- H2O2-mediated room temperature synthesis of 2-arylacetophenones from arylhydrazines and vinyl azides in water
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An environmentally benign, cost-efficient and practical methodology for the room temperature synthesis of 2-arylacetophenones in water has been discovered. The facile and efficient transformation involves the oxidative radical addition of arylhydrazines with α-aryl vinyl azides in the presence of H2O2 (as a radical initiator) and PEG-800 (as a phase-transfer catalyst). From the viewpoint of green chemistry and organic synthesis, the present protocol is of great significance because of using cheap, non-toxic and readily available starting materials and reagents as well as amenability to gram-scale synthesis, which provides an attractive strategy to access 2-arylacetophenones.
- Luo, Mengqiang,Zhang, Yaohong,Fang, Ping,Li, Yan,Qi, Chenze,Li, Yong,Shen, Runpu,Cheng, Kai,Wang, Hai
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supporting information
p. 630 - 635
(2022/02/01)
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- Benzylic Aroylation of Toluenes Mediated by a LiN(SiMe3)2/Cs+System
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Chemoselective deprotonative functionalization of benzylic C-H bonds is challenging, because the arene ring contains multiple aromatic C(sp2)-H bonds, which can be competitively deprotonated and lead to selectivity issues. Recently it was found that bimetallic [MN(SiMe3)2 M = Li, Na]/Cs+ combinations exhibit excellent benzylic selectivity. Herein, is reported the first deprotonative addition of toluenes to Weinreb amides mediated by LiN(SiMe3)2/CsF for the synthesis of a diverse array of 2-arylacetophenones. Surprisingly, simple methyl benzoates also react with toluenes under similar conditions to form 2-arylacetophenones without double addition to give tertiary alcohol products. This finding greatly increases the practicality and impact of this chemistry. Some challenging substrates with respect to benzylic deprotonations, such as fluoro and methoxy substituted toluenes, are selectively transformed to 2-aryl acetophenones. The value of benzylic deprotonation of 3-fluorotoluene is demonstrated by the synthesis of a key intermediate in the preparation of Polmacoxib.
- Gu, Yuanyun,Zhang, Zhen,Wang, Yan-En,Dai, Ziteng,Yuan, Yaqi,Xiong, Dan,Li, Jie,Walsh, Patrick J.,Mao, Jianyou
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supporting information
p. 406 - 418
(2022/01/14)
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- Palladium-catalyzed synthesis of α-aryl acetophenones from styryl ethers and aryl diazonium saltsviaregioselective Heck arylation at room temperature
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Preparation of α-aryl acetophenones from styryl ethers and aryldiazonium salts is described. The reaction is catalyzed by palladium acetate at room temperature in the absence of ligand and base. The developed method is highly attractive in terms of reaction conditions, substrate scope, functional group tolerance and yields. Synthetic applications of the present method are demonstrated by preparing α-aryl indoles and 3-aryl isocoumarin from styryl ethers.
- Kandasamy, Jeyakumar,Lee, Yong Rok,Singh, Adesh Kumar,Venkatesh, Rapelly
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supporting information
p. 7832 - 7837
(2021/09/28)
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- The organocatalytic enantiodivergent fluorination of β-ketodiaryl-phosphine oxides for the construction of carbon-fluorine quaternary stereocenters
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Commercially available cinchona alkaloids that can catalyze the enantiodivergent fluorination of β-ketodiarylphosphine oxides were developed to construct carbon-fluorine quaternary stereocenters. This protocol features a wide scope of substrates and excellent enantioselectivities, and it is scalable.
- Xie, Shaolei,He, Zhi-Juan,Zhang, Ling-Hui,Huang, Bo-Lun,Chen, Xiao-Wei,Zhan, Zong-Song,Zhang, Fu-Min
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supporting information
p. 2069 - 2072
(2021/03/01)
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- Iron-Catalyzed Enantioselective Radical Carboazidation and Diazidation of α,β-Unsaturated Carbonyl Compounds
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Azidation of alkenes is an efficient protocol to synthesize organic azides which are important structural motifs in organic synthesis. Enantioselective radical azidation, as a useful strategy to install a C-N3 bond, remains challenging due to the inherently instability and unique structure of radicals. Here, we disclose an efficient enantioselective radical carboazidation and diazidation of α,β-unsaturated ketones and amides catalyzed by chiral N,N′-dioxide/Fe(OTf)2 complexes. An array of substituted alkenes was transformed to the corresponding α-azido carbonyl derivatives in good to excellent enantioselectivities, benefiting the preparation of chiral α-amino ketones, vicinal amino alcohols, and vicinal diamines. Control experiments and mechanistic studies proved the radical pathway in the reaction process. The DFT calculations showed that the azido transferred to the radical intermediate via an intramolecular five-membered transition state with the internal nitrogen of the Fe-N3 species.
- Dong, Shunxi,Feng, Xiaoming,He, Jun,Liu, Wen,Liu, Xiaohua,Pu, Maoping,Wu, Yun-Dong,Zhang, Tinghui
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p. 11856 - 11863
(2021/08/16)
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- Ruthenium(II)-Catalyzed Cross-Coupling of Benzoyl Formic Acids with Toluenes: Synthesis of 2-Phenylacetophenones
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Herein, we report a direct method to synthesize 2-phenylacetophenone through a ruthenium(II)-catalyzed cross-coupling reaction between acyl and benzyl radical. The various derivatives of 2-phenylacetophenone were prepared easily in moderate to good yields. These reactions provide a straightforward pathway to synthesize a variety of ketones bearing various functional groups.
