- Multiple-Functional Diphosphines: Synthesis, Characterization, and Application to Pd-Catalyzed Alkoxycarbonylation of Alkynes
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A series of diphosphine ligands (L1-L5) containing bis-phosphino fragments and bis-amido groups as well as intensive electron-withdrawing F atoms were synthesized and fully characterized. The structures of the prepared complex of Pd-L5 demonstrate that as for L5, the incorporated two phosphino fragments participate in the chelation to the Pd center inversely along with two Cl-ligands to present a typical square-planar configuration, whereas the two amido groups simultaneously develop a hydrogen-bond interaction with Cl-ligands to facilitate the timely dissociation of Cl-ligands from the Pd center. It was found that L5 enabled the Pd complex to be more active in the alkoxycarbonylation of alkynes with MeOH for the synthesis of branched/linear α,β-unsaturated carboxylic esters with general yields of 60-89%. In L5, the incorporated diphosphino fragments, diamino groups, and F atoms conferred a catalytic effect to the Pd complex synergetic toward the reaction.
- Chen, Xiao-Chao,Guo, Lin,Liu, Lei,Liu, Ye,Lu, Yong,Yao, Yin-Qing,Zhao, Kai-Chun,Zhao, Xiao-Li
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p. 750 - 760
(2022/04/03)
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- Dramatic Effect of γ-Heteroatom Dienolate Substituents on Counterion Assisted Asymmetric Anionic Amino-Cope Reaction Cascades
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We report a dramatic effect on product outcomes of the lithium ion enabled amino-Cope-like anionic asymmetric cascade when different γ-dienolate heteroatom substituents are employed. For dienolates with azide, thiomethyl, and trifluoromethylthiol substituents, a Mannich/amino-Cope/cyclization cascade ensues to form chiral cyclohexenone products with two new stereocenters in an anti-relationship. For fluoride-substituted nucleophiles, a Mannich/amino-Cope cascade proceeds to afford chiral acyclic products with two new stereocenters in a syn-relationship. Bromide- and chloride-substituted nucleophiles appear to proceed via the same pathway as the fluoride albeit with the added twist of a 3-exo-trig cyclization to yield chiral cyclopropane products with three stereocenters. When this same class of nucleophiles is substituted with a γ-nitro group, the Mannich-initiated cascade is now diverted to a β-lactam product instead of the amino-Cope pathway. These anionic asymmetric cascades are solvent- and counterion-dependent, with a lithium counterion being essential in combination with etheral solvents such as MTBE and CPME. By altering the geometry of the imine double bond from E to Z, the configurations at the R1 and X stereocenters are flipped. Mechanistic, computational, substituent, and counterion studies suggest that these cascades proceed via a common Mannich-product intermediate, which then proceeds via either a chair (X = N3, SMe, or SCF3) or boat-like (X = F, Cl, or Br) transition state to afford amino-Cope-like products or β-lactam in the case of X = NO2.
- Das, Pradipta,Delost, Michael D.,Qureshi, Munaum H.,Bao, Jianhua,Fell, Jason S.,Houk, Kendall N.,Njardarson, Jon T.
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supporting information
p. 5793 - 5804
(2021/05/07)
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- Mizoroki-Heck Reaction of Unstrained Aryl Ketones via Ligand-Promoted C-C Bond Olefination
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Mizoroki-Heck reaction of unstrained aryl ketone with acrylate/styrene is accomplished via palladium-catalyzed ligand-promoted C-C bond cleavage. Various (hetero)aryl ketones are compatible in the reaction, affording the alkene product in good to excellent yields. Further applications in the late-stage olefination of some drugs, natural products, and fragrance-derived aryl ketones demonstrate the synthetic utility of this protocol. By employing ketone as both the directing group and the leaving group, 1,2-bifunctionalization is achieved via sequential ortho-C-H alkylation/ipso-Heck olefination.
