共查询到20条相似文献,搜索用时 15 毫秒
1.
Vanda R. Marinho 《合成通讯》2013,43(24):4423-4428
One relatively unexploited commercial ligand, Walphos 1, was tested in the Pd(0)-catalyzed asymmetric allylic alkylation using rac-1,3-diphenyl propenyl acetate and rac-1-acetoxycyclohexene as substrates, methyl malonate as nucleophile, and a variety of Pd precatalysts under standard conditions. The conversions and enantioselectivities were generally good, with the greatest substrate conversion of 99% and a greatest ee of 70%. With the latter cyclic substrate, an enantioselectivity of 98% was obtained, but the conversions were all poor (15–33%). 相似文献
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Benoît Blank Stefan Michlik Rhett Kempe Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(15):3790-3799
Selective amine alkylation : A P,N‐ligand‐stabilized iridium complex has been used as an efficient catalyst for the alkylation of (hetero)aromatic amines with alcohols at mild reaction temperatures and catalyst loadings as low as 0.1 mol % Ir (see scheme). The excellent selectivity of the catalyst for monoalkylation of the amine function has also been exploited for the N,N′‐dialkylation of diamines in both symmetric and nonsymmetric fashions.
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Oxidation and β‐Alkylation of Alcohols Catalysed by Iridium(I) Complexes with Functionalised N‐Heterocyclic Carbene Ligands 下载免费PDF全文
Dr. M. Victoria Jiménez Dr. Javier Fernández‐Tornos Dr. F. Javier Modrego Prof. Jesús J. Pérez‐Torrente Prof. Luis A. Oro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(49):17877-17889
The borrowing hydrogen methodology allows for the use of alcohols as alkylating agents for C?C bond forming processes offering significant environmental benefits over traditional approaches. Iridium(I)‐cyclooctadiene complexes having a NHC ligand with a O‐ or N‐functionalised wingtip efficiently catalysed the oxidation and β‐alkylation of secondary alcohols with primary alcohols in the presence of a base. The cationic complex [Ir(NCCH3)(cod)(MeIm(2‐ methoxybenzyl))][BF4] (cod=1,5‐cyclooctadiene, MeIm=1‐methylimidazolyl) having a rigid O‐functionalised wingtip, shows the best catalyst performance in the dehydrogenation of benzyl alcohol in acetone, with an initial turnover frequency (TOF0) of 1283 h?1, and also in the β‐alkylation of 2‐propanol with butan‐1‐ol, which gives a conversion of 94 % in 10 h with a selectivity of 99 % for heptan‐2‐ol. We have investigated the full reaction mechanism including the dehydrogenation, the cross‐aldol condensation and the hydrogenation step by DFT calculations. Interestingly, these studies revealed the participation of the iridium catalyst in the key step leading to the formation of the new C?C bond that involves the reaction of an O‐bound enolate generated in the basic medium with the electrophilic aldehyde. 相似文献
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Iridium‐Catalyzed Enantioselective CH Alkylation of Ferrocenes with Alkenes Using Chiral Diene Ligands 下载免费PDF全文
Prof. Dr. Takanori Shibata Tsubasa Shizuno 《Angewandte Chemie (International ed. in English)》2014,53(21):5410-5413
The first catalytic and enantioselective C? H alkylation of ferrocene derivatives with various alkenes was achieved. A cationic iridium complex, having a chiral diene ligand, and an isoquinolyl moiety as a directing group are essential for regioselective and enantioselective C? H bond activation. 相似文献
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Wen Ai Xueyan Yang Yunxiang Wu Xuan Wang Prof. Yuanchao Li Dr. Yaxi Yang Dr. Bing Zhou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(52):17653-17657
A RhIII‐catalyzed procedure for the C7‐selective C?H alkylation of various indolines with α‐diazo compounds at room temperature is reported. The advantages of this process are: 1) simple, mild, and pH‐neutral reaction conditions, 2) broad substrate scope, 3) complete regioselectivity, 4) no need for an external oxidant, and 5) N2 as the sole byproduct. Furthermore, alkylation and bis‐alkylation of carbazoles at the C1 and C8 positions have also been developed. More significantly, for the first time, a successful IrIII‐catalyzed intermolecular insertion of arene C?H bonds into α‐diazo compounds is reported. 相似文献
8.
