- N-Methylphenothiazine S-Oxide Enabled Oxidative C(sp2)–C(sp2) Coupling of Boronic Acids with Organolithiums via Phenothiaziniums
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Herein, we report the development of a transition-metal-free oxidative C(sp2)–C(sp2) coupling of readily available boronic acids and organolithiums via phenothiazinium ions. Various biaryl, styrene, and diene derivatives were obtained using this reaction system. The key to this process is N-methylphenothiazine S-oxide (PTZSO), which allows efficient conversion of boronic acids to phenothiazinium ions. The mechanism of phenothiazinium formation using PTZSO was investigated using theoretical calculations and experiments, which provided insight into the unique reactivity of PTZSO.
- Yoshida, Tatsuki,Honda, Yuki,Morofuji, Tatsuya,Kano, Naokazu
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p. 9664 - 9668
(2021/12/17)
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- Transition-Metal-Free Matsuda-Heck Type Cross-Coupling and Mechanistic Evidence for a Radical Mechanism
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The Matsuda-Heck reaction, usually performed with palladium catalysts, can be carried out under transition-metal-free conditions in the presence of a KOtBu/DMF couple. This system allows the selective and direct synthesis of stilbenes from aryldiazonium salts under mild temperature (20 °C). Mechanistic studies suggest a radical pathway in which the DMF acts as the initiator of the overall process.
- Bergès, Julien,Zaid, Yassir,Tlili, Anis,Sotiropoulos, Jean-Marc,Taillefer, Marc
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supporting information
p. 1559 - 1563
(2021/02/27)
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- Synthesis, crystal structure, and catalytic activity of bridged-bis(N-heterocyclic carbene) palladium(II) complexes in selective Mizoroki-Heck cross-coupling reactions
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A series of three 1,3-propanediyl bridged bis(N-heterocyclic carbene)palladium(II) complexes (Pd-BNH1, Pd-BNH2, and Pd-BNH3), with + I effect order of the N-substituents of the ligand (isopropyl > benzyl > methoxyphenyl), was the subject of a spectroscopic, structural, computational and catalytic investigation. The bis(NHC)PdBr2 complexes were evaluated in Mizoroki-Heck coupling reactions of aryl bromides with styrene or acrylate derivatives and showed high catalytic efficiency to produce diarylethenes and cinnamic acid derivatives. The X-ray structure of the most active palladium complex Pd-BNH3 shows that the Pd(II) center is bonded to the two carbon atoms of the bis(N-heterocyclic carbene) and two bromide ligands in cis position, resulting in a distorted square planar geometry. The NMR data of Pd-BNH3 are consistent with a single chair-boat rigid conformer in solution with no dynamic behavior of the 8-membered ring palladacycle in the temperature range 25–120 °C. The catalytic activities of three Pd-bridged bis(NHC) complexes in the Mizoroki-Heck cross-coupling reactions were not found to have a direct correlation with +I effect order of the N-substituents of the ligand. However, a direct correlation was found between the DFT calculated absolute softness of the three complexes with their respective catalytic activity. The highest calculated softness, in the case of Pd-BNH3, is expected to favor the coordination steps of both the soft aryl bromides and alkenes in the Heck catalytic cycle.
- El Ali, Bassam,Fettouhi, Mohammed,Iali, Wissam,Mansour, Waseem,Suleiman, Rami
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- Dual ligand-promoted palladium-catalyzed nondirected C-H alkenylation of aryl ethers
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Direct C-H functionalization of aryl ethers remains challenging owing to their low reactivity and selectivity. Herein, a novel strategy for nondirected C-H alkenylation of aryl ethers promoted by a dual ligand catalyst was demonstrated. This catalytic system readily achieved the highly efficient alkenylation of alkyl aryl ethers (anisole, phenetole, n-propyl phenyl ether, n-butyl phenyl ether and benzyl phenyl ether), cyclic aryl ethers (1,4-benzodioxan, 2,3-dihydrobenzofuran, dibenzofuran), and diphenyl oxides. Moreover, the proposed methodology was successfully employed for the late-stage modification of complex drugs containing the aryl ether motif. Interestingly, the compounds developed herein displayed fluorescent properties, which would facilitate their biological applications.
- Fu, Manlin,Liu, Jiang,Wang, Lei,Yin, Biao,Zhu, Qing
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supporting information
p. 3293 - 3296
(2020/04/02)
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- Palladium-catalyzed decarboxylative coupling of α,β-unsaturated carboxylic acids with aryl tosylates
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We report a general method for selective cross-coupling of α,β-unsaturated carboxylic acids with aryl tosylates enabled by versatile Pd(II) complexes. This method features the general cross-coupling of ubiquitous α,β-unsaturated carboxylic acids by decarboxylation. The transformation is characterized by its operational simplicity, the use of inexpensive, air-stable Pd(II) catalysts, scalability and wide substrate scope. The reaction proceeds with high trans selectivity to furnish valuable (E)-1,2-diarylethenes.
- Zhang, Wei,Chen, Gairong,Wang, Kaikai,Xia, Ran
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-
- Palladium nanoparticles immobilized on Schiff base-functionalized mesoporous silica as a highly efficient and magnetically recoverable nanocatalyst for Heck coupling reaction
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A new magnetically recoverable nanocatalyst was prepared by functionalization of mesoporous silica (SBA-15) with a Schiff base ligand, and then immobilization of palladium nanoparticles on it using a simple procedure. This heterogeneous catalyst was fully characterized using appropriate analyses and its catalytic efficiency was investigated in Heck reaction using iodo-, bromo- and chlorobenzene derivatives and styrene, with the aim of synthesizing stilbene derivatives, a class of compounds with a variety of pharmacological properties. Some of the characteristics of this nanocatalyst include good dispersion of palladium nanoparticles on the SBA-15 support, easy separation, catalyses the production of stilbene derivatives in a short time with excellent yields even for bromo- and chlorobenzene, and preservation of its catalytic activity after eight reaction cycles.
