- Structure of a monoclinic polymorph of N-[4-(acetyloxy)-phenyl]acetamide, a prodrug of acetaminophen
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The preparation, single crystal x-ray structure and the computed powder XRD pattern of a monoclinic polymorph of N-[4-(acetyloxy)phenyl]acetamide, a prodrug of acetaminophen, are reported. The polymorph crystallizes in the space group P21/n with Z = 4 and unit cell dimensions a = 7.219(2), b = 8.015(2), c = 16.575(2) A, β = 92.07(1)°, and V = 958.4(4) A3. Infinite spiral molecular arrays result from intermolecular head-to-tail hydrogen bonding between the amidic H atom of one molecule and the acetoxy carbonyl oxygen atom of a 21-related molecule.
- Caira,De Wet,Gerber
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Read Online
- Synthesis and antiproliferative activity of new 1,2,3-triazole/flavone hybrid heterocycles against human cancer cell lines
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A series of new 1,2,3-triazole/flavone hybrid heterocycles were synthesized from 6-amino flavone via key intermediate N-propargyl flavone 6 by adopting the Sharpless Click reaction. Copper(I) catalyzed 1,3-dipolar cycloaddition reaction that gave products in high yields. All the synthesized compounds were screened for their in vitro antiproliferative activity against four human cancer cell lines, HeLa (cervical cancer cell line), MIA PaCa (pancreatic cancer cell line), MDA-MB-231 (breast cancer cell line), and IMR 32 (neuroblastoma cancer cell line). Compounds 7a, 7b, 7d, 7g (GI50 = 0.01–0.68 μM) demonstrated promising antiproliferative activity.
- Sowjanya,Jayaprakash Rao,Murthy
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Read Online
- Molecules with: O -acetyl group protect protein glycation by acetylating lysine residues
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Pharmaceutical intervention for reduction of advanced glycation end products (AGEs) is considered as a therapeutic strategy to attenuate the pathogenesis of diabetes. Many molecules have been reported to possess antiglycation activity, one such example is acetylsalicylic acid (aspirin). It protects proteins from glycation by acetylating the lysine residues. Therefore, in this study we have synthesized and screened molecules containing free N-acetyl, O-acetyl and acetophenone groups. All the selected molecules in this study showed glycation inhibition but interestingly, only molecules with O-acetyl but not N-acetyl and acetophenone groups were capable of acetylating lysine residue. Furthermore, we have demonstrated that pre-acetylation or aspirin treatment prior to the induction of diabetes helps in reducing HbA1c and AGE formation in the streptozotocin induced diabetic mice. Hence pre-acetylation may have an additional therapeutic efficacy of reducing AGE levels in vivo. Incorporation of O-acetyl group into anti-diabetic molecules could be a useful strategy, as it may have an additive effect in reducing AGEs. Identification of such novel acetylating agents represents a new area in the drug discovery process.
- Vannuruswamy, Garikapati,Jagadeeshaprasad, Mashanipalya G.,Kashinath,Kesavan, Suresh K.,Bhat, Shweta,Korwar, Arvind M.,Chougale, Ashok D.,Boppana, Ramanamurthy,Reddy, D. Srinivasa,Kulkarni, Mahesh J.
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Read Online
- Chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes using carbon-supported palladium catalytic system in water
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Developing and/or modifying fundamental chemical reactions using chemical industry-favorite heterogeneous recoverable catalytic systems in the water solvent is very important. In this paper, we developed convenient, green, and efficient approaches for the chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes in the presence of the recoverable heterogeneous carbon-supported palladium (Pd/C) catalytic system in water. The utilize of the simple, effective, and recoverable catalyst and also using of water as an entirely green solvent along with relatively short reaction times and good-to-excellent yields of the desired products are some of the noticeable features of the presented synthetic protocols. Graphic abstract: [Figure not available: see fulltext.].
- Zeynizadeh, Behzad,Mohammad Aminzadeh, Farkhondeh,Mousavi, Hossein
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p. 3289 - 3312
(2021/05/11)
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- Method for diacetate intermediate 5 - acetamide group -2 - (2, 3 - epoxypropoxy) acetophenone
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The invention belongs to the field of organic photochemical and drug intermediate chemistry. The invention particularly relates to a method for synthesizing diacetate intermediate - acetamide group 5 - (-2 - 2 epoxypropoxy) acetophenone containing acetylated 3 - photochemical rearrangement reaction in series. The reactant is cooled to the polar organic solvent, Fries rearrangement is carried out directly by ultraviolet - visible light irradiation with specific wavelength, and the intermediate Fries acetyl 2 -4 - acetyl aminophenol is obtained by heating and evaporating the solvent after the reaction is finished. Sodium hydroxide was added to prepare the phenol salt. Then, an intermediate 5 - acetamide group -2 - (2, 3 - epoxypropoxy) acetophenone was obtained by reaction with epichlorohydrin. The tandem type synthesis method disclosed by the invention is simple and feasible, and low-toxicity, high-efficiency and cheap green chemical reagents are used in the synthesis process.
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Paragraph 0022; 0026-0027; 0029-0030; 0032-0033; 0035-0036..