- Wang, Mei-Ling,Xu, Hui,Li, Han-Yuan,Ma, Biao,Wang, Zhen-Yu,Wang, Xing,Dai, Hui-Xiong
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supporting information
p. 2147 - 2152
(2021/04/05)
-
- COMPOUNDS
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The invention provides a polymyxin compound of formula (I) and salts, solvates and protected forms thereof, pharmaceutical compositions comprising the compounds of formula (I), and the use of the compounds and compositions in methods of treatment, such as
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Page/Page column 44
(2020/01/24)
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- Design and synthesis of bitopic 2-phenylcyclopropylmethylamine (pcpma) derivatives as selective dopamine d3 receptor ligands
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2-Phenylcyclopropylmethylamine (PCPMA) analogues have been reported as selective serotonin 2C agonists. On the basis of the same scaffold, we designed and synthesized a series of bitopic derivatives as dopamine D3R ligands. A number of these new compounds show a high binding affinity for D3R with excellent selectivity. Compound (1R,2R)-22e and its enantiomer (1S,2S)-22e show a comparable binding affinity for the D3R, but the former is a potent D3R agonist, while the latter acts as an antagonist. Molecular docking studies revealed different binding poses of the PCPMA moiety within the orthosteric binding pocket of the D3R, which might explain the different functional profiles of the enantiomers. Compound (1R,2R)-30q shows a high binding affinity for the D3R (Ki = 2.2 nM) along with good selectivity, as well as good bioavailability and brain penetration properties in mice. These results reveal that the PCPMA scaffold may serve as a privileged scaffold for the design of aminergic GPCR ligands.
- Tan, Liang,Zhou, Qingtong,Yan, Wenzhong,Sun, Jian,Kozikowski, Alan P.,Zhao, Suwen,Huang, Xi-Ping,Cheng, Jianjun
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p. 4579 - 4602
(2020/06/08)
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- Phosphetane oxides as redox cycling catalysts in the catalytic wittig reaction at room temperature
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Recently, phosphorus redox cycling has gained significant importance for a number of transformations originally requiring the use of stoichiometric amounts of phosphorus reagents. While these methodologies have several benefits, high catalyst loadings (≥10 mol percent) and harsh reaction conditions (T ≥ 100 °C) often limit their versatility and applicability. Herein, we report differently substituted phosphetane oxides as efficient catalysts for the catalytic Wittig reaction. The phosphetane scaffold is easy to modify, and a number of catalysts can be obtained in a simple two-step synthesis. The activity in the Wittig reaction significantly surpasses previously reported phospholane-based catalysts and the reaction can be conducted with catalyst loadings as low as 1.0 mol percent even at room temperature. Furthermore, a Br?nsted acid additive is no longer required to achieve high yields at these mild conditions. A methyl-substituted phosphetane oxide was employed to synthesize 25 different alkenes with yields of up to 97percent. The methodology has a good functional group tolerance and the reaction can be performed starting with alkyl chlorides, bromides, or iodides. Additionally, it was possible to use poly(methylhydrosiloxane) as the terminal reductant in the catalytic Wittig reaction employing 2-MeTHF as a renewable solvent. The intermediates of the Wittig reaction were analyzed by 31P NMR spectroscopy, and in situ NMR experiments confirmed phosphane oxide as the resting state of the catalyst. Further kinetic investigations revealed a striking influence of the base on the rate of phosphane oxide reduction.
- Longwitz, Lars,Spannenberg, Anke,Werner, Thomas
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p. 9237 - 9244
(2019/10/08)
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- Selective Palladium-Catalyzed Carbonylation of Alkynes: An Atom-Economic Synthesis of 1,4-Dicarboxylic Acid Diesters
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A class of novel diphosphine ligands bearing pyridine substituents was designed and synthesized for the first time. The resulting palladium complexes of L1 allow for chemo- and regioselective dialkoxycarbonylation of various aromatic and aliphatic alkynes affording a wide range of 1,4-dicarboxylic acid diesters in high yields and selectivities. Kinetic studies suggest the generation of 1,4-dicarboxylic acid diesters via cascade hydroesterification of the corresponding alkynes. Based on these investigations, the chemo- and regioselectivities of alkyne carbonylations can be controlled as shown by switching the ligand from L1 to L3 or L9 to give α,β-unsaturated esters.
- Liu, Jiawang,Dong, Kaiwu,Franke, Robert,Neumann, Helfried,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 10282 - 10288
(2018/08/03)
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- Synthesis of olefins via a Wittig reaction mediated by triphenylarsine
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An arsine-mediated Wittig reaction for the synthesis of olefins is described. After heating triphenylarsine in the presence of an activated alkyl bromide for 30?min, the resulting arsonium salt condensed with aldehydes in as little as 5?min at room temperature, yielding the olefins in high yields. Aromatic, heteroaromatic, and alkyl aldehydes were all suitable substrates for this process.
- Li, Lun,Stimac, Jared C.,Geary, Laina M.