- Khodaei, Mohammad Mehdi,Dehghan, Mahsa
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- A tailored polymeric cationic tag-anionic Pd(ii) complex as a catalyst for the low-leaching Heck-Mizoroki coupling in flow and in biomass-derived GVL
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The [PdCl4]2- palladium complex has been immobilized on a polystyrene-type resin loaded with pincer-type imidazolium ionic tag binding sites. The catalytic system (Pd(ii)-POLI-TAG) has proved to be highly active in the definition of an efficient protocol for the Heck-Mizoroki coupling reaction under batch and flow conditions. Importantly, it is shown to be highly robust in combination with a safe non-toxic reaction medium, i.e. biomass-derived GVL, since it could be reused for multiple runs without significantly losing its activity.
- Mahmoudi, Hamed,Valentini, Federica,Ferlin, Francesco,Bivona, Lucia Anna,Anastasiou, Ioannis,Fusaro, Luca,Aprile, Carmela,Marrocchi, Assunta,Vaccaro, Luigi
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supporting information
p. 355 - 360
(2019/01/28)
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- Diarylethene synthesis method without transition metal catalysis
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The invention discloses a diarylethene synthesis method without transition metal catalysis. The method comprises the following steps: a cinnamic acid derivative and aryl trifluoroborate are subjectedto a decarboxylation coupling reaction in a solvent under the action of an oxidizing agent, postprocessing is performed after the reaction, and diarylethene is obtained. K2S2O8 is adopted to promote acatalytic system in the synthetic method, and a free radical coupling reaction can be performed directly under the condition that no ligand, transition metal or alkali is added. The method has widersubstrate range and higher yield; the method is simple to operate, reaction conditions are mild, and large-scale application is facilitated.
- -
-
Paragraph 0041-0045
(2019/02/06)
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- Preparation method of palladium catalyzed 1,2-trans diaryl alkene
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The invention discloses a preparation method of palladium catalyzed 1,2-trans diaryl alkene. The method comprises the following steps that under the effects of catalysts, cocatalysts and alkali, arylacrylic acid and aromatic esters p-toluene sulfonate take decarboxylation coupling reaction in an organic solvent; after the reaction is finished, the 1,2-trans diaryl alkene is obtained through posttreatment. The method has the advantages that through C-O bond fracture, the operation is simple; a stable palladium catalyst with low cost is used; the substrate applicability is high; the harsh reaction conditions and the addition of strong alkali are not needed; the trans 1,2-diaryl alkene can be generated at high selectivity.
- -
-
Paragraph 0043-0045
(2019/06/11)
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- Facile synthesis of a recyclable Pd-rGO/CNT/CaFe2O4 nanocomposite with high multifunctional photocatalytic activity under visible light irradiation
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We report a facile method to synthesize a magnetically separable Pd-rGO/CNT/CaFe2O4 photocatalyst. The incorporation of CNTs into rGO can form a conductive network structure to bridge the gaps between rGO sheets. This conductive netw
- Bagherzadeh, Mojtaba,Kaveh, Reyhaneh,Mahmoudi, Hamed
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p. 16257 - 16266
(2019/07/16)
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- Novel Carbazole-Based N-Heterocyclic Carbene Ligands to Access Synthetically Relevant Stilbenes in Pd-Catalyzed Coupling Processes
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A series of new carbazole-based N-heterocyclic carbene (NHC) ligands have been synthesized in a simple and facile synthetic route and subsequently used in a Pd/carbazole-based NHC catalytic system, which was found to be effective in catalyzing Heck reactions to provide substituted stilbene derivatives in good yields. Several bioactive stilbenes, including pterostilbene, pinosylvin, trimethoxy resveratrol, and resveratrol, were synthesized in good yields, and a 10 mmol scale-up was also performed for trimethoxy resveratrol. The synthetic application was also extended by performing a double-tandem chemoselective Heck reaction followed by Miyaura borylation in a one-pot procedure to give single-step access to synthetically useful stilbenyl boronate esters. Similarly, a unique triple-tandem protocol of a chemoselective Heck reaction/Miyaura borylation/Suzuki–Miyaura coupling reaction sequence was performed for the one-pot modification of biologically relevant molecules.
- Girase, Tejpalsingh Ramsingh,Kapdi, Anant R.
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supporting information
p. 2611 - 2619
(2019/07/05)
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- Synthesis and characterization of a new zwitterionic palladium complex as an environmentally friendly catalyst for the Heck-Mizoroki coupling reaction in GVL
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A new zwitterionic Palladium (II) complex has been synthesized by the one-pot mixing of Pd(OAc)2, 2-aminophenol and (3-formyl-4-hydroxy-5-methylbenzyl) triphenylphosphonium chloride, in refluxing ethanol. The metal complex formed was characterized by 1H NMR, 13C NMR, 31P NMR and X-ray crystallographic technique and its efficiency tested as a homogeneous pre-catalyst in Heck-Mizoroki cross coupling reaction using γ-Valerolactone (GVL) as a biomass-derived green medium. All the products were obtained in good to excellent yields.
