- Manganese-catalyzed homogeneous hydrogenation of ketones and conjugate reduction of α,β-unsaturated carboxylic acid derivatives: A chemoselective, robust, and phosphine-free in situ-protocol
-
We communicate a user-friendly and glove-box-free catalytic protocol for the manganese-catalyzed hydrogenation of ketones and conjugated C[dbnd]C[sbnd]bonds of esters and nitriles. The respective catalyst is readily assembled in situ from the privileged [Mn(CO)5Br] precursor and cheap 2-picolylamine. The catalytic transformations were performed in the presence of t-BuOK whereby the corresponding hydrogenation products were obtained in good to excellent yields. The described system offers a brisk and atom-efficient access to both secondary alcohols and saturated esters avoiding the use of oxygen-sensitive and expensive phosphine-based ligands.
- Topf, Christoph,Vielhaber, Thomas
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- Reduction of Electron-Deficient Alkenes Enabled by a Photoinduced Hydrogen Atom Transfer
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Direct hydrogen atom transfer from a photoredox-generated Hantzsch ester radical cation to electron-deficient alkenes has enabled the development of an efficient formal hydrogenation under mild, operationally simple conditions. The HAT-driven mechanism is supported by experimental and computational studies. The reaction is applied to a variety of cinnamate derivatives and related structures, irrespective of the presence of electron-donating or electron-withdrawing substituents in the aromatic ring and with good functional group compatibility. (Figure presented.).
- Larionova, Natalia A.,Ondozabal, Jun Miyatake,Cambeiro, Xacobe C.
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p. 558 - 564
(2020/12/07)
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- Iron-catalysed 1,2-aryl migration of tertiary azides
-
1,2-Aryl migration of α,α-diaryl tertiary azides was achieved by using the catalytic system of FeCl2/N-heterocyclic carbene (NHC) SIPr·HCl. The reaction generated aniline products in good yields after one-pot reduction of the migration-resultant imines.
- Wei, Kaijie,Yang, Tonghao,Chen, Qing,Liang, Siyu,Yu, Wei
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supporting information
p. 11685 - 11688
(2020/10/19)
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- Aldehyde as a Traceless Directing Group for Regioselective C-H Alkylation Catalyzed by Rhodium(III) in Air
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The aromatic aldehyde as a traceless directing group for the regionselective C-H alkylation catalyzed by rhodium(III) under aerobic atmospheric conditions has been developed. The process involves an aldehyde assisted direct addition of C-H bond to unsaturated electrophiles of acrylates or acrylic acids, and the subsequent decarbonylation. A trace amount of water is found to favor the reaction.
- Chen, Si-Qi,Fan, Juan,Li, Chao-Jun,Li, Xin-Ran,Liu, Zhong-Wen,Shi, Xian-Ying
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supporting information
p. 1259 - 1264
(2020/03/13)
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- Palladium-Catalyzed Alkoxycarbonylation of sec-Benzylic Ethers
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Herein, we report the palladium-catalyzed synthesis of 3-arylpropionate esters starting from secondary benzylic ethers. With this investigation it could be shown that ethers are suitable starting materials in addition to the established carbonylation reactions of olefins, alcohols, or aryl halides.
- Beller, Matthias,Jackstell, Ralf,Maes, Bert U. W.,Schneider, Carolin
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supporting information
(2020/02/25)
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- Diboron-Mediated Rhodium-Catalysed Transfer Hydrogenation of Alkenes and Carbonyls
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A diboron-mediated rhodium-catalysed transfer hydrogenation system using water as the hydrogen donor is developed. In addition to a series of alkenes with good functional group tolerance, this rhodium-based catalytic system also effectively reduces aldehydes and ketones. A plausible mechanism involving the RhI-catalysed hydrogen generation and Rh0-catalysed hydrogenation is proposed for the reaction.
- Lin, Xiao,Wang, Yuhan,Hu, Yan,Zhu, Wanjiang,Dou, Xiaowei
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supporting information
p. 1046 - 1049
(2020/02/25)
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- Efficient palladium-catalyzed synthesis of 2-aryl propionic acids
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A flexible two-step, one-pot procedure was developed to synthesize 2-aryl propionic acids including the anti-inflammatory drugs naproxen and flurbiprofen. Optimal results were obtained in the presence of the novel ligand neoisopinocampheyldiphenylphosphine (NISPCPP) (9) which enabled the efficient sequential palladium-catalyzed Heck coupling of aryl bromides with ethylene and hydroxycarbonylation of the resulting styrenes to 2-aryl propionic acids. This cascade transformation leads with high regioselectivity to the desired products in good yields and avoids the need for additional purification steps.
