- Benzene-1,3,5-triyl triformate (TFBen): a convenient, efficient, and non-reacting CO source in carbonylation reactions
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Benzene-1,3,5-triyl triformate (TFBen) as a kind of convenient and efficient CO source has been prepared for the first time. The character of TFBen as potent and non-reacting CO source has been proven by the successful synthetic applications in carbonylation reactions. Phloroglucinol (1,3,5-trihydroxybenzene) is abundant and naturally occurring has been applied as the reusable material for TFBen synthesis.
- Jiang, Li-Bing,Qi, Xinxin,Wu, Xiao-Feng
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- Direct esterification of aromatic aldehydes with tetraphenylphosphonium bromide under oxidative N-heterocyclic carbene catalysis
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An unconventional reagent, tetraphenylphosphonium bromide, was employed as a phenyl source in the direct transformation of aromatic aldehydes to the corresponding phenyl esters under oxidative N-heterocyclic carbene (NHC) catalysis. The phenyl esters were obtained in moderate yields under mild and organocatalytic conditions. Copyright
- Ramanjaneyulu, Bandaru T.,Pareek, Manish,Reddy, Virsinha,Vijaya Anand
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- Copper-catalysed synthesis of trifluoromethyl(hetero)arenes from di(hetero)aryl-λ3-iodanes
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An efficient synthesis of trifluoromethylated (hetero)arenes has been achieved through the regioselective copper-catalyzed trifluoromethylation of di(hetero)aryl-λ3-iodanes, employing readily available trifluoromethyltrimethylsilane. The reaction works well for both symmetrical and unsymmetrical di(hetero)aryl-λ3-iodanes with good regioselectivity and also tolerates diverse functional groups such as bromo, iodo, cyano, nitro, ester, ketone and enolizable ketone.
- Pandey, Vinay Kumar,Anbarasan, Pazhamalai
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- Conversion of esters to thioesters under mild conditions
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We report conversion of esters to thioestersviaselective C-O bond cleavage/weak C-S bond formation under transition-metal-free conditions. The method is notable for a general and practical transition-metal-free system, broad substrate scope and excellent functional group tolerance. The strategy was successfully deployed in late-stage thioesterification, site-selective cross-coupling/thioesterification/decarbonylation and easy-to-handle gram scale thioesterification. Selectivity and computational studies were performed to gain insight into the formation of weak C-S bonds by C-O bond cleavage, which contrasts with the traditional trend of nucleophilic additions to carboxylic acid derivatives.
- Shi, Yijun,Liu, Xuejing,Cao, Han,Bie, Fusheng,Han, Ying,Yan, Peng,Szostak, Roman,Szostak, Michal,Liu, Chengwei
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supporting information
p. 2991 - 2996
(2021/04/14)
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- Transition-Metal-Free DMAP-Mediated Aromatic Esterification of Amides with Organoboronic Acids
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A new, transition-metal-free, effective method for aromatic esterification of amides with organoboronic acids has been developed. A wide range of benzoate derivatives were obtained with yields ranging from moderate to good. The catalytic reaction shows a broad substrate scope and excellent functional group tolerance. Conceptually, DMAP mediates the reaction and is crucial for this transformation.
- Guo, Jiarui,Liu, Lantao,Wang, Tao,Wang, Yanqing,Xu, Kai,Zhang, Yuheng
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supporting information
p. 3274 - 3277
(2021/06/26)
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- Hydrogen-bond-assisted transition-metal-free catalytic transformation of amides to esters
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The amide C-N cleavage has drawn a broad interest in synthetic chemistry, biological process and pharmaceutical industry. Transition-metal, luxury ligand or excess base were always vital to the transformation. Here, we developed a transition-metal-free hydrogen-bond-assisted esterification of amides with only catalytic amount of base. The proposed crucial role of hydrogen bonding for assisting esterification was supported by control experiments, density functional theory (DFT) calculations and kinetic studies. Besides broad substrate scopes and excellent functional groups tolerance, this base-catalyzed protocol complements the conventional transition-metal-catalyzed esterification of amides and provides a new pathway to catalytic cleavage of amide C-N bonds for organic synthesis and pharmaceutical industry. [Figure not available: see fulltext.]
