共查询到20条相似文献,搜索用时 31 毫秒
1.
Anton Dmitrienko Prof. Melanie Pilkington Dr. James F. Britten Dr. Bulat M. Gabidullin Prof. Art van der Est Prof. Georgii I. Nikonov 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):16281-16287
The aluminum(I) compound NacNacAl (NacNac=[ArNC(Me)CHC(Me)NAr]−, Ar=2,6-iPr2C6H3, 1 ) shows diverse and substrate-controlled reactivity in reactions with N-heterocycles. 4-Dimethylaminopyridine (DMAP), a basic substrate in which the 4-position is blocked, induces rearrangement of NacNacAl by shifting a hydrogen atom from the methyl group of the NacNac backbone to the aluminum center. In contrast, C−H activation of the methyl group of 4-picoline takes place to produce a species with a reactive terminal methylene. Reaction of 1 with 3,5-lutidine results in the first example of an uncatalyzed, room-temperature cleavage of an sp2 C−H bond (in the 4-position) by an AlI species. Another reactivity mode was observed for quinoline, which undergoes 2,2′-coupling. Finally, the reaction of 1 with phthalazine produces the product of N−N bond cleavage. 相似文献
2.
Oxidative Cleavage of C=S and P=S Bonds at an AlI Center: Preparation of Terminally Bound Aluminum Sulfides
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Terry Chu Dr. Sergei F. Vyboishchikov Dr. Bulat Gabidullin Dr. Georgii I. Nikonov 《Angewandte Chemie (International ed. in English)》2016,55(42):13306-13311
The treatment of cyclic thioureas with the aluminum(I) compound NacNacAl ( 1 ; NacNac=[ArNC(Me)CHC(Me)NAr]?, Ar=2,6‐Pri2C6H3) resulted in oxidative cleavage of the C=S bond and the formation of 3 and 5 , the first monomeric aluminum complexes with an Al=S double bond stabilized by N‐heterocyclic carbenes. Compound 1 also reacted with triphenylphosphine sulfide in a similar manner, which resulted in cleavage of the P=S bond and production of the adduct [NacNacAl=S(S=PPh3)] ( 8 ). The Al=S double bond in 3 can react with phenyl isothiocyanate to furnish the cycloaddition product 9 and zwitterion 10 as a result of coupling between the liberated carbene and PhN=C=S. All novel complexes were characterized by multinuclear NMR spectroscopy, and the structures of 5 , 9 , and 10 were confirmed by X‐ray diffraction analysis. The nature of the Al=S bond in 5 was also probed by DFT calculations. 相似文献
3.
《Mendeleev Communications》2022,32(1):68-70
The reactivity of an aluminium(I) diketiminate compound NacNacAl (NacNac is [ArNC(Me)CHC(Me)NAr]?, where Ar is 2,6-diisopropylphenyl) towards arenes has been systematically explored. Heating NacNacAl in benzene results in a fragmentation of the NacNac moiety due to cleavage of the CN bond, while anthracene adds to the main group carbenoid in a [4+1] fashion. Reactions with phenanthrene, triphenylene and fluoranthene demonstrate a reversible [4+1] addition process. 相似文献
4.
Anton Dmitrienko Dr. James F. Britten Dr. Denis Spasyuk Dr. Georgii I. Nikonov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(1):206-211
Reaction of NacNacAl (NacNac=[DippNC(Me)CHC(Me)NDipp]−) with one equivalent of benzophenone affords a ketylate species NacNacAl(η2(C,O)-OCPh2) that undergoes easy cyclization reactions with unsaturated substrates. The scope of substrates included benzophenone, aldimine (PhNC(Ph)H), quinoline, phenyl nitrile, trimethylsilyl azide, and a saturated cyclic thiourea. The latter substrate reacted by an unusual C−N cleavage that left the C=S functionality intact. The new products were characterized by NMR spectroscopy and X-ray diffraction analysis. 相似文献
5.
Dr. Shaoguang Zhang Dr. Haixia Li Dr. Aaron M. Appel Prof. Michael B. Hall Dr. R. Morris Bullock 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9493-9497
Unusual cleavage of P?C and C?H bonds of the P2N2 ligand, in heteroleptic [Ni(P2N2)(diphosphine)]2+ complexes under mild conditions, results in the formation of an iminium formyl nickelate featuring a C,P,P‐tridentate coordination mode. The structures of both the heteroleptic [Ni(P2N2)(diphosphine)]2+ complexes and the resulting iminium formyl nickelate have been characterized by NMR spectroscopy and single‐crystal X‐ray diffraction analysis. Density functional theory (DFT) calculations were employed to investigate the mechanism of the P?C/C?H bond cleavage, which involves C?H bond cleavage, hydride rotation, Ni?C/P?H bond formation, and P?C bond cleavage. 相似文献
6.