- Neumann, Helfried,Sergeev, Alexey G.,Spannenberg, Anke,Beller, Matthias
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- A general platinum-catalyzed alkoxycarbonylation of olefins
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Hydroxy- and alkoxycarbonylation reactions constitute important industrial processes in homogeneous catalysis. Nowadays, palladium complexes constitute state-of-the-art catalysts for these transformations. Herein, we report the first efficient platinum-catalysed alkoxycarbonylations of olefins including sterically hindered and functionalized ones. This atom-efficient catalytic transformation provides straightforward access to a variety of valuable esters in good to excellent yields and often with high selectivities. In kinetic experiments the activities of Pd- and Pt-based catalysts were compared. Even at low catalyst loading, Pt shows high catalytic activity.
- Beller, Matthias,Dühren, Ricarda,Franke, Robert,Ge, Yao,Huang, Weiheng,Jackstell, Ralf,Liu, Jiawang,Neumann, Helfried,Schneider, Carolin,Yang, Ji
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supporting information
p. 5235 - 5238
(2020/07/30)
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- Remote Functionalization of α,β-Unsaturated Carbonyls by Multimetallic Sequential Catalysis
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The remote functionalization of α,β-unsaturated carbonyls by an array of multimetallic sequential catalytic systems is described. The reactions are triggered by hydrometalation using [Pd-H] or [Ru-H] isomerization catalysts and driven by the formation of thermodynamically more stable 1,2-vinyl arenes. The Pd-catalyzed deconjugative isomerization was combined with a Cu-catalyzed β-borylation of the transiently generated styrenyl derivatives to deliver a range of products that would not be accessible with the use of a single catalyst. [Pd/Cu] catalytic systems were also identified for the highly enantioselective α-hydroboration and α-hydroamination of the styrenyl intermediates. Difunctionalization simultaneously at the benzylic and homobenzylic positions was achieved by combining the isomerization process with Sharpless asymmetric dihydroxylation (SAD) using [Pd/Os] or [Ru/Os] couples. Starting from a simple α,β-unsaturated ester, an isomerization/dihydroxylation/lactonization sequence gave access to a naturally occurring γ-butyrolactone in good yield, with excellent diastereo- and enantioselectivity.
- Romano, Ciro,Fiorito, Daniele,Mazet, Clément
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supporting information
p. 16983 - 16990
(2019/10/28)
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- Cobalt(II)-Catalyzed Alkoxycarbonylation of Aliphatic Amines via C-N Bond Activation
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The first cobalt-catalyzed deaminative alkoxycarbonylation reaction was described for the conversion of readily available primary alkyl amines to synthetically versatile esters with moderate to high yields. This transformation shows good functional group compatibility and can serve as a powerful tool for the modification of alkyl amine-containing complex natural products and drug molecules.
- Li, Chong-Liang,Jiang, Xuan,Lu, Liang-Qiu,Xiao, Wen-Jing,Wu, Xiao-Feng
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p. 6919 - 6923
(2019/09/07)
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- Synthesis, in vitro and in silico evaluation of diaryl heptanones as potential 5LOX enzyme inhibitors
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A new series of diaryl heptanones (12a-q) were synthesized and their structures were confirmed by its 1H, 13C NMR and Mass spectral data. These analogs were evaluated for their anti-oxidant activity and potential to inhibit 5-lipoxygenase. Compounds 12k and 12o showed potent in vitro 5-lipoxygenase enzyme inhibitory activity with IC50 values of 22.2, 21.5 μM, which are comparable to curcumin (24.4 μM). Further they also have shown significant antioxidant activity. Molecular docking studies clearly showed correlation between binding energy and potency of these compounds.
- Meka, Bharani,Ravada, Suryachandra Rao,Muthyala, Murali Krishna Kumar,Kurre, Purna Nagasree,Golakoti, Trimurtulu
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p. 408 - 421
(2018/07/13)
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- Facial strategy for radical species through Ag(I)-mediated oxidation of the alkyl trifluoroborates
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A rapid and highly efficient method for the radical formation using potassium alkylfluoroborates as radical precursor is devised and developed which conducts under relatively mild condition using silver(I) oxide as the oxidant. The observed silver mirror
- Ding, Siyi,Tian, Shaopeng,Zhao, Yuzhen,Ma, Qiang,Zhu, Min,Ren, Huaping,Li, Kexuan,Miao, Zongcheng
-
supporting information
p. 936 - 945
(2018/03/21)
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- Metal-Free Catalytic Reduction of α,β-Unsaturated Esters by 1,3,2-Diazaphospholene and Subsequent C-C Coupling with Nitriles
-
1,3,2-Diazaphospholene 1 catalyzes the conjugate transfer hydrogenation as well as the 1,4-hydroboration of α,β-unsaturated esters. The initial step for both processes involves a 1,4-hydrophosphination of the α,β-unsaturated esters to afford a phosphinyl enol ether. Subsequent cleavage of the P-O bond in the phosphinyl enol ether by ammonia-borane (AB) generates an enol intermediate which tautomerizes to saturated esters, while the P-O bond cleavage by HBpin via a formal σ-bond metathesis affords boryl enolate intermediate. The latter could undergo a further coupling reaction with nitriles to form substituted amino diesters or 1,3-imino esters, depending on α,β-unsaturated ester substrates. These catalytic reactions can also be performed in a one-pot manner, illustrating a protocol for metal-free catalytic C-C bond construction.