(2021/11/14)
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- Tin(ii) chloride dihydrate/choline chloride deep eutectic solvent: Redox properties in the fast synthesis of: N -arylacetamides and indolo(pyrrolo)[1,2- a] quinoxalines
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In this contribution a physicochemical, IR and Raman characterization for the tin(ii) chloride dihydrate/choline chloride eutectic mixture is reported. The redox properties of this solvent were also studied by cyclic voltammetry finding that it can be successfully used as an electrochemical solvent for electrosynthesis and electroanalytical processes and does not require negative potentials as verified by the reduction of nitrobenzene. The potential use of this eutectic mixture as a redox solvent was further explored in obtaining aromatic amines and N-arylacetamides starting from a wide variety of nitroaromatic compounds. In addition, a fast synthetic strategy for the construction of a series of indolo(pyrrolo)[1,2-a]quinoxalines was developed by reacting 1-(2-nitrophenyl)-1H-indole(pyrrole) with aldehydes. This simple protocol offers a straightforward method for the construction of the target quinoxalines in short reaction times and high yields where the key step involves a tandem one-pot reductive cyclization-oxidation.
- Bejarano, Oscar Rodríguez,Ochoa-Puentes, Cristian,Pe?a-Solórzano, Diana,Trujillo, Sergio Alfonso
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p. 40552 - 40561
(2020/11/18)
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- An Electrochemical Beckmann Rearrangement: Traditional Reaction via Modern Radical Mechanism
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Abstract: Electrosynthesis as a potential means of introducing heteroatoms into the carbon framework is rarely studied. Herein, the electrochemical Beckmann rearrangement, i. e. the direct electrolysis of ketoximes to amides, is presented for the first time. Using a constant current as the driving force, the reaction can be easily carried out under neutral conditions at room temperature. Based on a series of mechanistic studies, a novel radical Beckmann rearrangement mechanism is proposed. This electrochemical Beckmann rearrangement does not follow the trans-migration rule of the classical Beckmann rearrangement.
- Tang, Li,Wang, Zhi-Lv,He, Yan-Hong,Guan, Zhi
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p. 4929 - 4936
(2020/08/21)
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- Synthesis and pharmacological evaluation of piperidine (piperazine)-amide substituted derivatives as multi-target antipsychotics
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We report the optimisation of a series of novel amide-piperidine (piperazine) derivatives using the multiple ligand approach with dopamine and serotonin receptors. Of the derivatives, compound 11 exhibited high affinity for the D2, 5-HT1A, and 5-HT2A receptors, but low affinity for the 5-HT2C and histamine H1 receptors and human ether-a-go-go-related gene (hERG) channels. In vivo, compound 11 reduced apomorphine-induced climbing, MK-801-induced hyperactivity and DOI-induced head twitching without observable catalepsy, even at the highest dose tested. In addition, it exhibited suppression in a CAR test. Furthermore, in a novel object recognition task, it displayed procognition properties. Therefore, compound 11 is a promising candidate multi-target antipsychotic.
- Huang, Ling,Gao, Lanchang,Zhang, Xiaohua,Yin, Lei,Hu, Jintao,Song, Ting,Chen, Yin
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supporting information
(2020/09/01)
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- The immobilized Ni(II)-thiourea complex on silica-layered copper ferrite: A novel and reusable nanocatalyst for one-pot reductive-acetylation of nitroarenes
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In this study, magnetically nanoparticles of CuFe2O4@SiO2@PTMS@Tu@Ni(II) as novel and reusable catalyst were prepared. Synthesis of the Ni (II)-nanocatalyst was carried out through the complexation of Ni(OAc)2·4H2O with the immobilized thiourea on silica-layered CuFe2O4. The prepared nanocomposite system was then characterized using SEM, EDX, XRD, VSM, ICP-OES, Raman, UV–Vis and FT-IR analyses. Catalytic activity of the Ni(II)-CuFe2O4 system was investigated towards rapid reduction of aromatic nitro compounds to arylamines with sodium borohydride as well as one-pot reductive-acetylation of nitroarenes to acetanilides with NaBH4/Ac2O system without the isolation of intermediate arylamines. All reactions were carried out in H2O within 3–7?min to afford the products arylamines/acetanilides in high to excellent yields. Reusability of the Ni(II)-nanocatalyst was examined for seven consecutive cycles without the significant loss of the catalytic activity.
- Zeynizadeh, Behzad,Shokri, Zahra,Hasanpour Galehban, Morteza
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- Copper-Catalyzed Acetylation of Electron-Rich Phenols and Anilines
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An approach has been developed for the copper-catalyzed acetylation of phenols and anilines with potassium thioacetate as an acetylating reagent. Although only electron-rich phenols and anilines are compatible with this protocol, the reaction can provide moderate to high yields under mild conditions. Compared with other acetylating reagents, the current reagent has certain advantages, such as its low cost, easy availability, stability, insensitivity to water or air, and ease of storage.
- Zhang, Jieyu,Ke, Qiumin,Tian, Feitao,Jiang, Bei,Ji, Chang-An,Zhang, Lingling,Yu, Jian,Huang, Dayun,Yan, Guobing
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supporting information
p. 726 - 730
(2019/03/26)
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- Acylamino-Directed Specific Sequential Difunctionalizations of Anilides via Metal-Free Relay Reactions for p-Oxygen and o-Nitrogen Incorporation
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Novel acylamino-directed relay disubstitutions realize the sequential difunctionalizations of anilides (1) under mild and metal-free conditions for the first time. This [bis(trifluoroacetoxy)iodo]benzene (PIFA) and BF3·Et2O promoted straightforward reaction produces a series of p-acetoxyl- or p-alkoxyl-o-nitro-N-arylamides (2), which are key scaffolds of various drugs, functional materials, and bioactive molecules. The flexibility with respect to the functional groups in these products affords this novel protocol excellent versatility for synthetic applications.
