rhodium(I) precursor [RhCl(cod)]2, chiral diphosphine ligands, and hydrochloric acid. Complexes from the series acted as efficient catalysts for asymmetric hydrogenation of (E)‐prop‐1‐ene‐1,2‐diyldibenzene and its derivatives without any directing groups, in sharp contrast to widely used rhodium(I) catalytic systems that require a directing group for high enantioselectivity. The catalytic system was applied to asymmetric hydrogenation of allylic alcohols, alkenylboranes, and unsaturated cyclic sulfones. Control experiments support the superiority of dinuclear rhodium(III) complexes 1 over typical rhodium(I) catalytic systems. 相似文献
6.
Richard Eisenberg 《中国化学会会志》1995,42(3):471-481
Parahydrogen-included polarization (PHIP), its occurrence and mechanistic implications in homogeneous hydrogenation chemistry, and its appearance in the oxidative addition of H2 to transition metal centers are described and analyzed. The PHIP phenomenon, which is characterized by unusual NMR absorptions and emissions in product spectra, arises when para-enriched H2 is employed in hydrogenation of unsaturated organic substrates with a homogeneous metal catalyst or when para-enriched H2 is added to a metal complex to form a metal dihydride. Examples of PHIP are found in ruthenium phosphine-catalyzed hydrogenations, catalysis by binuclear rhodium complexes, and in H2 oxidative addition to Ir(I) complexes. The decay of polarization has been shown in the case of asymmetric hydrogenation catalyzed by Rh(chiraphos)+ to correlate well with the measured rate of reaction. For asymmetric hydrogenation of aprotic substrates using Noyori's Ru(BINAP)(OAc)2 catalyst (1), PHIP is observed indicating a pairwise hydrogen transfer mechanism. Through the signal enhancement of PHIP, it has been possible to observe Rh hydride species never previously detected including binuclear complexes in the reaction of H2 with RhCl(CO)(PR3)2 (R = Ph, Me) and in hydrogenation catalysis promoted by RhCl(PPh3)3. Also observed in the hydrogenation catalysis is the putative olefin dihydride catalytic intermediate. 相似文献
7.
In recent years, transition‐metal‐catalyzed C?H activation has become a key strategy in the field of organic synthesis. Rhodium complexes are widely used as catalysts in a variety of C?H functionalization reactions because of their high reactivity and selectivity. The availability of a number of rhodium complexes in various oxidation states enables diverse reaction patterns to be obtained. Regioselectivity, an important issue in C?H activation chemistry, can be accomplished by using a directing group to assist the reaction. However, to obtain the target functionalized compounds, it is also necessary to use a directing group that can be easily removed. A wide range of directed C?H functionalization reactions catalyzed by rhodium complexes have been reported to date. In this Review, we discuss Rh‐catalyzed C?H functionalization reactions that are aided by the use of a removable directing group such as phenol, amine, aldehyde, ketones, ester, acid, sulfonic acid, and N‐heteroaromatic derivatives. 相似文献
8.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(40):12418-12422
An asymmetric pathway to the caged tetracyclic pyrrolidine alkaloid, dendrobine, is reported. The successful synthetic strategy features a one‐pot, sequential palladium‐catalyzed enyne cycloisomerization and rhodium‐catalyzed diene‐assisted pyrrolidine formation by allylic CH activation. The developed transition‐metal‐catalyzed cascade process permits rapid access to the dendrobine core structure and circumvents the handling of labile intermediates. An intramolecular aldol condensation under carefully defined reaction conditions takes place with a concomitant detosylation, followed by reductive amine methylation, to afford a late‐stage intermediate (previously identified by several prior dendrobine syntheses) in only 10 synthetic steps overall. 相似文献
9.
Hao Liang Dr. Laxmaiah Vasamsetty Dr. Teng Li Prof. Dr. Jijun Jiang Xingying Pang Prof. Dr. Jun Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(64):14546-14550
A new class of C2-symmetric, chiral cyclopentadienyl ligand based on planar chiral ferrocene backbone was developed. A series of its corresponding rhodium(I), iridium(I), and ruthenium(II) complexes were prepared as well. In addition, the rhodium(I) complexes were evaluated in the asymmetric catalytic intramolecular amidoarylation of olefin-tethered benzamides via C−H activation. 相似文献
10.