- Chong, Che Chang,Rao, Bin,Kinjo, Rei
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p. 5814 - 5819
(2017/09/15)
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- Palladium-Catalyzed Carbonylation of sec- and tert-Alcohols
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A general palladium-catalyzed synthesis of linear esters directly from sec- and tert-alcohols is described. Compared to the classic Koch–Haaf reaction, which leads to branched products, this new transformation gives the corresponding linear esters in high yields and selectivity. Key for this protocol is the use of an advanced palladium catalyst system with L2 (pytbpx) as the ligand. A variety of aliphatic and benzylic alcohols can be directly used and the catalyst efficiency for the benchmark reaction is outstanding (turnover number up to 89 000).
- Dong, Kaiwu,Sang, Rui,Liu, Jie,Razzaq, Rauf,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 6203 - 6207
(2017/05/22)
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- ARGININE METHYLTRANSFERASE INHIBITORS AND USES THEREOF
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Described herein are compounds of Formula (S-I), pharmaceutically acceptable salts thereof, and pharmaceutical compositions thereof. Compounds described herein are useful for inhibiting arginine methyltransferase activity. Methods of using the compounds for treating arginine methyltransferase-mediated disorders are also described.
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Paragraph 00344
(2016/04/20)
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- Acetylcholinesterase inhibition activity of some quinolinyl substituted triazolothiadiazole derivatives
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A series of aralkanoic acids was converted into aralkanoic acid hydrazides through their esters formation. The aralkanoic acid hydrazides upon treatment with carbon disulfide and methanolic potassium hydroxide yielded potassium dithiocarbazinate salts, which on refluxing with aqueous hydrazine hydrate yielded 5-aralkyl-4-amino-3-mercapto-1,2,4-triazoles. The target compounds, 3-aralkyl-6-(substitutedquinolinyl) [1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles, were synthesized by condensing various quinolinyl substituted carboxylic acids with 5-aralkyl-4-amino-3-mercapto-1,2,4-triazoles in phosphorus oxychloride. The structures of the newly synthesized triazolothiadiazoles were characterized by IR, 1H NMR, 13C NMR, and elemental analysis studies. The structure of one of the 5-aralkyl-4-amino-3-mercapto-1,2,4-triazoles was unambiguously deduced by single crystal X-ray diffraction analysis. All the synthesized compounds were screened for their acetylcholinesterase inhibition activities. Four of the triazolothiadiazoles exhibited excellent acetylcholinesterase inhibition activities as compared to the reference inhibitor.
- Rafiq, Muhammad,Saleem, Muhammad,Hanif, Muhammad,Abbas, Qamar,Lee, Ki Hwan,Seo, Sung-Yum
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p. 170 - 177
(2015/04/14)
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- A recyclable CO surrogate in regioselective alkoxycarbonylation of alkenes: Indirect use of carbon dioxide
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Herein, we report a Pd-catalysed alkoxycarbonylation of alkenes based on the use of a recyclable CO2 reduction product, the crystalline and air-stable N-formylsaccharin, as a CO surrogate. The carbonylation proceeds under ambient conditions in an exceptionally complementary regioselective fashion yielding the desired branched products from styrene derivatives and valuable linear esters from alkyl-substituted alkenes.
- Gehrtz,Hirschbeck,Fleischer
-
supporting information
p. 12574 - 12577
(2015/08/06)
-
- Ti/Ni-mediated inter- and intramolecular conjugate addition of aryl and alkenyl halides and triflates
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In this work, we show that the unique combination of a nickel catalyst and Cp2TiCl allows the direct conjugate addition of aryl and alkenyl iodides, bromides, and to a lesser extent, chlorides and triflates to α,β-unsaturated carbonyls at room temperature, without requiring the previous formation of an organometallic nucleophile. The reaction proceeds inter- and intramolecularly with good functional group compatibility, which is key for the development of free protecting group methodologies. Carbo- and heterocycles of five- and six-membered rings are obtained in good yields. Moreover, some insights about the mechanism involved have been obtained from cyclic voltammetry, UV-vis, and HRTEM measurements.
- Marquez, Irene R.,Miguel, Delia,Millan, Alba,Marcos, M. Luisa,De Cienfuegos, Luis Alvarez,Campana, Araceli G.,Cuerva, Juan M.