- Wan, Yameng,Zhang, Zhiguo,Ma, Nana,Bi, Jingjing,Zhang, Guisheng
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p. 780 - 791
(2019/01/24)
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- Total Synthesis of Fontanesine B and Its Isomer: Their Antiproliferative Activity against Human Colorectal Cancer Cells
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A concise synthesis of pyrano[3,2-e]indole alkaloid fontanesine B by a Fischer indolization is described. This key Fischer indolization starts with the pyran-ring and alkene intact, facilitating potential synthetic applications. Furthermore, fontanesine B and its isomer were evaluated for in vitro antiproliferative activity against human colorectal cancer cells. The isomer of fontanesine B showed higher antiproliferative activity than the natural product, fontanesine B (2).
- Abe, Takumi,Itoh, Tomoki,Terasaki, Masaru
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- Werner transition-metal complex (WTMC)-mediated mild and efficient chemo-selective acylation of phenols and anilines under solvent-free condition
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Werner-type transition-metal complexes (WTMC) such as [Co(NH3)5Cl]Cl2, Cu[(NH3)4]SO4, Mn(acac)3, Ni[(NH3)6]Cl2, Ni[(en)3]S2O3, and Hg[Co(SCN)4] efficiently promote the chemoselective acetylation of phenols and anilines under solvent-free condition. The results of this study clearly shows that the optimal condition for the acetylation of anilines/phenols (1 mmol) (2a–r) with acetic anhydride (1.2 mmol) in the presence of WTMC (1 mmol) and two drops of H3PO4 on heating for 10 min under solvent-free condition gives the corresponding acetanilides/phenyl acetate (3a–r) in good to excellent yield. Furthermore, the method is simple, efficient, chemoselective, and eco-friendly under solvent-free condition for the acetylation of anilines and phenols promoted by WTMC by using acetic anhydrate as the acetylating agent. The simple preparation of the catalyst, easy procedure of the acetylation reaction, and simple work-up indicate the importance of WTMC for such reactions.
- Sarief, Abdulla,Haque, SK Manirul,Feroze, Syed Mudabbir,Arifuddin, Mohammed
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p. 1104 - 1109
(2018/09/27)
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- Diazepinium perchlorate: a neutral catalyst for mild, solvent-free acetylation of carbohydrates and other substances
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Diazepinium perchlorate, an essentially neutral organic salt possessing excellent stability, has been found to be well suited for the acetylation of free as well as partially protected sugars, phenols, thiophenols, thiols and other alcohols as well as amines. The diazepinium perchlorate-catalyzed acetylation is mild, organic and solvent-free and leaves acid sensitive protecting groups such as TBDMS/TBDPS/Tr ethers and isopropylidene/benzylidene acetals present on a substrate unaffected. Regioselective hydroxyl protection in partially protected carbohydrate derivatives/polyhydroxylic compounds was possible and was proved to be a convenient time-saving alternative to the conventional synthesis of such compounds. Easy preparation of the catalyst, mild reaction conditions and an environmentally benign protocol are some of the notable features of this reaction. The results obtained on the acetylation of phenols and thiophenols could be rationalized through their local nucleophilicity index obtained from DFT calculations.
- Giri, Santosh Kumar,Gour, Rajesh,Kartha, K. P. Ravindranathan
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p. 13653 - 13667
(2017/03/11)
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- Synthesis method of important pharmaceutical and chemical intermediate 4-amino-3-chlorophenol
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The present invention discloses a synthesis method of important pharmaceutical and chemical intermediate 4-amino-3-chlorophenol, and the method comprises the following steps: acetylation of p-aminophenol, triethylamine and an acylating agent to obtain 4-acetamino phenyl acetate shown as a formula I; chlorination of the formula I compound and a chlorinated reagent to obtain 4-acetamino-3-phenyl chloroacetate shown as a formula II; and reaction of the formula II compound and an alkali at 80-120 DEG C to obtain the 4-amino-3-chlorophenol. The preparation method has the advantages of easy availability of raw materials, low cost, mild condition, high process operability and controllability, high yield and no need of complex post-treatment to obtain the high-purity 4-amino-3-chlorophenol.
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Paragraph 0025; 0028
(2017/08/29)
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- One-pot synthesis of amides from carboxylic acids activated using thionyl chloride
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A one-pot synthesis of secondary and tertiary amides from carboxylic acids and amines by using SOCl2 has been developed. Also when sterically hindered amines were used as the starting materials, excellent yields of the corresponding amides were obtained. The amidation of N-protected α-amino acids with secondary amines proceeds effectively with good yields. The process works well also in the presence of acid sensitive groups and occurs with almost complete retention of stereochemical integrity of chiral substrates. This protocol could be extended to industrial large-scale production processes.
