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1.
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
2.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(33):10108-10112
A CoIII‐catalyzed three‐component coupling of C(sp2)−H bonds, alkynes, and halogenating agents to give alkenyl halides is reported. This transformation proceeds with high regio‐ and diastereoselectivity, and is effective for a broad range of aryl and alkyl terminal alkynes. Diverse C−H bond partners also exhibit good reactivity for a range of heteroaryl and aryl systems as well as synthetically useful secondary and tertiary amide, urea, and pyrazole directing groups. This multicomponent transformation is also compatible with allenes in place of alkynes to furnish tetrasubstituted alkenyl halides, showcasing the first halo‐arylation of allenes. 相似文献
3.
The classical Ullmann C? S cross coupling reaction of aryl iodides with aromatic/alkyl thiols under catalysis of 15 mol% Cu(OAc)2·H2O and 15 mol% 2,2′‐biimidazole works at 80°C in DMSO for 3 h to provide a variety of aryl sulfides in good to excellent yields. 相似文献
4.
D‐Glucosamine in iron‐catalysed cross‐coupling reactions of Grignards with allylic and vinylic bromides: application to the synthesis of a key sitagliptin precursor
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A sustainable D ‐glucosamine ligand is successfully introduced into iron‐catalysed C ? C cross‐coupling reactions for the first time. The Fe(acac)2/D ‐glucosamine·HCl/Et3N catalytic system was effective at 5 mol% loading in coupling reactions of Grignard reagents with organic bromides. Moderate to high efficiency was achieved with preserved stereochemistry when allyl (Csp3) or alkenyl (Csp2) bromides were coupled with phenylmagnesium (Csp2) or benzylmagnesium (Csp3) bromides. The catalytic system developed was also successfully applied for the novel and economic preparation of a Michael‐acceptor‐like starting material used in an alternative synthesis of the drug sitagliptin, a known blockbuster for the treatment of type II diabetes mellitus. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(13):3164-3169
7‐Oxabenzonorbornadienes derivatives 1 a – d underwent reductive coupling with alkyl propiolates CH3C?CCO2CH3 ( 2 a ), PhC?CCO2Et ( 2 b ), CH3(CH2)3C?CCO2CH3 ( 2 c ), CH3(CH2)4C?CCO2CH3 ( 2 d ), TMSC?CCO2Et ( 2 e ), (CH3)3C?CCO2CH3 ( 2 f ) and HC?CCO2Et ( 2 g ) in the presence of [NiBr2(dppe)] (dppe=Ph2PCH2CH2PPh2), H2O and zinc powder in acetonitrile at room temperature to afford the corresponding 2alkenyl‐1,2‐dihydronapthalen‐1‐ol derivatives 3 a – n with remarkable regio‐ and diastereoselectivity in good to excellent yields. Similarly, the reaction of 7azabenzonorbornadienes derivative 1 e with propiolates 2 a, b and d proceeded smoothly to afford reductive coupling products 2alkenyl‐1,2‐dihydronapthalene carbamates 3 o – p in good yields with high regio‐ and stereoselectivity. This nickel‐catalyzed reductive coupling can be further extended to the reaction of 7oxabenzonorbornene derivatives. Thus, 5,6‐di(methoxymethyl)‐7‐oxabicyclo[2.2.1]hept‐2‐ene ( 4 ) reacted with 2 a and 2 d to furnish cyclohexenol derivatives bearing four cis substituents 5 a and b in 81 and 84 % yield, respectively. In contrast to the results of 4 with 2 , the reaction of dimethyl 7oxabicyclo[2.2.1]hept‐5‐ene‐2,3‐dicarboxylate ( 6 ) with propiolates 2 a – d afforded the corresponding reductive coupling/cyclization products, bicyclo[3.2.1]γ‐lactones 7 a – d in good yields. The reaction provides a convenient one‐pot synthesis of γ‐lactones with remarkably high regio‐ and stereoselectivity. 相似文献
6.
C. Foces‐Foces N. Jagerovic J. Elguero 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(2):215-218
The structures of 1‐methyl‐3‐nitropyrazole and 1‐methyl‐4‐nitropyrazole, C4H5N3O2, have been determined. The 3‐nitro derivative has crystallographic m‐symmetry while the 4‐nitro compound has no imposed symmetry. The significant differences in bond distances and angles between the structures are ascribable to the electron‐withdrawing effects of the nitro group attached to C3 or C4, respectively. In both structures, the molecules are organized into layers by an extensive network of C—H?O or C—H?N hydrogen interactions. Within a layer, the molecules are arranged in a similar way, although differences of up to 0.3 Å in the analogous H?O or H?N intermolecular distances are observed. The cohesion of the layers is due to van der Waals and C—H?O contacts. 相似文献
7.