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p. 1529 - 1541
(2014/03/21)
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- RE12 derivatives displaying Vaccinia H1-related phosphatase (VHR) inhibition in the presence of detergent and their anti-proliferative activity against HeLa cells
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New derivatives of Vaccinia H1-related phosphatase (VHR) inhibitor RE12 (5) were designed by replacing the long straight alkyl chain with other hydrophobic functionalities containing two aromatic rings, with the aim of obtaining potent, cell-active inhibitors. We established a direct coupling reaction between tetronic acid derivative and thioimidate to prepare the RE derivatives 6a-6i efficiently. These compounds all showed VHR-inhibitory activity in the presence of 0.001% NP-40, whereas RE12 (5) was inactive under this condition, even at 100 μM. Further structure-activity studies focused on terminal substitution afforded trifluoromethyl derivative 6k (RE176) and nitro derivative 6l (RE177). The IC50 value of 6l in the presence of NP-40 was almost equivalent to that of RE12 (5) in its absence. Compound 6k (RE176) potently inhibited proliferation of HeLa cells.
- Thuaud, Frederic,Kojima, Shuntaro,Hirai, Go,Oonuma, Kana,Tsuchiya, Ayako,Uchida, Takako,Tsuchimoto, Teruhisa,Sodeoka, Mikiko
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p. 2771 - 2782
(2014/05/06)
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- Similarities and differences in the crystal packing of methoxybenzyl and methoxyphenylethyl-1,3,4-oxadiazole-2(3H)-thiones
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This work reports the crystal and molecular structures of five 1,3,4-oxadiazol-2(3H)-thiones derived from 2, 3 and 4-methoxy substituted 2-phenylacetic acid and 2- and 4-methoxy substituted 3-phenylpropanoic acid. The methoxybenzyl-1,3,4-oxadiazol-2(3H)-thiones are V-shaped while the corresponding methoxyphenylethyl-systems are close to planar, which impacts the solid state molecular packing arrangement. For molecules 1-4, inversion related N-H...S hydrogen bonds generating R22(8) rings dominate the packing, supported by an eclectic mix of C-H...O, C-H...S, C-H...π and π...π contacts that stack the molecules into interconnected columns. In contrast, each of the two unique molecules in the asymmetric unit of 5 forms N-H...O contacts with like molecules augmented by C-H...S contacts for one molecule and C-H...O contacts for the other to generate planar layers that are interconnected though a series of π...π stacking interactions. The Royal Society of Chemistry.
- Khan, Imtiaz,Ibrar, Aliya,Simpson, Jim
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p. 164 - 174
(2014/01/06)
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- Photodriven Transfer Hydrogenation of Olefins
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An improved practical method for the photodriven diimide reduction of olefins was investigated. This catalyst-free procedure proceeds at ambient temperature, utilizes air as oxidant and a lower hydrazine loading, and produces inert nitrogen gas as the sole byproduct. Several functional groups were tolerated, and in some cases, the reaction was chemoselective. Challenging substrates such as cinnamate ester derivatives and trans-stilbene were reduced in excellent yields. The small amount of UVA rays emitted from a household compact fluorescent light bulb was proposed to enable the cis/trans isomerization of the diimide and to promote the loss of hydrogen from the diimide.
- Leow, Dasheng,Chen, Ying-Ho,Hung, Tzu-Hang,Su, Ying,Lin, Yi-Zhen
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supporting information
p. 7347 - 7352
(2016/02/18)
-
- The unexpected kinetic effect of enzyme mixture: The case of enzymatic esterification
-
During the studies towards synthesis of carboxylic acids esters, using ethyl carbonate and carboxylic acid as substrates, we found that different single enzyme systems provide model ethyl 3-phenylpropanoate in very low yield. Systematic studies proved tha
- Zysk, Malgorzata,Zadlo, Anna,Brodzka, Anna,Wisniewska, Catalina,Ostaszewski, Ryszard
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p. 225 - 229
(2014/04/03)
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- TMSCN/DBU-mediated facile redox transformation of α,β- unsaturated aldehydes to carboxylic acid derivatives
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Redox transformation of an α,β-unsaturated aldehyde to a carboxylic acid derivative by means of a combination of TMSCN and DBU was investigated. In addition to the wide use of the carboxylic acid derivatives provided by this reaction, temperature-dependent control of the kinetic or thermodynamic protonation pattern was found to selectively switch the stereochemistry of the acyl group in the product.