- Chen, Yujie,Dai, Chenyang,Huang, Zhibin,Jiang, Yaqiqi,Shu, Sai,Yang, Shan,Zhao, Yingsheng
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p. 2955 - 2961
(2021/07/22)
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- Versatile and base-free copper-catalyzed α-arylations of aromatic ketones using diaryliodonium salts
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A ligand and base-free copper catalyzed synthetic method for the efficient α-arylation of aromatic ketones is described. In order to avoid strong bases, ketone-derived silyl enol ethers were employed. Their reaction with diaryliodonium salts as aryl source provided the intermolecular C–C coupling displaying good functional group tolerance and requiring low catalyst loading.
- Bouquin, Maxime,Jaroschik, Florian,Taillefer, Marc
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- Benzylic aroylation of toluenes with unactivated tertiary benzamides promoted by directed ortho-lithiation
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The deprotonative functionalization of toluenes, for their weak acidity, generally needs strong bases, thus leading to the requirement of harsh conditions and the generation of by-products. Direct nucleophilic acyl substitution reaction of amides with organometallic reagents could provide an ideal solution for ketone synthesis. However, the inert amides and highly reactive organometallic reagents bring great challenges for an efficient and selective synthetic approach. Herein, we reported an lithium diisopropylamide (LDA)-promoted benzylic aroylation of toluenes with unactivated tertiary benzamides, providing a direct and efficient synthesis of various aryl benzyl ketones. This process features a kinetic deprotonative functionalization of toluenes with a readily available base LDA. Mechanism studies revealed that the directed ortho-lithiation of the tertiary benzamide with LDA promoted the benzylic kinetic deprotonation of toluene and triggered the nucleophilic acyl substitution reaction with the amide. [Figure not available: see fulltext.].
- Bao, Can-Can,Luo, Yan-Long,Du, Hui-Zhen,Guan, Bing-Tao
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p. 1349 - 1354
(2021/07/12)
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- Ring size and nothing else matters: unusual regioselectivity of alkyne hydration by NHC gold(i) complexes
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We have investigated the role of ring sizes and substituents in NHC ligands in some (NHC)Au(i) complexes in the hydration of internal alkynes. Despite the fact that using (NHC)Au(i) complexes in the hydration of diarylacetylenes leads to Markovnikov-type products, the precise tuning of ligands allows changing the regioselectivity in arylalkylacetylene hydration to the anti-Markovnikov-type.
- Ageshina, Alexandra A.,Asachenko, Andrey F.,Chesnokov, Gleb A.,Minaeva, Lidiya I.,Nechaev, Mikhail S.,Philippova, Anna N.,Rzhevskiy, Sergey A.,Topchiy, Maxim A.
-
supporting information
p. 5686 - 5689
(2021/06/16)
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- Copper-Catalyzed Three-Component Carboboronation of Allenes Using Highly Strained Cyclic Ketimines as Electrophiles
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A diastereoselective copper and NHC-ligand-catalyzed three-component difunctionalization of allenes with bis(pinacolato)diboron and 2H-azirines to afford borylated allylaziridines is described. The reaction exhibits complete diastereoselectivity and good yields, and the further chlorination of the corresponding borylated products was also performed. It is believed that the high ring-strain force of 2H-azirines facilitates the reaction. More chemical transformations of borylated allylaziridines are also reported.
- Deng, Hao,Dong, Yujie,Shangguan, Yu,Yang, Fazhou,Han, Sheng,Wu, Jiaqi,Liang, Bo,Guo, Hongchao,Zhang, Cheng
-
supporting information
p. 4431 - 4435
(2021/05/26)
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- Oxaprozin Analogues as Selective RXR Agonists with Superior Properties and Pharmacokinetics
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The retinoid X receptors (RXR) are ligand-activated transcription factors involved in multiple regulatory networks as universal heterodimer partners for nuclear receptors. Despite their high therapeutic potential in many pathologies, targeting of RXR has only been exploited in cancer treatment as the currently available RXR agonists suffer from exceptional lipophilicity, poor pharmacokinetics (PK), and adverse effects. Aiming to overcome the limitations and to provide improved RXR ligands, we developed a new potent RXR ligand chemotype based on the nonsteroidal anti-inflammatory drug oxaprozin. Systematic structure-activity relationship analysis enabled structural optimization toward low nanomolar potency similar to the well-established rexinoids. Cocrystal structures of the most active derivatives demonstrated orthosteric binding, and in vivo profiling revealed superior PK properties compared to current RXR agonists. The optimized compounds were highly selective for RXR activation and induced RXR-regulated gene expression in native cellular and in vivo settings suggesting them as excellent chemical tools to further explore the therapeutic potential of RXR.
- Schierle, Simone,Chaikuad, Apirat,Lillich, Felix F.,Ni, Xiaomin,Woltersdorf, Stefano,Schallmayer, Espen,Renelt, Beatrice,Ronchetti, Riccardo,Knapp, Stefan,Proschak, Ewgenij,Merk, Daniel
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supporting information
p. 5123 - 5136
(2021/05/04)
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- Combined Theoretical and Experimental Studies Unravel Multiple Pathways to Convergent Asymmetric Hydrogenation of Enamides
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We present a highly efficient convergent asymmetric hydrogenation of E/Z mixtures of enamides catalyzed by N,P-iridium complexes supported by mechanistic studies. It was found that reduction of the olefinic isomers (E and Z geometries) produces chiral amides with the same absolute configuration (enantioconvergent hydrogenation). This allowed the hydrogenation of a wide range of E/Z mixtures of trisubstituted enamides with excellent enantioselectivity (up to 99% ee). A detailed mechanistic study using deuterium labeling and kinetic experiments revealed two different pathways for the observed enantioconvergence. For α-aryl enamides, fast isomerization of the double bond takes place, and the overall process results in kinetic resolution of the two isomers. For α-alkyl enamides, no double bond isomerization is detected, and competition experiments suggested that substrate chelation is responsible for the enantioconvergent stereochemical outcome. DFT calculations were performed to predict the correct absolute configuration of the products and strengthen the proposed mechanism of the iridium-catalyzed isomerization pathway.