Qing Jing Dr. Krzysztof Okrasa Dr. Romas J. Kazlauskas Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(6):1370-1376
One useful synthetic reaction missing from nature's toolbox is the direct hydrogenation of substrates using hydrogen. Instead nature uses cofactors like NADH to reduce organic substrates, which adds complexity and cost to these reductions. To create an enzyme that can directly reduce organic substrates with hydrogen, researchers have combined metal hydrogenation catalysts with proteins. One approach is an indirect link where a ligand is linked to a protein and the metal binds to the ligand. Another approach is direct linking of the metal to protein, but nonspecific binding of the metal limits this approach. Herein, we report a direct hydrogenation of olefins catalyzed by rhodium(I) bound to carbonic anhydrase (CA‐[Rh]). We minimized nonspecific binding of rhodium by replacing histidine residues on the protein surface using site‐directed mutagenesis or by chemically modifying the histidine residues. Hydrogenation catalyzed by CA‐[Rh] is slightly slower than for uncomplexed rhodium(I), but the protein environment induces stereoselectivity favoring cis‐ over trans‐stilbene by about 20:1. This enzyme is the first cofactor‐independent reductase that reduces organic molecules using hydrogen. This catalyst is a good starting point to create variants with tailored reactivity and selectivity. This strategy to insert transition metals in the active site of metalloenzymes opens opportunities to a wider range of enzyme‐catalyzed reactions. 相似文献
11.
Ropartz L Meeuwenoord NJ van der Marel GA van Leeuwen PW Slawin AM Kamer PC 《Chemical communications (Cambridge, England)》2007,(15):1556-1558
Novel transition metal catalysts based on oligonucleotides can be easily obtained by functionalization of 5-iodouridine with phosphine ligands, resulting in good asymmetric induction in palladium catalyzed allylic nucleophilic substitution. 相似文献
12.
Zhiheng Li Danran Li Huaming Xiang Jian Huang Yinuo Zheng Cuiju Zhu Xiuling Cui Chao Pi Hao Xu 《中国化学快报》2022,33(2):867-870
Anthrones are key structural motifs in many natural products, bioactive compounds and pharmaceutical chemicals. Earth-abundant-metal-catalyzed asymmetric functionalization of anthrones has not proved to be viable. Herein, we disclosed a highly enantioselective propargylic substitution of anthrones with propargylic esters using copper salts with chiral N, N, P-ligand. This strategy is amenable to a broad range of substrates, uses readily available starting materials, provides excellent yields wit... 相似文献
13.
Transition‐metal‐catalyzed C–H bond functionalization has become one of the most promising strategies to prepare complex molecules from simple precursors. However, the utilization of environmentally unfriendly oxidants in the oxidative C–H bond functionalization reactions reduces their potential applications in organic synthesis. This account describes our recent efforts in the development of a redox‐neutral C–H bond functionalization strategy for direct addition of inert C–H bonds to unsaturated double bonds and a redox‐green C–H bond functionalization strategy for realization of oxidative C–H functionalization with O2 as the sole oxidant, aiming to circumvent the problems posed by utilizing environmentally unfriendly oxidants. In principle, these redox‐neutral and redox‐green strategies pave the way for establishing new environmentally benign transition‐metal‐catalyzed C–H bond functionalization strategies. 相似文献
14.
Efficient Asymmetric Hydrogenation of α‐Acetamidocinnamates through a Simple,Readily Available Monodentate Chiral H‐Phosphinate
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Dr. Xiang‐Bo Wang Dr. Midori Goto Dr. Li‐Biao Han 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(13):3631-3635
An air‐stable, simple (RP)‐mentylbenzylphosphinate, readily available in large quantities, can efficiently induce the rhodium‐catalyzed asymmetric hydrogenation of α‐acetamidocinnamates with high enantioselectivity (up to 99.6 % ee). Intramolecular hydrogen bonding plays an important role in this asymmetric induction. 相似文献
15.
Chiral Phosphate in Rhodium‐Catalyzed Asymmetric [2+2+2] Cycloaddition: Ligand,Counterion, or Both?
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Dr. Marion Barbazanges Dr. Elsa Caytan Dr. Denis Lesage Dr. Corinne Aubert Prof. Louis Fensterbank Prof. Vincent Gandon Dr. Cyril Ollivier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(25):8553-8558
Investigations based on NMR spectroscopy, mass spectrometry, and DFT calculations shed light on the metallic species generated in the rhodium‐catalyzed asymmetric [2+2+2] cycloaddition reaction between diynes and isocyanates with the chiral phosphate TRIP. The catalytic mixture comprising [{Rh(cod)Cl}2], 1,4‐diphenylphosphinobutane (dppb), and Ag(S)‐TRIP actually gives rise to two species, both having an effect on the stereoselectivity. One is a rhodium(I) complex in which TRIP is a weakly coordinating counterion, whereas the other is a bimetallic Rh/Ag complex in which TRIP is a strongly coordinating X‐type ligand. 相似文献
16.