- Kaise, Hiromi,Shimokawa, Jun,Fukuyama, Tohru
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supporting information
p. 727 - 729
(2014/03/21)
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- BIARYL-PROPIONIC ACID DERIVATIVES AND THEIR USE AS PHARMACEUTICALS
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The present invention relates to compounds of the formula (I), wherein X, R, R1, R2, D, E1, E2, E3, E4, G1, G2, G3 and G4 have the meanings indicated in the claims, which are valuable pharmaceutical active compounds. They are inhibitors of the protease ca
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Page/Page column 92
(2014/10/15)
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- BIARYL-PROPIONIC ACID DERIVATIVES AND THEIR USE AS PHARMACEUTICALS
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The present invention relates to compounds of the formula (I), wherein X, R, R1, R2, D, E1, E2, E3, E4, G1, G2, G3 and G4 have the meanings indicated in the claims, which are valuable pharmaceutical active compounds. They are inhibitors of the protease ca
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Page/Page column 100
(2014/10/15)
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- Asymmetric NHC-catalyzed redox α-amination of α- aroyloxyaldehydes
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Asymmetric α-amination through an N-heterocyclic carbene (NHC)-catalyzed redox reaction of α-aroyloxyaldehydes with N-aryl-N-aroyldiazenes to form α-hydrazino esters with high enantioselectivity (up to 99% ee) is reported. The hydrazide products are readily converted into enantioenriched N-aryl amino esters through samarium(II) iodide mediated N-N bond cleavage.
- Taylor, James E.,Daniels, David S. B.,Smith, Andrew D.
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p. 6058 - 6061
(2014/01/06)
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- Mechanistic studies on the CAN-mediated intramolecular cyclization of δ-aryl-β-dicarbonyl compounds
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The synthesis of 2-tetralones through the cyclization of δ-aryl-β-dicarbonyl substrates by using CAN is described. Appropriately functionalized aromatic substrates undergo intramolecular cyclizations generating 2-tetralone derivatives in moderate to good yields. DFT computational studies indicate that successful formation of 2-tetralones from δ-aryl-β-dicarbonyl radicals is dependent on the stability of the subsequent cyclohexadienyl radical intermediates. Furthermore, DFT computational studies were used to rationalize the observed site selectivity in the 2-tetralone products.
- Casey, Brian M.,Sadasivam, Dhandapani V.,Flowers II, Robert A.
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p. 1472 - 1479
(2013/08/23)
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- Synthesis, urease inhibition, antioxidant and antibacterial studies of some 4-Amino-5-aryl-3H-1,2,4-triazole-3-thiones and their 3,6-Disubstituted 1,2,4-Triazolo[3,4-b]1,3,4-thiadiazole derivatives
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A new series of 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones, bearing various methoxybenzyl- and methoxyphenethyl groups, was synthesized by refluxing potassium hydrazinecarbodithioate salts in dilute aqueous solution of hydrazine hydrate. These salts were formed by the reaction of acid hydrazides and carbon disulfide in methanolic potassium hydroxide solution at 0-5 °C. 4-Amino-5-aryl-3H-1,2,4-triazole-3-thiones were condensed with different substituted aromatic acids to yield 3,6-disubstituted-1,2,4-triazolo[3,4-b]1,3, 4-thiadiazoles. The structures of the synthesized compounds were characterized by infrared (IR), 1H and 13C nuclear magnetic resonance (NMR), elemental analysis and mass spectrometric (MS) studies. All the synthesized compounds were screened for their urease inhibition, antioxidant and antibacterial activities. Some compounds showed excellent urease inhibition activity, more than the standard drug. Others exhibited potent antioxidant activity. All the compounds showed significant antibacterial activities as compared to the standard drug.
- Hanif, Muhammad,Saleem, Muhammad,Hussain, Muhammad Tahir,Rama, Nasim Hasan,Zaib, Sumera,Aslam, Muhammad Adil M.,Jones, Peter G.,Iqbal, Jamshed
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experimental part
p. 854 - 860
(2012/07/28)
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- Synthesis, crystal structure and b-glucuronidase inhibition activity of some new hydrazinecarboxamides and their 1,2,4-triazole derivatives
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A new series of hydrazinecarboxamides (5a-n), bearing various methoxyphenyl and methoxyphenethyl groups, was synthesized by condensation of corresponding acid hydrazides (3a-f) with methoxyphenylisocyanates (4a-c). Dehydrocyclization of hydrazinecarboxamides (5a-n) yielded corresponding methoxyphenyl and methoxyphenethyl substituted triazoles (6a-l) by refluxing in 2 N aqueous sodium hydroxide solution. All the synthesized compounds were screened for their b-glucuronidase inhibition activity. Compounds 5a, 5e, 5h, and 5l exhibited an excellent b-glucuronidase inhibitory activity as compared to the standard inhibitor. Springer Science+Business Media, LLC 2011.
- Hanif, Muhammad,Khan, Imtiaz,Rama, Nasim Hasan,Noreen, Shagufta,Choudhary, Muhammad Iqbal,Jones, Peter G.,Iqbal, Mazhar
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p. 3885 - 3896
(2013/02/23)
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- A simple and straightforward approach toward selective C=C bond reduction by hydrazine
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A simple and straightforward method for reducing the C=C double bond with hydrazine is described. A number of representative C=C bonds in various steric and electronic environments were examined. Substituted alkenes can be selectively reduced in EtOH in the presence of hydrazine to give the corresponding products in up to 100% yields.
