- 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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- 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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- Comparison of Phenylacetates with Benzoates and Phenylpropanoates as Antifeedants for the Pine Weevil, Hylobius abietis
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This study concludes an extensive investigation of antifeedants for the pine weevil, Hylobius abietis (Coleoptera: Curculionidae), an economically important pest of planted conifer seedlings. Building on the previously reported antifeedant effects of benzoates and phenylpropanoids (aromatic compounds with one- or three-carbon-atom substituents on the benzene ring), we here report the antifeedant effects of compounds with two-carbon-atom side chains (i.e., phenylacetates). We also present new results; the best antifeedants from the benzoate class were tested at 10-fold lower concentrations in order to find the optimal antifeedants. Generally, for all three compound classes, efficient antifeedants were found to have one or two methyl, chloro, or methoxy substituents on the aromatic ring. For monosubstituted phenylpropanoids, the substituent preferably should be in the para-position. In the search for synergistic antifeedant effects among the three compound classes, combinations of compounds from the three classes were tested in binary and ternary mixtures.
- Unelius, C. Rikard,Bohman, Bj?rn,Nordlander, G?ran
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p. 11797 - 11805
(2018/11/21)
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- Palladium-Catalyzed β-C-H Arylation of Alkyl Carboxamides with Sterically Hindered Aryl Iodides Using ortho-Sulfinyl Aniline Auxiliaries
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We disclose a pair of ortho-sulfinylaniline auxiliaries for palladium-catalyzed β-C-H arylation of alkyl carboxamides. Together, these auxiliaries offer a means to effect efficient β-methyl and methylene C-H bond arylation with sterically hindered aryl iodides. ortho-Methylsulfinylaniline (MSOA) enables efficient β-methyl C-H arylation of propanamide substrates with aryl iodides bearing various ortho-substituents including alkyl groups. ortho-Tosylsulfinylaniline (TSOA) enables β-methylene C-H arylation with ortho-substituted aryl iodides. Both amide-linked MSOA and TSOA auxiliaries can be easily removed to give ester products under relatively mild conditions.
- Mu, Delong,Gao, Fang,Chen, Gong,He, Gang
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p. 1880 - 1885
(2017/08/14)
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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
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supporting information
p. 12574 - 12577
(2015/08/06)
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- Structure-activity relationships of phenylpropanoids as antifeedants for the pine weevil Hylobius abietis
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Ethyl cinnamate has been isolated from the bark of Pinus contorta in the search for antifeedants for the pine weevil, Hylobius abietis. Based on this lead compound, a number of structurally related compounds were synthesized and tested. The usability of the Topliss scheme, a flow diagram previously used in numerous structure-activity relationship (SAR) studies, was evaluated in an attempt to find the most potent antifeedants. The scheme was initially followed stepwise; subsequently, all compounds found in the scheme were compared. In total, 51 phenylpropanoids were tested and analyzed for SARs by using arguments from the field of medicinal chemistry (rational drug design). Individual Hansch parameters based on hydrophobicity, steric, and electronic properties were examined. The effects of position and numbers of substituents on the aromatic ring, the effects of conjugation in the molecules, and the effects of the properties of the parent alcohol part of the esters were also evaluated. It proved difficult to find strong SARs derived from single physicochemical descriptors, but our study led to numerous new, potent, phenylpropanoid antifeedants for the pine weevil. Among the most potent were methyl 3-phenylpropanoates monosubstituted with chloro, fluoro, or methyl groups and the 3,4-dichlorinated methyl 3-phenylpropanoate.
- Bohman,Nordlander,Nordenhem,Sunnerheim,Borg-Karlson,Unelius
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p. 339 - 352
(2008/09/18)
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- Quantitative structure-activity relationships of pine weevil antifeedants, a multivariate approach
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Antifeedant activity of mainly phenylpropanoic, cinnamic, and benzoic acids esters was tested on the pine weevil, Hylobius abietis (L.). Of 105 compounds screened for activity, 9 phenylpropanoates, 3 cinnamates, and 4 benzoates were found to be highly active antifeedants. To understand the structure-activity relationships of these compounds, a multivariate analysis study was performed. A number of molecular and substituent descriptors were calculated and correlated to results from two-choice feeding tests with H. abietis. Three local models were developed that had good internal predictive ability. External test sets showed moderate predictivity. In general, low polarity, small size, and high lipophilicity were characteristics for compounds having good antifeedant activity.
- Sunnerheim, Kerstin,Nordqvist, Anneli,Nordlander, Goeran,Borg-Karlson, Anna-Karin,Unelius, C. Rickard,Bohman, Bjoern,Nordenhem, Henrik,Hellqvist, Claes,Karlen, Anders
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p. 9365 - 9372
(2008/03/17)
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- Highly regioselective anti-markovnikov palladium-borate-catalyzed methoxycarbonylation reactions: Unprecedented results for aryl olefins
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(Chemical Equation Presented) A general, highly efficient and regioselective methoxycarbonylation, by means of a palladium-salicylicborate- catalyzed protocol, of terminal alkyl and aryl olefins is described. The substrates include aliphatic alkenes, allylbenzenes, and styrene derivatives. The yields are very good (60-92%) and the regioselectivity, in favor of the linear ester, is up to quantitative - unprecedented in the case of styrenes.
- Vieira, Tiago O.,Green, Mike J.,Alper, Howard
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p. 6143 - 6145
(2007/10/03)
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- Hydroesterification Reactions with Palladium-Complexed PAMAM Dendrimers Immobilized on Silica
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Highly active, recyclable catalytic systems for the hydroesterification reaction of olefins with methanol and carbon monoxide were prepared by complexing various palladium species to generation zero through four PAMAM dendrimers immobilized on silica. The silica-dendrimer-Pd(PPh3) 2 complexes were the most facile recyclable catalysts and could be recycled four to six times by filtration under air. These catalysts show selectivity for the linear reaction product.
- Reynhardt, Jan P. K.,Alper, Howard
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p. 8353 - 8360
(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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