- Bagherzadeh, Mojtaba,Mahmoudi, Hamed,Ataie, Saeed,Bahjati, Mohammad,Kia, Reza,Raithby, Paul R.,Vaccaro, Luigi
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- O -Iodoxybenzoic acid mediated generation of aryl free radicals: Synthesis of stilbenes through C-C cross-coupling with β-nitrostyrenes
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The generation of an aryl free radicals in the presence of nitrostyrenes through a combination of aryl hydrazines and o-iodoxybenzoic acid led to the synthesis of stilbenes by forming a new carbon-carbon bond after subsequent elimination of a nitrosyl radical. The symmetrical and unsymmetrical stilbenes with excellent E-selectivity were synthesized in good yields, with advantages of broad substrate scope and transition metal free, mild reaction conditions, under an open atmosphere in a short reaction time. A free radical mediated mechanism was postulated and supported by radical trapping experiments. Application of the developed methodology is demonstrated through a simple, two step synthesis of resveratrol, a valuable stilbenoid for anticancer and neurological studies via its prodrug E-1,3-dimethoxy-5-(4-methoxystyryl)benzene.
- Wagh, Ganesh,Autade, Snehalata,Patil, Pravin C.,Akamanchi, Krishnacharya G.
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p. 3301 - 3309
(2018/03/06)
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- Group 4 Metallocene Difluoride/Palladium Bimetallic Catalysts for the Reductive Cross-Coupling of Alkynes with Aryl Iodides and Bromides
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A novel protocol has been developed for the selective synthesis of (E)-alkenes via the reductive cross-coupling of alkynes and aryl halides using a bimetallic catalyst system composed of a group 4 metallocene difluoride (Cp2[M]F2; [M] = Hf or Zr; Cp = cyclopentadienide) and palladium dichloride. This reaction proceeds via a coupling between an aryl halide and an in situ generated alkenyl metallocene intermediate derived from the group 4 metallocene difluoride, a hydrosilane, and an alkyne. For a catalytic reductive coupling, the addition of sodium fluoride (NaF) to the reaction system is required. Moreover, in the presence of NaF, a ligand exchange was observed by NMR spectroscopy in hafnocene diiodide (Cp2HfI2) to afford hafnocene difluoride (Cp2HfF2).
- Takahashi, Keita,Morishita, Hiromitsu,Ogiwara, Yohei,Sakai, Norio
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p. 13734 - 13742
(2018/11/03)
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- Palladium-Catalyzed Reductive Coupling Reaction of Terminal Alkynes with Aryl Iodides Utilizing Hafnocene Difluoride as a Hafnium Hydride Precursor Leading to trans-Alkenes
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Herein, we describe a reductive cross-coupling of alkynes and aryl iodides by using a novel catalytic system composed of a catalytic amount of palladium dichloride and a promoter precursor, hafnocene difluoride (Cp2HfF2, Cp=cyclopentadienyl anion), in the presence of a mild reducing reagent, a hydrosilane, leading to a one-pot preparation of trans-alkenes. In this process, a series of coupling reactions efficiently proceeds through the following three steps: (i) an initial formation of hafnocene hydride from hafnocene difluoride and the hydrosilane, (ii) a subsequent hydrohafnation toward alkynes, and (iii) a final transmetalation of the alkenyl hafnium species to a palladium complex. This reductive coupling could be chemoselectively applied to the preparation of trans-alkenes with various functional groups, such as an alkyl group, a halogen, an ester, a nitro group, a heterocycle, a boronic ester, and an internal alkyne.
- Takahashi, Keita,Ogiwara, Yohei,Sakai, Norio
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supporting information
p. 809 - 814
(2018/03/13)
-
- Olefination of N-Sulfinylimines under Mild Conditions
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A very simple and efficient diastereoselective synthesis of 1,2-disubstituted alkenes has been achieved under mild conditions. Sulfoxide stabilised N-sulfinylimines reacted with in-situ-generated phosphonate carbanions to give 1,2-disubtituted alkenes in good to excellent yields. Different aryl phosphonates reacted with a range of electronically diverse N-sulfinylimines to give alkenes with >99:1 E selectivity. The most important feature of this protocol is that the reaction can be carried out at room temperature with inexpensive sodium hydride as the most effective base to generate the reactive phosphonate carbanions, and producing the alkenes with E selectivity in up to 85 % isolated yield.
- Dhara, Shubhendu,Diesendruck, Charles E.
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p. 1184 - 1190
(2017/03/11)
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- Synthesis, structure and catalytic activity of xylylene-bridged dipalladium complexes with triazolylidene ligands
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A series of di-N-heterocyclic carbene (NHC) dipalladium complexes, [PdPyBr2]2(di-NHC) (2a–h), in which di-NHC represents a di-triazolylidene, featuring a 1,4-xylylene spacer between the carbene units, have been prepared from the reactions of the corresponding ditriazolium bromides with PdCl2 and excess NaBr as an additive in the presence of K2CO3 in pyridine. All of the complexes were fully characterized by NMR spectra, IR and elemental analyses. The molecular structure of 2b was determined by X-ray diffraction study, showing the intermolecular hydrogen bonding of Br···H–C. The influences of size of ligands on the catalytic activity have been investigated in the Heck reaction of styrene with bromobenzene. The complex 2g showed the best catalytic activity, and it is active for various aryl bromides with different electronic and steric properties and styrenes with both electron-donating and electron-withdrawing groups.