- Chen, Hao,Wang, Jianmin,Hong, Xuechuan,Zhou, Hai-Bing,Dong, Chune
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supporting information
p. 758 - 761
(2012/11/07)
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- Nickel-catalyzed reductive hydroesterification of styrenes using CO 2 and MeOH
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Complexes [(dippe)Ni(μ-H)]2 (A) (dippe = 1,2-bis-di- isopropylphosphino)ethane) and [(dtbpe)Ni(μ-H)]2 (B) (dtbpe = 1,2-bis-di-tert-butylphospino)ethane) catalyze the reductive hydroesterification of styrenes with the use of CO2 and MeOH. The latter acts as a hydrogen source and as an esterificating agent, to yield the corresponding branched and linear esters in moderate to good yields. In all of the studied reactions the linear esters were obtained in higher amounts than the branched ones. When the hydroesterification reaction was carried out using a stoichiometric metal/substrate ratio, the complexes [(P-P)Ni(CO)2] and [(P-P)Ni(CO3)] (P-P = dippe or dtbpe) were isolated and characterized by standard spectroscopic methods. Compounds [(dtbpe)Ni(CO) 2] and [(dtbpe)Ni(CO3)] were also fully characterized by single-crystal X-ray diffraction.
- Gonzalez-Sebastian, Lucero,Flores-Alamo, Marcos,Garcia, Juventino J.
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p. 8200 - 8207
(2013/02/22)
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- Mild method for the selective esterification of carboxylic acids based on the Garegg-samuelsson reaction
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A mild method for the selective esterification of primary alcohols is described. The use of different phosphines, I2, and imidazole allows the selective esterification of a wide variety of acids with excellent results. The generation of a bulky phosphonium-carboxylate salt as intermediate could justify the selectivity observed in this process. Additionally, amides also can be synthesized with use of this method.
- Morcillo, Sara P.,Alvarez De Cienfuegos, Luis,Mota, Antonio J.,Justicia, Jose,Robles, Rafael
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experimental part
p. 2277 - 2281
(2011/05/19)
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- Oligonucleotide-selenide conjugate: Synthesis and its inducible sequence-specific alkylation of DNA
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Oligonucleotide-selenium conjugate was designed and synthesized and its sequence-specific cross-linking ability was investigated. The selenide derivatives can generate covalent interstrand cross-linking with its complementary strand through the formation
- Du, Yuhao,Weng, Xiaocheng,Huang, Jing,Zhang, Dan,Ma, Heng,Chen, Dong,Zhou, Xiang,Constant, Jean-Fran?ois
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experimental part
p. 4149 - 4153
(2010/08/03)
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- Synthesis of the alkaloid tyroscherin by an aldol/Curtius strategy
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The alkaloid tyroscherin (2), which contains a vicinal anti-amino alcohol subunit was prepared from 4-hydroxyphenylpropionic acid (5) and meso-diol 9. After desymmetrization of diol 9 and suitable protecting group manipulations, one terminus was extended via a Claisen rearrangement giving rise to enoate ent-15. The missing carbon on the other end could be incorporated using MeMgCl/CuBr·SMe2 leading eventually to aldehyde ent-22. The acylated oxazolidinone 32 derived from acid 5 and aldehyde ent-22 were combined in an aldol reaction. A subsequent Curtius rearrangement on the carboxylic group furnished the amino function of tyroscherin (2). In a proof of concept study the same strategy was used to prepare tyroscherin analog 28.
- Ugele, Markus,Maier, Martin E.
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supporting information; scheme or table
p. 2633 - 2641
(2010/05/01)
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- Palladium-catalyzed heck coupling-hydrogenation: Highly efficient one-pot synthesis of dibenzyls and alkyl phenyl esters
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An efficient method for the synthesis of industrially important dibenzyls and alkyl phenyl esters via sequential Heck coupling and hydrogenation of the alkenyl double bond in one pot with a single recyclable catalyst under mild conditions has been realised. The catalyst was recovered by simple filteration and reused for several cycles with consistent activity.
- Kantam, M. Lakshmi,Chakravarti, Rajashree,Chintareddy, Venkat Reddy,Sreedhar,Bhargava, Suresh
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supporting information; experimental part
p. 2544 - 2550
(2009/08/14)
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- REAGENTS FOR HIGHLY SPECIFIC DETECTION OF PEROXYNITRITE
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This invention provides compositions which specifically reacts with peroxynitrite rather than other reactive oxygen species and reactive nitrogen species. This invention also provides related agents for measuring peroxynitrite. This invention also provides related methods for measuring peroxynitrite in a sample, high-throughput screening fluorescent methods for detecting peroxynitrite and high-throughput methods for screening compounds that increase or decrease the production of peroxynitrite comprising using such compositions and agents.