- Yang, Jianping,Massaro, Luca,Krajangsri, Suppachai,Singh, Thishana,Su, Hao,Silvi, Emanuele,Ponra, Sudipta,Eriksson, Lars,Ahlquist, M?rten S. G.,Andersson, Pher G.
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supporting information
p. 21594 - 21603
(2021/12/27)
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- Thianthrenation-enabled α-arylation of carbonyl compounds with arenes
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The Pd-catalyzed α-arylation of carbonyl compounds with simple arenes enabled by site-selective thianthrenation has been demonstrated. This onepot process using thianthrenium salts as the traceless arylating reagents features mild conditions and a broad substrate scope. In addition, this protocol could also tolerate the heterocyclic carbonyl compounds and complex bioactive molecules, which is appealing for medicinal chemistry.
- Huang, Yu-Hao,Nie, Xiao-Xue,Wang, Peng
-
supporting information
p. 7716 - 7720
(2020/11/02)
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- Synthesis of unsymmetrical ketones by applying visible-light benzophenone/nickel dual catalysis for direct benzylic acylation
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Herein, we report a dual catalytic system for the direct benzylic C-H acylation reaction furnishing a variety of unsymmetrical ketones. A benzophenone-derived photosensitizer combined with a nickel catalyst has been established as the catalytic system. Both acid chlorides and anhydrides are able to acylate the benzylic position of toluene and other methylbenzenes. The method offers a valuable alternative to late transition metal catalyzed C-H acylation reactions.
- Krach, Patricia E.,Dewanji, Abhishek,Yuan, Tingting,Rueping, Magnus
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supporting information
p. 6082 - 6085
(2020/06/18)
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- Blue Light Promoted Difluoroalkylation of Aryl Ketones: Synthesis of Quaternary Alkyl Difluorides and Tetrasubstituted Monofluoroalkenes
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A facile and cost-effective method for the preparation of fluoroalkylated compounds has been described by the direct photoexcitation of halofluoroalkanes with blue light absorptivity, enabling the difluoroalkylation of aryl ketones. The methodology has provided an efficient, mild, and catalyst-free synthetic method for quaternary difluoroalkylated arenes and tetrasubstituted monofluoroalkenes.
- Li, Kangkui,Chen, Jingchao,Yang, Chunhui,Zhang, Keyang,Pan, Chunxiang,Fan, Baomin,Fan, Baomin
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supporting information
p. 4261 - 4265
(2020/06/04)
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- Iron-Catalyzed Synthesis of Tetrahydronaphthalenes via 3,4-Dihydro-2H-pyran Intermediates
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The development of an iron(III)-catalyzed synthetic strategy toward functionalized tetrahydronaphthalenes is described. This approach is characterized by its operational simplicity and is distinct from currently available procedures that rely on [4 + 2]-cycloadditions. Our strategy takes advantage of the divergent reactivity observed for simple aryl ketone precursors to gain exclusive access to tetrahydronaphthalene products (23 examples). Detailed mechanistic investigations identified pyrans as reactive intermediates that afford the desired tetrahydronaphthalenes in high yields upon iron(III)-catalyzed Friedel-Crafts alkylation.
- Watson, Rebecca B.,Schindler, Corinna S.
-
supporting information
p. 68 - 71
(2018/01/17)
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- Silver/NBS-Catalyzed Synthesis of α-Alkylated Aryl Ketones from Internal Alkynes and Benzyl Alcohols via Ether Intermediates
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The silver hexafluoroantimonate/N-bromosuccinimide (NBS)-catalyzed synthesis of α-alkylated aryl ketones with a tertiary carbon center from internal alkynes and benzyl alcohols is reported. This reaction proceeds via the etherification of benzyl alcohols with an in situ generated benzyl bromide, formed by the reaction of benzyl alcohol with a catalytic amount of NBS and AgSbF6. Ag-catalyzed C-O cleavage of the ether leads to a tolyl radical, which undergoes addition to the alkyne, ultimately leading to the α-alkylated aryl ketone products.
- Chun, Supill,Chung, Young Keun
-
supporting information
p. 5583 - 5586
(2018/09/21)
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- Two-Step One-Pot Synthesis of Unsymmetrical (Hetero)Aryl 1,2-Diketones by Addition-Oxygenation of Potassium Aryltrifluoroborates to (Hetero)Arylacetonitriles
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An efficient one-pot two-step procedure for the synthesis of unsymmetrical (hetero)aryl 1,2-diketones has been developed. The reaction proceeds through a palladium-catalyzed nucleophilic addition of potassium aryltrifluoroborates to aliphatic nitriles followed by a copper-catalyzed aerobic benzylic C–H oxygenation using molecular oxygen as a green oxidant. This represents the first example of the direct synthesis of unsymmetrical diaryl 1,2-diketones from arylacetonitriles. This method utilizes inexpensive, stable, nontoxic, and readily available starting materials, is highly effective in the presence of both electron-rich and electron-poor nitriles and aryltrifluoroborates, and tolerates a wide variety of functional groups. The synthetic utility of this transformation was shown by increasing the scale of the reaction and by carrying out the one-pot protocol for the preparation of quinoxaline and benzimidazole derivatives. A plausible reaction mechanism has also been proposed.
- Kumar, Yogesh,Jaiswal, Yogesh,Kumar, Amit
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p. 494 - 505
(2018/02/09)
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- Novel bisamide palladium(II) pincer complexes: effective catalysts in α-arylation of ketones
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Three benzenedicarboxamide ligands (L) were designed and synthesized, and each was used to prepare a palladium(II) complex Pd(L)Br and Pd(L)(OAc). These NCN pincer complexes were used to catalyze the α-arylations of a variety of ketones with aryl chlorides or bromides in various solvents, and moderate-to-excellent yields were obtained (up to 95%). Further research showed that unactivated and sterically hindered aryl halides and ketones are also suitable substrates for the synthesis of α-arylation. Graphical Abstract: [Figure not available: see fulltext.].