- Leggio,Belsito,De Luca,Di Gioia,Leotta,Romio,Siciliano,Liguori
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p. 34468 - 34475
(2016/06/13)
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- Acetaminophen prodrug: Microwave-assisted synthesis and in vitro metabolism evaluation by mass spectrometry
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Propacetamol is an acetaminophen prodrug of intravenous administration used to control fever and pain of perioperative period in multimodal analgesia therapy. After injection, it is completely converted by plasma esterases into N,N-diethylglycine and acetaminophen, its active metabolite whose mechanism of action is the inhibition of prostaglandin synthesis. Herein, we report an improved protocol for the synthesis of propacetamol hydrochloride that allows the isolation of the active pharmaceutical ingredient (API) with high purity and yield. In addition, the in vitro metabolism of propacetamol in a microssomal reaction was evaluated by ion trap tandem mass spectrometry.
- Murie, Valter E.,Marques, Lucas M.M.,Souza, Glória E.P.,Oliveira, Anderson R.M.,Lopes, Norberto P.,Clososkic, Giuliano C.
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p. 1121 - 1128
(2016/07/06)
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- Tunable microwave-assisted method for the solvent-free and catalyst-free peracetylation of natural products
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Background: The peracetylation is a simple chemical modification that can be used to enhance the bioavailability of hydrophilic products and to obtain safe and stable pro-drugs. Results: A totally green, solvent-free and catalyst-free microwave (MW)-assisted method for peracetylation of natural products such as oleuropein, alpha-hederin, quercetin and rutin is presented. By simply tuning the MW heating program, polyols with chemical diverse -OH groups or thermolabile functionalities can be peracetylated to improve the biological activity without degradation of the natural starting molecules. An evaluation of the process greenness was performed. Conclusion: The method is potentially universally applicable for green acetylation of hydrophilic biological molecules, potentially easily scalable for industrial applications, including pharmaceutical, cosmetic and food industry.
- Oliverio, Manuela,Costanzo, Paola,Nardi, Monica,Calandruccio, Carla,Salerno, Raffaele,Procopio, Antonio
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supporting information
p. 2222 - 2233
(2016/11/17)
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- Synthesis and Energetic Properties of 4-Diazo-2,6-dinitrophenol and 6-Diazo-3-hydroxy-2,4-dinitrophenol
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4-Amino-3,5-dinitroaniline (3) was synthesized by fluorine/amine exchange of 4-fluoro-3,5-dinitroaniline in ethanol. 4-Diazo-2,6-dinitrophenol (Iso-DDNP, 4) was obtained after nitration in HNO3 (100%) and acetic anhydrid. 4-Amino-2,3,5-trinitrophenol (7) was obtained by nitration of N-(4-acetoxyphenyl)acetamide and deprotection of the amine. Further nitration resulted in 6-diazo-3-hydroxy-2,4-dinitrophenol (8). The thermal stability and sensitivity of 4 and 8 toward impact and friction was compared to commercially used DDNP (2-diazo-4,6-dinitrophenol). All target compounds were characterized by single-crystal X-ray diffraction, NMR and elemental analysis and DSC. The sensitivities were determined by BAM methods (drophammer and friction tester). The heats of formation were calculated by using CBS-4M electronic enthalpies and the atomization method. Various detonation parameters such as detonation velocity and pressure were computed by using the EXPLO5 computer code V6.01. The very sensitive diazophenol derivatives diazo-2,6-dinitrophenol and 6-diazo-3-hydroxy-2,4-dinitrophenol could be synthesized by nitration reactions. They are promising alternatives to the commercially used sensitizer DDNP (2-diazo-4,6-dinitrophenol).
- Klap?tke, Thomas M.,Preimesser, Andreas,Stierstorfer, J?rg
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p. 4311 - 4315
(2015/07/27)
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- One drop chemical derivatization - DESI-MS analysis for metabolite structure identification
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Structural elucidation of metabolites is an important part during the discovery and development process of new pharmaceutical drugs. Liquid Chromatography (LC) in combination with Mass Spectrometry (MS) is usually the technique of choice for structural identification but cannot always provide precise structural identification of the studied metabolite (e.g. site of hydroxylation and site of glucuronidation). In order to identify those metabolites, different approaches are used combined with MS data including nuclear magnetic resonance, hydrogen/deuterium exchange and chemical derivatization followed by LC-MS. Those techniques are often time-consuming and/or require extra sample pre-treatment. In this paper, a fast and easy to set up tool using desorption electrospray ionization-MS for metabolite identification is presented. In the developed method, analytes in solution are simply dried on a glass plate with printed Teflon spots and then a single drop of derivatization mixture is added. Once the spot is dried, the derivatized compound is analyzed. Six classic chemical derivatizations were adjusted to work as a one drop reaction and applied on a list of compounds with relevant functional groups. Subsequently, two successive reactions on a single spot of amoxicillin were tested and the methodology described was successfully applied on an in vitro incubated alprazolam metabolite. All reactions and analyses were performed within an hour and gave useful structural information by derivatizing functional groups, making the method a time-saving and efficient tool for metabolite identification if used in addition or in some cases as an alternative to common methods.