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Page/Page column 19
(2010/11/27)
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- Spirocyclohexadienones: VIII. 1-R-3,3-Dimethyl-2-azaspiro[5.5]undeca-1,7, 10-trien-9-ones
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1-R-3,3-Dimethyl-2-azaspiro[5.5]undeca-1,7,10-trien-9-ones were synthesized by condensation of 4-(p-methoxyphenyl)-2-methylbutan-2-ol with nitriles RCN in the presence of a concn. sulfuric acid. Nauka/Interperiodica 2006.
- Glushkov,Vetoshkina,Kolgashev,Maiorova,Shurov,Shklyaev
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p. 1131 - 1136
(2007/10/03)
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- Intermolecular rhodium-catalyzed carbometalation/Heck-type reaction in water
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(Chemical Equation Presented) Only in water: A fully intermolecular rhodium-catalyzed domino coupling reaction, in which aryl boronic acids react with alkynes and acrylates to afford substituted 1,3-dienes, can only be successfully carried out in water. The reaction predominantly provides 1,4-addition products in aqueous THF and Heck-type addition products in a homogenized system with sodium decyl sulfate. cod = 1,5-cyclooctadiene.
- Kurahashi, Takuya,Shinokubo, Hiroshi,Osuka, Atsuhiro
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p. 6336 - 6338
(2007/10/03)
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- Novel Rh catalysis in cross-coupling between alkyl halides and arylzinc compounds possessing ortho-COX (X = OR, NMe2, or Ph) groups
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Rh-dppf was found to be an efficient catalyst for the cross-coupling between primary alkyl halides bearings-hydrogens and arylzinc compounds possessing carbonyl groups such as ester, amide, or ketone at the ortho position. Various functional groups such as ester, nitrite, or acyloxylate moieties on the halides were tolerated under the catalysis conditions. Arylzinc compounds free of ortho-carbonyl groups reacted well with ethyl 3-iodopropanoate, suggesting that the essential intramolecular interaction between carbonyl groups and Rh promotes the reductive elimination.
- Takahashi, Hideki,Inagaki, Shinya,Nishihara, Yasushi,Shibata, Takanori,Takagi, Kentaro
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p. 3037 - 3040
(2007/10/03)
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- Facile oxidative conversion of alcohols to esters using molecular iodine
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A simple, efficient, and high-yield procedure for the oxidative conversion of alcohols to various types of esters and ketones, with molecular iodine and potassium carbonate was successfully carried out.
- Mori, Naoshi,Togo, Hideo
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p. 5915 - 5925
(2007/10/03)
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- Iron tricarbonyl stabilized pentadienyl cation as initiator for cascade polycyclizations: A diastereoselective entry into octahydrophenanthrenes
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A new example is provided of completely diastereoselective polycyclization, affording the octahydrophenanthrene framework. Generation of an iron tricarbonyl stabilized pentadienyl carbocation is the triggering event of the cascade reaction. The carbocation is generated by anchimerically assisted regiospecific protonation of a double bond adjacent to the iron tricarbonyl diene moiety. Tetrafluoroboric acid ether complex appears to be the optimum reagent, affording good yields, even under catalytic conditions.
- Pearson, Anthony J.,Ghidu, Victor P.
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p. 8975 - 8978
(2007/10/03)
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- Michael addition reactions with η2-coordinaied anisoles: Controlling the stereochemistry of the para and benzylic carbons
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Several η2-coordinated anisole complexes were treated with various Michael acceptors in the presence of a Lewis or Br?nsted acid to generate stable 4H-anisolium complexes. These reactions were found to proceed with high stereochemical control with predictable outcomes, provided that the moderate acid (NH2Ph2)OTf was used and the complex was dissolved in an acidic solution. The stereochemistry is shown to originate from an unexpectedly high preference for one coordination diastereomer of the anisole complex in the solid state and a Diels-Alder like transition state for the Michael reaction.
- Smith, Philip L.,Keane, Joseph M.,Shankman, Sarah E.,Chordia, Mahendra D.,Harman, W. Dean
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p. 15543 - 15551
(2007/10/03)
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- Design and Synthesis of a Potent and Selective Triazolone-Based Peroxisome Proliferator-Activated Receptor α Agonist
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A new series of hPPARα agonists containing a 2,4-dihydro-3H-1,2,4-triazol-3-one (triazolone) core is described leading to the discovery of 5 (LY518674), a highly potent and selective PPARα agonist.