Samuel Grams Jonathan Eyselein Jens Langer Christian Frber Sjoerd Harder 《Angewandte Chemie (International ed. in English)》2020,59(37):15982-15986
The reagent RK [R=CH(SiMe3)2 or N(SiMe3)2] was expected to react with the low‐valent (DIPPBDI)Al (DIPPBDI=HC[C(Me)N(DIPP)]2, DIPP=2,6‐iPr‐phenyl) to give [(DIPPBDI)AlR]?K+. However, deprotonation of the Me group in the ligand backbone was observed and [H2C=C(N‐DIPP)?C(H)=C(Me)?N?DIPP]Al?K+ ( 1 ) crystallized as a bright‐yellow product (73 %). Like most anionic AlI complexes, 1 forms a dimer in which formally negatively charged Al centers are bridged by K+ ions, showing strong K+???DIPP interactions. The rather short Al–K bonds [3.499(1)–3.588(1) Å] indicate tight bonding of the dimer. According to DOSY NMR analysis, 1 is dimeric in C6H6 and monomeric in THF, but slowly reacts with both solvents. In reaction with C6H6, two C?H bond activations are observed and a product with a para‐phenylene moiety was exclusively isolated. DFT calculations confirm that the Al center in 1 is more reactive than that in (DIPPBDI)Al. Calculations show that both AlI and K+ work in concert and determines the reactivity of 1 . 相似文献
7.
Anton Dmitrienko Prof. Melanie Pilkington Prof. Georgii I. Nikonov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(18):5730-5736
The AlI compound NacNacAl ( 1 , NacNac = [ArNC(Me)CHC(Me)NAr]−, Ar = 2,6-iPr2C6H3) serves as a template for the chemoselective coupling between carbonyls (benzophenone, fenchone, isophorone, p-tolyl benzoate, N,N-dimethylbenzamide, (1-phenylethylidene)aniline) and pyridine. With the CH-acidic ketone (1R)-(+) camphor, the reaction affords a hydrido alkoxide compound of Al, formed as the result of enolization, whereas an enolizable imine, (1-phenylethylidene)aniline, and the bulky ketone isophorone, still chemoselectively couple with pyridine. In contrast, reaction with the ester p-tolyl benzoate results in cleavage of the ester bond together with replacement of the alkoxy group by a hydrogen atom of the pyridine moiety. This study demonstrates that for carbonyl substrates featuring phenyl substituents, the reaction proceeds via intermediate formation of η2(C,X)-coordinated (X = O, N) carbonyl adducts, whereas the reaction of 1 with (R)-(−)-fenchone in the absence of pyridine leads to CH activation in the pendant isopropyl group of the Ar substituent of the NacNac ligand. 相似文献
8.
Ruthenium(II)‐Catalyzed Traceless C−H Functionalization Using an N−N Bond as an Internal Oxidant
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Dr. Shuguang Zhou Jinhu Wang Pei Chen Kehao Chen Prof. Dr. Jin Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(41):14508-14512
A previously elusive RuII‐catalyzed N?N bond‐based traceless C?H functionalization strategy is reported. An N‐amino (i.e., hydrazine) group is used for the directed C?H functionalization with either an alkyne or an alkene, affording an indole derivative or olefination product. The synthesis features a broad substrate scope, superior atom and step economy, as well as mild reaction conditions. 相似文献
9.
Ruthenium(II)‐Catalyzed C−H Activation of Imidamides and Divergent Couplings with Diazo Compounds: Substrate‐Controlled Synthesis of Indoles and 3H‐Indoles
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Yunyun Li Dr. Zisong Qi Dr. He Wang Xifa Yang Prof. Xingwei Li 《Angewandte Chemie (International ed. in English)》2016,55(39):11877-11881
Indoles are an important structural motif that is commonly found in biologically active molecules. In this work, conditions for divergent couplings between imidamides and acceptor–acceptor diazo compounds were developed that afforded NH indoles and 3H‐indoles under ruthenium catalysis. The coupling of α‐diazoketoesters afforded NH indoles by cleavage of the C(N2)?C(acyl) bond whereas α‐diazomalonates gave 3H‐indoles by C?N bond cleavage. This reaction constitutes the first intermolecular coupling of diazo substrates with arenes by ruthenium‐catalyzed C?H activation. 相似文献
10.
