- Pyridinium saccharinate salts as efficient recyclable acylation catalyst: A new bridge between heterogeneous and homogeneous catalysis
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It is important to find a way for separation of concerned chemicals from product mixture after reaction, in order to avoid spreading harmful chemicals to society. The homogeneous nature of DMAP-catalyzed acylation still suffers from the problems of catalyst separation and/or residual DMAP contamination. DMAP causes acute dermal toxicity, whereas the corresponding DMAP salt exhibits only slight irritation to the skin. Very recently, we found that the DMAP saccharinate salt is also great recyclable catalyst, whose acylation of alcohols has been successfully and effectively carried out 10 times without loss in activity. This report covers our comprehensive studies on using the pyridinium saccharinate salts as efficient recyclable acylation catalysts including 4-N,N-dimethylaminopyridinium saccharinate (A), 4-(1-pyrrolidinyl) pyridinium saccharinate (B), 2-N,N-dimethylaminopyridinium saccharinate (C), and pyridinium saccharinate (D). Their structure and reactivity have been studied. The salts A, C, and D contain very interesting seven-membered synthon showing multiple H-bonding interactions for pair of pyridinium cation and saccharinate anion in the solid state. The salt B exhibits H-bonding interaction of N(sac) ... H-N(py) in the solid state, instead of seven-membered synthon. The catalytic reactivity studies show that salts A and B are both very effective, with salt B even better in reactivity, and are both recyclable in the esterification of a variety of alcohols, under solvent-free and base-free conditions at room temperature.
- Lu, Norman,Chang, Wei-Hsuan,Wei, Rong-Jyun,Fang, Yung-Cheng,Han, Tu-Wen,Wang, Guo-Quan,Chang, Jia-Yaw,Wen, Yuh-Sheng,Liu, Ling-Kang
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p. 3468 - 3476
(2016/06/06)
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- DMAP-based flexible polymer networks formed via Heck coupling as efficient heterogeneous organocatalysts
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Two DMAP-based flexible polymer networks TPB-DMAP and TPA-DMAP have been successfully synthesized via palladium catalyzed Heck cross-coupling. The structures of these polymers were confirmed by solid state 13C CP/MAS and Fourier transform infrared spectroscopy (FTIR). Although both polymers have negligible surface areas, they exhibit excellent catalytic efficiency for the acylation of 1-phenylethanol with acetic anhydride due to their good swelling capacities. Utilized as a typical catalyst, the polymer TPA-DMAP shows high activities for acylation of a variety of alcohols to the corresponding esters. Moreover, the catalyst can be recycled at least ten times without obvious loss of catalytic activity.
- Xu, Wei,Xia, Wu,Guan, Yukun,Wang, Yiming,Lu, Cuifen,Yang, Guichun,Nie, Junqi,Chen, Zuxing
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- RECYCLABLE CATALYSTS FOR ESTERIFICATION OR ACYLATION OF ALCOHOLS
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A compound is useful as a recyclable catalyst for esterification or acylation of alcohols and consists of saccharine and a compound comprising a pyridine moiety. In addition, also a method of preparing the compound and an ester synthesis method using the compound are introduced.
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Page/Page column 3
(2012/07/28)
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- A salt made of 4-N,N-dimethylaminopyridine (DMAP) and saccharin as an efficient recyclable acylation catalyst: A new bridge between heterogeneous and homogeneous catalysis
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Here, we report insights into the new recyclable catalyst 1, (DMAP·saccharin). The DMAP·saccharin-catalysed acylation of alcohols has been successfully carried out more than 8 times. Only 1 mol% of catalyst 1 efficiently promotes acylation with almost equimolar amounts of acid anhydrides, under both base-free and solvent-free conditions.
- Lu, Norman,Chang, Wei-Hsuan,Tu, Wen-Han,Li, Chieh-Keng
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supporting information; experimental part
p. 7227 - 7229
(2011/09/12)
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- Fluorous 4-N,N-dimethylaminopyridine (DMAP) salts as simple recyclable acylation catalysts
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The use of an easily accessible fluorous salt of DMAP, 1-R, as an active and recyclable acylation catalyst, under simple conditions has been reported. The recyclability of organic- and metal-based catalysts is of prime interest for the development of sustainable synthesis processes. The alcohol and the anhydride were mixed in a 10 mL round-bottomed flask and 1-R was added. The DMAP-catalyzed esterification reaction of an alcohol is performed in nonpolar solvents with an anhydride as the acyl donor, in the presence of a base in stoichiometric amounts. The simplicity of the process (readily accessible catalyst, easy to handle and to recover) makes it an attractive alternative for cleaner and safer acylation reactions, which could be used with asymmetric dialkylaminopyridines, or in other transformations, such as the Baylis Hillman reaction.