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supporting information
p. 1379 - 1381
(2017/03/17)
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- Palladium nanoparticles immobilized on amphiphilic and hyperbranched polymer-functionalized magnetic nanoparticles: An efficient semi-heterogeneous catalyst for Heck reaction
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To address the obstacles facing the use of palladium-based homogeneous and heterogeneous catalysts in C─C cross-coupling reactions, a novel semi-heterogeneous support was developed based on hyperbranched poly(ethylene glycol)-block-poly(citric acid)-functionalized Fe3O4 magnetic nanoparticles (Fe3O4@PCA-b-PEG). Because of the surface modification of the Fe3O4 nanoparticles with amphiphilic and hyperbranched polymers (PCA-b-PEG), these hybrid materials are not only soluble in a wide range of solvents (e.g. water, ethanol and dimethylformamide) but also are able to trap Pd2+ ions via complex formation of free carboxyl groups of the PCA dendrimer with metal ions. The reduction of trapped palladium ions in the dendritic shell of Fe3O4@PCA-b-PEG leads to immobilized palladium nanoparticles. The morphology and structural features of the catalyst were characterized using various microscopic and spectroscopic techniques. The catalyst was effectively used in the palladium-catalysed Mizoroki–Heck coupling reaction in water as a green solvent. In addition, the catalyst can be easily recovered from the reaction mixture by applying an external magnetic field and reused for more than ten consecutive cycles without much loss in activity, exhibiting an example of a sustainable and green methodology.
- Tabatabaei Rezaei, Seyed Jamal,Shamseddin, Azin,Ramazani, Ali,Mashhadi Malekzadeh, Asemeh,Azimzadeh Asiabi, Pegah
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- Diastereoselective Synthesis of Biologically Active Cyclopenta[b]indoles
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The cyclopenta[b]indole motif is present in several natural and synthetic biologically active compounds, being directly responsible for the biological effects some of them present. We described herein a three step sequence for the synthesis of cyclopenta[
- Santos, Marilia S.,Fernandes, Daniara C.,Rodrigues, Manoel T.,Regiani, Thais,Andricopulo, Adriano D.,Ruiz, Ana Lúcia T. G.,Vendramini-Costa, Débora B.,De Carvalho, Jo?o E.,Eberlin, Marcos N.,Coelho, Fernando
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p. 6626 - 6639
(2016/08/16)
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- Regioselective Heck reaction catalyzed by Pd nanoparticles immobilized on DNA-modified MWCNTs
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This is the first report of regioselective Heck reaction of aryl iodides with 2,3-dihydrofuran using heterogonous nanocatalyst. Herein, palladium nanoparticles is immobilized on DNA-modified multi walled carbon nanotubes and characterized by FT-IR spectroscopy, UV-vis spectroscopy, field emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy, inductively coupled plasma and elemental analysis. DNA as a well-defined structure and biodegradable natural polymer generate the palladium catalyst which showed high activity in common and regioselective Heck reaction in excellent yields and good selectivity under ligand-free and mild reaction conditions. Moreover, the catalyst could be recovered and reused at least nine times without any considerable loss of its catalytic activity.
- Hajipour, Abdol R.,Khorsandi, Zahra,Farrokhpour, Hossein
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p. 59124 - 59130
(2016/07/06)
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- Silica-acetylacetone-supported palladium nanoparticles as an efficient and reusable catalyst in the Heck-Mizoroki C-C cross-coupling reaction
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The preparation of palladium nanoparticles supported on acetylacetone-modified silica gel and their catalytic application for Heck olefination of aryl halides were investigated. The catalyst was characterized using X-ray diffraction, X-ray photoelectron spectroscopy, and transmission and scanning electron microscopies. The supported palladium nanoparticles are demonstrated to be a highly active and reusable catalyst for the Heck reaction. Several reaction parameters, including type and amount of solvent and base, were evaluated. The heterogeneity of the catalytic system was investigated with results indicating that there is a slight palladium leaching into the reaction solution under the applied reaction conditions. Despite this metal leaching, the catalyst can be reused nine times without significant loss of catalytic activity.
- Hajipour, Abdolreza,Shirdashtzade, Zohre,Azizi, Ghobad
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p. 143 - 146
(2015/03/30)
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- (2-Arylethenyl)-1,3,5-triazin-2-amines as a novel histamine H4 receptor ligands
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Within the constantly growing number of histamine H4 (H4R) receptor ligands there is a large group of azine derivatives. A series of novel compounds in the group of 4-methylpiperazine-1,3,5-triazine-2-amines were designed and obtained. Considered structures were modified at the triazine 6-position by introduction of variously substituted arylethenyl moieties. Their affinities to histamine H4 receptors were evaluated in radioligand binding assays with use of Sf9 cells, transiently expressing human H4R. Pharmacological studies results allowed to identify 4-[(E)-2-(3-chlorophenyl)ethenyl]-6-(4-methylpiperazin-1-yl)-1,3,5-triazin-2-amine (Ki Combining double low line 253 nM) as the most potent compound in the present series.
