- Nickel-Catalyzed Benzylic Substitution of Benzyl Esters with Malonates as a Soft Carbon Nucleophile
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The nickel-catalyzed benzylic substitution of benzyl alcohol derivatives with a soft carbon nucleophile is extremely rare compared to that with a hard carbon nucleophile. We have achieved the nickel-catalyzed benzylic substitution of benzyl esters with malonates as a soft carbon nucleophile. Primary and secondary benzyl 2,3,4,5,6-pentafluorobenzoates as well as a wide variety of malonate derivatives were well tolerated in the nickel-catalyzed reaction, providing the corresponding alkylation products in 46-86% yields (34 examples). Additionally, we propose a possible reaction mechanism that would undergo via the ??1- A nd ??3-benzylnickel intermediates.
- Tsuji, Hiroaki,Hashimoto, Keisuke,Kawatsura, Motoi
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p. 8837 - 8841
(2019/11/11)
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- Syntheses, Structures and Optoelectronic Properties of Spiroconjugated Cyclic Ketones
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Synthetic investigations towards spiroconjugated ketones and derivatives thereof are presented. These studies led to the development of a short procedure for the synthesis of spiroconjugated tetraketone 1 in two steps with 10 % overall yield and the first-time synthesis of spirocyclic trindone 2. The optoelectronic properties of these compounds based on spectroscopic and electrochemical measurements in combination with DFT calculations as well as their molecular structures in the solid state are presented and discussed.
- Wilbuer, Jennifer,Schnakenburg, Gregor,Esser, Birgit
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p. 2404 - 2412
(2016/06/01)
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- Overturning established chemoselectivities: Selective reduction of arenes over malonates and cyanoacetates by photoactivated organic electron donors
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The prevalence of metal-based reducing reagents, including metals, metal complexes, and metal salts, has produced an empirical order of reactivity that governs our approach to chemical synthesis. However, this reactivity may be influenced by stabilization of transition states, intermediates, and products through substrate-metal bonding. This article reports that in the absence of such stabilizing interactions, established chemoselectivities can be overthrown. Thus, photoactivation of the recently developed neutral organic superelectron donor 5 selectively reduces alkyl-substituted benzene rings in the presence of activated esters and nitriles, in direct contrast to metal-based reductions, opening a new perspective on reactivity. The altered outcomes arising from the organic electron donors are attributed to selective interactions between the neutral organic donors and the arene rings of the substrates.
- Doni, Eswararao,Mondal, Bhaskar,O'Sullivan, Steven,Tuttle, Tell,Murphy, John A.
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supporting information
p. 10934 - 10937
(2013/08/23)
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- Mixed-ligand manganese(II)-phenolate complexes: Study of DNA cleavage, cytotoxic activity, and induction of apoptosis
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Two manganese complexes, [Mn(L1)2(dibe) 2](L1) (1) and [Mn(L2)2(dibe) 2] (2) (where L1= 2,2'- bipyridine (bipy), L 2=1,10-phenanthroline (phen)), were synthesized by using a carboxylic acid ligand (dibe= 2,2-dibenzylmalonate acid). The two complexes were characterized using IR, elemental analysis, and X-ray crystallography. Fluorescence analysis indicates that the two complexes can bind to HeLa cell DNA (HC-DNA), and gel electrophoresis assay demonstrates the ability of the complexes to cleave the HC-DNA. The two complexes exhibit cytotoxic specificity and significant cancer cell inhibitory rate. Furthermore, apoptotic tests demonstrate that these two complexes have apoptotic effects on HeLa cells. 2011 Taylor & Francis.