Gaowen Zhai Xueting Liu Wentao Ma Guoqiang Wang Liu Yang Shuhua Li Youting Wu Xingbang Hu 《化学:亚洲杂志》2020,15(19):3082-3086
Tandem Friedel‐Crafts (FC) and C?H/C?O coupling reactions catalyzed by tris(pentafluorophenyl) borane (B(C6F5)3) were achieved without using any other additive in the absence of solvent. This process can be used for the reactions between a series of dialkylanilines and vinyl ethers with good isolated yields of bis(4‐dialkylaminophenyl) compounds. Based on combined theoretical and experimental studies, the possible reaction mechanism was proposed. B(C6F5)3 can activate the C=C and C?O bond for FC and C?H/C?O coupling reactions respectively. The FC reaction is slow, which is followed by a fast C?H/C?O coupling. 相似文献
8.
Protic N‐Heterocyclic Carbene Versus Pyrazole: Rigorous Comparison of Proton‐ and Electron‐Donating Abilities in a Pincer‐Type Framework
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Tatsuro Toda Akihiro Yoshinari Prof. Dr. Takao Ikariya Prof. Dr. Shigeki Kuwata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(46):16675-16683
Evaluation of the acidity of proton‐responsive ligands such as protic N‐heterocyclic carbenes (NHCs) bearing an NH‐wingtip provides a key to understanding the metal–ligand cooperation in enzymatic and artificial catalysis. Here, we design a CNN pincer‐type ruthenium complex 2 bearing protic NHC and isoelectronic pyrazole units in a symmetrical skeleton, to compare their acidities and electron‐donating abilities. The synthesis is achieved by direct C?H metalation of 2‐(imidazol‐1‐yl)‐6‐(pyrazol‐3‐yl)pyridine with [RuCl2(PPh3)3]. 15N‐Labeling experiments confirm that deprotonation of 2 occurs first at the pyrazole side, indicating clearly that the protic pyrazole is more acidic than the NHC group. The electrochemical measurements as well as derivatization to carbonyl complexes demonstrate that the protic NHC is more electron‐donating than pyrazole in both protonated and deprotonated forms. 相似文献
9.
Synthesis and Crystal Structure of the Zirkonocene Alkynyl Alkenyl Complex (Z)? Cp2Zr(C?CPh){C(Ph) = C(H)P(SiMe3)2} The reaction of ( Z )? Cp2Zr(C(Ph) = C(H)P(SiMe3)2}(Cl) with lithium phenylacetylide yields the zirconocene alkynyl alkenyl complex ( Z )? Cp2Zr(C?CPh){C(Ph) = C(H)P(SiMe3)2} ( 1 ). 1 was characterised spectroscopically (IR, NMR, MS) and by X-ray structure determination. The complex crystallises triclinic in the space group P1 with a = 10.561(10), b = 11.226(12), c = 14.274(13) Å, α = 70.87(7), β = 77.70(7), γ = 77.85(7)°. In 1 , there are two different Zr? C bond distances (Zr? C(=C) 2.415(6), Zr? C(?C) 2.309(6) Å). A Zr? P interaction (Zr? P 2.774(3) Å) is observed in the solid state. 相似文献
10.
Based on the gold‐catalyzed synthesis of methyleneoxazolines, a one‐pot combination with an Alder‐ene reaction was developed. For azodicarboxylates, good to very good yields (51–99 %) of the oxazolemethylhydrazinedicarboxylates were achieved with 3 mol % of the Gagosz catalyst, [Ph3PAuNTf3]. In a less‐selective reaction, 4‐phenyl‐3H‐1,2,4‐triazol‐3,5(4 H)‐dione gave lower yields (41–49 %) of the corresponding oxazolemethylphenyltriazolidinediones. Overall, five new bonds were formed. Tetracyanoethylene afforded a cyclobutane derivative through a [2+2] cycloaddition reaction at ?40 °C, but only 45 % of the spiro compound was obtained. The less‐readily available KITPHOS ligands on gold gave even higher yields at lower catalyst loadings (2 mol %), but longer reaction times were required. 相似文献
11.
Junting Chen Jiakun Li Matthew B. Plutschack Florian Berger Tobias Ritter 《Angewandte Chemie (International ed. in English)》2020,59(14):5616-5620
Herein, we report a regioselective alkenyl electrophile synthesis from unactivated olefins that is based on a direct and regioselective C?H thianthrenation reaction. The selectivity is proposed to arise from an unusual inverse‐electron‐demand hetero‐Diels–Alder reaction. The alkenyl sulfonium salts can serve as electrophiles in palladium‐ and ruthenium‐catalyzed cross‐coupling reactions to make alkenyl C?C, C?Cl, C?Br, and C?SCF3 bonds with stereoretention. 相似文献
12.