- Kamińska, Katarzyna,Ziemba, Julia,Ner, Joanna,Schwed, Johannes Stephan,?azewska, Dorota,Wi?cek, Ma?gorzata,Karcz, Tadeusz,Olejarz, Agnieszka,Latacz, Gniewomir,Kuder, Kamil,Kottke, Tim,Zygmunt, Ma?gorzata,Sapa, Jacek,Karolak-Wojciechowska, Janina,Stark, Holger,Kie?-Kononowicz, Katarzyna
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p. 238 - 251
(2015/09/22)
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- Scope and Limitation of the Microwave-Assisted Catalytic Wittig Reaction
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We have developed a microwave-assisted catalytic Wittig reaction. In this paper, we give full account of the scope and limitations of this reaction. A screening of various commercially available phosphine oxides as precatalysts revealed Bu3P=O to be the most promising candidate. We tested 10 silanes for the in situ reduction of the phosphine oxide to generate Bu3P as the actual catalyst. Different epoxides were tested as masked bases. In this context, cyclohexene oxide as well as butylene oxide proved to be suitable. The reaction could be carried out at 125 C, but higher yields and E/Z selectivities were obtained at 150 °C. Under the optimised reaction conditions, more than 40 examples for the conversion of various aldehydes into the corresponding alkenes are reported. The products were obtained in yields of up to 88 with high E selectivities. Moreover, we also describe the further screening of several chiral phosphines as catalysts for the microwave-assisted enantioselective catalytic Wittig reaction. The scope and limitations of the microwave-assisted catalytic Wittig reaction have been evaluated with respect to the catalyst, silane, solvent, reaction conditions, and substrates.
- Hoffmann, Marcel,Deshmukh, Sunetra,Werner, Thomas
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p. 4532 - 4543
(2015/07/27)
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- Ozonolysis of some 8-alkoxyquinolines, and synthesis of a precursor to the non-sedating antihistamine Claritin
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3-Formyl-2-methoxycarbonylpyridine and isopropyl 3-formylpyridine-2-carboxylate have each been efficiently accessed in one step via the ozonolyses of 8-methoxy- or of 8-isopropoxyquinoline under near-ambient conditions. The compounds can be utilized as intermediates for syntheses of the tricyclic ketone 8-chloro-6,11-dihydro-5H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-one, a precursor to the important non-sedating antihistamine Claritin.
- Eichler, Mathias C.,Grayson, David H.
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- Iminophosphine palladium(II) complexes: Synthesis, characterization, and application in Heck cross-coupling reaction of aryl bromides
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Palladium(II) complexes containing phosphorus and nitrogen donor atoms (iminophosphine), dichlorido{N-[2-(diphenylphosphino)benzylidene]-2- trifluoromethylaniline}palladium(II) 1, dichlorido{N-[2-(diphenylphosphino) benzylidene]-3-trifluoromethylaniline}palladium(II) 2, dichlorido{N-[2- (diphenylphosphino)benzylidene]-2-methylaniline}palladium(II) 3, dichlorido{N-[2-(diphenylphosphino)benzylidene]-3-methylaniline}palladium(II) 4 have been successfully synthesized and fully characterized by FT-IR and NMR (1H, 31P, 19F, and 13C) spectroscopy techniques. These complexes were first step tested in the reaction of bromobenzene and styrene to determine the optimal coupling reaction conditions and then successfully applied as catalysts for Heck cross-coupling reactions of activated and deactivated aryl bromides with styrene derivatives and several acrylates. Copyright
- Yilmaz, Mustafa Kemal,Guezel, Bilgehan
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p. 529 - 536
(2014/07/07)
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- A deacetylation-diazotation-coupling sequence: Palladium-catalyzed C-C bond formation with acetanilides as formal leaving groups
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Acetanilides can be deacetylated and diazotized in situ, and subsequently used in Pd-catalyzed coupling reactions without isolation of the diazonium intermediate. Heck reactions, Suzuki crosscoupling reactions, and a Pd-catalyzed [2+2+1] cycloaddition hav
- Schmidt, Bernd,Berger, Rene
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supporting information
p. 463 - 476
(2013/05/08)
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- The [RPPhPd as a catalyst precursor for the heck cross-coupling reaction by in situ formation of stabilized Pd(0) nanoparticles
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Pd(II) anionic, square planar complexes of the type [RPPhPdl, where X = Cl, Br, have been applied for the first time as a catalyst precursor for the Heck reaction carried out in DMF at 140 °C. The highest yield was obtained for the most reducible ones, [MePPhPdrl, in DMF in the presence of NaHCOas a base. It was found that during the reaction, phosphonium halide stabilized Pd(0) nanoparticles of about 10 nm, which have been formed in situ from the palladium(II) precursor and Pd(0) colloidal nanoparticles acts as the reservoir for Pd(II) species via activation of the metal surface through the oxidative addition of aryl halides. Georg Thieme Verlag Stuttgart New York.