- Du, Yufeng,Liang, Beibei,Yang, Fenglei,Shi, Yanhui,Li, Xiuling,Pang, Guangsheng,Cao, Changsheng
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p. 193 - 201
(2017/03/16)
-
- The aromatic production of olefins
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PROBLEM TO BE SOLVED: To provide a method for efficiently producing aromatic olefins useful for various functional chemicals.SOLUTION: Aromatic olefins are produced by reaction of an aromatic compound with an epoxide or aldehyde in the presence of a solid
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-
Paragraph 0032; 0033
(2017/02/09)
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- Preparation of Vinyl Arenes by Nickel-Catalyzed Reductive Coupling of Aryl Halides with Vinyl Bromides
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This work emphasizes the synthesis of substituted vinyl arenes by reductive coupling of aryl halides with vinyl bromides under mild and easy-to-operate nickel-catalyzed reaction conditions. A broad range of aryl halides, including heteroaromatics, and vinyl bromides were employed to yielding products in moderate to excellent yields with high functional-group tolerance. The nickel-catalytic system displays good chemoselectivity between the two C(sp2)-halide coupling partners, thus demonstrating a mechanistic pathway distinct from other stepwise protocols.
- Liu, Jiandong,Ren, Qinghua,Zhang, Xinghua,Gong, Hegui
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supporting information
p. 15544 - 15548
(2016/12/09)
-
- Synthesis of stilbene derivatives via visible-light-induced cross-coupling of aryl diazonium salts with nitroalkenes using-NO2 as a leaving group
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The straightforward visible-light-induced synthesis of stilbene compounds via the cross-coupling of nitroalkenes and diazonium tetrafluoroborates under transition-metal-free conditions is described. The protocol uses green LEDs as light sources and eosin Y as an organophotoredox catalyst. Broad substrate scope and exclusive selectivity for the (E)-configuration of stilbenes are observed. This protocol proceeds via a radical pathway, with nitroalkenes serving as the radical acceptor, and the nitro group is cleaved during the process.
- Zhang, Na,Quan, Zheng-Jun,Zhang, Zhang,Da, Yu-Xia,Wang, Xi-Cun
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supporting information
p. 14234 - 14237
(2016/12/14)
-
- A stilbene compound of preparation method
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The invention provides a preparation method of toluylene compounds. A deep eutectic solvent formed by use of choline chloride and amide is taken as a reaction solvent, and substituted or unsubstituted diethyl benzylphosphonate and substituted or unsubstituted benzaldehyde are taken as raw materials to have a Wittig-Horner reaction under catalysis of an alkali, and consequently, the toluylene compounds can be obtained. According to the preparation method, the deep eutectic solvent formed by use of choline chloride and amide is taken as the reaction solvent, and the solvent is suitable for the synthesis of the toluylene compounds; the preparation method has the advantages of good universality, mild reaction conditions, convenient operations, low cost, environmental friendliness and the like, and is suitable for industrial production.
- -
-
Paragraph 0056-0058
(2017/05/04)
-
- TRIARYLAMINE DERIVATIVE AND ELECTROPHOTOGRAPHIC PHOTOSENSITIVE MEMBER
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A triarylamine derivative is represented by general formula (1) shown below. In general formula (1), R1, R2, and R3 each represent, independently of one another, a halogen atom, an optionally substituted alkyl group having a carbon number of at least 1 and no greater than 6, an optionally substituted alkoxy group having a carbon number of at least 1 and no greater than 6, or an optionally substituted aryl group having a carbon number of at least 6 and no greater than 12. In general formula (1), o, p, and q each represent, independently of one another, an integer of at least 0 and no greater than 4, and m and n each represent, independently of one another, an integer of at least 1 and no greater than 2.
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-
-
- Palladium-catalyzed Mizoroki-Heck-type reactions of [Ph2SRfn][OTf] with alkenes at room temperature
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The first Pd-catalyzed Mizoroki-Heck-type reaction of [Ph2SRfn][OTf] with alkenes is described. The reaction of [Ph2SRfn][OTf] (Rfn = CF3, CH2CF3) with alkenes in the presence of 10 mol% Pd[P(t-Bu)3]2 and TsOH at room temperature provided the corresponding phenylation products in good to high yields. The bases that benefit the traditional Mizoroki-Heck reactions severely inhibited the transformation with [Ph2SRfn][OTf], whereas acids significantly improved the reaction. This protocol supplies a new class of cross-coupling partners for Mizoroki-Heck-type reactions and gains important insights into the reactivity of phenylsulfonium salts either with or without fluorine-containing alkyl groups as the promising phenylation reagents in organic synthesis.
- Wang, Shi-Meng,Song, Hai-Xia,Wang, Xiao-Yan,Liu, Nan,Qin, Hua-Li,Zhang, Cheng-Pan
-
supporting information
p. 11893 - 11896
(2016/10/09)
-
- Supported C60-IL-PdNPs as extremely active nanocatalysts for C-C cross-coupling reactions
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A C60-ionic liquid hybrid has been covalently linked to three different solid supports, namely amorphous silica, SBA-15 and Fe2O3@SiO2, and the resulting materials have been employed as covalently supported ioni
- Giacalone, Francesco,Campisciano, Vincenzo,Calabrese, Carla,La Parola, Valeria,Liotta, Leonarda F.,Aprile, Carmela,Gruttadauria, Michelangelo
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p. 17193 - 17206
(2016/11/11)
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- Triphenylamine derivative, electrophotographic photosensitive member, and image forming apparatus
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A triarylamine derivative is represented by general formula (I). In general formula (I), R1 and R2 each represent, independently of one another, a chemical group selected from the group consisting of a halogen atom, an optionally substituted alkyl group having a carbon number of 1-6, an optionally substituted alkoxy group having a carbon number of 1-6, and an optionally substituted aryl group having a carbon number of 6-12. In general formula (I), k and l each represent an integer of at least 0 and no greater than 4. When k and l represent integers greater than 1, chemical groups R1 bonded to the same aromatic ring and chemical groups R2 bonded to the same aromatic ring may be the same or different to one another. In general formula (I), m and n each represent a different integer of at least 1 and no greater than 3.