Christopher Glidewell John N. Low Justo Cobo Manuel Nogueras Adolfo Snchez Emerson Rengifo Rodrigo Abonia 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):o314-o317
In the title compound, C20H22N6, the molecules are linked into a chain of rings by N—H?N [H?N 2.16 Å, N?N 2.950 (3) Å and N—H?N 149°] and C—H?N [H?N 2.55 Å, C?N 3.481 (3) Å and C—H?N 165°] hydrogen bonds, and these chains are linked into sheets by means of C—H?π(pyrazole) interactions. 相似文献
13.
Palladium/Norbornene‐Mediated Tandem CH Amination/CI Alkenylation Reaction of Aryl Iodides with Secondary Cyclic O‐Benzoyl Hydroxylamines and Activated Terminal Olefins
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Prof. Dr. Zhi‐Yuan Chen Chang‐Qing Ye Hui Zhu Xing‐Ping Zeng Jian‐Jun Yuan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(15):4237-4241
A novel palladium‐catalyzed norbornene‐mediated three‐component reaction for the construction of ortho‐alkenyl aromatic tertiary amines has been achieved, which represents a useful extension of the Catellani‐type tandem ortho‐selective C?H amination transformations. 相似文献
14.
Mercedes Cano JosV. Heras M.Luz Gallego Josefina Perles Caridad Ruiz‐Valero Elena Pinilla M.Rosario Torres 《Helvetica chimica acta》2003,86(9):3194-3203
Two new (η3‐allyl)palladium complexes containing the ligand 3,5‐dimethyl‐4‐nitro‐1H‐pyrazole (Hdmnpz) were synthesized and characterized as [Pd(η3‐C3H5)(Hdmnpz)2]BF4 ( 1 ) and [Pd(η3‐C3H5)(Hdmnpz)2]NO3 ( 2 ). The structures of these compounds were determined by single‐crystal X‐ray diffraction to evaluate the intermolecular assembly. Each complex exhibits similar coordination behavior consistent with cationic entities comprised of two pyrazole ligands coordinated with the [Pd(η3‐C3H5)]+ fragment in an almost square‐planar coordination geometry. In 1 , the cationic entities are propagated through strong intermolecular H‐bonds formed between the pyrazole NH groups and BF ions in one‐dimensional polymer chains along the a axis. These chains are extended into two‐dimensional sheet networks via bifurcated H‐bonds. New intermolecular interactions established between NO2 and Me substituents at the pyrazole ligand of neighboring sheets give rise to a three‐dimensional network. By contrast, compound 2 presents molecular cyclic dimers formed through N? H???O H‐bonds between two NO counterions and the pyrazole NH groups of two cationic entities. The dimers are also connected to each other through C? H???O H‐bonds between the remaining O‐atom of each NO ion and the allyl CH2 H‐atom. Those interactions expand in a layer which lies parallel to the face (101). 相似文献
15.
Zhong‐Ming Sun Dr. Shuo‐Ping Chen Pinjing Zhao Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(8):2619-2627
A convenient and waste‐free synthesis of indene‐based tertiary carbinamines by rhodium‐catalyzed imine/alkyne [3+2] annulation is described. Under the optimized conditions of 0.5–2.5 mol % [{(cod)Rh(OH)}2] (cod=1,5‐cyclooctadiene) catalyst, 1,3‐bis(diphenylphosphanyl)propane (DPPP) ligand, in toluene at 120 °C, N‐unsubstituted aromatic ketimines and internal alkynes were coupled in a 1:1 ratio to form tertiary 1H‐inden‐1‐amines in good yields and with high selectivities over isoquinoline products. A plausible catalytic cycle involves sequential imine‐directed aromatic C? H bond activation, alkyne insertion, and a rare example of intramolecular ketimine insertion into a RhI–alkenyl linkage. 相似文献
16.
Fuctionalization of Linear and Angular Phenothiazine and Phenoxazine Ring Systems via Pd(0)/XPhos Mediated Suzuki‐Miyaura Cross‐coupling Reactions
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Efeturi A. Onoabedje Uchechukwu C. Okoro David W. Knight Amitabha Sarkar 《Journal of heterocyclic chemistry》2016,53(6):1787-1794
Chloro‐substituted phenothiazines and phenoxazines were successfully derivatized with phenylboronic and styrylboronic acids using Suzuki–Miyaura cross‐coupling reaction catalyzed by Pd(0)/XPhos for the first time in good yields. The protocol employed 4 mol% Pd and 7 mol% XPhos with K3PO4 in acetonitrile at 80°C. The reaction condition is compatible with carbonyl and unprotected N–H groups in substrates. Structural assignments were established by combined spectroscopic (UV, IR, 1H, and 13C NMR), MS, and elemental analytical data. 相似文献
17.