- Kai, Wang,Liu, Dabin,Qian, Hua,Ye, Zhiwen
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p. 443 - 450
(2017/07/12)
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- Container Chemistry: Manipulating excited state behavior of organic guests within cavitands that form capsules in water
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Two new cavitands substituted with acid and alcohol groups (tetra-acid tetra-alcohol [TATA] and inverted TATA [iTATA]) bearing the same molecular skeleton as octa acid (OA) have been synthesized and their use as photochemical reaction containers explored. Isothermal calorimetric titration experiments suggest that the inclusion of organic molecules within these cavitands is driven both by favorable ΔH and ΔS and the substituents at the portals have little role to play. Comparison of the 2 new cavitands with the previous results on OA reveals that the presence of benzoate anion at the top periphery is essential for the cavitand to be a triplet sensitizer. Polarity within the water-soluble capsules, resulting from TATA and iTATA, was found to be close to that of ethylacetate and hydrocarbons, similar to that of OA. Photophysical studies with anthracene and camphorthione as guests disclose that the capsules made of 2 molecules of cavitands do not disassemble in the time scale of the excited states of the above guests (S1 in the case of anthracene and T1 in the case of camphorthione). Capsules ability to confine guests and the resulting photochemical intermediates has been tested by examining the photochemistry of 1-phenyl-3-para-tolyl-2-propanone. The radicals resulting from the Norrish type 1 cleavage of 1-phenyl-3-para-tolyl-2-propanone did not escape the cage and gave products, resulting from 100% cage effect. Availability of TATA and iTATA along with already reported similar cavitands expands the list of water-soluble capsule forming cavitands that could be used as molecular containers.
- Jagadesan, Pradeepkumar,Samanta, Shampa R.,Choudhury, Rajib,Ramamurthy, Vaidhyanathan
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-
- Structure-Kinetics Correlations in Isostructural Crystals of α-(ortho-Tolyl)-acetophenones: Pinning Down Electronic Effects Using Laser-Flash Photolysis in the Solid State
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Aqueous suspensions of nanocrystals in the 200-500 nm size range of isostructural α-(ortho-tolyl)-acetophenone (1a) and α-(ortho-tolyl)-para-methylacetophenone (1b) displayed good absorption characteristics for flash photolysis experiments in a flow system, with transient spectra and decay kinetics with a quality that is similar to that recorded in solution. In contrast to solution measurements, reactions in the solid state were characterized by a rate limiting hydrogen transfer reaction from the triplet excited state and a very short-lived biradical intermediate, which does not accumulate. Notably, the rate for δ-hydrogen atom transfer of 1a (2.7 × 107 s-1) in the crystalline phase is 18-fold larger than that of 1b (1.5 × 106 s-1). With nearly identical molecular and crystal structures, this decrease in the rate of δ-hydrogen abstraction can be assigned unambiguously to an electronic effect by the para-methyl group in 1b, which increases the contribution of the 3π,π? configuration relative to the reactive 3n,π? configuration in the lowest triplet excited state. These results highlight the potential of relating single crystal X-ray structural data with absolute kinetics from laser flash photolysis.
- Ayitou, Anoklase J.-L.,Flynn, Kristen,Jockusch, Steffen,Khan, Saeed I.,Garcia-Garibay, Miguel A.
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supporting information
p. 2644 - 2648
(2016/03/12)
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- Preparation of a highly congested carbazoyl-derived p,n-type phosphine ligand for acetone monoarylations
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We report a newly developed carbazoyl-derived P,N-type phosphine ligand (L1) for the monoarylation of acetone with aryl chlorides. The proposed Pd(dba)2/L1 catalyst exhibited remarkable catalytic reactivity toward highly electron rich and sterically congested aryl chlorides, with catalyst loading as low as 0.1 mol % of Pd along with excellent chemoselectivity. A reaction rate study of the system using electronically diverse aryl chlorides determined the mechanisms regarding the rate-limiting steps in this reaction. The oxidative addition adduct of Pd-PhenCar-Phos with p-chlorotoluene showed the participation of N-Pd coordination in the metal complex. The isolated palladium complex C1 could be utilized as a precatalyst in the transformation and achieved performance comparable to that of the in situ generated palladium species.
- Fu, Wai Chung,Zhou, Zhongyuan,Kwong, Fuk Yee
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supporting information
p. 1553 - 1558
(2016/06/09)
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- Nickel catalyzed α-arylation of ketones with aryltrimethylammonium triflates
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Nickel-catalyzed α-arylation of ketones involving aromatic C-N cleavage has been accomplished. Intermolecular coupling of aromatic ketones with a variety of aryltrimethylammonium triflates was achieved in the presence of Ni(COD)2, IPr·HCl, and LiOBut, giving α-arylated ketones in reasonable to excellent yields.
- Li, Jing,Wang, Zhong-Xia
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p. 7579 - 7584
(2016/08/16)
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- Selective Metal-Free Deoxygenation of Unsymmetrical 1,2-Dicarbonyl Compounds by Chlorotrimethylsilane and Sodium Iodide
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For the first time, the combination of chlorotrimethylsilane with NaI is used as a selective reducting system toward 1,2-diketones. This combination is successfully evaluated with several unsymmetrically benzil derivatives, which are reduced in good yield
- Yuan, Ling-Zhi,Renko, Dolor,Khelifi, Ilhem,Provot, Olivier,Brion, Jean-Daniel,Hamze, Abdallah,Alami, Mouad
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supporting information
p. 3238 - 3241
(2016/07/14)
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- Microwave role in the thermally induced SRN1 reaction for α-arylation of ketones
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The coupling between iodobenzene and the enolate anion of acetophenone is accelerated by microwave irradiation. This increase in reaction rate is only ascribed to thermal effects. The coupling reaction gave the corresponding substitution product 1,2-di-phenylethanone in a 50% yield when microwave irradiation was applied between 15-60 s according to the intensity of the pulse. Moreover, this reaction is effective in a temperature window of 70-120 °C. The presence of ionic and dipolar species is not involved in the initiation process as molecular radiators. The excess of tBuOK in the reaction medium may also act as an electron donor helping to generate radicals when the solution temperature increases to 70 °C. This journal is
- Caminos, Daniel A.,Garro, Alexis D.,Soria-Castro, Silvia M.,Pe?é?ory, Alicia B.
