- An expeditious method to synthesize difluoroboron complexes of β-keto amides from β-keto nitriles and BF3·OEt2
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A convenient and expeditious strategy to synthesize difluoroboron complexes of β-keto amides has been developed from β-keto nitriles and BF3·OEt2. BF3·OEt2 serves as both a BF2 source and a Lewis acid catalyst in the synthetic strategy. The formation mechanism of the difluoroboron complexes from β-keto nitriles and BF3·OEt2 was proposed. The difluoroboron complexes can be further converted into β-keto amides by treatment with sodium acetate. The strategy features advantages such as a wide substrate scope, non-metal catalysis, and easy operation. Some of the difluoroboron complexes display good fluorescence properties in the solid state and potential application in solid-state luminescent materials.
- Xu, Chuangchuang,Xu, Jiaxi
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- A boron-nitrogen transborylation enabled, borane-catalysed reductive cyanation of enones
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Cyanation offers a simple method for the introduction of a nitrile group into organic molecules and an orthogonal route for the installation of a wide array of functional groups using simple transformations. Cyanation methods are dominated by transition metal catalysis and the use of hydrogen cyanide gas. Here, the electrophilic cyanation of enones was achieved using a main-group catalyst and a non-toxic, electrophilic cyanide source. This protocol was applied across a broad substrate scope including those containing reducible functional groups. Mechanistic studies indicated an amino-borane intermediate which underwent B-N transborylation (B-N/B-H exchange) to achieve catalytic turnover.
- Benn, Kieran,Nicholson, Kieran,Langer, Thomas,Thomas, Stephen P.
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supporting information
p. 9406 - 9409
(2021/09/22)
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- Selective Synthesis of β-Ketonitriles via Catalytic Carbopalladation of Dinitriles
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A practical, convenient, and highly selective method of synthesizing β-ketonitriles from the Pd-catalyzed addition of organoboron reagents to dinitriles has been developed. This method provides excellent functional-group tolerance, a broad scope of substrates, and the convenience of using commercially available substrates. The method is expected to show further utility in future synthetic procedures.
- Zeng, Ge,Liu, Jichao,Shao, Yinlin,Zhang, Fangjun,Chen, Zhongyan,Lv, Ningning,Chen, Jiuxi,Li, Renhao
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p. 861 - 867
(2021/01/09)
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- Highly Selective Hydrogenation of C═C Bonds Catalyzed by a Rhodium Hydride
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Under mild conditions (room temperature, 80 psi of H2) Cp*Rh(2-(2-pyridyl)phenyl)H catalyzes the selective hydrogenation of the C═C bond in α,β-unsaturated carbonyl compounds, including natural product precursors with bulky substituents in the β position and substrates possessing an array of additional functional groups. It also catalyzes the hydrogenation of many isolated double bonds. Mechanistic studies reveal that no radical intermediates are involved, and the catalyst appears to be homogeneous, thereby affording important complementarity to existing protocols for similar hydrogenation processes.
- Gu, Yiting,Lisnyak, Vladislav G.,Norton, Jack R.,Salahi, Farbod,Snyder, Scott A.,Zhou, Zhiyao
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supporting information
p. 9657 - 9663
(2021/07/19)
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- Asymmetric Transfer Hydrogenation of α-Substituted-β-Keto Carbonitriles via Dynamic Kinetic Resolution
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A catalytic protocol for the enantio- and diastereoselective reduction of α-substituted-β-keto carbonitriles is described. The reaction involves a DKR-ATH process with the simultaneous construction of β-hydroxy carbonitrile scaffolds with two contiguous stereogenic centers. A wide range of α-substituted-β-keto carbonitriles were obtained in high yields (94%-98%) and excellent enantio- and diastereoselectivities (up to >99% ee, up to >99:1 dr). The origin of the diastereoselectivity was also rationalized by DFT calculations. Furthermore, this methodology offers rapid access to the pharmaceutical intermediates of Ipenoxazone and Tapentadol.
- Wang, Fangyuan,Yang, Tilong,Wu, Ting,Zheng, Long-Sheng,Yin, Congcong,Shi, Yongjie,Ye, Xiang-Yu,Chen, Gen-Qiang,Zhang, Xumu
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supporting information
p. 2477 - 2483
(2021/02/16)
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- Neutral-eosin Y-catalyzed regioselective hydroacylation of aryl alkenes under visible-light irradiation
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Styrene derivatives were hydroacylated with exclusive anti-Markovnikov selectivity by using neutral eosin Y as a direct hydrogen-atom-transfer (HAT) catalyst under visible-light irradiation. Aldehydes and styrenes with various substituents were tolerated (>20 examples), giving the corresponding products in moderate to high yields. The key acyl radical intermediate was generated from a direct HAT process induced by photoexcited eosin Y. Subsequent addition to styrenes and a reverse HAT process generated the ketone products.
