- Palladium-catalyzed intermolecular alkene carboacylation via ester C-O bond activation
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We report palladium-catalyzed intermolecular carboacylation of alkenes with ester electrophiles and tetraarylborate nucleophiles. Bicyclic alkenes react with a variety of pentafluorophenyl benzoate and alkanoate esters and sodium tetraarylborates to form ketone products in ≤99% yields. These reactions occur in the absence of a directing group and demonstrate esters are competent acyl electrophiles for intermolecular alkene carboacylation reactions.
- Banovetz, Haley K.,Vickerman, Kevin L.,David, Colton M.,Alkan, Melisa,Stanley, Levi M.
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- Evaluation of Cyclic Amides as Activating Groups in N-C Bond Cross-Coupling: Discovery of N-Acyl-δ-valerolactams as Effective Twisted Amide Precursors for Cross-Coupling Reactions
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The development of efficient methods for facilitating N-C(O) bond activation in amides is an important objective in organic synthesis that permits the manipulation of the traditionally unreactive amide bonds. Herein, we report a comparative evaluation of a series of cyclic amides as activating groups in amide N-C(O) bond cross-coupling. Evaluation of N-acyl-imides, N-acyl-lactams, and N-acyl-oxazolidinones bearing five- and six-membered rings using Pd(II)-NHC and Pd-phosphine systems reveals the relative reactivity order of N-activating groups in Suzuki-Miyaura cross-coupling. The reactivity of activated phenolic esters and thioesters is evaluated for comparison in O-C(O) and S-C(O) cross-coupling under the same reaction conditions. Most notably, the study reveals N-acyl-δ-valerolactams as a highly effective class of mono-N-acyl-activated amide precursors in cross-coupling. The X-ray structure of the model N-acyl-δ-valerolactam is characterized by an additive Winkler-Dunitz distortion parameter ?(τ+χN) of 54.0°, placing this amide in a medium distortion range of twisted amides. Computational studies provide insight into the structural and energetic parameters of the amide bond, including amidic resonance, N/O-protonation aptitude, and the rotational barrier around the N-C(O) axis. This class of N-acyl-lactams will be a valuable addition to the growing portfolio of amide electrophiles for cross-coupling reactions by acyl-metal intermediates.
- Rahman, Md. Mahbubur,Pyle, Daniel J.,Bisz, Elwira,Dziuk, B?a?ej,Ejsmont, Krzysztof,Lalancette, Roger,Wang, Qi,Chen, Hao,Szostak, Roman,Szostak, Michal
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p. 10455 - 10466
(2021/07/31)
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- Formation of 1-hydroxymethylene-1,1-bisphosphinates through the addition of a silylated phosphonite on various trivalent derivatives
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An easily handled one-pot synthetic procedure was previously developed for the synthesis of bisphosphinates starting from acyl chlorides. Herein, other trivalent derivatives as acid anhydrides and activated esters were tested to form various bisphosphinates. This modulation of the reactivity can be controlled according to the nature of the acid derivative for the use of sensitive and functionalized substrates.
- Dussart-Gautheret, Jade,Deschamp, Julia,Monteil, Maelle,Gager, Olivier,Legigan, Thibaut,Migianu-Griffoni, Evelyne,Lecouvey, Marc
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p. 14559 - 14569
(2020/12/29)
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- Heterogeneous Suzuki-Miyaura coupling of heteroaryl ester: Via chemoselective C(acyl)-O bond activation
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A site-selective supported palladium nanoparticle catalyzed Suzuki-Miyaura cross-coupling reaction with heteroaryl esters and arylboronic acids as coupling partners was developed. This methodology provides a heterogeneous catalytic route for aryl ketone formation via C(acyl)-O bond activation of esters by successful suppression of the undesired decarbonylation phenomenon. The catalyst can be reused and shows high activity after eight cycles. The XPS analysis of the catalyst before and after the reaction suggested that the reaction might be performed via a Pd0/PdII catalytic cycle that began with Pd0.
- Ma, Hongpeng,Bai, Chaolumen,Bao, Yong-Sheng
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p. 17266 - 17272
(2019/06/24)
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- Transesterification of (hetero)aryl esters with phenols by an Earth-abundant metal catalyst
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Readily available and inexpensive Earth-abundant alkali metal species are used as efficient catalysts for the transesterification of aryl or heteroaryl esters with phenols which is a challenging and underdeveloped transformation. The simple conditions and the use of heterogeneous alkali metal catalyst make this protocol very environmentally friendly and practical. This reaction fills in the missing part in transesterification reaction of phenols and provides an efficient approach to aryl esters, which are widely used in the synthetic and pharmaceutical industry.