A photoredox catalytic ensemble consisting of CuO‐Fe2O3 nanocomposites and oligomeric derivative of phenazine has been developed. The prepared system acts as an efficient photoredox catalyst for C?N bond formation reaction via SET mechanism under ‘green’ conditions (aerial environment, mixed aqueous media, recyclable), requiring less equivalents of base and amine substrate. The present study demonstrates the significant role of supramolecular assemblies as photooxidants and reductants upon irradiation and their important contribution towards the activation of the metallic centre through energy transfer and electron transfer pathways. The potential of oligomer 4 : CuO‐Fe2O3 has also been explored for C?C bond formation reactions via the Sonogashira protocol. 相似文献
11.
Formation and High Reactivity of the anti‐Dioxo Form of High‐Spin μ‐Oxodioxodiiron(IV) as the Active Species That Cleaves Strong C−H Bonds
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Prof. Dr. Masahito Kodera Shin Ishiga Tomokazu Tsuji Katsutoshi Sakurai Prof. Dr. Yutaka Hitomi Dr. Yoshihito Shiota Dr. P. K. Sajith Prof. Dr. Kazunari Yoshizawa Dr. Kaoru Mieda Prof. Dr. Takashi Ogura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(17):5924-5936
Recently, it was shown that μ‐oxo‐μ‐peroxodiiron(III) is converted to high‐spin μ‐oxodioxodiiron(IV) through O?O bond scission. Herein, the formation and high reactivity of the anti‐dioxo form of high‐spin μ‐oxodioxodiiron(IV) as the active oxidant are demonstrated on the basis of resonance Raman and electronic‐absorption spectral changes, detailed kinetic studies, DFT calculations, activation parameters, kinetic isotope effects (KIE), and catalytic oxidation of alkanes. Decay of μ‐oxodioxodiiron(IV) was greatly accelerated on addition of substrate. The reactivity order of substrates is toluene<ethylbenzene≈cumene<trans‐β‐methylstyrene. The rate constants increased proportionally to the substrate concentration at low substrate concentration. At high substrate concentration, however, the rate constants converge to the same value regardless of the kind of substrate. This is explained by a two‐step mechanism in which anti‐μ‐oxodioxodiiron(IV) is formed by syn‐to‐anti transformation of the syn‐dioxo form and reacts with substrates as the oxidant. The anti‐dioxo form is 620 times more reactive in the C?H bond cleavage of ethylbenzene than the most reactive diiron system reported so far. The KIE for the reaction with toluene/[D8]toluene is 95 at ?30 °C, which the largest in diiron systems reported so far. The present diiron complex efficiently catalyzes the oxidation of various alkanes with H2O2. 相似文献
12.
Clemens Taube Kai Schwedtmann Medena Noikham Ekasith Somsook Felix Hennersdorf Robert Wolf Jan J. Weigand 《Angewandte Chemie (International ed. in English)》2020,59(9):3585-3591
[LCRP((PhP)2C2H4)][OTf] ( 4 a,b [OTf]) and [LCiPrP(PPh2)2][OTf] ( 5 b [OTf]) were prepared from the reaction of imidazoliumyl‐substituted dipyrazolylphosphane triflate salts [LCRP(pyr)2][OTf] ( 3 a,b [OTf]; a : R=Me, b =iPr; LCR=1,3‐dialkyl‐4,5‐dimethylimidazol‐2‐yl; pyr=3,5‐dimethylpyrazol‐1‐yl) with the secondary phosphanes PhP(H)C2H4P(H)Ph) and Ph2PH. A stepwise double P?N/P?P bond metathesis to catena‐tetraphosphane‐2,3‐diium triflate salt [(Ph2P)2(LCMeP)2][OTf]2 ( 7 a [OTf]2) is observed when reacting 3 a [OTf] with diphosphane P2Ph4. The coordination ability of 5 b [OTf] was probed with selected coinage metal salts [Cu(CH3CN)4]OTf, AgOTf and AuCl(tht) (tht=tetrahydrothiophene). For AuCl(tht), the helical complex [{(Ph2PPLCiPr)Au}4][OTf]4 ( 9 [OTf]4) was unexpectedly formed as a result of a chloride‐induced P?P bond cleavage. The weakly coordinating triflate anion enables the formation of the expected copper(I) and silver(I) complexes [( 5 b )M(CH3CN)3][OTf]2 (M=Cu, Ag) ( 10 [OTf]2, 11 [OTf]2). 相似文献
13.