- Huang, Changyu,Li, Jinpeng,Wang, Jiaquan,Zheng, Qingshu,Li, Zhenhua,Tu, Tao
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- Method for preparing diaryl ester compound through efficient catalysis of pyridine palladium
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The invention discloses a method for preparing a diaryl ester compound through efficient catalysis of pyridine palladium. The method is used for high-efficiency high-yield preparation of the diaryl ester compound under mild conditions by taking a phenol compound, an iodobenzene compound and carbon monoxide as raw materials, triethylamine as alkali and pyridine palladium as a catalyst. The method provided by the invention has the advantages of less usage amount of the palladium catalyst, high catalytic activity of the palladium catalyst, stability of the palladium catalyst to air, simple operation, short reaction time and high atom economy, opens up a low-cost, green and efficient way for preparation of diaryl ester compounds, and has broad application prospects.
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Paragraph 0016-0020; 0051-0055
(2020/12/31)
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- Designing heterocyclic chalcones, benzoyl/sulfonyl hydrazones: An insight into their biological activities and molecular docking study
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The aim of this study is to investigate the antioxidant, anticholinesterase and the antiproliferative activities of some chalcones, benzoyl and sulfonyl hydrazones. The antioxidant activity was studied by way of four complimentary assays and the anticholinesterase activity was studied using the Ellman method. The antiproliferative activity of the compounds was determined using a BrdU cell proliferation ELISA assay. Compound 32 (IC50: 15.58 ± 0.01 μg/mL) against the brain (C6) and 29 (IC50: 5.02 ± 0.05 μg/mL) against cervical (HeLa) cancer cell lines exhibited higher antiproliferative activity than the other compounds. Two sulfonyl hydrazone derivatives 45 and 47 exhibited very good antioxidant activity. The results of anticholinesterase activity indicated that nine compounds 3, 8, 10, 14, 24, 25, 27, 38, and 45 significantly inhibited acetylcholinesterase enzymes and thirty-three compounds 1–4, 7–14, 22–28, 32–41, 44–47 inhibited butyrylcholinesterase enzymes (BChE) more than galantamine. In addition, virtual screening methods based on ligand 45 having the best activity against BChE was used to define new human BChE inhibitors. The interactions of ligand 8 against acetylcholinesterase (AChE) were also examined. Important key residues were determined and visualized on completion of the methodology. All calculations indicated the suitability of use of the molecular docking approach for understanding interaction mechanisms and crucial fragments of novel hit compounds such as the potential lead AChE and BChE inhibitor candidates.
- ?ztürk, Mehmet,Demirta?, Ibrahim,Iyido?an, Ay?egül Karakü?ük,Kur?un Aktar, Bedriye Seda,Oru?-Emre, Emine El?in,S?cak, Yusuf,Tok, Tu?ba Ta?k?n,Ya?l?o?lu, Ayse ?ahin
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- Nickel-Mediated Trifluoromethylation of Phenol Derivatives by Aryl C?O Bond Activation
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The increasing pharmaceutical importance of trifluoromethylarenes has stimulated the development of more efficient trifluoromethylation reactions. Tremendous efforts have focused on copper- and palladium-mediated/catalyzed trifluoromethylation of aryl halides. In contrast, no general method exists for the conversion of widely available inert electrophiles, such as phenol derivatives, into the corresponding trifluoromethylated arenes. Reported herein is a practical nickel-mediated trifluoromethylation of phenol derivatives with readily available trimethyl(trifluoromethyl)silane (TMSCF3). The strategy relies on PMe3-promoted oxidative addition and transmetalation, and CCl3CN-induced reductive elimination. The broad utility of this transformation has been demonstrated through the direct incorporation of trifluoromethyl into aromatic and heteroaromatic systems, including biorelevant compounds.
- Hu, Wei-Qiang,Pan, Shen,Qing, Feng-Ling,Vicic, David A.,Xu, Xiu-Hua
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p. 16076 - 16082
(2020/07/04)
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- Palladium-Catalyzed Aerobic Oxidative Coupling of Amides with Arylboronic Acids by Cooperative Catalysis
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The first fluoride and palladium co-catalyzed conversion of amide to ester through an aerobic oxidative coupling pathway is reported. This new approach presents a practical process that employs easily available oxygen and commercially available arylboronic acids as coupling partners, uses a wide range of N- tosylamides, and proceeds under mild reaction conditions. This protocol demonstrates broad functional group tolerance, and provides an alternative option to synthesize esters from N-tosylamides which obtained by simply N-functionalization of secondary amides.
