- Acid- And base-switched palladium-catalyzed γ-C(sp3)-H alkylation and alkenylation of neopentylamine
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The functionalization of remote unactivated C(sp3)-H and the reaction selectivity are among the core pursuits for transition-metal catalytic system development. Herein, we report Pd-catalyzed γ-C(sp3)-H-selective alkylation and alkenylation with removable 7-azaindole as a directing group. Acid and base were found to be the decisive regulators for the selective alkylation and alkenylation, respectively, on the same single substrate under otherwise the same reaction conditions. Various acrylates were compatible for the formation of C(sp3)-C(sp3) and C(sp3)-C(sp2) bonds. The alkenylation protocol could be further extended to acrylates with natural product units and α,β-unsaturated ketones. The preliminary synthetic manipulation of the alkylation and alkenylation products demonstrates the potential of this strategy for structurally diverse aliphatic chain extension and functionalization. Mechanistic experimental studies showed that the acidic and basic catalytic transformations shared the same six-membered dimer palladacycle.
- Zhang, Jinquan,Zhang, Shuaizhong,Zou, Hongbin
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supporting information
p. 3466 - 3471
(2021/05/31)
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- Palladium-catalyzed remote C-H functionalization of 2-aminopyrimidines
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A straightforward strategy was developed for the arylation and olefination at the C5-position of the N-(alkyl)pyrimidin-2-amine core with readily available aryl halides and alkenes, respectively. This approach was highly regioselective, and the transformation was achieved based on two different (Pd(ii)/Pd(iv)) and (Pd(0)/Pd(ii)) catalytic cycles.
- Das, Animesh,Jana, Akash,Maji, Biplab
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supporting information
p. 4284 - 4287
(2020/04/27)
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- Photoredox/Cobalt Dual Catalysis for Visible-Light-Mediated Alkene-Alkyne Coupling
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Dual photoredox transition-metal catalysis has recently emerged as a powerful tool for making synthetically challenging carbon-carbon bonds under milder reaction conditions. Herein, we report on the visible-light-mediated controlled generation of low-valent cobalt catalyst without the need for a metallic reductant. It enabled C-C bond formation via ene-yne coupling at room temperature. The generality of this dual catalysis is demonstrated via the creation of sizable molecular diversity with the accommodation of several functional groups.
- Rai, Pramod,Maji, Kakoli,Maji, Biplab
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supporting information
p. 3755 - 3759
(2019/05/24)
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- Ruthenium(II) Catalysed Highly Regioselective C-3 Alkenylation of Indolizines and Pyrrolo[1,2-a]quinolines
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Discovered the Ruthenium(II) catalysed highly stereo- and regioselective protocol for the oxidative C-3 alkenylation of indolizines and pyrrolo[1,2-a]quinolines. The methodology represents the first example for the directing group assisted C–C bond formation reaction of the indolizines. Under mild reaction conditions, this method provides an ample substrate scope to produce C-3 alkenyl indolizines in excellent to moderate yields. However, pyrrolo[1,2-a]quinolines underwent alkenynation at elevated temperature to furnish C-3 alkenyl derivatives. The functionalized indolizines were selectively reduced to obtain their saturated derivatives.
- Jadhav, Pankaj Pandit,Kahar, Nilesh Machhindra,Dawande, Sudam Ganpat
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supporting information
p. 7831 - 7835
(2019/12/24)
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- Ti-Catalyzed Radical Alkylation of Secondary and Tertiary Alkyl Chlorides Using Michael Acceptors
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Alkyl chlorides are common functional groups in synthetic organic chemistry. However, the engagement of unactivated alkyl chlorides, especially tertiary alkyl chlorides, in transition-metal-catalyzed C-C bond formation remains challenging. Herein, we describe the development of a TiIII-catalyzed radical addition of 2° and 3° alkyl chlorides to electron-deficient alkenes. Mechanistic data are consistent with inner-sphere activation of the C-Cl bond featuring TiIII-mediated Cl atom abstraction. Evidence suggests that the active TiIII catalyst is generated from the TiIV precursor in a Lewis-acid-assisted electron transfer process.
- Wu, Xiangyu,Hao, Wei,Ye, Ke-Yin,Jiang, Binyang,Pombar, Gisselle,Song, Zhidong,Lin, Song
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supporting information
p. 14836 - 14843
(2018/11/10)
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- How much does the hybridization of a carbon atom affect the transmission of the substituent effect on the chemical shift?