Guangying Tan Shuang He Xiaolei Huang Xingrong Liao Yangyang Cheng Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2016,55(35):10414-10418
The first example of cobalt‐catalyzed oxidative C?H/C?H cross‐coupling between two heteroarenes is reported, which exhibits a broad substrate scope and a high tolerance level for sensitive functional groups. When the amount of Co(OAc)2?4 H2O is reduced from 6.0 to 0.5 mol %, an excellent yield is still obtained at an elevated temperature with a prolonged reaction time. The method can be extended to the reaction between an arene and a heteroarene. It is worth noting that the Ag2CO3 oxidant is renewable. Preliminary mechanistic studies by radical trapping experiments, hydrogen/deuterium exchange experiments, kinetic isotope effect, electron paramagnetic resonance (EPR), and high resolution mass spectrometry (HRMS) suggest that a single electron transfer (SET) pathway is operative, which is distinctly different from the dual C?H bond activation pathway that the well‐described oxidative C?H/C?H cross‐coupling reactions between two heteroarenes typically undergo. 相似文献
14.
Qian‐Qian Lu Prof. Dr. Hai‐Zhu Yu Prof. Dr. Yao Fu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(13):4584-4591
The mechanism of formic acid dehydrogenation catalyzed by the bis(imino)pyridine‐ligated aluminum hydride complex (PDI2?)Al(THF)H (PDI=bis(imino)pyridine) was studied by density functional theory calculations. The overall transformation is composed of two stages: catalyst activation and the catalytic cycle. The catalyst activation begins with O?H bond cleavage of HCOOH promoted by aluminum–ligand cooperation, followed by HCOOH‐assisted Al?H bond cleavage, and protonation of the imine carbon atom of the bis(imino)pyridine ligand. The resultant doubly protonated complex (H,HPDI)Al(OOCH)3 is the active catalyst for formic acid dehydrogenation. Given this, the catalytic cycle includes β‐hydride elimination of (H,HPDI)Al(OOCH)3 to produce CO2, and the formed (H,HPDI)Al(OOCH)2H mediates HCOOH to release H2. 相似文献
15.
《化学:亚洲杂志》2017,12(2):239-247
Five bis(quinolylmethyl)‐(1H ‐indolylmethyl)amine (BQIA) compounds, that is, {(quinol‐8‐yl‐CH2)2NCH2(3‐Br‐1H ‐indol‐2‐yl)} ( L1H ) and {[(8‐R3‐quinol‐2‐yl)CH2]2NCH(R2)[3‐R1‐1H ‐indol‐2‐yl]} ( L2–5H ) ( L2H : R1=Br, R2=H, R3=H; L3H : R1=Br, R2=H, R3=i Pr; L4H : R1=H, R2=CH3, R3=i Pr; L5H : R1=H, R2=n Bu, R3=i Pr) were synthesized and used to prepare calcium complexes. The reactions of L1–5H with silylamido calcium precursors (Ca[N(SiMe2R)2]2(THF)2, R=Me or H) at room temperature gave heteroleptic products ( L1, 2 )CaN(SiMe3)2 ( 1 , 2 ), ( L3, 4 )CaN(SiHMe2)2 ( 3 a , 4 a ) and homoleptic complexes ( L3, 5 )2Ca ( D3 , D5 ). NMR and X‐ray analyses proved that these calcium complexes were stabilized through Ca⋅⋅⋅C−Si, Ca⋅⋅⋅H−Si or Ca⋅⋅⋅H−C agostic interactions. Unexpectedly, calcium complexes (( L3–5 )CaN(SiMe3)2) bearing more sterically encumbered ligands of the same type were extremely unstable and underwent C−N bond cleavage processes as a consequence of intramolecular C−H bond activation, leading to the exclusive formation of (E )‐1,2‐bis(8‐isopropylquinol‐2‐yl)ethane. 相似文献
16.
Structural Characterization of N‐Alkylated Twisted Amides: Consequences for Amide Bond Resonance and N−C Cleavage
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Dr. Feng Hu Prof. Dr. Roger Lalancette Prof. Dr. Michal Szostak 《Angewandte Chemie (International ed. in English)》2016,55(16):5062-5066
Herein, we describe the first structural characterization of N‐alkylated twisted amides prepared directly by N‐alkylation of the corresponding non‐planar lactams. This study provides the first experimental evidence that N‐alkylation results in a dramatic increase of non‐planarity around the amide N?C(O) bond. Moreover, we report a rare example of a molecular wire supported by the same amide C=O‐Ag bonds. Reactivity studies demonstrate rapid nucleophilic addition to the N?C(O) moiety of N‐alkylated amides, indicating the lack of nN to π*C=O conjugation. Most crucially, we demonstrate that N‐alkylation activates the otherwise unreactive amide bond towards σ N?C cleavage by switchable coordination. 相似文献
17.