- -
-
Paragraph 0260; 0267; 0268; 0309; 0310
(2016/10/08)
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- An efficient trifunctional benzhydrazone ligated Pd(II) complex for Heck reaction of aryl bromides
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Synthesis of air and thermally stable trifunctional O, N, and O-terdentate benzhydrazone Pd(II) complex is reported and characterized by elemental analysis, spectral methods, and single crystal X-ray crystallographic technique. The new and reusable homogeneous catalyst has been effectively applied to the Mizoroki-Heck reaction of activated and deactivated aryl bromides with various olefins under mild reaction conditions in good to excellent yields up to 99%.
- Muthumari, Subramanian,Mohan, Nanjan,Ramesh, Rengan
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supporting information
p. 4170 - 4174
(2015/06/22)
-
- THERAPEUTIC AGENTS FOR SKIN DISEASES AND CONDITIONS
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The present invention relates to method(s) of treating a subject afflicted with a skin disease or condition, the method comprising administering to the subject or patient in need a composition comprising a therapeutically effective amount of a substituted cis or trans- stilbene or a stilbene hybrid. A method of treating or reducing the likelihood of a skin disease or condition in a patient is an additional embodiment of the present invention. Preferred pharmaceutical compositions of the invention include nanoemulsions comprising a therapeutically effective amount of a substituted cis or trans-stilbene or stilbene hybrid and at least one antibiotic.
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Page/Page column 36; 48-49; 53
(2015/06/18)
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- Pd nanoparticles immobilized on Fe3O4 @ poly(ethylene glycol) bridged amine functionalized imidazolium ionic liquid: A magnetically separable catalyst for heck in water
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A palladium-based catalyst supported on novel Fe3O4 @ Poly(ethylene glycol) bridged amine functionalized imidazolium ionic liquid (Fe3O4@PEG-AIm-NH2- IL) was successfully prepared by a facile method. The catalyst was characterized by FT-IR, TEM, VSM, XRD, XPS and TGA-DSC, which showed high activity and stability for the Heck reaction in pure water. Furthermore, the catalyst could be recovered in a facile manner from the reaction mixture and recycled five times without any loss in activity.
- Liu, Xiang,Zhao, Xiaohua,Lu, Ming
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p. 1549 - 1556
(2019/11/28)
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- Pd(II) complexes with amide-based macrocycles: Syntheses, properties and applications in cross-coupling reactions
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This work shows Pd(ii) complexes in a set of 13-membered amide-based macrocyclic ligands varied by the placement of e--donating and e--withdrawing substituents on the ligand framework. Ligands constitute a N4 square-planar cavity and optimally house the Pd(ii) ion. The solution-state structure via NMR and absorption spectra substantiates the solid-state structure obtained by crystallography. The electrochemical studies display the impact of electronic substituents on ligands that significantly influence the redox properties and also shift the locus of oxidation. These complexes were used in the Suzuki and Heck cross-coupling reactions. The moderate cross-coupling reaction results are due to limited redox accessibility that can be improved either by using substrates with a better leaving group or by placing electron-withdrawing substituents on the macrocyclic ligands.
- Kumar, Sushil,Jha, Rajeev Ranjan,Yadav, Sunil,Gupta, Rajeev
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p. 2042 - 2051
(2015/03/18)
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- Improving reactivity and selectivity of aqueous-based Heck reactions by the local hydrophobicity of phosphine ligands
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Modification of a triarylphosphine with a cholate moiety affords a new ligand, 1, which is effective in palladium-catalyzed Heck cross-couplings between acrylates and aryl iodides under mild, aqueous reaction conditions. High yields, up to 99%, were achieved in water at 40 °C. In competition studies, a more hydrophobic substrate (n-Bu acrylate) was preferred over the least hydrophobic substrate (methyl acrylate), supportive of a localized hydrophobic microenvironment near the catalytic center. The enhanced reactivity and selectivity for hydrophobic substrates disappeared when the local hydrophobicity was eliminated using a standard water-soluble phosphine or in organic solvents.
- Roberts, Gina M.,Zhang, Shiyong,Zhao, Yan,Woo, L. Keith
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p. 8263 - 8270
(2015/10/05)
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- Controlled synthesis of uniform palladium nanoparticles on novel micro-porous carbon as a recyclable heterogeneous catalyst for the Heck reaction
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Novel dual-porous carbon-supported palladium nanoparticle (Pd NP) catalysts were prepared by sequential carbonization and reduction of microporous organic polymer-encaged PdCl2. The diverse pore structure of microporous organic polymers provides a reservoir for the palladium precursors and prevents Pd NPs from sintering during the carbonization and reaction. The microporous structure has a significant effect on the size and dispersion of palladium NPs. The average size of the Pd NPs (in the range of 4-6 nm) was tuned by changing the pore size distribution and the carbonization temperature. The resulting carbon-supported Pd NPs were characterized by TEM, BET, XRD, and XPS and the Pd loading was calculated by AAS. The encaged Pd NP catalysts prepared by this methodology exhibited outstanding stability and reusability in the Heck reaction and could be reused at least 10 times without appreciable loss of activity.