Yun‐Fei Zhang Bin Wu Prof. Dr. Zhang‐Jie Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(49):17808-17812
Ir‐catalyzed sp2 C?H amidation of aldehydes with various anilines as stoichiometric or catalytic directing groups was accomplished. A wide range of substrates were selectively amidated in good to excellent yields with broad functional group tolerance. The iridacycle complexes were isolated, characterized, and proved as key intermediates. Kinetic studies and Hammett plots provided detailed understandings of this amidation. According to the mechanism, the electron‐rich ArSO2N3 was proved effective for intermolecular sp3 C?H amidation. 相似文献
18.
Rhodium(III)‐Catalyzed ortho Alkenylation of N‐Phenoxyacetamides with N‐Tosylhydrazones or Diazoesters through CH Activation
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Fangdong Hu Ying Xia Fei Ye Zhenxing Liu Prof. Dr. Chen Ma Prof. Dr. Yan Zhang Prof. Dr. Jianbo Wang 《Angewandte Chemie (International ed. in English)》2014,53(5):1364-1367
A coupling reaction of N‐phenoxyacetamides with N‐tosylhydrazones or diazoesters through RhIII‐catalyzed C? H activation is reported. In this reaction, ortho‐alkenyl phenols were obtained in good yields and with excellent regio‐ and stereoselectivity. Rh–carbene migratory insertion is proposed as the key step in the reaction mechanism. 相似文献
19.
Cooperative GeN Bond Activation in Aluminium‐Functionalised Aminogermanes and Spontaneous Imine Elimination via an Intermediate Germyl Cation
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Prof. Dr. Werner Uhl Dr. Jens Tannert Christian Honacker Dr. Marcus Layh Dr. Zheng‐Wang Qu Dr. Tobias Risthaus Prof. Dr. Stefan Grimme 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2638-2650
Hydrometallation of iPr2N?Ge(CMe3)(C?C?CMe3)2 with H?M(CMe3)2 (M=Al, Ga) affords alkenyl–alkynylgermanes in which the Lewis‐acidic metal atoms are not coordinated by the amino N atoms but by the α‐C atoms of the ethynyl groups. These interactions result in a lengthening of the Ge?C bonds by approximately 10 pm and a comparably strong deviation of the Ge?C?C angle from linearity (154.3(1)°). This unusual behaviour may be caused by steric shielding of the N atoms. Coordination of the metal atoms by the amino groups is observed upon hydrometallation of Et2N?Ge(C6H5)(C?C?CMe3)2, bearing a smaller NR2 group. Strong M?N interactions lead to a lengthening of the Ge?N bonds by 10 to 15 pm and a strong deviation of the M atoms from the MC3 plane by 52 and 47 pm, for Al and Ga, respectively. Dual hydrometallation is achieved only with HAl(CMe3)2. In the product, there is a strong Al?N bond with converging Al?N and Ge?N distances (208 vs. 200 pm) and an interaction of the second Al atom to the phenyl group. Addition of chloride anions terminates the latter interaction while the activated Ge?N bond undergoes an unprecedented elimination of EtN?C(H)Me at room temperature, leading to a germane with a Ge?H bond. State‐of‐the‐art DFT calculations reveal that the unique mechanism comprises the transfer of the amino group from Ge to Al to yield an intermediate germyl cation as a strong Lewis acid, which induces β‐hydride elimination, with chloride binding being crucial for providing the thermodynamic driving force. 相似文献
20.
1,1‐Organoboration, using triethyl‐, triallyl‐ and triphenyl‐borane (BEt3, BAll3, BPh3), of dimethysilylethynyl(trimethyl)stannane, Me3Sn? C?C? Si(H)Me2 ( 1 ), affords alkenes bearing three different organometallic groups at the C?C bond. For BEt3 and BPh3, the first products are the alkenes 4 with boryl and stannyl groups in cis‐positions. These rearrange by consecutive 1,1‐deorganoboration and 1,1‐organoboration into the isomers 5 as the final products, where boryl and silyl groups are in cis‐positions linked by an electron‐deficient Si? H? B bridge. 1,1‐Ethylboration of bis(dimethylsilylethynyl)dimethylstannane, Me2Sn[C?C? Si(H)Me2]2 ( 2 ), leads to the stannacyclopentadiene 6 along with non‐cyclic di(alkenyl)tin compounds 7 and 8 . 1,1‐Ethylboration of ethynyl(trimethylstannylethynyl)methylsilane, Me(H)Si(C?C? SnMe3)C?C? H ( 3 ), leads selectively to a new silacyclopentadiene 13 as the final product. The reactions were monitored and the products were characterized by multinuclear magnetic resonance spectroscopy (1H, 11B, 13C, 29Si and 119Sn NMR). Copyright © 2005 John Wiley & Sons, Ltd. 相似文献