- Li, Yue,Wu, Hongxiang,Zeng, Zhuo
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supporting information
p. 4357 - 4361
(2019/07/09)
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- Nickel-Catalyzed Cross-Coupling of Aryl Redoxactive Esters with Aryl Zinc Reagents
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A nickel-catalyzed aryl-aroyloxyl C(sp2)-O radical cross-coupling reaction conducted using a redox active ester with aryl zinc reagent was developed. This method demonstrates a new disconnection approach for formation of aryl aryl esters. In the one-pot sequential process, the readily available aryl carboxylic acids can be converted into functionalized aryl aryl esters and heteroaryl esters. This protocol is amenable to the gram-scale synthesis. The present method has a wide substrate scope and high functional group tolerance.
- Shih, Bo-Hao,Basha, R. Sidick,Lee, Chin Fa
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p. 8862 - 8866
(2019/09/30)
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- Transition-Metal-Free Esterification of Amides via Selective N-C Cleavage under Mild Conditions
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A general, transition-metal-free, and operationally simple method for esterification of amides by a highly selective cleavage of N-C(O) bonds under exceedingly mild conditions is reported. The reaction is characterized by broad substrate scope and excellent functional group tolerance. The potential of this mild esterification is highlighted by late-stage diversification of natural products and pharmaceuticals. Conceptually, the metal-free acyl functionalization of amides represents a significant step forward as a practical alternative to ligand exchange in acylmetal intermediates.
- Li, Guangchen,Lei, Peng,Szostak, Michal
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supporting information
p. 5622 - 5625
(2018/09/25)
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- Palladium-catalyzed Suzuki-Miyaura coupling of aryl esters
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The Suzuki-Miyaura coupling is among the most important C-C bond-forming reactions available due to its reliability, chemoselectivity, and diversity. Aryl halides and pseudohalides such as iodides, bromides, and triflates are traditionally used as the electrophilic coupling partner. The expansion of the reaction scope to nontraditional electrophiles is an ongoing challenge to enable an even greater number of useful products to be made from simple starting materials. Herein, we present how an NHC-based Pd catalyst can enable Suzuki-Miyaura coupling where the C(acyl)-0 bond of aryl esters takes on the role of electrophile, allowing the synthesis of various ketone-containing products. This contrasts known reactions of similar esters that provide biaryls via nickel catalysis. The underlying cause of this mechanistic divergence is investigated by DFT calculations, and the robustness of esters compared to more electrophilic acylative coupling partners is analyzed.
- Halima, Taoufik Ben,Zhang, Wanying,Yalaoui, Imane,Hong, Xin,Yang, Yun-Fang,Houk, Kendall N.,Newman, Stephen G.
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supporting information
p. 1311 - 1318
(2017/05/16)
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- Metal-Free O-Arylation of Carboxylic Acid by Active Diaryliodonium(III) Intermediates Generated in situ from Iodosoarenes
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The metal-free arylative coupling of carboxylic acids using iodosoarenes without the use of a catalyst and base, which is applicable to even a highly-polar molecule bearing multiple alcohol groups, is reported. The in situ preparation of the reactive diaryliodonium(III) carboxylates is the important key to this approach, and the introduction of the trimethoxybenzene auxiliary enables both the smooth salt formations and the selective aryl transfer events during the couplings. (Figure presented.).
- Dohi, Toshifumi,Koseki, Daichi,Sumida, Kohei,Okada, Kana,Mizuno, Serina,Kato, Asami,Morimoto, Koji,Kita, Yasuyuki
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p. 3503 - 3508
(2017/09/13)
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- Transition-Metal-Free Poly(thiazolium) Iodide/1,8-Diazabicyclo[5.4.0]undec-7-ene/Phenazine-Catalyzed Esterification of Aldehydes with Alcohols
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Poly(3,4-dimethyl-5-vinylthiazolium) iodide was used as a polymer precatalyst in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and phenazine for the oxidative esterification of aldehydes with alcohols. Selective functionalization of OH groups was achieved in the presence of NH2 groups. The poly(thiazolium) iodide/DBU/phenazine system exhibited excellent catalytic activity and could be reused five times without loss of activity.