- Song, Kunpeng,Liu, Peng,Wang, Jingyu,Pang, Lei,Chen, Jian,Hussain, Irshad,Tan, Bien,Li, Tao
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p. 13906 - 13913
(2015/08/18)
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- Cross-Linked Thiazolidine Network as Support for Palladium: A New Catalyst for Suzuki and Heck Reactions
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A thiazolidine-based material was used for the first time as support for palladium. The support was prepared by starting from a highly cross-linked thiazolium-based material, obtained by radical oligomerization of a bisvinylthiazolium dibromide salt in the presence of 3-mercaptopropyl-modified silica SBA-15. Palladium was immobilized by treatment with tetrachloropalladate salt. Reduction with sodium borohydride afforded a thiazolidine-based material that acted as ligands for the Pd species. The thiazolidine-based palladium catalyst was fully characterized and, working in only 0.1 mol% amount, displayed good activity in the Suzuki-Miyaura and in the Heck reactions. Several biphenyl and alkene compounds could be prepared in high yields. The catalytic material proved to be fully recoverable and it was representatively used for three times in the Suzuki-Miyaura reaction without showing any decrease in its activity.
- Bivona, Lucia Anna,Giacalone, Francesco,Vaccaro, Luigi,Aprile, Carmela,Gruttadauria, Michelangelo
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p. 2526 - 2533
(2015/08/24)
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- Biomimetic oxidative dimerization of anodically generated stilbene radical cations: Effect of aromatic substitution on product distribution and reaction pathways
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A systematic study of the electrochemical oxidation of 1,2-diarylalkenes was carried out with the focus on detailed product studies and variation of product type as a function of aromatic substitution. A reinvestigation of the electrochemical oxidation of 4,4′-dimethoxystilbene under various conditions was first carried out, and all products formed were fully characterized and quantitated. This was followed by a systematic investigation of the effect of aromatic substitution on the nature and distribution of the products. The aromatic substituents were found to fall into three main categories, viz., substrates in which the nature and position of the aromatic substituents gave rise to essentially the same products as 4,4′- dimethoxystilbene, for example, tetraaryltetrahydrofurans, dehydrotetralins, and aldehydes (p-MeO or p-NMe2 on one ring and X on the other ring, where X = o-MeO or p-alkyl, or m- or p-EWG; e.g., 4-methoxy-4′- trifluoromethylstilbene); those that gave rise to a mixture of indanyl (or tetralinyl) acetamides and dehydrotetralins (or pallidols) (both or one ring substituted by alkyl groups, e.g., 4,4′-dimethylstilbene); and those where strategic placement of donor groups, such as OMe and OH, led to the formation of ampelopsin F and pallidol-type carbon skeletons (e.g., 4,3′,4′- trimethoxystilbene). Reaction pathways to rationalize the formation of the different products are presented.
- Hong, Fong-Jiao,Low, Yun-Yee,Chong, Kam-Weng,Thomas, Noel F.,Kam, Toh-Seok
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supporting information
p. 4528 - 4543
(2014/06/09)
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- Synthesis and bioactivity of resveratrol analogues
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It has been reported that resveratrol enhanced SIRT1 expression and significantly mimicked calorie restriction by stimulating Sir2 which is the most homologic homologue of SIRT1 of mammalian. A series of novel resveratrol derivatives were designed and synthesized as novel SIRT1 activator candidates. These synthesized compounds were characterized by spectral (1H NMR) analysis and examined for their Sir2 activation against yeast parental strain-BY4743 at a concentration of 100 μM/L by Bioscreen C MBR machine. Several compounds showed a promising Sir2 activation activity compared with resveratrol. Meanwhile, the structure-activity relationships with Sirt2 activation activities were also discussed.
- Ao, Junli,Chen, Yuanmou,Xu, Xiaoling,Zhang, Xu,Yu, Yue,Yu, Peng,Hua, Erbing
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p. 2092 - 2098
(2014/06/09)
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- Aerobic oxidative coupling of resveratrol and its analogues by visible light using mesoporous graphitic carbon nitride (mpg-C3N4) as a bioinspired catalyst
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The first aerobic oxidative coupling of resveratrol and its analogues by mesoporous graphitic carbon nitride as a bioinspired catalyst with visible light has been developed. With this method, δ-viniferin and its analogues were synthesized in moderate to high yield. The metal-free conditions, visible-light irradiation, and the ideal oxidant, molecular oxygen, make this coupling reaction environmental friendly and practical. Copyright
- Song, Tao,Zhou, Bo,Peng, Guang-Wei,Zhang, Qing-Bao,Wu, Li-Zhu,Liu, Qiang,Wang, Yong
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supporting information
p. 678 - 682
(2014/01/23)
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- Evidences of release and catch mechanism in the Heck reaction catalyzed by palladium immobilized on highly cross-linked-supported imidazolium salts
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Palladium (10 wt%) on a highly cross-linked imidazolium-based material was used as catalyst in 0.1 mol% in the Heck reaction between several alkenes and aryl iodides. Products were obtained from good to high yields. Deeper investigations showed a release of Pd species in solution and their capture by the imidazolium-based support. When a sixfold amount of support was employed the re-captured Pd species (0.5-0.6 wt%) were not anymore catalytically active. This result represents a new interesting aspect of this work since the highly cross-linked imidazolium-based material can act also as Pd scavenger avoiding the release of the metal in solution. Important differences between Heck and Suzuki reactions have been evidenced when the reactions were carried out in the presence of the scavenging support.
