- C-C bond formation from alcohols and malonate half esters using borrowing hydrogen methodology
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Alcohols have been used as alkylating agents in a decarboxylative reaction with malonate half esters via a borrowing hydrogen pathway catalysed by readily available Ru(PPh3)3Cl2.
- Pridmore, Simon J.,Williams, Jonathan M.J.
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- Facile synthesis of highly congested 1,2-diphosphinobenzenes from bis(phosphine)boronium salts
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(Chemical Equation Presented) Bis(phosphine)boronium salts 3a-c were designed and prepared as key building blocks for the synthesis of highly congested diphosphinobenzenes. The preparation of sterically hindered ortho-phenylene-bridged diphosphines 1a-c was achieved by the reaction of the bis(phosphine)boronium salts 3a-c with difluorobenzenechromium complex 2 and subsequent removal of the BH2 group. The steric nature of diphosphine 1a was revealed in single-crystal X-ray analysis of its Rh complex.
- Yamamoto, Yoshikazu,Koizumi, Toru,Katagiri, Kosuke,Furuya, Yui,Danjo, Hiroshi,Imamoto, Tsuneo,Yamaguchi, Kentaro
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- One-Pot, Tandem Wittig Hydrogenation: Formal C(sp3)-C(sp3) Bond Formation with Extensive Scope
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A one-pot, tandem Wittig hydrogenation of aldehydes with stabilized ylides is reported, representing a formal C(sp3)-C(sp3) bond construction. The tandem reaction operates under mild conditions, is high yielding, and is broad in scope. Chemoselectivity for olefin reduction is observed, and the methodology is demonstrated in the synthesis of lapatinib analogues and a formal synthesis of (±)-cuspareine. Early insights suggest that the chemoselectivity observed in the reduction step is due to partial poisoning of the catalyst, after step one, thus adding to the power of the one-pot procedure.
- Devlin, Rory,Jones, David J.,Mcglacken, Gerard P.
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supporting information
p. 5223 - 5228
(2020/07/14)
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- Anodic benzylic C(sp3)-H amination: Unified access to pyrrolidines and piperidines
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An electrochemical aliphatic C-H amination strategy was developed to access the important heterocyclic motifs of pyrrolidines and piperidines within a uniform reaction protocol. The mechanism of this unprecedented C-H amination strategy involves anodic C-H activation to generate a benzylic cation, which is efficiently trapped by a nitrogen nucleophile. The applicability of the process is demonstrated for 40 examples comprising both 5- and 6-membered ring formations.
- Herold, Sebastian,Bafaluy, Daniel,Mu?iz, Kilian
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p. 3191 - 3196
(2018/07/29)
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- Controllable mono-/dialkenylation of benzyl thioethers through rh-catalyzed aryl C-H activation
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Under solvent control: Benzyl thioethers were alkenylated in excellent yields with broad substrate scope and the selectivity (mono- vs. disubstituted product) was controlled by the solvent and ratio of reactants (see scheme). Sequential alkenylation with two different alkenes was also carried out in a one-pot process. In addition, the thioether directing group was removed in a one-pot process with simultaneous hydrogenation of the double bond to give the toluene derivatives. Copyright
- Zhang, Xi-Sha,Zhu, Qi-Lei,Zhang, Yun-Fei,Li, Yan-Bang,Shi, Zhang-Jie
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p. 11898 - 11903
(2013/09/23)
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- Heck reactions catalyzed by Pd(0)-PVP nanoparticles under conventional and microwave heating
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Pd(0) nanoparticles stabilized by polyvinylpyrrolidone (Pd-PVP) with a diameter of 3-6 nm in ethanol catalyzed Heck coupling of iodobenzene with different alkenes under microwave heating. Products were obtained in good yields (62-99%) and good selectivity to the E-isomers. Microwave heating proved to be superior to conventional heating, providing products in higher yields and selectivities in short times (12 min).
- Martins, Daniela De L.,Alvarez, Heiddy M.,Aguiar, Lúcia C.S.,Antunes, Octavio A.C.
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scheme or table
p. 47 - 53
(2012/04/11)
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- Chemoselective Heck arylation of acrolein diethyl acetal catalyzed by an oxime-derived palladacycle
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A dimeric 4-hydroxyacetophenone oxime-derived palladacycle has been used as a very efficient precatalyst for the chemoselective arylation of acrolein diethyl acetal to give either cinnamaldehyde derivatives or 3-arylpropanoate esters by proper choice of the reaction conditions. The synthesis of cinnamaldehyde derivatives can be performed by Heck reaction of acrolein diethyl acetal with iodo-, bromo- or chloroarenes in N,N-dimethylacetamide (DMA) using K2CO3 as base at 120°C and tetra-n-butylammonium acetate (TBAA) and KCl as additives, followed by acid workup. In the case of 3-arylpropanoate esters the corresponding arylation of acrolein diethyl acetal with iodoarenes can be performed at 90°C in aqueous DMA using (dicylohexyl)methylamine as base, whereas for bromoarenes the reaction has to be performed at 120°C using tetra-n-butylammonium bromide (TBAB) as additive. Alternatively, this process can be performed under microwave irradiation. These couplings take place in good yields and with lower catalyst loading than with palladium(II) acetate as well as in shorter reaction times and with lower excess of acrolein diethyl acetal.