Transition Metal‐Catalyzed Carbonylative CH Bond Functionalization of Arenes and C(sp3)H Bond of Alkanes
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Sandip T. Gadge Prashant Gautam Bhalchandra M. Bhanage 《Chemical record (New York, N.Y.)》2016,16(2):835-856
In this article, we present the progress made in the area of carbonylative C? H functionalization, with special emphasis on arenes and alkanes. The importance of directing group assistance and C? H functionalization using CO surrogates is also included. The budding development in the area of transition metal‐catalyzed C(sp3)? H activation makes us feel it necessary to file a summary on the past, as well as current, contributions and a prospective outlook on the transition metal‐catalyzed carbonylative transformation of C? H bonds, which is the focus of this review. 相似文献
17.
Base‐Free Conditions for Rhodium‐Catalyzed Asymmetric Arylation To Produce Stereochemically Labile α‐Aryl Ketones
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Dr. Xiaowei Dou Prof. Dr. Yixin Lu Prof. Dr. Tamio Hayashi 《Angewandte Chemie (International ed. in English)》2016,55(23):6739-6743
The asymmetric arylation of 2,2‐dialkyl cyclopent‐4‐ene‐1,3‐diones with aryl boronic acids was found to be efficiently catalyzed by a chiral diene–rhodium μ‐chloro dimer, [{RhCl((R)‐diene*)}2], in the absence of bases in toluene/H2O to give 2,2‐dialkyl 4‐aryl cyclopentane‐1,3‐diones in high yields with high enantioselectivity. Such compounds can not be obtained with high enantiomeric purity under the standard basic conditions used for rhodium‐catalyzed asymmetric arylation because the α‐aryl ketone products undergo racemization under the basic conditions. 相似文献
18.
Complementary Strategies for Directed C(sp3)−H Functionalization: A Comparison of Transition‐Metal‐Catalyzed Activation,Hydrogen Atom Transfer,and Carbene/Nitrene Transfer
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John C. K. Chu Prof. Tomislav Rovis 《Angewandte Chemie (International ed. in English)》2018,57(1):62-101
The functionalization of C(sp3)?H bonds streamlines chemical synthesis by allowing the use of simple molecules and providing novel synthetic disconnections. Intensive recent efforts in the development of new reactions based on C?H functionalization have led to its wider adoption across a range of research areas. This Review discusses the strengths and weaknesses of three main approaches: transition‐metal‐catalyzed C?H activation, 1,n‐hydrogen atom transfer, and transition‐metal‐catalyzed carbene/nitrene transfer, for the directed functionalization of unactivated C(sp3)?H bonds. For each strategy, the scope, the reactivity of different C?H bonds, the position of the reacting C?H bonds relative to the directing group, and stereochemical outcomes are illustrated with examples in the literature. The aim of this Review is to provide guidance for the use of C?H functionalization reactions and inspire future research in this area. 相似文献
19.
Mgane Valero Thomas Kruissink Jennifer Blass Remo Weck Stefan Güssregen Alleyn T. Plowright Volker Derdau 《Angewandte Chemie (International ed. in English)》2020,59(14):5626-5631
An assessment of the C?H activation catalyst [(COD)Ir(IMes)(PPh3)]PF6 (COD=1,5‐cyclooctadiene, IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene) in the deuteration of phenyl rings containing different functional directing groups is divulged. Competition experiments have revealed a clear order of the directing groups in the hydrogen isotope exchange (HIE) with an iridium (I) catalyst. Through DFT calculations the iridium–substrate coordination complex has been identified to be the main trigger for reactivity and selectivity in the competition situation with two or more directing groups. We postulate that the competition concept found in this HIE reaction can be used to explain regioselectivities in other transition‐metal‐catalyzed functionalization reactions of complex drug‐type molecules as long as a C?H activation mechanism is involved. 相似文献
20.
Jossian Oppenheimer 《Tetrahedron》2009,65(26):5001-920
A rhodium(I)-xylyl-BINAP catalyzed asymmetric [2+2+2] cycloaddition of achiral conjugated aryl ynamides with various diynes is described here. This asymmetric cycloaddition provides a series of structurally interesting chiral N,O-biaryls with excellent enantioselectivity along with a modest diastereoselectivity with respect to both C-C and C-N axial chirality. 相似文献