- Liu, Haiwang,Xue, Fei,Wang, Mu,Tang, Xinxin,Wu, Jie
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supporting information
p. 406 - 410
(2020/12/30)
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- Reductive C?C Coupling from α,β-Unsaturated Nitriles by Intercepting Keteniminates
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We present an atom-economic strategy to catalytically generate and intercept nitrile anion equivalents using hydrogen transfer catalysis. Addition of α,β-unsaturated nitriles to a pincer-based Ru?H complex affords structurally characterized κ-N-coordinated keteniminates by selective 1,4-hydride transfer. When generated in situ under catalytic hydrogenation conditions, electrophilic addition to the keteniminate was achieved using anhydrides to provide α-cyanoacetates in high yields. This work represents a new application of hydrogen transfer catalysis using α,β-unsaturated nitriles for reductive C?C coupling reactions.
- Hale, Lillian V. A.,Sikes, N. Marianne,Szymczak, Nathaniel K.
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supporting information
p. 8531 - 8535
(2019/05/21)
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- α-Arylation of Carbonyl Compounds through Oxidative C?C Bond Activation
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A synthetically useful approach for the direct α-arylation of carbonyl compounds through a novel oxidative C?C bond activation is reported. This mechanistically unusual process relies on a 1,2-aryl shift and results in all-carbon quaternary centers. The transformation displays broad functional-group tolerance and can in principle also be applied as an asymmetric variant.
- Li, Jing,Bauer, Adriano,Di Mauro, Giovanni,Maulide, Nuno
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supporting information
p. 9816 - 9819
(2019/06/25)
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- Rhodium-Catalyzed Addition of Aryl Boronic Acids to 2,2-Disubstituted Malononitriles
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β-Ketonitriles bearing a quaternary carbon at the 2-position were prepared through Rh-catalyzed addition of aryl boronic acids to 2,2-disubstituted malononitriles. In contrast to the previously described transnitrilative cyanation of aryl boronic acids with dialkylmalononitriles, the present reaction avoids retro-Thorpe collapse of the intermediate addition product through the use of a milder base. The reaction was amenable to a variety of aryl boronic acids and disubstituted malononitriles, providing a diverse array of β-ketonitriles. The products could be further derivatized to valuable chiral α,α-disubstituted-β-aminonitriles through addition reactions to the corresponding N-tert-butanesulfinyl imines.
- Malapit, Christian A.,Caldwell, Donald R.,Luvaga, Irungu K.,Reeves, Jonathan T.,Volchkov, Ivan,Gonnella, Nina C.,Han, Zhengxu S.,Busacca, Carl A.,Howell, Amy R.,Senanayake, Chris H.
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supporting information
p. 6999 - 7002
(2017/06/06)
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- Electrophilic Cyanation of Boron Enolates: Efficient Access to Various β-Ketonitrile Derivatives
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The highly efficient electrophilic cyanation of boron enolates using readily available cyanating reagents, N-cyano-N-phenyl-p-toluenesulfonamide (NCTS) and p-toluenesulfonyl cyanide (TsCN), is reported. Various β-ketonitriles were prepared by this new protocol, which has a remarkably broad substrate scope compared to existing methods. The present method also allowed efficient synthesis of β-ketonitriles containing a quaternary α-carbon center. In addition, a preliminary result with the use of a chiral boron enolate for the enantioselective cyanation reaction is described.
- Kiyokawa, Kensuke,Nagata, Takaya,Minakata, Satoshi
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supporting information
p. 10458 - 10462
(2016/08/24)
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- Ametoctradin is a Potent Qo Site Inhibitor of the Mitochondrial Respiration Complex III
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Ametoctradin is a new Oomycete-specific fungicide under development by BASF. It is a potent inhibitor of the bc1 complex in mitochondrial respiration. However, its detailed action mechanism remains unknown. In the present work, the binding mode of ametoctradin was first uncovered by integrating molecular docking, MD simulations, and MM/PBSA calculations, which showed that ametoctradin should be a Qo site inhibitor of bc1 complex. Subsequently, a series of new 1,2,4-triazolo[1,5-a]pyrimidine derivatives were designed and synthesized to further understand the substituent effects on the 5- and 6-position of 1,2,4-triazolo[1,5-a]pyrimidine. The calculated binding free energies (ΔGcal) of newly synthesized analogues as Qo site inhibitors correlated very well (R2 = 0.96) with their experimental binding free energies (ΔGexp). Two compounds (4a and 4c) with higher inhibitory activity against porcine SQR than ametoctradin were successfully identified. The structural and mechanistic insights obtained from the present study will provide a valuable clue for future designing of a new promising bc1 inhibitor.