- Hajipour, Abdol Reza,Azizi, Ghobad
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supporting information
p. 254 - 258
(2013/03/13)
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- Catalytic asymmetric cross-dehydrogenative coupling: Activation of C-H bonds by a cooperative bimetallic catalyst system
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A cooperative bimetallic catalyst system was applied in the catalytic asymmetric cross-dehydrogenative coupling of β-ketoesters and xanthene. Various optically active xanthene derivatives bearing a quaternary stereogenic carbon center were obtained in moderate to good yields (up to 90%) with excellent enantioselectivities (up to 99% ee). Meanwhile, a transition-state model was proposed to explain the origin of the asymmetric induction.
- Cao, Weidi,Liu, Xiaohua,Peng, Ruixue,He, Peng,Lin, Lili,Feng, Xiaoming
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supporting information
p. 3470 - 3472
(2013/05/23)
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- Mizoroki-Heck coupling reactions of arenediazonium tetrafluoroborate salts catalyzed by aluminium hydroxide-supported palladium nanoparticles
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Mizoroki-Heck cross-couplings of arenediazonium tetrafluoroborate salts catalyzed by highly active aluminium hydroxide-supported palladium nanoparticles catalyst have been investigated for the first time. The reactions are performed at 25 C in EtOH without any base and ligand to afford the corresponding coupling products in good to excellent yields under non-anhydrous and non-degassed conditions.
- Li, Xing,Wang, Li-Chao,Chang, Hong-Hong,Zhang, Cong-Xia,Wei, Wen-Long
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- Non-cross-linked polystyrene-supported triphenylarsonium halides and their use in the arsa-Wittig reaction
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Non-cross-linked polystyrene-supported (carbomethoxymethyl) triphenylarsonium bromide (1) and benzyltriphenylarsonium iodide (2) were synthesized. They showed similar reactivities compared with the free arsonium salts in the arsa-Wittig reaction. The use of the polymer-supported reagents facilitated product purification and rendered the organoarsenic reagents easily separable and recyclable.
- Lau, Kelvin C.Y.,Chiu, Pauline
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experimental part
p. 8769 - 8774
(2011/12/02)
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- Aryldiazonium silica sulfates as efficient reagents for Heck-type arylation reactions under mild conditions
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An efficient and straightforward procedure for Heck-type arylation reactions was studied using aryldiazonium silica sulfates and olefins in the presence of a catalytic amount of Pd(OAc)2. These reactions were carried out in water at room temperature without using a base or additional ligands. The use of a non-toxic solvent, a simple and clean work-up, short reaction times, and good yields are advantages of this method.
- Zarei, Amin,Khazdooz, Leila,Pirisedigh, Azadeh,Hajipour, Abdol R.,Seyedjamali, Hojjat,Aghaei, Hamidreza
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experimental part
p. 4554 - 4557
(2011/09/20)
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- Application of dimeric cyclopalladated complex of tribenzylamine as an efficient catalyst in the Heck cross-coupling reaction
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The activity of [Pd{C6H4(CH2N(CH 2Ph)2)} (μ-Br)]2 complex was investigated in the Heck-Mizoroki C-C cross-coupling reaction. This complex is an active and efficient catalyst for the Heck reaction of aryl iodides, bromides and even chlorides and also arenesulfonyl chlorides. The cross-coupled products were produced in excellent yields in short reaction time using a catalytic amount of [Pd{C6H4(CH2N(CH2Ph)2) (μ-Br)]2 complex in NMP at 130 °C.