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p. 20058 - 20065
(2015/03/30)
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- Copper-catalyzed base-accelerated direct oxidation of C-H bond to synthesize benzils, isatins, and quinoxalines with molecular oxygen as terminal oxidant
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We describe herein an efficient and general copper (II)-catalyzed base-accelerated oxidation of the C-H bond to synthesize benzils and isatins. With similar oxidation system an efficient one-pot procedure for the synthesis of quinoxaline derivatives was realized. The two protocols feature using molecular oxygen as terminal oxidant, low catalyst loading, wide substrate scope, and high functional-group tolerance.
- Yu, Jing-Wen,Mao, Shuai,Wang, Yong-Qiang
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p. 1575 - 1580
(2015/03/14)
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- Ruthenium-catalyzed cascade C-H functionalization of phenylacetophenones
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Three orthogonal cascade C-H functionalization processes are described, based on ruthenium-catalyzed C-H alkenylation. 1-Indanones, indeno indenes, and indeno furanones were accessed through cascade pathways by using arylacetophenones as substrates under conditions of catalytic [{Ru(p-cymene)Cl2}2] and stoichiometric Cu(OAc) 2. Each transformation uses C-H functionalization methods to form C-C bonds sequentially, with the indeno furanone synthesis featuring a C-O bond formation as the terminating step. This work demonstrates the power of ruthenium-catalyzed alkenylation as a platform reaction to develop more complex transformations, with multiple C-H functionalization steps taking place in a single operation to access novel carbocyclic structures. Carbon coupling cascade: Arylacetophenones react with Michael acceptors under ruthenium catalysis to set up triple and quadruple C-H functionalization pathways. Through choice of reaction conditions, novel indanone carbacycles, indeno indene carbacycles, and indeno furanone heterocycles can each be accessed in a single step.
- Mehta, Vaibhav P.,Garcia-Lopez, Jose-Antonio,Greaney, Michael F.
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supporting information
p. 1529 - 1533
(2014/03/21)
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- Palladium-catalyzed α-arylation of arylketones at low catalyst loadings
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A general catalytic protocol for the α-arylation of aryl ketones has been developed. It involves the use of a preformed, bench-stable Pd-N-heterocyclic carbene pre-catalyst bearing IHept as an ancillary ligand, and allows the coupling of various functiona
- Marelli, Enrico,Corpet, Martin,Davies, Sian R.,Nolan, Steven P.
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supporting information
p. 17272 - 17276
(2015/02/05)
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- DIALKYL(2-ALKOXY-6-AMINOPHENYL)PHOSPHINE, THE PREPARATION METHOD AND USE THEREOF
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The present invention relates to the compound of dialkyl(2-alkoxy-6-aminophenyl)phosphine and the preparation method thereof and the application in the palladium catalyzed coupling reactions of aryl chloride and ketone. The dialkyl(2-alkoxy-6-aminophenyl)phosphine of the present invention could coordinate with the palladium catalyst to highly selectively activate the inert carbon-chlorine bond, and to catalyze direct arylation reaction in the α-position of ketones to produce corresponding coupling compounds. The preparation method of the present invention is a simple one-step method which produces the air-stable dialkyl(2-alkoxy-6-aminophenyl)phosphine. Compared with the synthetic routes of ligands to be used in the activation of carbon-chlorine bonds in the prior arts, the preparation method of the present invention has the advantages of short route and easy operation.
- -
-
Paragraph 0057; 0058
(2014/10/29)
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- Catalyst-controlled highly selective coupling and oxygenation of olefins: A direct approach to alcohols, ketones, and diketones
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Oxygen? That's radical! A method for the direct synthesis of substituted alcohols, ketones, and diketones through a catalyst-controlled highly chemoselective coupling and oxygenation of olefins has been developed. The method is simple and practical, can be switched by the selection of different catalysts, and employs molecular oxygen as both an oxidant and a reagent. Copyright
- Su, Yijin,Sun, Xiang,Wu, Guolin,Jiao, Ning
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supporting information
p. 9808 - 9812
(2013/09/23)
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- Palladium-catalyzed reaction of arylboronic acids with aliphatic nitriles: Synthesis of alkyl aryl ketones and 2-arylbenzofurans
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An efficient palladium-catalyzed addition of arylboronic acids to aliphatic nitriles has been developed, providing a wide range of alkyl aryl ketones in moderate to excellent yields. It is noteworthy that sequential addition and intramolecular annulation reaction of 2-(2-hydroxyphenyl)acetonitriles with arylboronic acids are also conducted smoothly to afford 2-arylbenzofurans in good yields under the standard conditions. Georg Thieme Verlag Stuttgart. New York.
- Wang, Xingyong,Wang, Xiaodong,Liu, Miaochang,Ding, Jinchang,Chen, Jiuxi,Wu, Huayue
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p. 2241 - 2244
(2013/09/02)
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- Palladium-catalyzed carbonylative negishi-type coupling of aryl iodides with benzyl chlorides
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Do the competition: The synthesis of 1,2-diarylethanones has been accomplished using the palladium-catalyzed coupling of aryl iodides and CO/benzyl chlorides or benzoyl chlorides. These reactions proceed smoothly in the presence of zinc powder to afford the products in moderate to excellent yields.