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
18.
A Cobalt(I) Pincer Complex with an η2‐Caryl−H Agostic Bond: Facile C−H Bond Cleavage through Deprotonation,Radical Abstraction,and Oxidative Addition
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Sathiyamoorthy Murugesan Dr. Berthold Stöger Dr. Ernst Pittenauer Prof. Dr. Günter Allmaier Prof. Dr. Luis F. Veiros Prof. Dr. Karl Kirchner 《Angewandte Chemie (International ed. in English)》2016,55(9):3045-3048
The synthesis and reactivity of a CoI pincer complex [Co(?3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ featuring an η2‐ Caryl?H agostic bond is described. This complex was obtained by protonation of the CoI complex [Co(PCPNMe‐iPr)(CO)2]. The CoIII hydride complex [Co(PCPNMe‐iPr)(CNtBu)2(H)]+ was obtained upon protonation of [Co(PCPNMe‐iPr)(CNtBu)2]. Three ways to cleave the agostic C?H bond are presented. First, owing to the acidity of the agostic proton, treatment with pyridine results in facile deprotonation (C?H bond cleavage) and reformation of [Co(PCPNMe‐iPr)(CO)2]. Second, C?H bond cleavage is achieved upon exposure of [Co(?3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ to oxygen or TEMPO to yield the paramagnetic CoII PCP complex [Co(PCPNMe‐iPr)(CO)2]+. Finally, replacement of one CO ligand in [Co(?3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ by CNtBu promotes the rapid oxidative addition of the agostic η2‐Caryl?H bond to give two isomeric hydride complexes of the type [Co(PCPNMe‐iPr)(CNtBu)(CO)(H)]+. 相似文献
19.
Iridium‐Catalyzed,Silyl‐Directed,peri‐Borylation of C−H Bonds in Fused Polycyclic Arenes and Heteroarenes
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Dr. Bo Su Prof. Dr. John F. Hartwig 《Angewandte Chemie (International ed. in English)》2018,57(32):10163-10167
peri‐Disubstituted naphthalenes exhibit interesting physical properties and unique chemical reactivity, due to the parallel arrangement of the bonds to the two peri‐disposed substituents. Regioselective installation of a functional group at the position peri to 1‐substituted naphthalenes is challenging due to the steric interaction between the existing substituent and the position at which the second one would be installed. We report an iridium‐catalyzed borylation of the C?H bond peri to a silyl group in naphthalenes and analogous polyaromatic hydrocarbons. The reaction occurs under mild conditions with wide functional group tolerance. The silyl group and the boryl group in the resulting products are precursors to a range of functional groups bound to the naphthalene ring through C?C, C?O, C?N, C?Br and C?Cl bonds. 相似文献
20.
Jeffrey A. Boerth Joshua R. Hummel Prof. Dr. Jonathan A. Ellman 《Angewandte Chemie (International ed. in English)》2016,55(41):12650-12654
A highly stereoselective three‐component C(sp2)?H bond addition across alkene and polarized π‐bonds is reported for which CoIII catalysis was shown to be much more effective than RhIII. The reaction proceeds at ambient temperature with both aryl and alkyl enones employed as efficient coupling partners. Moreover, the reaction exhibits extremely broad scope with respect to the aldehyde input; electron rich and poor aromatic, alkenyl, and branched and unbranched alkyl aldehydes all couple in good yield and with high diastereoselectivity. Multiple directing groups participate in this transformation, including pyrazole, pyridine, and imine functional groups. Both aromatic and alkenyl C(sp2)?H bonds undergo the three‐component addition cascade, and the alkenyl addition product can readily be converted into diastereomerically pure five‐membered lactones. Additionally, the first asymmetric reactions with CoIII‐catalyzed C?H functionalization are demonstrated with three‐component C?H bond addition cascades employing N‐tert‐butanesulfinyl imines. These examples represent the first transition metal catalyzed C?H bond additions to N‐tert‐butanesulfinyl imines, which are versatile and extensively used intermediates for the asymmetric synthesis of amines. 相似文献