- Pavia, Cinzia,Giacalone, Francesco,Bivona, Lucia Anna,Salvo, Anna Maria Pia,Petrucci, Chiara,Strappaveccia, Giacomo,Vaccaro, Luigi,Aprile, Carmela,Gruttadauria, Michelangelo
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- β-cyclodextrin-capped palladium nanoparticle-catalyzed ligand-free Suzuki and Heck couplings in low-melting β-cyclodextrin/NMU mixtures
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Low-melting β-cyclodextrin/N-methylurea (NMU) mixture, an efficient catalytic system for ligand-free Suzuki and Heck couplings in the presence of fresh native β-CD-capped Pd0 nanoparticles, has been successfully reported. This natural and convenient system can be performed in air and could afford the corresponding cross-coupled products in good to excellent isolated yields after a simple workup under every low Pd loading (0.05 mol%). Remarkably, the catalytic system can be recycled and reused without loss of catalytic activity. Copyright
- Zhao, Xiaohua,Liu, Xiang,Lu, Ming
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p. 635 - 640
(2014/08/05)
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- Cross-coupling reactions catalyzed by an N-heterocyclic carbene-Pd(ii) complex under aerobic and CuI-free conditions
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A Pd-complex, (Cat. 3), has been successfully employed as a highly efficient and recyclable catalyst for the Sonogashira and Heck reactions of aryl bromides with various terminal acetylenes and olefins. The catalytic reactions proceed with excellent yields with a low catalyst loading (1.0 mol%) under aerobic and CuI-free conditions. A plausible mechanism has also been proposed for the reaction. the Partner Organisations 2014.
- Lu, Hongfei,Wang, Lin,Yang, Feifei,Wu, Runze,Shen, Wei
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p. 30447 - 30452
(2014/08/05)
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- Scope and limitations of the Heck-Matsuda-coupling of phenol diazonium salts and styrenes: A protecting-group economic synthesis of phenolic stilbenes
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4-Phenol diazonium salts undergo Pd-catalyzed Heck reactions with various styrenes to 4′-hydroxy stilbenes. In almost all cases higher yields and fewer side products were observed, compared to the analogous 4-methoxy benzene diazonium salts. In contrast, the reaction fails completely with 2- and 3-phenol diazonium salts. For these substitution patterns the methoxy-substituted derivatives are superior. The Royal Society of Chemistry 2013.
- Schmidt, Bernd,Elizarov, Nelli,Berger, René,H?lter, Frank
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p. 3674 - 3691
(2013/06/27)
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- Heck-Matsuda reaction of arenediazonium salts in water
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The palladium-catalyzed arylation of alkenes with aryldiazonium salts can be carried out through an environmentally friendly protocol using neat water low palladium loadings at room temperature under base-additive- and ligand-free conditions.
- Salabert, Jordi,Sebastián, Rosa María,Vallribera, Adelina,Cívicos, José Francisco,Nájera, Carmen
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p. 2655 - 2659
(2013/03/28)
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- Catalytic application of dinuclear palladium(II) bis(thiosemicarbazone) complex in the Mizoroki-Heck reaction
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A convenient synthesis of new square planar dinuclear palladium(II) terephthaldehyde bis(thiosemicarbazone) complex has been described. The compositions of the complex have been established by elemental analysis, spectral methods and single crystal X-ray crystallographic technique. The new complex acts as an active recyclable homogeneous catalyst for the Mizoroki-Heck reaction of electron deficient (activating) and electron rich (deactivating) aryl halides with various olefins under optimized conditions.
- Prabhu, Rupesh Narayana,Ramesh, Rengan
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supporting information
p. 5961 - 5965,5
(2020/08/20)
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- Cu(acac)2-catalyzed synthesis of functionalized bis(arylmethyl)zinc reagents and their olefination reaction with aromatic aldehydes
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An efficient and facile copper(II) acetylacetonate catalyzed synthesis of functionalized bis(arylmethyl)zinc reagents from arylmethyl halides and their olefination reaction with aromatic aldehydes is reported. Aluminum trichloride was found to be the key ingredient in these reactions and (E)-stilbenes were obtained in high yields. Georg Thieme Verlag Stuttgart · New York.
- Fu, Ying,Hu, Xuemei,Chen, Yaojuan,Yang, Yanshou,Hou, Hongxia,Hu, Yulai
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experimental part
p. 1030 - 1036
(2012/05/04)
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- Operationally simple and highly (E)-styrenyl-selective heck reactions of electronically nonbiased olefins
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Simple, mild, and efficient conditions are reported for a Pd 0-catalyzed Heck reaction that delivers high yields and selectivity for (E)-styrenyl products using electronically nonbiased olefin substrates bearing a range of useful functionality. Preliminary mechanistic studies demonstrate that the σ-donating DMA solvent is crucial for high selectivity. Further studies suggest that the catalyst distinguishes between β-hydrogens on the basis of their relative hydridic character, in contrast to previously reported PdII-catalyzed oxidative reaction conditions.
- Werner, Erik W.,Sigman, Matthew S.
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supporting information; experimental part
p. 9692 - 9695
(2011/08/06)
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- Effects of substituent and solvent on the UV absorption energy of 4,4′-disubstituted stilbenes
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Twenty five samples of 4,4′-disubstituted stilbene derivatives were synthesized, and their UV absorption max wavelengths were determined in over 10 kinds of solvents including cyclohexane, ether, chloroform, acetonitrile and ethanol, in which 242 experimental data were recorded. The effects of substituents and solvents on the energy of their UV absorption max wavelengths were discussed. The research results showed: the energy of UV absorption max wavelengths of 4,4′-disubstituted stilbenes was mainly affected by their intramolecular structure (substituent effect) in a given solvent, that is, the energy is dominated by both of excited-state substituent parameter σ CC ex and polar substituent constant σ p. While their energy was dominated by the substituent effect and solvent effect in different kinds of solvents. An equation quantifying the energy of UV absorption max wavelengths of 4,4′-disubstituted stilbenes was developed. In addition, it is found that the n-octanol/water partition coefficient (logP) is more effective than the solvatochromic dye (E T(30)) in scaling the solvent effect. The equation employed the parameter logP has a better correlation and more specific physical meaning. Further, the energies of UV absorption max wavelengths of some reported compounds were predicted by the obtained equation, which are in agreement with their experimental values.