- Wu, Xiao-Feng,Schranck, Johannes,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 40 - 44
(2012/03/11)
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- N-heterocyclic carbene adducts of cyclopalladated ferrocenylpyridazine: Synthesis, structural characterization, and application in α-arylation of ketones with aryl chlorides
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A new ferrocene-based ligand 3-chloro-6-pyridazinylferrocene 1 and its N-heterocyclic carbene adducts 2-3 were synthesized and characterized by 1H NMR and IR spectroscopy, ESI-MS, and elemental analysis. Additionally, detailed structures of complexes 2-3 have been determined by single-crystal X-ray analysis. Complex 3 exhibited high catalytic activity for α-arylation of ketones with aryl chlorides. Typically, using 1mol% catalyst in the presence of 1.5 equivalents of tBuOK as base in dioxane at 100°C provided coupled products in good yields.
- Xu, Chen,Li, Hong-Mei,Wang, Zhi-Qiang,Fu, Wei-Jun,Zhang, Yu-Qing,Ji, Bao-Ming
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experimental part
p. 366 - 370
(2012/07/16)
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- Palladium-catalyzed mono-α-arylation of carbonyl-containing compounds with aryl halides using dalphos ligands
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We report the extension and optimization of the [Pd(cinnamyl)Cl] 2/DalPhos catalyst system, previously found effective for the mono-α-arylation of acetone, to the mono-α-arylation of a variety of carbonyl-containing compounds with aryl halides and heteroaryl halides. Aryl methyl ketones, heteroaryl methyl ketones, propiophenones, malonates, and methoxyacetone can be α-arylated under relatively mild conditions and in good yields. We also report the limitations of the ligand/catalyst system towards other classes of carbonyl-containing compounds. We report the application of the [Pd(cinnamyl)Cl]2/DalPhos catalyst system, previously found effective for the mono-α-arylation of acetone, to the mono-α-arylation of a variety of carbonyl-containing compounds with aryl halides and heteroaryl halides.
- Crawford, Sarah M.,Alsabeh, Pamela G.,Stradiotto, Mark
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p. 6042 - 6050,9
(2020/09/02)
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- Carbene adduct of cyclopalladated ferrocenylimine catalyzed α-arylation of ketones with aryl chlorides or bromides
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Carbene adduct of cyclopalladated ferrocenylimine exhibited highly catalytic activity for the α-arylation of ketones with aryl halides. The corresponding products were obtained in moderate to excellent yields. Such protocol was applied to various ketones and a broad scope of aryl halides including aryl chlorides, bromides as well as unactivated and sterically hindered aryl halides.
- Zhang, Jinli,Yang, Xueqian,Cui, Xiuling,Wu, Yangjie
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experimental part
p. 8800 - 8807
(2011/12/02)
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- Arylation of α-pivaloxyl ketones with arylboronic reagents via Ni-catalyzed sp3 C-O activation
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A Suzuki-Miyaura coupling of α-pivaloxyl ketones via Ni-catalyzed sp3 C-O activation to produce α-aryl ketones is developed. This study offers a convenient method to construct α-arylation products from readily available α-hydroxyl carbonyl compounds.
- Huang, Kun,Li, Gang,Huang, Wei-Ping,Yu, Da-Gang,Shi, Zhang-Jie
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p. 7224 - 7226
(2011/08/09)
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- Palladium-catalyzed carbonylative suzuki coupling of benzyl halides with potassium aryltrifluoroborates in aqueous media
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A general palladium-catalyzed carbonylative cross-coupling reaction of benzyl chlorides with potassium aryltrifluoroborates in water has been developed. Applying this improved methodology 16 different 1,2-diarylethanones have been synthesized in 40-89% yield. Copyright
- Wu, Xiao-Feng,Neumann, Helfried,Beller, Matthias
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experimental part
p. 788 - 792
(2011/05/15)
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- (N-Heterocyclic Carbene)-Pd-catalyzed anaerobic oxidation of secondary alcohols and domino oxidation-arylation reactions
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The use of commercially available (SIPr)Pd(cinnamyl)Cl (SIPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene) as a precatalyst for the anaerobic oxidation of secondary alcohols is described. The use of this complex allows for a drastic reduction in the reaction times and catalyst loading when compared to the unsaturated counterpart. This catalytic system is compatible with the use of microwave dielectric heating, decreasing even further catalyst loading and reaction times. Domino Pd-catalyzed oxidation-arylation reactions of secondary alcohols are also presented.(Figure Presented)
- Landers, Brant,Berini, Christophe,Wang, Chao,Navarro, Oscar
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experimental part
p. 1390 - 1397
(2011/05/02)
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- Palladium-catalyzed carbonylative coupling of benzyl chlorides with aryl boronic acids in aqueous media
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A novel chemoselective protocol for the carbonylative Suzuki coupling of benzyl chlorides with aryl boronic acids at low pressure of carbon monoxide has been developed. Applying a commercially available palladium acetate/PCy 3 catalyst system in the presence of potassium phosphate as the base and water as the solvent the coupling reactions proceeded smoothly. To demonstrate the general applicability 12 different α-arylated acetophenones have been synthesized in moderate to good yields (41-78%) under mild conditions.
- Wu, Xiao-Feng,Neumann, Helfried,Beller, Matthias
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experimental part
p. 6146 - 6149
(2010/12/24)
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- Deoxybenzoins from Stille carbonylative cross-couplings using molybdenum hexacarbonyl
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Stille-type carbonylative cross-couplings, employing palladium catalysis and Mo(CO)6 as the carbon monoxide carrier, were used for the preparation of deoxybenzoins. Straightforward transformations were conveniently performed in closed vessels at 100 °C, providing the products in good yields. Benzyl bromides and chlorides were used as coupling partners with aryl and heteroaryl stannanes. This mild three-component carbonylation employs the destabilizing agent DBU to promote smooth release of carbon monoxide from Mo(CO)6, which made this protocol operationally simple and minimized the formation of Stille diarylmethane products.