- Nájera, Carmen,Botella, Luis
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p. 9688 - 9695
(2007/10/03)
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- Direct synthesis of 3-arylpropionic acids by tetraphosphine/palladium catalysed Heck reactions of aryl halides with acrolein ethylene acetal
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Through the use of [PdCl(C3H5)]2/Cis,cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as a catalyst, a range of aryl bromides undergoes Heck reaction with acrolein ethylene acetal. With this acetal, the selective formation of 3-arylpropionic acids/esters was observed. The functional group tolerance on the aryl halide is remarkable; substituents such as fluoro, methyl, methoxy, acetyl, formyl, benzoyl, nitro or nitrile are tolerated. Furthermore, this catalyst can be used at low loading, even for reactions of sterically hindered aryl bromides. Graphical Abstract.
- Lemhadri, Mhamed,Doucet, Henri,Santelli, Maurice
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p. 11533 - 11540
(2007/10/03)
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- 3-arylpropanoate esters through the palladium-catalyzed reaction of aryl halides with acrolein diethyl acetal
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The reaction of aryl halides with acrolein diethyl acetal in the presence of Pd(OAc)2, n-Bu3N, and n-Bu4NCl in DMF at 90°C affords ethyl 3-arylpropanoates. A variety of functional groups are tolerated in the aryl halides, including ether, aldehyde, ketone, ester, nitrile, and nitro groups. ortho-Substituents do not hamper the reaction. 3-Arylpropanoate esters were isolated in good to excellent yields with many neutral, electron-rich and electron-poor aryl iodides and electron-poor aryl bromide. Neutral and electron-rich aryl bromides gave the desired ester in moderate yields.
- Battistuzzi, Gianfranco,Cacchi, Sandro,Fabrizi, Giancarlo,Bernini, Roberta
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p. 1133 - 1136
(2007/10/03)
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- Inhibition of uridine phosphorylase: Synthesis and structure-activity relationships of aryl-substituted 5-benzyluracils and 1-[(2- hydroxyethoxy)methyl]-5-benzyluracils
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A series of 1-[(2-hydroxyethoxy)methyl]-5-benzyluracils were synthesized and tested for inhibition of murine liver uridine phosphorylase (UrdPase). Inhibitors of UrdPase are reported to enhance the chemotherapeutic utility of 5-fluoro-2'-deoxyuridine and 5-fluorouracil and to ameliorate zidovudine- induced anemia in animal models. We prepared a series of 5-aryl-substituted analogues of 5-benzylacyclouridine (BAU), a good inhibitor of UrdPase (IC50 of 0.46 μM), to develop a compound with enhanced potency and improved pharmacokinetics. The first phase of structure-activity relationship studies on a series of 32 aryl-substituted 5-benzyluracils found several 5-(3- alkoxybenzyl) analogues of 5-benzyluracil with enhanced potency. The acyclovir side chain, the (2-hydroxyethoxy)methyl group, was substituted on the more potent aryl-substituted 5-benzyluracils. The two most potent compounds, 10y (3-propoxy) and 10dd (3-sec-butoxy), were inhibitors of UrdPase with IC50s of 0.047 and 0.027 μM, respectively. Six compounds were tested in vivo for effects on steady-state concentrations of circulating uridine in rats. Plasma uridine levels were elevated 3-9-fold by compound levels that ranged from 8 to 50 μM.
- Orr,Musso,Boswell,Kelley,Joyner,Davis,Baccanari
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p. 3850 - 3856
(2007/10/02)
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- Carbon-Carbon Bond-Forming Reactions of Zinc Homoenolate of Esters. A Novel Three-Carbon Nucleophile with General Synthetic Utility
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In the presence of suitable catalysts and additives, the zinc homoenolate of alkyl propionate and its congeners undergo a variety of carbon-carbon bond-forming reactions, e.g., addition onto carbonyl compounds, allylation, arylation, vinylation, and acylation, to produce diverse kinds of alkanoates and cyclopropane derivatives.The moderately reactive zinc homoenolate exhibited a very high degree of chemoselectivity in these reactions.Me3SiCl has been found to greatly accelerate 1,2- or 1,4-addition and the allylation reaction of the zinc reagent.
- Nakamura, Eiichi,Aoki, Satoshi,Sekiya, Kouichi,Oshino, Hiroji,Kuwajima, Isao
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p. 8056 - 8066
(2007/10/02)
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- PALLADIUM CATALYZED REACTIONS OF PROPIONATE HOMOENOLATE. ARYLATION, VINYLATION, AND ACYLATION
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Zinc homoanolate of alkyl propionate undergoes clean C-C bond forming reactions with aryl, vinyl and acid halides in the presence of a palladium catalyst.
- Nakamura, Eiichi,Kuwajima, Isao
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- ARYLATION AND VINYLATION OF 2-CARBOETHOXYETHYLZINC IODIDE AND 3-CARBOETHOXYPROPYLZINC IODIDE CATALYZED BY PALLADIUM
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By the palladium catalysis 2-carboethoxyethylzinc iodide reacts with aryl iodides and vinyl iodides or triflates to provide the coupling products (ethyl 3-arylpropionates and ethyl 4-pentenoates, respectively) in satisfactory yields.The similar coupling reaction is observed for the reaction with 3-carboethoxypropylzinc iodide.
- Tamaru, Y.,Ochiai, H.,Nakamura, T.,Yoshida, Z.
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p. 955 - 958
(2007/10/02)
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