- Lubin, Arnaud,Cabooter, Deirdre,Augustijns, Patrick,Cuyckens, Filip
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p. 871 - 878
(2015/11/11)
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- Process modeling of reduction and acetylation reactions by spectrophotometric and chemometrics methods
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Achieving high levels of chemoselectivity is a pivotal feature of chemical synthesis. Although significant progress has been made in this regards, lots of challenges lie ahead. Herein, multivariate curve resolution-alternating least square (MCR-ALS) was employed to overcome the spectral overlapping of the reactants and products in the model reactions of methyl-(4-formyl) benzoate by NaBH4 and acetylation of p-aminophenol by acetyl chloride. The first-order ultraviolet/visible absorbance spectra were recorded during the addition of different quantities of reagent to the substrate. The absorbing species, coexisting in the system, were detected through employing factor analysis. The soft-modeling analysis of the evolutionary absorbance data by MCR-ALS revealed that both model reactions proceed through a two-step consecutive manner. Using the obtained concentration profiles, one can obtain an idea about the suitable molar ratio of reagent/substrate for selective production of one of the reaction products. Moreover, the pure spectrum of the intermediate species could be estimated.
- Hemmateenejad, Bahram,Shadabipour, Parisa,Mohamadizadeh, Moahamad Reza
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p. 147 - 154
(2014/01/23)
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- Thioacids mediated selective and mild N-acylation of amines
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N-Acylated amines are ubiquitous in nature. Selective N-acylation at neutral conditions remains a key area of interest. Here we are reporting the copper sulfate-mediated highly selective, mild, and rapid N-acylation of various aliphatic and aromatic amines using thioacids in methanol at neutral conditions. All N-acylated products of primary and secondary amines were isolated in good to excellent yields. This method is found to be highly selective for the amines and not sensitive to other functional groups such as phenols, alcohols, and thiols. The simple workup, high yields, and high selectivity of this reaction can be an attractive alternative to those of the existing acyl halide- and acid anhydride-mediated N-acylation reactions.
- Mali, Sachitanand M.,Bhaisare, Rupal D.,Gopi, Hosahudya N.
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p. 5550 - 5555
(2013/07/25)
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- Hypervalent iodine mediated para -selective fluorination of anilides
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A metal-free method for the direct regioselective fluorination of anilides has been developed. In the presence of bis(tert-butylcarbonyloxy)iodobenzene (PhI(OPiv)2) and hydrogen fluoride-pyridine, the para-fluorination products of anilides were obtained in moderate to good yields. Because of its operational safety and the use of readily available reagents, this new procedure provides facile access to a variety of para-fluorinated anilides.
- Tian, Tian,Zhong, Wen-He,Meng, Shuai,Meng, Xiang-Bao,Li, Zhong-Jun
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p. 728 - 732
(2013/02/25)
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- Stannous chloride dihydrate-mediated efficient access to secondary and primary amides from oximes
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Highly selective, efficient and expeditious Beckmann rearrangement of a wide range of ketoximes to secondary amides (20 examples) has been accomplished using stoichiometric amount of stannous chloride dihydrate in the presence of nucleophilic additive, tetra-n-butylammonium iodide (TBAI) (10 moI%) and 4 ? MS in dry acetonitrile at reflux temperature. Aldoximes delivered primary amides through intermediacy of nitriles upon heating with an equimolar amount of SnCl2·2H2O and DBU in dry toluene at reflux in good to acceptable yields (12 examples). Utilization of mild Lewis acid, inexpensive rack reagents and procedural simplicity including easy isolation of products are key advantageous features of the protocol.
- Ganguly, Nemai C.,Nayek, Subhasis,Chandra, Sumanta
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p. 1695 - 1702
(2014/01/17)
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- HF-Pyridine: A versatile promoter for monoacylation/sulfonylation of phenolic diols and for direct conversion of t-butyldimethylsilyl ethers to the corresponding acetates
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Monoacylation and trifluoromethanesulfonylation of phenolic diols were achieved by the aid of HF-pyridine, whereas diacylation occurred with pyridine alone. Furthermore, HF-pyridine was found to promote the direct conversion of t-butyldimethylsilyl ethers to the corresponding acetates.
- Michigami, Kyosuke,Yoshimoto, Kazuya,Hayashi, Masahiko
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scheme or table
p. 138 - 139
(2012/03/09)
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- Silver triflate catalyzed acetylation of alcohols, thiols, phenols, and amines
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A variety of alcohols, thiols, phenols, and amines were subjected to acetylation reaction using acetic anhydride in the presence of catalytic quantity of silver triflate. The method described has a wide range of applications, proceeds under mild conditions, does not involve cumbersome workup, and the resulting products are obtained in high yields within a reasonable time. Georg Thieme Verlag Stuttgart · New York.
- Das, Rima,Chakraborty, Debashis
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experimental part
p. 1621 - 1625
(2011/06/25)
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- Direct acetoxylation and etherification of anilides using phenyliodine bis(trifluoroacetate)
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Treatment of various anilides with 1.5 equiv. of phenyliodine bis(trifluoroacetate) (PIFA) and 1.0 equiv. of BF3·OEt 2 in AcOH at room temperature afforded the corresponding para-acetoxylated products with high regioselectivity. In addition, this reaction could be expanded to the etherification of anilides. In the presence of 2.0 equiv. of PIFA and 2.0 equiv. of BF3·OEt2, the reaction of anilides with alcohols provided the corresponding para-etherified products in good yields. The Royal Society of Chemistry 2011.