- Vuluga, Daniela,Legros, Julien,Crousse, Benoit,Bonnet-Delpon, Daniele
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supporting information; experimental part
p. 1776 - 1779
(2010/06/14)
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- Widely useful DMAP-catalyzed esterification under auxiliary base- and solvent-free conditions
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With regard to atom economy and E-factor, catalytic condensation of carboxylic acids with equimolar amounts of alcohols is the most desirable. Although several highly active dehydration catalysts have been reported, more efficient alternatives are still strongly needed because the dehydrative esterification of tertiary alcohols, phenols, acid-sensitive alcohols, amino acids, and hardly soluble alcohols has never proceeded satisfactorily. Here we report new insights into the classical DMAP-catalyzed acylation of alcohols: surprisingly, only a 0.05-2 mol % of DMAP can efficiently promote acylation of alcohols with acid anhydrides under auxiliary base- and solvent-free conditions to give the corresponding esters in high yields. Furthermore, we achieved the recovery and reuse of commercially available polystyrene-supported DMAP without using any solvents. These serendipitous findings provide widely useful and environmentally benign esterification methods, which might be more practical and reliable than catalytic dehydrative condensation methods, in particular, for the less reactive alcohols which hardly condense with carboxylic acid directly.
- Sakakura, Akira,Kawajiri, Kimio,Ohkubo, Takuro,Kosugi, Yuji,Ishihara, Kazuaki
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p. 14775 - 14779
(2008/09/17)
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- BENZENE DERIVATIVES,PROCESS FOR PREPARING THE SAME AND USE THEREOF
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Novel benzene derivatives represented by the formula (I) : wherein R1, R4 and R6 each independently represents a hydrogen atom, a halogen atom or a hydrocarbon group, R2 represents a hydrocarbon group or a heterocyclic group, R3 represents a hydrocarbon group, NR7'R7 or OR8 (wherein R7' represents a hydrogen atom or a hydrocarbon group, R7 represents a non-aromatic group, or R7' and R7 may form a ring with the adjacent nitrogen atom, and R8 represents a hydrocarbon group or a heterocyclic group), R5 represents a hydrocarbon group or a heterocyclic group (except for a quinolyl group), R5' represents a hydrogen atom, or a hydrocarbon group, or R5 and R5' may form a ring with the adjacent nitrogen atom, and R5" represents a hydrogen atom or a hydrocarbon group, which have vanilloid receptor agonist activity and are useful as a drug such as an analgesic and an agent for preventing and/or treating urinary frequency and/or urinary incontinence.
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- PEPTIDIC THROMBIN INHIBITOR COMPOUND
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The present invention relates to a novel thrombin inhibitor compound which has a good inhibitory effect against thrombosis and can be orally administered, a process for preparing the same, and to a composition for the therapeutic and/or prophylactic treatment of various diseases associated with thrombin inhibition mechanism, which comprises the same as an active ingredient.
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- Fluoroboric acid adsorbed on silica gel as a new and efficient catalyst for acylation of phenols, thiols, alcohols, and amines
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Fluoroboric acid supported on silica gel efficiently catalyzes acylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions. Acid-sensitive alcohols are smoothly acylated without competitive side reactions.
- Chakraborti, Asit K.,Gulhane, Rajesh
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p. 3521 - 3525
(2007/10/03)
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- Ozone-mediated Reaction of Anilides and Phenyl Esters with Nitrogen Dioxide: Enhanced Ortho-reactivity and Mechanistic Implications
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In the presence of ozone, anilides 1 can be nitrated rapidly with nitrogen dioxide in chloroform at 0 deg C to give a high proportion of ortho-nitro derivatives (ortho:para = 1.2-4.4) in good yields.The phenyl esters 15 can be similarly nitrated on the aromatic ring without significant cleavage of the ester bond, giving a mixture of isomeric nitro derivatives in which the ortho-isomer predominantes (ortho:para = 1.1-1.5).The oridin of the enhanced ortho reactivity is discussed in terms of an electron-transfer process involving the nitrogen trioxide as initial electrophile.