- Cao, Chenzhong,Chen, Guanfan,Wu, Yaxin
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scheme or table
p. 1735 - 1744
(2012/05/05)
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- The synthesis of non-symmetrical stilbene analogs of trans-resveratrol using the same Pd catalyst in a sequential double-Heck arylation of ethylene
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We have developed a sequential and selective Pd-catalyzed double-Heck arylation of ethylene that results in non-symmetrical nitro-stilbene analogs of trans-resveratrol at excellent yields. A catalytic system consisting of Pd(OAc)2 and P(o-tolyl)3 permitted us to carry out the two consecutive Heck arylations without losing activity from the first to the second Heck reaction. After the first Heck arylation of ethylene, no isolation or additional catalyst loading is required for the second Heck arylation reaction. This protocol was applied to the synthesis of methylated trans-resveratrol, which was obtained at a 65% overall yield.
- Nobre, Sabrina M.,Muniz, Mauro N.,Seferin, Marcus,Da Silva, Wagner M.,Monteiro, Adriano L.
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p. 289 - 293
(2012/01/04)
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- Direct C5-arylation reaction between imidazoles and aryl chlorides catalyzed by palladium complexes with phosphines and N-heterocyclic carbenes
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Palladium(II) acetate complexes bearing phosphines and carbene ligands, Pd(L)(PR3)(OAc)2 (1a, R = Ph; 1b, R = Cy; L = 1,3-dibenzylimidazol-2-ylidene), were prepared by salt metathesis reactions of their chloro complexes with AgOAc in good yields. The electron-rich 1b was efficient in catalyzing C-5 direct arylation of imidazoles with aryl halides. Most significantly, the catalytic system allows a range of aryl chlorides as substrates. Microwave irradiation effectively promotes the reactions, with good yields obtainable in only 2 h. In combination with the classical method of C-C bond formation reactions, novel imidazole derivatives featuring biaryl and styryl subunits were successfully obtained from 1,4-dichlorobenzene and 1-bromo-4-chlorobenzene.
- Kumar, P. Vijaya,Lin, Wu-Shien,Shen, Jiun-Shian,Nandi, Debkumar,Lee, Hon Man
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experimental part
p. 5160 - 5169
(2011/11/14)
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- N-Heterocyclic carbene-Pd(II) complex derived from proline for the Mizoroki-Heck reaction in water
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N-Heterocyclic carbene-Pd(II) complex 1 derived from proline was found to be an efficient catalyst in the Mizoroki-Heck reaction of aryl bromides and iodides performed in water. The reactions can tolerate various functional groups in the substrates and all gave the corresponding coupling products in good to high yields.
- Tang, Yi-Qiang,Chu, Chun-Yan,Zhu, Lei,Qian, Bin,Shao, Li-Xiong
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experimental part
p. 9479 - 9483
(2011/12/15)
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- One-pot synthesis of stilbenes by dehydrohalogenation-Heck olefination and multicomponent Wittig-Heck reaction
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A variant of olefination reaction involving in situ generation of styrene by either one-pot dehydrohalogenation-Heck or one-pot multicomponent Wittig-Heck reaction is developed.
- Saiyed, Akeel S.,Bedekar, Ashutosh V.
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experimental part
p. 6227 - 6231
(2011/01/04)
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- A highly tunable stereoselective olefination of semistabilized triphenylphosphonium ylides with N -Sulfonyl imines
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The Wittig reaction involving direct olefination of triphenylphosphonium ylides (Ph3PCHR) with aldehydes is arguably the most often used method for alkene synthesis, but in general it yields mixtures of Z- and E-alkenes for semistabilized triphenylphosphonium ylides (R = aryl or vinyl). We have developed a simple and efficient protocol to improve the stereoselectivity significantly by replacing the aldehydes used in the Wittig reaction with N-sulfonyl imines, which possess distinct electronic and steric properties relative to aldehydes. A broad range of aromatic, α,β-unsaturated, and aliphatic imines bearing appropriate N-sulfonyl groups smoothly undergo olefination reaction with various benzylidenetriphenylphosphoranes or allylidenetriphenylphosphoranes under mild reaction conditions to afford an array of both Z- and E-isomers of conjugated alkenes in good to excellent yields and with greater than 99:1 stereoselectivity. Moreover, this tunable protocol has been successfully applied to the highly stereoselective synthesis of two anticancer agents, DMU-212 and its Z-isomer.
- Dong, De-Jun,Li, Hai-Hua,Tian, Shi-Kai
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supporting information; experimental part
p. 5018 - 5020
(2010/06/13)
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- Substituent effect on the UV spectra of p-disubstituted compounds XPh(CH=CHPh)nY (n=0, 1, 2)
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Three parameters, θCCex, θ CCex(XY) and Vmax,parent, are developed to express the substituent effect and the effect of the parent molecular structure of p-disubstituted compounds XPh(CH=CHPh)nY (n=0, 1, 2). The investigated result shows a good correlation between the UV absorption wavenumbers (Vmax) and the three parameters for a diverse set of title compounds, and the correlation equation can be used to predict the UV absorption energy of compounds with the mentioned structure. This approach provides a new insight for the quantitative structure-property relationship (QSPR) correlation of the UV absorption energy of p-disubstituted homologues. Copyright
- Chen, Guanfan,Cao, Chenzhong
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scheme or table
p. 776 - 782
(2011/05/05)
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