- Chun, Supill,Chung, Young Keun
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supporting information
p. 3787 - 3790
(2017/07/26)
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- New piperidine-hydrazone derivatives: Synthesis, biological evaluations and molecular docking studies as AChE and BChE inhibitors
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Hydrazones and the piperidine ring containing compounds were considered as beneficial substrates in drug design. Therefore, this study was aimed at the synthesis of new benzoyl hydrazones derived from ethyl 4-oxopiperidine-1-carboxylate and 2,6-diphenylpiperidin-4-one. The synthesized compounds (1?19) were screened for their antioxidant, anticholinesterase and anticancer activities. The antioxidant capacity of the compounds was evaluated by using four complementary tests. The results showed that compound 7 and 17 have the higher lipid peroxidation inhibitory activity than the other compounds. In DPPH˙ scavenging assay, compounds 5, 6, 10, 14, 17 demonstrated better activity than that of standard BHT, while in ABTS+˙ scavenging assay compound 6 and 17 exhibited better activity among the other compounds. The CUPRAC assay disclosed that compound 2 displayed better activity than α-tocopherol. The anticholinesterase activity was performed against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Compound 11 (IC50: 35.30?±?1.11?μM) inhibited BChE better than galantamine (IC50: 46.03?±?0.14?μM). We conclude that the compound 11 can be considered as a candidate for BChE inhibitor. Moreover docking method was applied to elucidate the AChE and BChE inhibitory mechanism of the compound 11. Molecular docking analysis revealed that compound 11 bound to BChE enzyme more efficiently when compared to the AChE due to its orientations and different types of interactions. In addition, the non-cytotoxic properties of the compounds brought them into prominence, although they did not show significant anticancer properties.
- Karaman, Nurcan,S?cak, Yusuf,Ta?k?n-Tok, Tu?ba,?ztürk, Mehmet,Karakü?ük-?yido?an, Ay?egül,Dikmen, Miris,Ko?yi?it-Kaymak??o?lu, Bedia,Oru?-Emre, Emine El?in
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p. 270 - 283
(2016/09/09)
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- Palladium-catalyzed alkoxycarbonylation of aryl halides with phenols employing formic acid as the CO source
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An efficient palladium-catalyzed alkoxycarbonylation of aryl halides with phenols has been developed. Various aryl benzoates have been isolated in good to excellent yields with formic acid as the CO source. The reaction proceeds smoothly under mild conditions and good functional group tolerance was observed.
- Qi, Xinxin,Li, Chong-Liang,Jiang, Li-Bing,Zhang, Wan-Quan,Wu, Xiao-Feng
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p. 3099 - 3107
(2016/05/24)
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- Ruthenium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols
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An efficient methodology to access benzoate derivatives via tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols catalyzed by ruthenium/NHC was developed. This operationally simple one-pot process uses O2 as the clean oxidant, producing esters in good to excellent yields.
- Zhang, Di,Pan, Changduo
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experimental part
p. 41 - 45
(2012/06/18)
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- Palladium-catalyzed carbonylation of aryl, alkenyl, and allyl halides with phenyl formate
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Highly efficient palladium-catalyzed carbonylation of aryl, alkenyl, and allyl halides with phenyl formate is reported. This procedure does not use carbon monoxide and affords one-carbon-elongated carboxylic acid phenyl esters in excellent yields. The reaction proceeds smoothly under mild conditions and tolerates a wide range of functional groups including aldehyde, ether, ketone, ester, and cyano groups. Furthermore, a variety of heteroaromatic bromides can be converted to the corresponding phenyl esters in high yields.
- Ueda, Tsuyoshi,Konishi, Hideyuki,Manabe, Kei
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p. 3100 - 3103
(2012/07/27)
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- Palladium-catalyzed esterification of aryl halides using aryl formates without the use of external carbon monoxide
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Aryl formates are efficient carbon monoxide sources in palladium-catalyzed esterification of aryl halides. The carbonylation readily proceeds at ambient pressure without the use of external carbon monoxide to afford the corresponding esters in high yields.
- Fujihara, Tetsuaki,Hosoki, Tomoya,Katafuchi, Yuko,Iwai, Tomohiro,Terao, Jun,Tsuji, Yasushi
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p. 8012 - 8014
(2012/09/08)
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- Palladium/NHC-catalyzed oxidative esterification of aldehydes with phenols
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A palladium-catalyzed oxidative esterification of aldehydes with phenols is described, using air as the clean oxidant. This reaction tolerates many functional groups, providing esters with yields ranging from moderate to excellent.