- Hajipour, Abdol R.,Rafiee, Fatemeh
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experimental part
p. 2669 - 2675
(2011/07/09)
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- Applications of a monomeric orthopalladate complex containing mixed phosphorus-nitrogen donors in the Heck reaction
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The [Pd{C6H2(CH2CH2NH 2)-(OMe)2,3,4}Br(PPh3)] monomeric orthopalladate complex of homoveratrylamine and triphenylphosphine was synthesized and its application in Heck coupling reactions was investigated. This complex had been demonstrated to be more active than the corresponding dimeric catalyst for Heck reactions of aryl iodides, bromides and even chlorides and also arenesulfonyl chlorides. The cross-coupled products were produced in excellent yields using catalytic amounts of [Pd{C6H 2(CH2CH2NH2)-(OMe) 2,3,4}Br(PPh3)] as a thermally stable and oxygen insensitive complex in NMP at 130 °C.
- Hajipour, Abdol Reza,Rafiee, Fatemeh,Rouho, Arnold E.
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experimental part
p. 4782 - 4787
(2011/10/04)
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- Accelerated Heck reaction using ortho-palladated complex in a nonaqueous ionic liquid with controlled microwave heating
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The activity of {Pd[C6H2(CH2CH 2NH2)-(OMe)2,3,4] (μ-Br)}2 complex was investigated in the Heck-Mizoroki C-C cross-coupling reaction under conventional heating and microwave irradiation conditions in molten salt tetrabutylammonium bromide as the solvent and promoter at 130 °C. This complex in these conditions is an active and efficient catalyst for the Heck reaction of aryl iodides, bromides and even chlorides, and also arenesulfonyl chlorides. Copyright
- Hajipour, Abdol R.,Rafiee, Fatemeh
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experimental part
p. 542 - 551
(2012/04/04)
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- Stereoselective synthesis of unsymmetrical β,β-diarylacrylates by a heck-matsuda reaction: Versatile building blocks for asymmetric synthesis of β,β-diphenylpropanoates, 3-Aryl-indole, and 4-Aryl-3,4-dihydro- quinolin-2-one and formal synthesis of (-)-indatraline
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β,β-Disubstituted R,β-unsaturated esters may serve as valuable derivatives for the preparation of other highly functionalized systems found in many natural products and marketed drugs. The stereoselective synthesis of unsymmetrical β,β-diarylacrylate compounds possessing two similar aromatic groups remains a substantial challenge. A simple and convenient stereoselective protocol for the preparation of β,β- disubstituted acrylates via a Heck-Matsuda reaction is reported. Good to high yields were accomplished by a "ligand-free" Pd-catalyzed arylation reaction of cinnamate esters with arenediazonium tetrafluoroborates. Both electron-deficient and electron-rich arenediazonium salts could be employed as arylating reagents, and cinnamate esters were generally more reactive when substituted with an electron-donating group. The overall methodology is highly stereoselective, and this attribute was taken advantage of in the asymmetric Cu-catalyzed 1,4 reduction reaction to provide β,β-diarylpropanoates in high enantioselectivities. The synthesis of a 3-aryl indole and a chiral 4-aryl-2-quinolone from β,β-diarylacrylates was achieved by cyclization in the presence of a diphosphine ligated CuH catalyst. A convenient route for the asymmetric formal synthesis of the psychoactive compound (-)-Indatraline is also presented.
- Taylor, Jason G.,Correia, Carlos Roque D.
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supporting information; scheme or table
p. 857 - 869
(2011/04/18)
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- Heck coupling reaction using monomeric ortho-palladated complex of 4-methoxy- benzoylmethylenetriphenylphosphorane under microwave irradiation
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The activity of [Pd(C6H4CH2 NH 2-κ2-C-N)PPh3MOBPPY]OTf complex, A (MOBPPY = 4-methoxybenzoylmethylenetriphenyl- phosphoraneylide), was investigated in the Heck-Mizoroki C-C cross-coupling reaction under conventional heating and microwave irradiation conditions. The complex is an active and efficient catalyst for the Heck reaction of aryl halides. The yields were excellent using a catalytic amount of [Pd(C6H4CH 2 NH2-κ2-C-N)PPh3MOBPPY]OTf complex in N-methyl-2-pyrrolidinone (NMP) at 130 °C and 600 W. In comparison to conventional heating conditions, the reactions under microwave irradiation gave higher yields in shorter reaction times. Copyright
- Hajipour, Abdol R.,Karami, Kazem,Tavakoli, Ghazal
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experimental part
p. 798 - 804
(2011/06/20)
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- Application of dimeric orthopalladate complex of homoveratrylamine as an efficient catalyst in the Heck cross-coupling reaction
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The [Pd{C6H2(CH2CH2NH2)-(OMe)2,3,4} (μ-Br)]2 complex of homoveratrylamine was synthesized and its application in the Heck coupling reaction was studied. This complex had been demonstrated to be active and efficient catalyst for the Heck reaction of aryl iodides, bromides and even chlorides. The cross-coupled products were produced in excellent yields in a short reaction time using catalytic amounts of [Pd{C6H2(CH2CH2NH2)-(OMe)2,3,4} (μ-Br)]2 complex in N-methyl-2-pyrrolidinone (NMP at 130 °C).