- Liu, Huan,Wang, Xuemin,Gu, Yonghong
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experimental part
p. 1614 - 1620
(2011/04/22)
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- Efficient iodine-mediated beckmann rearrangement of ketoximes to amides under mild neutral conditions
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Aryl ketoximes readily underwent Beckmann rearrangement to give N-substituted amides in excellent yields on electrophilic activation by elemental iodine in anhydrous acetonitrile under reflux. The main advantages of this environmentally friendly protocol include a high selectivity as a result of the absence of any accompanying deprotection to form the parent ketones as byproducts, mild neutral conditions, procedural simplicity, and particularly ease of isolation of the products.
- Ganguly, Nemai C.,Mondal, Pallab
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experimental part
p. 3705 - 3709
(2011/01/03)
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- Mizoroki-heck reactions with 4-phenoldiazonium salts
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Significantly better yields were achieved in Mizoroki-Heck reactions using 4-phenoldiazonium salts instead of their O-alkylated analogues under otherwise identical conditions. We found that a one-flask deacetylation-diazotation- precipitation sequence starting from paracetamol or acetanilides derived thereof provides a convenient access to the required diazonium tetrafluoroborates. The utility of these arylating agents in palladium-catalyzed C-C bond forming reactions was demonstrated for a one-flask-synthesis of the heterocyclic core of the drug aripiprazole. Notably, the diazonium salt formation from an acetanilide could be combined with two Pd-catalyzed steps in a one-flask sequence, without any exchange of solvents or isolation of intermediates.
- Schmidt, Bernd,Hoelter, Frank,Berger, Rene,Jessel, Soenke
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supporting information; experimental part
p. 2463 - 2473
(2010/12/25)
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- A TFAA-H3PO4-mediated direct, metal-free and high-speed synthesis of aryl carboxylate esters from phenols
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An operationally simple, mild and single-step method for the direct and metal-free synthesis of aryl carboxylate esters is described under a solvent free condition. The reaction of phenols including 2-naphthol (or 1-naphthol) with a variety of carboxylic acids in the presence of TFAA and 85% H3PO4 provided a range of aryl carboxylate esters in good yields within few minutes.
- Kankanala, Kavitha,Reddy, Vangala Ranga,Mukkanti, Khagga,Pal, Sarbani
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experimental part
p. 505 - 508
(2009/12/26)
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- Reaction of α-(n-alkylcarbonyloxy)alkyl (ACOA) halides with 4-hydroxyacetanilide and 2,2,5,7,8-pentamethyl-6-chromanol: The effect of steric hindrance on reaction path
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A convenient synthesis of α-(n-alkylcarbonyloxy)alkyl (ACOA) iodides has been developed and a homologous series of n-alkylcarbonyloxymethyl (ACOM) iodides have been used to alkylate 4-hydroxyacetanilide (acetaminophen, APAP), a sterically unhindered phenol, and a sterically hindered phenol (2,2,5,7,8-pentamethyl-6-chromanol). Steric hindrance was not a significant factor in the ratio of acylated (Path b) to alkylated (Path a) for these reactions. Given the reported toxicity associated with sterically hindered ACOM prodrugs, n-alkyl ACOM and ACOA promoieties present themselves as viable alternatives to the more commonly used pivalate-based derivatives. Georg Thieme Verlag Stuttgart.
- Thomas, Joshua D.,Sloan, Kenneth B.
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p. 272 - 278
(2008/12/22)
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- SbCl3 as a highly efficient catalyst for the acetylation of alcohols, phenols, and amines under solvent-free conditions
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Antimony trichloride has been found to be an efficient and expedient catalyst for the acylation of alcohols, phenols, amines, and sugars with acetic anhydride in high yields and in a short reaction time under solvent-free conditions at room temperature. Also, racemization of chiral alcohols and epimerization of sugars were not observed in any of the substrates. Copyright Taylor & Francis Group, LLC.
- Bhattacharya, Asish K.,Diallo, Mamadou A.,Ganesh, Krishna N.
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p. 1518 - 1526
(2008/09/20)
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- Reaction of alkylcarbonyloxymethyl halides with phenols: reevaluating the influence of steric hindrance
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Evidence is presented that contradicts an earlier finding that, in the absence of steric hindrance, the coupling reaction of alkylcarbonyloxymethyl (ACOM) halides with phenols favors acylated product. A one-step synthesis is used to generate sterically unhindered ACOM iodides, which are then reacted with several phenols to give mainly alkylated phenol.
- Thomas, Joshua D.,Sloan, Kenneth B.
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p. 8785 - 8787
(2007/10/03)
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- A simple and efficient method for reductive acylation of azides using aluminium iodide and acetic anhydride
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A combination of aluminium iodide and acetic anhydride effectively converts a variety of azides to their corresponding acetamides in good to excellent yields without perturbing many active functionalities such as ether, ester, nitro etc.