- Zhang, Manli,Zhang, Shouhui,Zhang, Guoying,Chen, Fan,Cheng, Jiang
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experimental part
p. 2480 - 2483
(2011/05/16)
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- Carbonylation of aryl chlorides with oxygen nucleophiles at atmospheric pressure. Preparation of phenyl esters as acyl transfer agents and the direct preparation of alkyl esters and carboxylic acids
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(Chemical Equation Presented) A mild, functional group tolerant method of the preparation of phenyl esters from aryl chlorides via palladium-catalyzed carbonylation is described using atmospheric pressure of carbon monoxide. Phenyl esters are shown to be useful acylating agents, delivering libraries of carbonyl derivatives, including alkyl, allyl and thioesters, under very mild conditions. Direct preparation of alkyl esters and carboxylic acids is also demonstrated, providing the first method for the preparation of methyl and ethyl esters from aryl chlorides without pressured reactors.
- Watson, Donald A.,Fan, Xuexiang,Buchwald, Stephen L.
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supporting information; experimental part
p. 7096 - 7101
(2009/05/09)
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- A new method for the synthesis of carboxylic esters and lactones with di-2-thienyl carbonate (2-DTC) by the promotion of DMAP and iodine
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The esterification of carboxylic acids with alcohols by using di-2-thienyl carbonate (2-DTC) in the presence of a catalytic amount of 4-(dimethylamino) pyridine (DMAP) proceeded smoothly to afford the corresponding esters in good-to-high yields along with 2(5H)-thiophenone. This esterification was accelerated by the addition of an equimolar amount of iodine to afford the esters in higher yields within a shorter reaction time. Further, cyclization of ω-hydroxycarboxylic acids with an equimolar amount of 2-DTC in the presence of a catalytic amount of DMAP, followed by the addition of 1-4 equimolar amounts of iodine, afforded the corresponding lactones in good-to-high yields under mild conditions. This method was successfully employed in the synthesis of erythro-aleuritic acid lactone.
- Oohashi, Yoshiaki,Fukumoto, Kentarou,Mukaiyama, Teruaki
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p. 1508 - 1519
(2007/10/03)
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- Substituent effects on the base-catalysed hydrolysis of phenyl esters of para-substituted benzoic acids
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Seventeen model phenyl esters of 4-substituted benzoic acids were synthesised by the reaction of substituted benzoyl chlorides with phenol in aqueous alkaline solutions (Schotten-Baumann reaction), in pyridine (Einhorn reaction), or by the reaction of substituted benzoic acids with phosphorus oxychloride. Structures and purity of the model compounds were confirmed by 1H NMR and 13C NMR spectroscopy as well as by HPLC and elemental analysis. Phenyl 4-aminobenzoate was synthesised by reduction of phenyl 4-nitrobenzoate in methanol on palladium. Kinetics of base-catalysed hydrolysis of model phenyl esters occurring by the BAc2 mechanism were measured by UV spectrophotometry in 50% (v/v) aqueous dimethyl sulfoxide solutions at 25°C under pseudo-first-order conditions, (c[NaOH] = 0.001-1.0 mol l-1). The addition of OH- to phenyl benzoates was used to establish the kinetic J-E acidity scale. Linear relation between J-E and log kobs with the slope near unity was found for all the model compounds. The kinetic constants of hydrolysis of phenyl esters of 4-substituted benzoic acids precisely obey the Hammett relationship (σp) with ρ = 2.44. Quantitatively comparable results have been obtained by application of Alter-native Interpretation of Substituent Effects theory (AISE) using the σi set of substituent constants.
- Bauerova, Ingrid,Ludwig, Miroslav
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p. 1777 - 1790
(2007/10/03)
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- ON THE NATURE OF RESONANCE INTERACTIONS IN SUBSTITUTED BENZENES. II. 13C NMR INVESTIGATIONS ON ARYL 4-X-BENZOATES
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The response of the carbonyl-carbon chemical shift to the substituent effect in aryl 4-X-benzoates 3-6 has been studied in CDCl3.The comparison with relevant data for methyl benzoates 1 and acetophenones 2 shows, along the 3-to-6 sequence, a gradual shift
- Dell'Erba, Carlo,Sancassan, Fernando,Leandri, Giuseppe,Novi, Marino,Petrillo, Giovanni,et al.
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p. 643 - 648
(2007/10/02)
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