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1H and 13C NMR spectra of aryl esters of propionic acid, acrylic acid, and propiolic acid were systematically examined to find out the substituent effect on the chemical shift. The values of the chemical shift of the carbonyl carbon showed an inverse correlation with the Hammett ?3 values, and the magnitude of the slope was the largest with the propiolates. The ?± carbons of acrylates and propiolates also showed an inverse correlation with much smaller values of the slopes than those of the carbonyl carbons; but those of the propionates showed absolutely no correlation. However, the ?2 carbons of acrylates and propiolates showed normal correlation with larger values of the slopes. The signs and the magnitudes of the slopes may be understood by the transmission of the substituent electronic effect through bonds as well as through space. The propiolyloxy group also showed a significantly large effect on the 13C chemical shift values of the benzene ring.
- Jeong, Eun Jeong,Lee, In-Sook Han
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p. 295 - 299
(2015/03/03)
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- Biofilm Resistant Polymer Materials
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The present invention relates to compounds and materials that reduce the accumulation of microorganisms on a surface by interfering with the attachment of the organisms to the surface. The compounds and materials of the present invention are thus useful in preventing the formation of biofilms. The compounds of the present invention may be either adhered to a surface or integrated within a polymer. Surfaces coated by the present invention are resistant to biofilm formation, in part due to the smoothness of the surface coated with the present invention.
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Page/Page column 11-12
(2009/12/24)
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- TRICYCLIC COMPOUND AND PHARMACEUTICAL USE THEREOF
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The present invention provides a compound represented by the formula which is useful as an agent for the prophylaxis or treatment of diseases related to the action of melatonin, or a salt thereof and the like.
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Page/Page column 120-121
(2008/06/13)
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- Reversal of Regioselection in the Sharpless Asymmetric Aminohydroxylation of Aryl Ester Substrates
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(Matrix Presented) The asymmetric synthesis of β-hydroxy-α-amino acids is reported which relies on the use of α,β-unsaturated aryl ester substrates and the dihydroquinyl alkaloid ligand system (DHQ)2-AQN to control the regio- and enantioselectivity of the asymmetric aminohydroxylation (AA) process. α,β-Unsaturated ester substrates of type 1 have a significant effect on the substrate - ligand recognition event which results in a reversal of regioselectivity in the AA reaction.
- Morgan, Adam J.,Masse, Craig E.,Panek, James S.
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p. 1949 - 1952
(2008/02/11)
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- Dehydrobromination of Some Substituted Phenyl 3-Bromopropionates and Phenyl 3-Bromothiolopropionates. Transmission of Activation Effects through Acyl Bonds
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Thirteen aryl 3-bromopropionates and nine aryl 3-bromothiolopropionates were prepared and subjected to dehydrohalogenation with sodium 3,4-dinitrophenoxide in dry tetrahydrofuran at 34.25 deg C.The second-order rate constants for the sulfur esters were approximately 10 times those for the corresponding oxygen esters.Good Hammett plots with ρ's of +0.81+/-0.04 and 0.98+/-0.04 for the oxygen and sulfur series, respectively, were obtained by using ?n.Activation parameters were measured for two oxygen and two sulfur esters; in both bases, low (12-13 kcal/mol) activatio n enthalpies and moderately large negative (19-21 eu) activation entropies were found.At 34.25 deg C, 3'-nitrophenyl 3-bromopropionate dehydrohalogenated 14 times more rapidly than 3'-nitrophenyl 3-chloropropionate; phenyl 3-bromothiolopropionate dehydrohalogenated 11 times more rapidly than the phenyl 3-chlorothiolopropionate.The rate constant ratio for 4'-bromophenyl 3-bromopropionate vs. 4'-bromophenyl 3-bromopropionate-2-d was 1.84; the monodeuterated compound yielded olefinic product with 65percent D.H was abstracted preferentially from 4'-chlorophenyl 3-bromothiolopropionate partially deuterated in the 2-position, but no kinetic results were obtained.No evidence of reversibility was found with 2,4-dinitrophenol-d, and the addition of 2,4-dinitrophenol to kinetic mixtures had essentially no effect on the rate conatants.The results are interpreted to indicate an E2 process near the EL/E1cB borderline with the thiolo ester deviating somewhat more toward an E1cB-I process.
- Gilbert, Arthur B.,Peters, Frances B.,Johnson, H. W.
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p. 2724 - 2728
(2007/10/02)
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