Philip Andreetta Dr. Robert T. Martin Charafa Souilah Dr. Ángel Rentería-Gómez Dr. Zhihui Song Yas Khorramshahi Bayat Dr. Sergei Ivlev Prof. Dr. Osvaldo Gutierrez Prof. Dr. Alicia Casitas 《Angewandte Chemie (International ed. in English)》2023,62(46):e202310129
Here, we report the development of cobalt(I)-catalyzed regioselective allylic alkylation reactions of tertiary allyl carbonates with 1,3-dicarbonyl compounds. A family of well-defined tetrahedral cobalt(I) complexes bearing commercially available bidentate bis(phosphine) ligands [(P,P)Co(PPh3)Cl] are synthesized and explored as catalysts in allylic alkylation reactions. The catalyst [(dppp)Co(PPh3)Cl] (dppp=1,3-Bis(diphenylphosphino)propane) enables the alkylation of a large variety of tertiary allyl carbonates with high yields and excellent regioselectivity for the branched product. Remarkably, this methodology is selective for the activation of tertiary allyl carbonates even in the presence of secondary allyl carbonates. This contrasts with the selectivity observed in cobalt-catalyzed allylic alkylations enabled by visible light photocatalysis. Mechanistic insights by means of experimental and computational investigations support a Co(I)/Co(III) catalytic cycle. 相似文献
9.
Roland Lang Arno Schrwerth Kurt Polborn Walter Ponikwar Wolfgang Beck Theodor Severin Kay Severin 《无机化学与普通化学杂志》1999,625(8):1384-1390
Organometallic Compounds with N -substituted 3-Hydroxy-2-methyl-4-pyridone Ligands: square planar Rhodium(I), Iridium(I), and Palladium(II) Complexes Reactions of [(OC)2MCl]2 (M = Rh, Ir) or [(cod)RhCl]2 with the anions of N-Aryl or N-Alkyl substituted 3-hydroxy-2-methyl-4-pyridones (O–O′) yield complexes of the general formula [L2M(O–O′)]. Compounds of this type are also available from reactions of [(OC)2Rh(acac)] with the corresponding neutral ligands. Substitution of one carbonyl-ligand of the N-phenyl complex [(OC)2Rh(C12H10NO2)] ( 2 ) with cyclooctene affords [(OC)(C8H14)Rh(C12H10NO2)] ( 8 ). The palladium complexes [(R3P)Pd(O–O′)Cl] (R = Et, Bu), [(C6H4CH2NMe2) · Pd(O–O′)] and [(Et3P)2Pd(O–O′)]BF4 ( 9 – 12 ) were synthesized from [(R3P)PdCl2]2, [(C6H4CH2NMe2)PdCl]2 or [(Et3P)PdCl2]. The structures of the N-methyl compounds [(OC)2Rh(C7H8NO2)] ( 1 ) and [(Ph3P)Pd(C7H8NO2)Cl] ( 9 ) were determined by single crystal X-ray diffraction. 相似文献
10.
Rsuini U. Gutirrez Mayra Hernndez-Montes Aarn Mendieta-Moctezuma Francisco Delgado Joaquín Tamariz 《Molecules (Basel, Switzerland)》2021,26(13)
An efficient synthesis of ketimines was achieved through a regioselective Hg(I)-catalyzed hydroamination of terminal acetylenes in the presence of anilines. The Pd(II)-catalyzed cyclization of these imines into the 2-substituted indoles was satisfactorily carried out by a C-H activation. In a single-step approach, a variety of 2-substituted indoles were also generated via a Hg(I)/Pd(II)-catalyzed, one-pot, two-step process, starting from anilines and terminal acetylenes. The arylacetylenes proved to be more effective than the alkyl derivatives. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(35):10666-10670
The development of new and practical 3‐pentoxythiocarbonyl auxiliaries for IrI‐catalyzed C−H alkylation of azacycles is described. This method allows for the α‐C−H alkylation of a variety of substituted pyrrolidines, piperidines, and tetrahydroisoquinolines through alkylation with alkenes. While the practicality of these simple carbamate‐type auxiliaries is underscored by the ease of installation and removal, the method's utility is demonstrated in its ability to functionalize biologically relevant l ‐proline and l ‐trans ‐hydroxyproline, delivering unique 2,5‐dialkylated amino acid analogues that are not accessible by other C−H functionalization methods. 相似文献
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The common use of NHC complexes in transition‐metal mediated C–C coupling and metathesis reactions in recent decades has established N‐heterocyclic carbenes as a new class of ligand for catalysis. The field of asymmetric catalysis with complexes bearing NHC‐containing chiral ligands is dominated by mixed carbene/oxazoline or carbene/phosphane chelating ligands. In contrast, applications of complexes with chiral, chelating bis(NHC) ligands are rare. In the present work new chiral iridium(I) bis(NHC) complexes and their application in the asymmetric transfer hydrogenation of ketones are described. A series of chiral bis(azolium) salts have been prepared following a synthetic pathway, starting from L ‐valinol and the modular buildup allows the structural variation of the ligand precursors. The iridium complexes were formed via a one‐pot transmetallation procedure. The prepared complexes were applied as catalysts in the asymmetric transfer hydrogenation of various prochiral ketones, affording the corresponding chiral alcohols in high yields and moderate to good enantioselectivities of up to 68%. The enantioselectivities of the catalysts were strongly affected by the various, terminal N‐substituents of the chelating bis(NHC) ligands. The results presented in this work indicate the potential of bis‐carbenes as stereodirecting ligands for asymmetric catalysis and are offering a base for further developments. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
13.