- Chen, Jianxia,Namila,Bai, Chaolumen,Baiyin, Menghe,Agula, Bao,Bao, Yong-Sheng
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p. 25168 - 25176
(2018/07/29)
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- Fe-Catalyzed Aerobic Oxidative C-CN Bond Cleavage of Arylacetonitriles Leading to Various Esters
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Fe-catalyzed aerobic oxidative esterifications of arylacetonitriles with alcohols, tri alkoxsilanes, silicate esters, or borate esters have been developed. The acyl groups which were in situ generated via chemoselective C(CO)-CN bond cleavage were directly used as electrophiles, leading to corresponding aryl esters in good to excellent yields under molecular oxygen when attacked by alcohols or alcohol surrogates. Dioxygen serves as both oxidant and reactant in this protocol. The reaction has a very broad substrate scope. Cheap starting materials as well as environmentally benign and inexpensive iron catalyst and ideal oxidant O2 feature this transformation and make it a practical and sustainable protocol to afford esters.
- Kong, Weiguang,Li, Bingnan,Xu, Xuezhao,Song, Qiuling
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p. 8436 - 8443
(2016/09/28)
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- Chemoselective synthesis of β-ketophosphonates using lithiated α-(trimethylsilyl)methylphosphonate
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A highly chemoselective synthesis of β-ketophosphonates from pentafluorophenyl esters and lithiated methyl α-(trimethylsilyl)methylphosphonate has been developed. This mild lithiated phosphonate reagent allows the synthesis of functionalized β-ketophosphonates in the presence of unactivated esters with high yields. This method has been compared with the standard lithiated methylphosphonate reagent.
- Specklin, Simon,Cossy, Janine
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p. 3302 - 3308
(2015/03/30)
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- Aminolysis of aryl ester using tertiary amine as amino donor via c-o and c-n bond activations
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An aminolysis reaction between various aryl esters and inert tertiary amines by C-O and C-N bond activations has been developed for the selective synthesis of a broad scope of tertiary amides under neutral and mild conditions. The mechanism may undergo the two key steps of oxidative addition of acyl C-O bond in parent ester and C-N bond cleavage of tertiary amine via an iminium-type intermediate.
- Bao, Yong-Sheng,Zhaorigetu, Bao,Agula, Bao,Baiyin, Menghe,Jia, Meilin
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p. 803 - 808
(2014/04/03)
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- Energy-efficient green catalysis: Supported gold nanoparticle-catalyzed aminolysis of esters with inert tertiary amines by C-O and C-N bond activations
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Catalyzed by supported gold nanoparticles, an aminolysis reaction between various aryl esters and inert tertiary amines by C-O and C-N bond activations has been developed for the selective synthesis of tertiary amides. Comparison studies indicated that the gold nanoparticles could perform energy-efficient green catalysis at room temperature, whereas Pd(OAc)2 could not.
- Bao, Yong-Sheng,Baiyin, Menghe,Agula, Bao,Jia, Meilin,Zhaorigetu, Bao
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p. 6715 - 6719
(2014/08/05)
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- COPOLYMERIZABLE PHOTOINITIATORS
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Benzophenone derivatives of formula (I) in which X is O, S or NR3, and R3 is H or linear or branched C1-C10 alkyl; R1 is H or methyl, R2 is H, halogen, linear or branched C1-C10 alkoxy, linear or branched C1-C10 alkyl, linear or branched C1-C10 alkylthio or a group NR4R5, wherein R4 and R5 are independently linear or branched C1-C10 alkyl, can be used as copolymerizable photoinitiators and photocrosslinkers.
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Page/Page column 13; 14
(2014/01/08)
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- Transesterification for synthesis of carboxylates using aldehydes as acyl donors via C-H and C-O bond activations
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A new type of transesterification between aryl, heteroaryl, alkyl N-heteroarene-2-carboxylates and various aldehydes by C-H and C-O bond activations has been developed for the synthesis of versatile carboxylates. A possible mechanism containing oxidative addition of acyl-O bond in parent ester and radical cleavage of sp2 C-H bond in aldehyde is proposed.