- Bez, Ghanashyam
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p. 3625 - 3628
(2007/10/03)
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- Effect of -C(CF3)2- on the surface energy of main-chain liquid crystalline and crystalline polymers
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Novel fluorinated main-chain liquid crystalline/crystalline polymers were prepared through thin film polymerization. Two polymer systems were studied: one from 2,6-acetoxynaphthoic acid (ANA), acetoxyacetanilide (AAA), and 4,4a?2-(hexafluoroisopropylidene)bis(benzoic acid) (6F acid) and the other from ANA, hydroquinone diacetate (HQAT), and 6F acid. The surface energy was estimated using contact angles of water, glycerol, and diiodomethane. A small amount of -C(CF3)2- in the main chain lowered the surface energy, and the fluorocarbons were preferentially enriched at the air-polymer interface, causing low surface energy and large water contact angles. These results agreed with XPS data. Since the -O-Ar-O- unit in the HQAT moiety is more rigid than the -O-Ar-N- unit in the AAA moiety, LC texture formed more easily in the ANA/HQAT/6F acid system than in the ANA/AAA/6F acid system. Contrarily, the fluorocarbons enriched more preferentially at the surface in the ANA/AAA/6F acid system than in the ANA/HQAT/6F acid system. Moreover, the hydrogen bonding originating from the amide group hindered further decrease of surface energy with an increase in 6F acid content in the ANA/AAA/6F acid system.
- Ma, Kui-Xiang,Chung, Tai-Shung
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p. 4145 - 4150
(2007/10/03)
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- Synthesis and in-vitro evaluation of platelet aggregation inhibitory activity of paeonol and its analogues
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Paeonol (1-(2-hydroxy-4-methoxyphenyl)ethanone) and a series of substituted 1-(2-hydroxyphenyl)ethanone derivatives were synthesized and screened as inhibitors of platelet aggregation. The compounds with the greatest anti-platelet potential among the series tested were 1-(2,5-dihydroxyphenyl)ethanone (65.36% inhibition at 300 μM against 5 μM ADP), paeonol(36.31%), 1-(2-hydroxy-5-methoxyphenyl)ethanone (24.47%), 1-(2-hydroxy-5-nitrophenyl) ethanone (30.40%) and 1-(5-chloro-2-hydroxy-4-methylphenyl)ethanone (24.43%).
- Akamanchi,Padmawar,Thatte,Rege,Dahanukar
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p. 323 - 329
(2007/10/03)
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- Retention behavior of compounds with active hydrogen atoms and their acetylated derivatives in reversed-phase HPLC
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In view of poor interlaboratory reproducibility of retention indices I in reversed-phase high-performance liquid chromatography, not the indices themselves but their differences for reactants and products of interaction with various reagents can be used to identify compounds with active hydrogen atoms. For acetylated derivatives of phenols and aromatic amines, the quantity ?I = I(ArXH) -I(ArXCOCH3), where X = O or NH. has statistically significant distinguishable values of 126 ± 15 and 70 ± 20, respectively. The additivity of the parameters ?I is first revealed for the polyfunctional compounds of these classes that are incapable of intramolecular hydrogen bonding. Abnormal ?I values and deviations from the additivity rule are observed only for substances with intramolecular hydrogen bonding. This finding can be used to confirm the presence of relevant structural units in molecules.
- Zenkevich,Kosman
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p. 1173 - 1176
(2007/10/03)
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- A New Synthetic Route to 6,7-Dichloro-5,8-quinoxalinedione and Synthesis of Its Derivatives
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6,7-Dichloro-5,8-quinoxalinedione (2), an analogue of Dichlone, was prepared from 4-aminophenol (3) in 27percent overall yield in 8 steps via chloroxidation of the sulfuric acid salt of 8-amino-5-quinoxalinol (9) as a key step.And two derivatives, 6-chloro-5-hydroxypyrazinophenazine (10) and pyridoimidazoquinoxaline-6,11-dione (11), were prepared by reaction of 2 with 1,2-phenylenediamine and 2-aminopyridine in 79percent and 46percent yields, respectively.
- Han, Gyoonhee,Shin, Kye Jung,Kim, Dong Chan,Yoo, Kyung Ho,Kim, Dong Jin,Park, Sang Woo
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p. 2495 - 2502
(2007/10/03)
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- Structure-reactivity correlations for reactions of substituted phenolate anions with acetate and formate esters
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The reactions of substituted phenolate anions with m-nitrophenyl, p-nitrophenyl, and 3,4-dinitrophenyl formates follow nonlinear Br?nsted-type correlations that might be taken as evidence for a change in the rate-limiting step of a reaction that proceeds through a tetrahedral addition intermediate. However, the correlation actually represents two different Br?nsted lines that are defined by meta- and para-substituted phenolate anions and by meta- and para-substituted o-chlorophenolate anions. A concerted mechanism for both acetyl- and formyl-transfer reactions is supported by the absence of a detectable change in the Br?nsted slope at ΔpK = 0 for the attacking and leaving phenolate anions within each class of Br?nsted correlations. Regular increases in the dependence of log k on the pKa of the nucleophile with increasing pKa of the leaving group correspond to a positive interaction coefficient pxy = ?β1g/?(pKnuc) = ?βnuc/?(pK1g). The observation of two different Br?nsted lines for the reactions of substituted phenolate anions with phenyl acetates is attributed to a steric effect that decreases the rate of reaction of substituted o-chlorophenolate anions by 25-50%. The reactions of meta- and para-substituted phenolate and o-chlorophenolate anions with substituted phenyl acetate esters follow values of βnuc = 0.53-0.66 and -β1g = 0.50-0.63. The reactions of meta- and para-substituted phenolate anions with formate esters are ～ 103 times faster and follow smaller values of βnuc = 0.43-0.64 and -β1g = 0.31-0.48. However, the reactions of meta- and para-substituted o-chlorophenolate anions with the same formate esters follow larger values of βnuc = 0.63-0.90 and -β1g = 0.46-0.90. The large values of βnuc and -β1g for the reactions of substituted o-chlorophenolate anions with formate esters may arise from destabilization by the o-chloro group of a stacking interaction that is present in the transition state for reactions of formate esters, but not acetate esters.