- Xu, Yanping,Mayhugh, Daniel,Saeed, Ashraf,Wang, Xiaodong,Thompson, Richard C.,Dominianni, Samuel J.,Kauffman, Raymond F.,Singh, Jaipal,Bean, James S.,Bensch, William R.,Barr, Robert J.,Osborne, John,Montrose-Rafizadeh, Chahrzad,Zink, Richard W.,Yumibe, Nathan P.,Huang, Naijia,Luffer-Atlas, Debra,Rungta, Deepa,Maise, Dale E.,Mantlo, Nathan B.
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p. 5121 - 5124
(2007/10/03)
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- Electrochemically induced Favorsky rearrangement of alkyl benzyl ketones
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Electrolysis of alkyl benzyl ketones in MeOH in an undivided electrolyzer in the presence of the Nal-NaOH mediator system induces the process similar to the Favorsky rearrangement to produce arylalkanecarboxylates in 80-90% yield (per substance) and with the 50-55% current efficiency.
- Elinson,Feducovich,Dorofeev,Vereshchagin,Nikishin
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p. 228 - 231
(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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- Electrochemical vinylation of aryl and vinyl halides with acrylate esters catalyzed by cobalt bromide
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A consumable anode process permits the electrochemical Heck reaction between aromatic or vinylic halides and acrylate esters using cobalt bromide as catalyst associated with bipyridine as ligand in a mixture of acetonitrile/triethylamine/pyridine as solvent.
- Gomes, Paulo,Gosmini, Corinne,Nédélec, Jean-Yves,Périchon, Jacques
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p. 5901 - 5903
(2007/10/03)
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- Stereoselective hydrocoupling of cinnamic acid esters by electroreduction: Application to asymmetric synthesis of hydrodimers
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The electroreduction of Ar-substituted methyl cinnamates in acetonitrile gave all-trans cyclized hydrodimers stereoselectively (58-90% de). In all cases, small amounts (2-symmetric dl-3,4-diaryladipic acids and trans-3,4-diarylcyclopentanones. The chiral auxiliary [(1R)-exo]-3-exo-(diphenylmethyl)borneol, prepared from (1R)-(+)-camphor, was highly effective for the stereoselective hydrocoupling of its cinnamates by electroreduction. From the resulting hydrodimers, (3R,4R)-3,4-diaryladipic acid esters and (3R,4R)-3,4-diarylhexane-1,6-diols were synthesized in 87-95% ee.
- Kise, Naoki,Iitaka, Shumei,Iwasaki, Keisuke,Ueda, Nasuo
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p. 8305 - 8315
(2007/10/03)
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- Precipiton strategies applied to the isolation of α-substituted β-ketoesters
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Diaryl alkene 1Z is a 'precipiton', a protecting group that allows reaction products to be isolated by simple filtration. Here we illustrate the use of this protecting group for the preparation and isolation, without distillation or chromatography, of pure α-substituted β-ketoesters. The precipiton 1Z was prepared in 43% overall yield. It is anticipated that development of precipiton-based syntheses will provide a new alternative for automated reaction product isolation that may be useful for bench-scale and process-scale chemical preparations.
- Bosanac, Todd,Wilcox, Craig S.
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p. 4309 - 4312
(2007/10/03)
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- Synthesis and in vitro evaluation of human FP-receptor selective prostaglandin analogues
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The in vitro evaluation of a series of saturated prostaglandins revealed that compounds with omega chin aromatic rings retain nanomolar potency for the human prostaglandin F receptor (hFP receptor), exemplified by compound 8. In contrast, the double bonds are required for activity in the series with an acyclic omega chain as in PGF(2α). (C) 2000 Published by Elsevier Science Ltd.
- DeLong, Mitchell A.,Amburgey, Jack,Taylor, Cynthia,Wos, John A.,Soper, David L.,Wang, Yili,Hicks, Renee
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p. 1519 - 1522
(2007/10/03)
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- Regioselective intramolecular oxidation of phenols and anisoles by dioxiranes generated in situ
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A novel method for regioselective oxidation of phenols and anisoles has been developed in which dioxiranes, generated in situ from ketones and Ozone, oxidize phenol derivatives in an intramolecular fashion. A series of ketones with electron-withdrawing groups, such as CF3, COOMe, and CH2Cl, were attached to phenols, anisoles, or aryl rings via a C2 or C3 methylene linker. In a homogeneous solvent system of CH3CN and H2O, oxidation of phenol derivatives 1-10 afforded spiro 2-hydroxydienones in 24-55% yields regardless of the presence of other substituents (ortho Me, meta Me or Br) on the aryl ring and the length of the linker. Experimental evidences were provided to support the mechanism that involves a regioselective π bond epoxidation of aryl rings followed by epoxide rearrangement and hemiketal formation.
- Yang, Dan,Wong, Man-Kin,Yan, Zheng
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p. 4179 - 4184
(2007/10/03)
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