- Bao, Yong-Sheng,Chen, Chao-Yue,Huang, Zhi-Zhen
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p. 8344 - 8349,6
(2020/10/15)
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- A synthesis of 1-substituted 5-[2-(acylamino)ethyl]-1H-pyrazole-4-carboxamides
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A seven-step synthesis of 1-substituted 5-(2-acylaminoethyl)-1H-pyrazole-4-carboxamides 20 as the pyrazole analogues of histamine was developed. The synthesis starts with a three-step preparation of N(1)-substituted methyl 5-(2-tert-butoxycarbonylaminoethyl)-1H-pyrazole-4-carboxylates 7 from commercially available Boc-β-alanine (1). Subsequent four-step transformation of the key-intermediates 7 into the final products 20 was performed following two complementary reaction sequences comprising acidolytic removal of the Boc group, hydrolysis of the COOMe group, amidations of the COOH group, and acylations of the NH2 group. The structures of pyrazole derivatives were determined by spectroscopic methods and by X-ray diffraction.
- Kralj, David,Friedrich, Miha,Gro?elj, Uro?,Kiraly-Potpara, Sonja,Meden, Anton,Wagger, Jernej,Dahmann, Georg,Stanovnik, Branko,Svete, Jurij
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experimental part
p. 7151 - 7162
(2009/12/06)
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- Direct carbon - Carbon bond formation via soft enolization: A facile and efficient synthesis of 1,3-diketones
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Ketones undergo soft enolate formation and acylation on treatment with MgBr2·OEt2, i-Pr2NEt, and various acylating agents to give 1,3-diketones. The process is particularly efficient for N-acylbenzotriazoles and O-Pfp esters, and, in these cases, is conducted with untreated, reagent-grade CH2Cl2 open to the air, thus providing an exceptionally simple approach to the synthesis of this important class of compounds.
- Lim, Daniel,Fang, Fang,Zhou, Guoqiang,Coltart, Don M.
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p. 4139 - 4142
(2008/02/12)
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- Convenient syntheses of 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols and the corresponding trimethylsilyl ethers
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A new convenient synthetic procedure to obtain various 1,1,1,3,3,3- hexafluoro-2-organyl-propan-2-ols and the corresponding trimethylsilyl ethers has been worked out starting from anhydrides or activated esters of carboxylic acids and trimethyl(trifluoromethyl)silane in the presence of tetramethylammonium fluoride. Conditions for the selective formation of 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols as well as the trimethylsilyl derivatives have been found.
- Babadzhanova,Kirij,Yagupolskii,Tyrra,Naumann
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p. 1813 - 1819
(2007/10/03)
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- New approaches to bicylic vinyl heterocycles from propargylic acetals
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(Chemical Equation Presented) The paper describes further studies on the intramolecular carbolithiation of propargylic acetals with aryllithiums leading to 2-vinylbenzofurans and 3-vinylfuropyridines. Attempts to extend the cascade to [4.4.0] binuclear he
- Le Strat, Frederic,Harrowven, David C.,Maddaluno, Jacques
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p. 489 - 498
(2007/10/03)
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- Anti-tumor compounds
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The invention relates to quinazoline derivatives, or pharmaceutically-acceptable salts thereof, which possess anti-tumour activity; to processes for their manufacture; and to pharmaceutical compositions containing them. The invention provides a quinazoline of the formula: STR1 wherein R1 includes hydrogen, amino and alkyl or alkoxy each of up to 4 carbon atoms; R2 includes hydrogen, alkyl, hydroxyalkyl and halogenoalkyl each of up to 4 carbon atoms; R3 is hydrogen or alkyl or up to 3 carbon atoms; Ar is phenylene or heterocyclene; L is a group of the formula --CO.NH--, --NH.CO--, --CO.NR4 --, --NR4.CO--, --CH=CH-- or --CO.O--, wherein R4 is alkyl of up to 4 carbon atoms; and Y is a branched alkyl group bearing substituents Y2 and Y3 the definition of each independently including hydroxy, cyano, aryl and heteroaryl, and the definition of Y3 also optionally including sulpho, N-phenylsulphonylcarbamoyl and 5-tetrazolyl; or a pharmaceutically-acceptable salt thereof.
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