- S?vmarker, Jonas,Lindh, Jonas,Nilsson, Peter
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supporting information; experimental part
p. 6886 - 6889
(2011/03/17)
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- Pd-catalyzed synthesis of α-aryl ketones through couplings of α-arylacetyl chlorides with triarylbismuths as multi-coupling nucleophiles
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The cross-coupling reaction of α-arylacetyl chlorides with triarylbismuths was studied under Pd-catalyzed conditions. The reaction was found to be facile under the established protocol and furnished high yields of α-aryl ketones in short reaction times. T
- Rao, Maddali L.N.,Giri, Somnath,Jadhav, Deepak N.
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experimental part
p. 6133 - 6138
(2010/02/27)
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- The chemistry of α,β-ditosyloxyketones: Novel routes for the synthesis of desoxybenzoins and α-aryl-β-ketoaldehyde dimethylacetals from α,β-chalcone ditosylates
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The reaction of α,β-chalcone ditosylates 3 with potassium hydroxide in suitable conditions leads to 1,2-aryl shift and carbon-carbon bond cleavage, thereby providing a novel route for the synthesis of 1,2-diarylethan-1-ones 4 and 1,2-diaryl-3,3-dimethoxy propan-1-ones 5. Georg Thieme Verlag Stuttgart.
- Prakash, Om,Kumar, Rajesh,Sharma, Deepak,Pannu, Kamaljeet,Kamal, Raj
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p. 2189 - 2192
(2008/02/10)
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- Direct preparation of benzylic manganese reagents from benzyl halides, sulfonates, and phosphates and their reactions: Applications in organic synthesis
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The use of highly active manganese (Mn)*, prepared by the Rieke method, was investigated for the direct preparation of benzylic manganese reagents. The oxidative addition of the highly active manganese to benzylic halides was easily completed under mild conditions. Moreover, benzylic manganese sulfonates and phosphates were prepared by direct oxidative addition of Mn* to the carbon-oxygen bonds of benzylic sulfonates and phosphates. The resulting benzylic manganese reagents were found to undergo cross-coupling reactions with a variety of electrophiles. Most of these reactions were carried out in the absence of any transition metal catalyst under mild conditions. In addition, the use of highly active manganese was also studied for preparation of homo-coupled products of functionalized benzyl halides without transition metal catalysts. These useful approaches provided not only a facile synthetic route to the preparation of resoricinolic lipids but a facile synthesis of functionalized 4-benzylpyridines by regioselective and chemo selective γ-addition of benzylic group to N-alkoxycarbonylpyridinum salts.
- Suh, YoungSung,Lee, Jun-Sik,Kim, Seoung-Hoi,Rieke, Reuben D.
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- Well-defined, air-stable (NHC)Pd(Allyl)Cl (NHC = N-heterocyclic carbene) catalysts for the arylation of ketones
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(formula presented) A number of palladium-N-heterocyclic carbene (NHC) complexes were found to be active catalysts for the arylation of ketones. A large number of substrates, both aryl halides and ketones, are compatible with the reaction conditions. The ketone arylation reactions are achieved with low catalyst loading in short reaction times using aryl chlorides and triflates as reactive partners.
- Viciu, Mihai S.,Germaneau, Romain F.,Nolan, Steven P.
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p. 4053 - 4055
(2007/10/03)
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- Highly regioselective, sequential, and multiple palladium-catalyzed arylations of vinyl ethers carrying a coordinating auxiliary: An example of a heck triarylation process
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This article describes the development of new auxiliary-accelerated Heck multiarylations by intramolecular presentation of the oxidative addition complex. The introduction of a specific, palladium-coordinating dimethylamino group allows for the desired chelation-accelerated and chelation-controlled tri- and diarylation reactions. We report (a) the first example of a Heck triarylation process, (b) highly selective palladium-catalyzed diarylations of alkyl vinyl ethers, and (c) a very rapid two-phase protocol for the microwave-assisted hydrolysis of amino-substituted, arylated vinyl ethers constituting an entry to diarylated ethanals and substituted desoxybenzoins. X-ray structures and product patterns support the suggested substrate-controlled Heck reaction pathway. The catalyst-directing alkyl dimethylamino functionality was rapidly (1-2 min) and efficiently released by microwave hydrolysis after Heck multiarylation reactions. The liberated aromatic carbonyl compounds were thereafter isolated and fully characterized.
- Nilsson,Larhed,Hallberg
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p. 8217 - 8225
(2007/10/03)
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- A simple method for the synthesis of substituted benzylic ketones: Homologation of aldehydes via the in situ generation of aryldiazomethanes from aromatic aldehydes
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A general method for the homologation of aldehydes to benzylic ketones has been developed. Aryldiazomethanes were generated in situ in the presence of an aldehyde by simply heating the tosylhydrazones of aromatic aldehydes in the presence of a stoichiometric amount of base in polar protic solvents. The resulting polar protic solvent promoted homologation afforded benzylic ketones in moderate to excellent yields with a variety of aldehydes. Isolation of the tosylhydrazones was not necessary; they could be prepared in ethanol and carried through the sequence without isolation. This methodology allows easy access to a wide variety of substituted aryldiazomethanes that would be difficult, or even impossible, to prepare via conventional methods and circumvents the toxicity and stability problems associated with the isolation and/or handling solutions of aryldiazomethanes.
- Angle, Steven R.,Neitzel, Martin L.