- Gao, En-Jun,Zhang, Ying,Lin, Lin,Wang, Ren-Shu,Dai, Lei,Liang, Qi,Zhu, Ming-Chang,Wang, Mei-Lin,Liu, Lei,He, Wen-Xuan,Zhang, Yan-Jin
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experimental part
p. 3992 - 4005
(2012/03/10)
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- Folded H-stacking polymers by conformational control with 2-substituted trimethylene tethers
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Oligomers and polymers of type [-CH2CHRCH2-(π)-] n comprising aryl units tethered by 2-substituted trimethylene were found to exist as a folding H-stacking structure in polar solvents such as CH3CN and in film,
- Watanabe, Jun-Ichi,Hoshino, Tohru,Nakamura, Yu-Suke,Sakai, Edo,Okamoto, Sentaro
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body text
p. 6562 - 6569
(2011/11/12)
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- The synthesis and crystal structure of β-substituted thiaporphyrins with novel cyclic substituents
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21,23-Dithiaporphyrins and 21-monothiaporphyrins with propane-1,3-diyldioxy and its derivatives at the β-thiophene carbons were synthesized and characterized. The cyclic substituents introduced at the β-thiophene carbons altered the electronic properties of the porphyrins. The X-ray structure for 2,3-bis(2,2-dibenzylpropane-1,3-diyldioxy) substituted 21-monothiaporphyrin showed a more planar structure compared to the saddle shaped structure reported for β-unsubstituted 21-monothiaporphyrins.
- Agarwal, Neeraj,Mishra, Sarada Prasad,Hung, Chen-Hsiung,Kumar, Anil,Ravikanth, Mangalampalli
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p. 1173 - 1180
(2007/10/03)
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- Alkylation of malonic and acetoacetic esters in an ionic liquid
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1-Butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) has been used as a recyclable medium in the alkylation of malonic and acetoacetic esters with alkyl, benzyl and prenyl halides.
- Kryshtal, Galina V.,Zhdankina, Galina M.,Zlotin, Sergei G.
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- Synthesis of a poly(ethylene glycol)-supported tetrakis ammonium salt: A recyclable phase-transfer catalyst of improved catalytic efficiency
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The immobilization of four quaternary ammonium groups on a poly(ethylene glycol) support provided an efficient and recyclable phase-transfer catalyst.
- Benaglia, Maurizio,Cinquini, Mauro,Cozzi, Franco,Tocco, Graziella
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p. 3391 - 3393
(2007/10/03)
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- Rational design of an electrochromic polymer with high contrast in the visible region: Dibenzyl substituted poly(3,4-propylenedioxythiophene)
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A dibenzyl substituted poly(3,4-propylenedioxythiophene) was designed and synthesized, and exhibited a contrast of 89% at 632 nm with switching speeds of 400 ms and coloration efficiency of 575 cm2 C-1.
- Krishnamoorthy,Ambade,Kanungo,Contractor,Kumar
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p. 2909 - 2911
(2007/10/03)
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- Synthesis, structure, and nucleophile-induced rearrangements of spiroketones
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Three tetraketones based on the 2,2'-spirobiindan-1,1',3,3'-tetraone skeleton were prepared and investigated. All three compounds show spiroconjugation between their perpendicular π-networks. The interaction results in lowering of the energy of the LUMO of the systems by ca. 0.2-0.3 eV as compared to non-spiroconjugated models. The spiroketones are susceptible to nucleophile-induced retro-Claisen condensations that lead to molecular rearrangements destroying spiro connectivity.
- Maslak, Przemyslaw,Varadarajan, Sridhar,Burkey, Jeffrey D.
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p. 8201 - 8209
(2007/10/03)
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- Mono- vs. dialkylation of carbanions. Effects of absolute and relative acidity of the conjugate carbon acids in selectivity control
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The title problem was investigated in the reaction of the dibromide 1 with carbanions 2a-2g covering a range greater than 15 pK units in DMSO. It was found that the bis(monoalkylated) product 3 arises exclusively or predominantly from the carbanions 2d-2g derived from the less acidic carbon acids 7d-7g whereas the cyclic product of dialkylation 4 prevails in the reaction of the carbanions 2a-2c derived from the more acidic carbon acids 7a-7c. The alkylation selectivity thus depends critically on the absolute acidity of the carbon acid participating in the reaction. Rationale for this novel, and on basis of earlier studies unexpected finding is provided in terms of eqs. (1)-(4).