- Hajipour, Abdol R.,Karami, Kazem,Pirisedigh, Azadeh,Ruoho, Arnold E.
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experimental part
p. 2548 - 2554
(2009/12/24)
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- Oxygen and base-free oxidative heck reactions of arylboronic acids with olefins
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A mild and efficient protocol for palladium-catalyzed oxidative Heck reactions of arylboronic acids with both electron-rich and -deficient olefins is described. In contrast to the normal oxidative Heck coupling, this new method works in the absence of a base, oxygen, or other external oxidants. With a wide variety of substrates tolerated, the method broadens the scope of palladium-catalyzed coupling reactions. Copyright
- Ruan, Jiwu,Li, Xinming,Saidi, Ourida,Xiao, Jianliang
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p. 2424 - 2425
(2008/09/18)
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- CYCLOPROPYL PYRROLIDINE OREXIN RECEPTOR ANTAGONISTS
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The present invention is directed to cyclopropyl proline bis-amide compounds which are antagonists of orexin receptors, and which are useful in the treatment or prevention of neurological and psychiatric disorders and diseases in which orexin receptors are involved. The invention is also directed to pharmaceutical compositions comprising these compounds and the use of these compounds and compositions in the prevention or treatment of such diseases in which orexin receptors are involved.
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Page/Page column 46
(2009/01/24)
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- Sodium 2-(2-pyridin-3-ylethylamino)sulfonate: an efficient ligand and base for palladium-catalyzed Heck reaction in aqueous media
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The first successful Pd(OAc)2, N-donor ligand and base mediated Heck coupling reaction of aryl halides and alkenes in water is described. The corresponding Heck products were obtained in good to excellent yields.
- Pawar, Shivaji S.,Dekhane, Deepak V.,Shingare, Murlidhar S.,Thore, Shivaji N.
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p. 4252 - 4255
(2008/09/21)
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- A microwave-accelerated esterification of α,β-unsaturated acids with alkyl or aryl carbonochloridate and triethylamine in acetonitrile as a novel esterifying reagent mixture
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An efficient synthesis of α,β-unsaturated esters by treatment of the corresponding acids with alkyl or aryl carbonochloridate, triethylamine, and acetonitrile was accomplished for the first time under microwave irradiation for 10 min. The esters 1b-24b were isolated in 71-97% yield.
- Pathania, Vinod,Sharma, Anuj,Sinha, Arun K.
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p. 811 - 816
(2007/10/03)
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- Exploring distal regions of the A3 adenosine receptor binding site: Sterically constrained N6-(2-phenylethyl)adenosine derivatives as potent ligands
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We synthesized phenyl ring-substituted analogues of N6-(1S,2R)- (2-phenyl-1-cyclopropyl)adenosine, which is highly potent in binding to the human A3AR with a Ki value of 0.63nM. The effects of these structural changes on affinity at human and rat adenosine receptors and on intrinsic efficacy at the hA3AR were measured. A 3-nitrophenyl analogue was resolved chromatographically into pure diastereomers, which displayed 10-fold stereoselectivity in A3AR binding in favor of the 1S,2R isomer. A molecular model defined a hydrophobic region (Phe168) in the putative A3AR binding site around the phenyl moiety. A heteroaromatic group (3-thienyl) could substitute for the phenyl moiety with retention of high affinity of A3AR binding. Other related N6-substituted adenosine derivatives were included for comparison. Although the N 6-(2-phenyl-1-cyclopropyl) derivatives were full A3AR agonists, several other derivatives had greatly reduced efficacy. N 6-Cyclopropyladenosine was an A3AR antagonist, and adding either one or two phenyl rings at the 2-position of the cyclopropyl moiety restored efficacy. N6-(2,2-Diphenylethyl)adenosine was an A 3AR antagonist, and either adding a bond between the two phenyl rings (N6-9-fluorenylmethyl) or shortening the ethyl moiety (N 6-diphenylmethyl) restored efficacy. A QSAR study of the N 6 region provided a model that was complementary to the putative A3AR binding site in a rhodopsin-based homology model. Thus, a new series of high-affinity A3AR agonists and related nucleoside antagonists was explored through both empirical and theoretical approaches.