- Zhu, Xiaolei,Zhang, Mengmeng,Liu, Jingjing,Ge, Jingming,Yang, Guangfu
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p. 3377 - 3386
(2015/04/14)
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- Direct synthesis of pyrazoles from esters using tert-butoxide-assisted C-(C=O) coupling
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This paper describes the direct synthesis of pyrazoles from esters that comprises two sequential reactions: tert-butoxide-assisted C-C(=O) coupling reaction to yield β-ketonitrile or α,β-alkynone intermediates, and condensation by hydrazine addition. The method reported allows for easy control of the regioselectivity and structure of substituents at N-1, C-3, C-4 and/or C-5 positions.
- Kim, Bo Ram,Sung, Gi Hyeon,Ryu, Ki Eun,Lee, Sang-Gyeong,Yoon, Hyo Jae,Shin, Dong-Soo,Yoon, Yong-Jin
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supporting information
p. 9201 - 9204
(2015/06/08)
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- IBX-mediated dehydrogenation of substituted β-oxonitriles
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A convenient method for the mild dehydrogenation of β-oxonitriles is presented. When treated with o-iodoxybenzoic acid (IBX), a range of these compounds were transformed into their unsaturated counterparts. Furthermore, we show that the products of the dehydrogenation can react in situ, undergoing rapid hetero-Diels-Alder reactions with enol ethers to give multiply substituted dihydropyrans. We also describe the dehydrogenation of cyclic β-oxonitriles, which leads to the formation of substituted phenols. Copyright
- Klahn, Philipp,Kirsch, Stefan F.
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supporting information
p. 3149 - 3155
(2014/06/09)
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- Direct amino acid-catalyzed cascade reductive alkylation of arylacetonitriles: High-yielding synthesis of ibuprofen analogs
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A novel approach for a one-pot, three-component reductive alkylation (TCRA) reaction of arylacetonitriles-containing electron-withdrawing groups with aldehydes/ketones and 1,4-dihydropyridine via iminium-catalysis has been developed. Many TCRA reaction products have direct applications in agricultural and pharmaceutical chemistry.
- Ramachary, Dhevalapally B.,Shiva Prasad
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scheme or table
p. 5246 - 5251
(2010/11/03)
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- Superacid-catalyzed intramolecular cyclization reaction of arylcyanopropionate: Geminal substitution effect on superelectrophilicity
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(Chemical Equation Presented) We present superacid-catalyzed intramolecular cyclization reactions of arylcyanopropionates to give cyclized five- and six-membered β-enamino esters in moderate to high yields. Known intramolecular ring-closing reactions of protonated nitrile to aromatic carbon atom are limited to the 6-membered case. Interestingly, a significant synergistic increase of reactivity of the cyano functionality was observed, and the cyano nitrogen atom was converted into an amino group, when an ester group was present in a geminal arrangement. Deuterium exchange experiments excluded the involvement of deprotonation of the α-proton in the cyclization process. The acidity dependence of the cyclization reactions and 13C NMR studies of a model compound, methyl cyanoacetate, in various acidic media were consistent with the involvement of the O,N-diprotonated dication of methyl cyanoacetate, a distonic dication, in strong acid, and this is considered to be the de facto electrophile in the present cyclization reaction of arylcyanopropionates.
- Nakamura, Satoshi,Sugimoto, Hiromichi,Ohwada, Tomohiko
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p. 4219 - 4224
(2008/09/20)
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- A high-yielding preparation of β-ketonitriles
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β-Ketonitriles are important precursors for a wide variety of biologically active heterocycles. A facile procedure for the high-yielding acylation of nitrite anions with unactivated esters to provide β-ketonitriles is reported. The procedure is successful with enolizable and nonenolizable esters as well as hindered nitrile anions.
- Ji, Yaohui,Trenkle, William C.,Vowles, James V.
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p. 1161 - 1163
(2007/10/03)
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