- Ridvan, Ludek,Zavada, Jiri
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p. 14793 - 14806
(2007/10/03)
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- Synthesis of substituted cyclopropanes from 1,3-diols through the corresponding cyclic sulfates
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The reaction of different cyclic sulfates 2 (easily prepared from the corresponding 1,3-diols 1 following the Sharpless methodology) with an excess of lithium powder and a catalytic amount of DTBB (5 mol %) leads to the corresponding substituted cyclopropanes 3 through a γ-elimination process, the sulfate ion acting as leaving group.
- Guijarro, David,Yus, Miguel
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p. 11445 - 11456
(2007/10/02)
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- Surface-mediated Solid-phase Reaction. Part 2. Highly Selective Mono- and Di-C-alkylation of 1,3-Dicarbonyl Compounds on the Surface of Alumina
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Highly selective mono- and di-C-alkylation of 1,3-dicarbonyl compounds with different, structurally varied alkyl halides has been achieved in high yields through a simple solvent-free reaction on the surface of alumina impregnated with sodium or potassium alkoxide.
- Ranu, Brindaban C.,Bhar, Sanjay
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p. 365 - 368
(2007/10/02)
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- Role of Substituents in Copper(II) Extraction with N,N'-Bis(8-quinolyl)malonamides
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It has been found that substituents on N,N'-bis (8-quinolyl)malonamide play an important role in copper(II) extraction: among the substituents studied, benzyl groups dramatically increased extractability of the malonamide complex.The role of substituents is discussed on the basis of the results of titration and 1H NMR measurements of copper(II) or nickel(II) complexes as well as copper(II)-extraction experiments.Intramolecular interactions between ? electrons of the benzyl group and the metal centre of the complex are proposed to occur.
- Hirose, Takuji,Hiratani, Kazuhisa,Kasuga, Kazuyuki,Saito, Kiyoshi,Koike, Tohru,et al.
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p. 2679 - 2684
(2007/10/02)
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- Synthesis of Benzo-13-crown-4 Derivatives
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A series of nine, new benzo-13-crown-4 compounds which bear one or two substituents on the three-carbon bridge has been prepared in good yields by cesium fluoride-assisted cyclization reactions of catechol with ditosylates of the appropriate glycols.The solid state structure of 9,9-dibenzyl-2,3-benzo-13-crown-4 is determined and compared with the reported structure for the unsubstituted crown ether.
- Czech, Bronislaw P.,Zazulak, Wolodymyr,Kumar, Anand,Dalley, N. Kent,Weiming, Jiang,Bartsch, Richard A.
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p. 1387 - 1394
(2007/10/02)
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- Dipeptides as renin inhibitors
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Dipeptides are described which are represented by the formula STR1 wherein the various substituents are defined hereinbelow. These compounds have a strong inhibitory efect on human renin, and are useful as a therapeutically active agent for the treatment of hypertension, especially renin-associated hypertension.
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- CHEMIOSELECTIVITY IN THE PRESENCE OF SURFACTANTS. I. C- vs. O-ALKYLATION IN β-DICARBONYL COMPOUNDS
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A number of β-dicarbonyl compounds (2,4-pentanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-cyclopentanedione, ethyl 3-oxobutanoate, and diethyl propanedioate) reacted with benzyl bromide in basic aqueous solutions of hexadecyltrimethylammonium bromide at room temperature.The presence of the cationic surfactant directed the reaction toward the carbon nucleophilic site, with high chemioselectivity.C-Dialkylated species were generally predominant, due to the increased lipophilicity of the monoalkylated species, with respect to the reagent.No hydrolysis of benzyl bromide was observed in the presence of the surfactant.
- Bassetti, Mauro,Cerichelli, Giorgio,Floris, Barbara
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p. 583 - 586
(2007/10/02)
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