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p. 6458 - 6461
(2007/10/03)
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- Carbon-carbon bond cleavage of α-substituted benzoins by retro-benzoin condensation; A new method of synthesizing ketones
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When α-benzylbenzoin (3a, α-benzyl-α-hydroxybenzyl phenyl ketone) was treated with potassium cyanide (1) in N,N-dimethylformamide at 80°C for 1h, the carbon-carbon bond was cleaved, resulting in the formation of deoxybenzoin (4a, benzyl phenyl ketone) and benzaldehyde (2a). This carbon- carbon bond cleavage proceeds through a retro-benzoin condensation mechanism. This method of synthesizing ketones was applied to several α-substituted benzoins (3), and the corresponding ketones (4) were formed in good yields. Further, we found that the cyanide ion-donating ability of tetrabutylammonium cyanide (6, Bu4NCN) is more effective than that of potassium cyanide (1, KCN). As expected from the chemical analogy between cyanide ion and azolium ylide, several azolium salts (7) can also be employed in the retro-benzoin condensation as catalysts. The benzoin derivatives 3 were synthesized in the following three ways; reaction of alkyl halide (9) with benzoin (5), Michael addition of benzoin (5) with acceptors (10), and Grignard reaction of benzils (8). Alkylation of the benzoins without isolation, followed by carbon-carbon bond cleavage, readily afforded the corresponding ketones (4).
- Miyashita, Akira,Suzuki, Yumiko,Okumura, Yoko,Iwamoto, Ken-Ichi,Higashino, Takeo
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- A new method of synthesizing deoxybenzoins from 1,3-dimethyl-2-(α- benzyloxybenzyl)imidazolium and 1,3-dimethyl-2-(α- benzyloxybenzyl)benzimidazolium iodides based on Wittig-type rearrangement
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The treatment of 1,3-dimethyl-2-(α-benzyloxybenzyl)benzimidazolium iodides 1 with a base gave deoxybenzoins 2 in moderate yields. Sodium hydride (NaH), potassium carbonate (K2CO3), and cesium carbonate (Cs2CO3) were effective bases in this reaction. Deoxybenzoins 2 were produced through rearrangement of the benzyl group followed by expulsion of the 1,3- dimethylbenzimidazolium ylide (A). The rearrangement proceeds in a way similar to Wittig rearrangement. Deoxybenzoins 2 were also formed in good yields from 1,3-dimethyl-2-(α-benzyloxybenzyl)imidazolium iodides 4 upon similar treatment. However, the quaternary salts having a thiazolium moiety 5a and a pyridinium moiety 6a failed to produce deoxybenzoin (2a).
- Miyashita, Akira,Matsuoka, Yoshiyuki,Suzuki, Yumiko,Iwamoto, Ken-Ichi,Higashino, Takeo
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p. 1235 - 1242
(2007/10/03)
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- Cis-trans isomerization and oxidation of radical cations of stilbene derivatives
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Isomerization from cis stilbene derivatives (c-S (S = RCH=CHC6H5: 1, R = C6H5; 2, R = 4-CH3C6H4; 3, R = 4-CH3OC6H4 (= An); 4, R = 2,4-(CH3O)2C6H3; 5, R = 3,4-(CH3O)2C6H3; 6, R = 3,5-(CH3O)2C6H3; 7, AnCH=C(CH3)C6H5; 8, AnCH=CHAn)) to trans isomers (t-S) and oxidation of S with O2 were studied in γ-ray radiolyses of c-S in Ar-saturated 1,2-dichloroethane (DCE) and of S in O2-saturated DCE, respectively. On the basis of product analyses, it is suggested that a smaller barrier to c-t unimolecular isomerization for c-3.+-5.+ and 8.+ than for c-1.+, 2.+, and 6.+ due to the single bond character of the central C=C double bond for c-3.+-5.+ and 8.+ with a p-methoxyl group but not for c-l.+, 2.+, and 6.+ without a p-methoxyl group because of the contribution of a quinoid-type structure induced by charge-spin separation. The isomerization proceeds via chain reaction mechanisms involving c-t unimolecular isomerization and endergonic hole transfer or dimerization and decomposition. The isomerization of c-3.+ to t-3.+ is catalyzed by addition of 1,4-dimethoxybenzene but terminated by triethylamine. The regioselective formation of 3d in oxidation of 3.+ with O2 is explained by spin localization on the β-olefinic carbon in 3.+. The results of product analyses are compared with the rate constants of the unimolecular isomerization and the oxidation for S.+ measured with pulse radiolyses.
- Majima, Tetsuro,Tojo, Sachiko,Ishida, Akito,Takamuku, Setsuo
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p. 7793 - 7800
(2007/10/03)
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- 10,5-(Iminomethano)-10,11-dihydro-5H-dibenzo[a,d]cycloheptene and derivatives. Potent PCP receptor ligands
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IDDC (3, 10,5-(iminomethano)-10,11-dihydro-5H-dibenzo[a,d]cycloheptene) and a series of substituted derivatives were synthesized and evaluated in vitro for their ability to displace tritiated MK-801 ([3H]-2) from its specific binding site in guinea pig brain homogenate. Substitution at the 3- position of 3 with bromine, chlorine, and fluorine led to increased binding affinity. In contrast, substitution of donor groups at the 3-position gave decreased binding affinities, as did all substitutions at the 7-position and on nitrogen. Where racemic mixtures were resolved, the (+)-optical antipodes were more active than their enantiomers or racemates. The most active ligand found in this study was (+)-13e (IC50 = 15.5 ± 4.5 nM). The affinity of (+)-13e for the PCP receptor makes it among the most potent ligands known. In vitro neuroprotection was demonstrated by 3, (+)-3, and (+)-6 (N-Me-IDDC) against glutamate-induced cell death in rat hippocampal cells.
- Gee,Barmettler,Rhodes,McBurney,Reddy,Hu -,Cotter,Hamilton,Weber,Keana
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p. 1938 - 1946
(2007/10/02)
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