- Stefanidis, Dimitrios,Cho, Sayeon,Dhe-Paganon, Sirano,Jencks, William P.
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p. 1650 - 1656
(2007/10/02)
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- Immunomodulating agent
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Phenylacetic acid derivatives of the formula: STR1 wherein R1 is hydrogen or STR2 wherein R5 is an alkyl group of 1-6 carbon atoms or an aryl group; R2 and R3 are independently hydrogen or an alkyl group of 1-4 carbon atoms; R4 is hydrogen or an alkyl group of 1-4 carbon atoms, have been found to possess immunomodulating activity.
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- Vinylsilylalkoxy arylbenzotriazole compounds and UV absorbing compositions made therefrom
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Vinylsilylalkoxy arylbenzotriazol monomers such as 2-[3′-t-butyl-5′-(3″-dimethylvinylsilylpropoxy)-2′-hydroxy-phenyl]-5-methoxybenzotriazole are disclosed. These monomers can be incorporated in optically clear silicone polymers to form intraocular lenses, contact lenses, and the like, which have UV absorbing properties.
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- A New Acylation Catalyst
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Cobalt(II) chloride catalyses the acylation of alcohols and amines with anhydrides in excellent yields.
- Ahmad, Saeed,Iqbal, Javed
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p. 114 - 115
(2007/10/02)
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- Process for producing n-acyl-acyloxy aromatic amines
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A process is provided for producing N-acyl-acyloxy aromatic amine, such as 4-acetoxyacetanilide by reacting a hydroxy-aromatic ketoxime with a carboxylic acid anhydride, e.g. acetic anhydride, in the presence of phosphoric or oxalic acid as a Beckmann rearrangement catalyst. Preferably the ketoxime is prepared by reacting a hydroxy aromatic ketone such as 4-hydroxyacetophone with a hydroxyl amine salt, and the ketone is obtained by the Fries rearrangement of a phenolic ester, e.g. phenyl acetate or the Friedel-Crafts acylation of a phenolic compound, e.g. phenol, with an acylating agent, e.g. acetic acid.
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- Photolysis and Thermolysis of Phenyl Azide in Acetic Acid. Trapping of 1-Azacyclohepta-1,2,4,6-tetraene and Nucleophilic Aromatic Substitution
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Photolysis and thermolysis of phenyl azide in acetic acid yielded 1H-azepin-2(3H)-one (4), 2-methylbenzoxazole (15), 2- and 4- acetamidophenyl acetates (16) and (12), 2- and 4- acetamidophenols (14) and (13), acetanilide, and azobenzene.Addition of ethanol to the system caused a linear decrease in the yield of (4) and a more remarkable decrease in total yield for the para-products than that for the ortho-products to give 2- and 4- acetamidophenyl ethyl ethers (9) and (8).Photolysis of the azide in ethanol in the presence of phenol afforded 2-phenoxy-3H-azepine (5) and aniline, but no 2- and 4-phenetidines.The yield of compounds (4) and (12)-(16) was independent of the presence of penta-1,3-diene(0.01 M), and somewhat decreased by an addition of bromobenzene.The rate of decomposition of azide in acetic acid was not accelerated as compared with that in 1,4-dioxan, and the activation parameters varied little in the two solvents.The results suggest that 1-azacyclohepta-1,2,4,6-tetraene (1) formed via singlet phenylnitrene or via singlet excited phenyl azide is trapped by acetic acid or phenol to give (4) or (5), and that a resonance-stabilized ion (3) neighbouring acetate anion is formed by an attack of the singlet nitrene on acetic acid to give aromatic nucleophilic substitution.
- Takeuchi, Hiroshi,Koyama, Kikuhiko
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p. 1269 - 1274
(2007/10/02)
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- Photolysis and Thermolysis of Phenyl Azide in Acetic Acid
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The photolysis and thermolysis of phenyl azide in acetic acid gave 2,3-dihydro-1H-azepin-2-one via 1-azacyclohepta-1,2,4,6-tetraene, and ring-disubstituted products via a resonance-stabilized ion formed by attack of singlet phenylnitrene on acetic acid.
- Takeuchi, Hiroshi,Koyama, Kikuhiko
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p. 202 - 204
(2007/10/02)
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- A USEFUL METHOD FOR SELECTIVE ACYLATION OF ALCOHOLS USING 2,2'-BIPYRIDYL-6-YL CARBOXYLATE AND CESIUM FLUORIDE
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Primary and secondary alcohols are acylated under mild conditions by the of use 2,2'-bipyridyl-6-yl carboxylates and cesium fluoride.Furthermore, the reaction is successfully applied to selective acylation of a primary carbinol group of diols containing primary and secondary carbinol groups or exclusive O-acylation of aromatic amino alcohols.
- Mukaiyama, Teruaki,Pai, Fong-Chang,Onaka, Makoto,Narasaka, Koichi
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p. 563 - 566
(2007/10/02)
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