Eiki Tomita Kodai Yamada Yu Shibata Ken Tanaka Masahiro Kojima Tatsuhiko Yoshino Shigeki Matsunaga 《Angewandte Chemie (International ed. in English)》2020,59(26):10474-10478
The synthesis, characterization, and catalytic performance of iridium(III) catalysts that bear an amide‐pendant cyclopentadienyl ligand ([CpAIrI2]2) is reported. These [CpAIrI2]2 catalysts were obtained from the complexation of a CpA ligand precursor with [Ir(cod)OAc]2 followed by oxidation. Double aromatic homologation reactions of benzamides with alkynes by fourfold C?H activation proceeded in good to high yield with these [CpAIrI2]2 catalysts, demonstrating their superior catalytic performance in this challenging transformation. 相似文献
14.
Xi‐Jia Liu Shicheng Jin Wen‐Yun Zhang Qiang‐Qiang Liu Chao Zheng Shu‐Li You 《Angewandte Chemie (International ed. in English)》2020,59(5):2039-2043
The stereodivergent iridium‐catalyzed allylic alkylation and fluorination of acyclic ketones is described. α‐Pyridyl‐α‐fluoroketones with vicinal tertiary and quaternary stereocenters were obtained in moderate to excellent yields and stereoselectivities. Distinct from known stereodivergent synthesis, for which two different chiral catalysts are required in general, herein we report a sequence‐dependent stereodivergent synthesis. With only a single chiral Ir catalyst, all four possible stereoisomers of the products were prepared from the same starting materials by simply adjusting the sequence of asymmetric allylic alkylation and fluorination and varying the absolute configuration of the Ir catalyst. 相似文献
15.
An Iridium(I) N‐Heterocyclic Carbene Complex Catalyzes Asymmetric Intramolecular Allylic Amination Reactions 下载免费PDF全文
Dr. Ke‐Yin Ye Qiang Cheng Dr. Chun‐Xiang Zhuo Prof. Li‐Xin Dai Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2016,55(28):8113-8116
A chiral iridium(I) N‐heterocyclic carbene complex was reported for the first time as the catalyst in the highly enantioselective intramolecular allylic amination reaction. The current method provides facile access to biologically important enantioenriched indolopiperazinones and piperazinones in good yields (74–91 %) and excellent enantioselectivities (92–99 % ee). Preliminary mechanistic investigations reveal that the C?H activation occurs at the position ortho to the N‐aryl group of the ligand. 相似文献
16.