- Tchilibon, Susanna,Kim, Soo-Kyung,Gao, Zhan-Guo,Harris, Brian A.,Blaustein, Joshua B.,Gross, Ariel S.,Duong, Heng T.,Melman, Neli,Jacobson, Kenneth A.
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p. 2021 - 2034
(2007/10/03)
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- Synthesis of N-glyoxyl prolyl and pipecolyl amides and thioesters and evaluation of their in vitro and in vivo nerve regenerative effects
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The recent discovery that small molecule ligands for the peptidyl-prolyl isomerase (PPIase) FKBP12 possess powerful neuroprotective and neuroregenerative properties in vitro and in vivo suggests therapeutic utility for such compounds in neurodegenerative disease. The neurotrophic effects of these compounds are independent of the immunosuppressive pathways by which drugs such as FK506 and rapamycin operate. Previous work by ourselves and other groups exploring the structure-activity relationships (SAR) of small molecules that mimic only the FKBP binding domain portion of FK506 has focused on esters of proline and pipecolic acid. We have explored amide and thioester analogues of these earlier structures and found that they too are extremely potent in promoting recovery of lesioned dopaminergic pathways in a mouse model of Parkinson's disease. Several compounds were shown to be highly effective upon oral administration after lesioning of the dopaminergic pathway, providing further evidence of the potential clinical utility of a variety of structural classes of FKBP12 ligands.
- Hamilton, Gregory S.,Wu, Yong-Qian,Limburg, David C.,Wilkinson, Douglas E.,Vaal, Mark J.,Li, Jia-He,Thomas, Christine,Huang, Wei,Sauer, Hansjorg,Ross, Douglas T.,Soni, Raj,Chen, Yi,Guo, Hongshi,Howorth, Pamela,Valentine, Heather,Liang, Shi,Spicer, Dawn,Fuller, Mike,Steiner, Joseph P.
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p. 3549 - 3557
(2007/10/03)
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- New isoxazole derivatives designed as nicotinic acetylcholine receptor ligand candidates
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In this work we report the synthesis and evaluation of the analgesic properties of new isosteric heterocyclic derivatives, presenting the isoxazole nucleus, designed as nicotinic acetylcholine receptor ligand candidates, analogues to alkaloid epibatidine. Compound 2-(3-methyl-5-isoxazolyl)pyridine (3) presented the best analgesic profile of this series in hot plate test, which was partially prevented by pretreatment with nicotinic receptor antagonist mecamylamine.
- Silva, Nilda M,Tributino, Jorge L.M,Miranda, Ana L.P,Barreiro, Eliezer J,Fraga, Carlos A.M
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p. 163 - 170
(2007/10/03)
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- Synthesis and biological activity of new 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase inhibitors: 2-oxetanones with a side chain mimicking the folded structure of 1233A.
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To mimic the folded side chain conformation of 1233A (1), which is a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase inhibitor, 1233A analogs with aromatic rings in the side chain were synthesized. The 2-oxetanone moiety was kept intact. Among 1233A and its synthetic analogs, trans-3-hydroxymethyl-4-[2-(7-methoxycarbonyl-1-naphthyl)ethyl]-2-oxe tanone (23) showed the highest HMG-CoA synthase inhibitory activity in vitro. The structure-activity relationship at the side chain is discussed.
- Hashizume,Ito,Yamada,Nagashima,Kanao,Tomoda,Sunazuka,Kumagai,Omura
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p. 512 - 520
(2007/10/02)
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- Protonation of Substituted Methyl Cinnamates
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The protonation of methyl cinnamate and its eight meta and para derivatives has been studied by ultraviolet spectrophotometry in perchloric acid. pKBH+ value of methyl cinnamate calculated by characteristic vector analysis-titration curve analysis is -4.41.Methyl cinnamate is a weaker base than cinnamic acid.All esters studied follow amide acidity function HA in their protonation.The effect of substituents on pKBH+ has been expressed in terms of Hammett equation with the reaction constant ρ = -0.483.
- Sarkice, Aramice Y.,Zalewski, Romuald I.
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p. 515 - 518
(2007/10/02)
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