Meng-Xi Mao Fang-Ling Li Yan Shen Qi-Ming Liu Shuai Xing Xu-Feng Luo Zhen-Long Tu Xue-Jun Wu You-Xuan Zheng 《Molecules (Basel, Switzerland)》2021,26(9)
Phosphorescent iridium(III) complexes have been widely researched for the fabrication of efficient organic light-emitting diodes (OLEDs). In this work, three red Ir(III) complexes named Ir-1, Ir-2, and Ir-3, with Ir-S-C-S four-membered framework rings, were synthesized efficiently at room temperature within 5 min using sulfur-containing ancillary ligands with electron-donating groups of 9,10-dihydro-9,9-dimethylacridine, phenoxazine, and phenothiazine, respectively. Due to the same main ligand of 4-(4-(trifluoromethyl)phenyl)quinazoline, all Ir(III) complexes showed similar photoluminescence emissions at 622, 619, and 622 nm with phosphorescence quantum yields of 35.4%, 50.4%, and 52.8%, respectively. OLEDs employing these complexes as emitters with the structure of ITO (indium tin oxide)/HAT-CN (dipyra-zino[2,3-f,2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile, 5 nm)/TAPC (4,4′-cyclohexylidenebis[N,N-bis-(4-methylphenyl)aniline], 40 nm)/TCTA (4,4″,4″-tris(carbazol-9-yl)triphenylamine, 10 nm)/Ir(III) complex (10 wt%): 2,6DCzPPy (2,6-bis-(3-(carbazol-9-yl)phenyl)pyridine, 10 nm)/TmPyPB (1,3,5-tri(mpyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) achieved good performance. In particular, the device based on complex Ir-3 with the phenothiazine unit showed the best performance with a maximum brightness of 22,480 cd m−2, a maximum current efficiency of 23.71 cd A−1, and a maximum external quantum efficiency of 18.1%. The research results suggest the Ir(III) complexes with a four-membered ring Ir-S-C-S backbone provide ideas for the rapid preparation of Ir(III) complexes for OLEDs. 相似文献
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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
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Synthesis, Structure, and Photochemical Behavior of Olefine Iridium(I) Complexes with Acetylacetonato Ligands The bis(ethene) complex [Ir(κ2‐acac)(C2H4)2] ( 1 ) reacts with tertiary phosphanes to give the monosubstitution products [Ir(κ2‐acac)(C2H4)(PR3)] ( 2 – 5 ). While 2 (R = iPr) is inert toward PiPr3, the reaction of 2 with diphenylacetylene affords the π‐alkyne complex [Ir(κ2‐acac)(C2Ph2)(PiPr3)] ( 6 ). Treatment of [IrCl(C2H4)4] with C‐functionalized acetylacetonates yields the compounds [Ir(κ2‐acacR1,2)(C2H4)2] ( 8 , 9 ), which react with PiPr3 to give [Ir(κ2‐acacR1,2)(C2H4)(PiPr3)] ( 10 , 11 ) by displacement of one ethene ligand. UV irradiation of 5 (PR3 = iPr2PCH2CO2Me) and 11 (R2 = (CH2)3CO2Me) leads, after addition of PiPr3, to the formation of the hydrido(vinyl)iridium(III) complexes 7 and 12 . The reaction of 2 with the ethene derivatives CH2=CHR (R = CN, OC(O)Me, C(O)Me) affords the compounds [Ir(κ2‐acac)(CH2=CHR)(PiPr3)] ( 13 – 15 ), which on photolysis in the presence of PiPr3 also undergo an intramolecular C–H activation. In contrast, the analogous complexes [Ir(κ2‐acac)(olefin)(PiPr3)] (olefin = (E)‐C2H2(CO2Me)2 16 , (Z)‐C2H2(CO2Me)2 17 ) are photochemically inert. 相似文献
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Xiaonan Li Dr. Xiaoxu Qi Chuanqi Hou Dr. Pinhong Chen Prof. Dr. Guosheng Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(39):17392-17397
The first Pd-catalyzed enantioselective azidation of unactivated alkenes has been established by using readily accessible 1-azido-1,2-benziodoxol-3(1H)-one (ABX) as an azidating reagent, which affords a wide variety of structurally diverse 3-N3-substituted piperidines in good yields with excellent enantioselectivity. The reaction features good functional-group compatibility and mild reaction conditions. Notably, both an electrophilic azidating reagent and the sterically bulky chiral pyridinyl-oxazoline (Pyox) ligand are crucial to the successful reaction. 相似文献
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Addition of traces of iridium(III) chloride with cerium(IV) sulfate (catalyst–substrate ratio (1:2994 to 1:10,000) in traditional water-bath heating resulted in the oxidation of p-chlorobenzaldehyde, p-nitrobenzaldehyde, benzyl alcohol, p-methoxy benzyl alcohol, p-xylene, and p-nitrotoluene dissolved in acetic acid to give 77%, 90%, 21.7%, 88.6%, 86.2%, and 18% yields of the products, respectively, while catechol and resorcinol polymerized. Oxidation of aldehydes and alcohols resulted as usual in the corresponding acids and aldehydes, respectively, while p-xylene and p-nitrotoluene gave p-tolualdehyde and p-nitrobenzoic acid. Conditions were obtained for getting the highest yields under the experimental conditions. 相似文献