- Suzuki, Hitomi,Tatsumi, Atsuo,Ishibashi, Taro,Mori, Tadashi
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p. 339 - 344
(2007/10/02)
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- An invesigation of activities and paraoxon sensitivities of hepatic aliesterases in β-naphthoflavone-treated rats
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Aliesterases (carboxylesterases, EC 3.1.1.1) are serine esterases which may protect acetylcholinesterase during organophosphorus insecticide intoxication by providing alternative phosphorylation sites. Levels of hepatic aliesterase activity were investigated after the intraperitoneal administration of β-naphthoflavone (BNF) to female rats using nine 4-nitrophenyl esters as substrates (including straight and branched chain aliphatic and aromatic esters) and 1-naphthyl acetate. In addition, the in vitro sensitivities of aliesterases to inhibition by paraoxon, the active metabolite of the common insecticide parathion, were studied. Hepatic aliesterases from BNF-treated rats displayed lower activities than those from controls with all substrates except 4-nitrophenyl phenylbutyrate and isovalerate. The aliesterases from BNF-treated rats were more sensitive to paraoxon inhibition with 4-nitrophenyl phenylbutyrate, valerate, and butyrate. Esterases hydrolyzing 4-nitrophenyl butyrate, valerate, and branched chain esters were most sensitive to paraoxon inhibition while those hydrolyzing 4-nitrophenyl hexanoate and aromatic esters were least sensitive. The results suggested that BNF-induced changes in hepatic aliesterases could alter responses to organophosphates. Keywords: Aliesterases; β-Naphthoflavone; Paraoxon; Organophosphate
- Watson, Angela M.,Chambers, Howard,Chambers, Janice E.
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p. 217 - 226
(2007/10/03)
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- A New and Efficient Esterification Reaction via Mixed Anhydrides by the Promotion of a Catalytic Amount of Lewis Acid
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In the presence of a catalytic amount of Lewis acid, various carboxylic esters or S-phenyl carbothioates are prepared in excellent yields by the respective reactions of equimolar amounts of silyl carboxylates and alkyl silyl ethers or phenyl silyl sulfides with 4-trifluoromethylbenzoic anhydride.
- Miyashita, Mitsutomo,Shiina, Isamu,Miyoshi, So,Mukaiyama, Teruaki
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p. 1516 - 1527
(2007/10/02)
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- A New and Efficient Method for the Preparation of S-Phenyl Carbothioates via Mixed Anhydrides Using Active Titanium(IV) Salts
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In the presence of a catalytic amount of titanium(IV) salt, various S-phenyl carbothioates are prepared in excallent yields by the reaction of nearly equimolar amounts of silyl derivatives of carboxylic acids and benzenethiols with p-trifluoromethylbenzoic anhydride.
- Mukaiyama, Teruaki,Miyashita, Mitsutomo,Shiina,, Isamu
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p. 1747 - 1750
(2007/10/02)
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- Water-Soluble Acylating Agents: Preparation of 2-Acylthio-1-alkylpyridinium Salts and Acylation of Phenols, Acids, and/or Amines with These Salts in an Aqueous Phase
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Reaction of phenols, amines, and acids with 2-benzoylthio-1-methylpyridinium chloride prepared in situ from benzoyl chloride and 1-methyl-2(1H)-pyridinethione, afforded the corresponding benzoyl derivatives in good yields.In the reaction of p-nitrophenol, even catalytic amount of 1-methyl-2(1H)-pyridinethione proved to be effective.Similar reactions of p-nitrophenol with isobutyryl chloride and acetyl chloride in the presence of 1-methyl-2(1H)-pyridinethione afforded p-nitrophenyl isobutyrate and p-nitrophenyl acetate in 63 and 44percent yields, respectively. 2-Benzoylthio-, 2-acetylthio-, and 2-isobutyrylthio-1-ethylpyridinium tetrafluorobora tes were prepared by treatment of the corresponding 2-acylthiopyridines with triethyloxonium tetrafluoroborate.These pyridinium salts also acted as acylating agents in an aqueous phase. some competitive reactions of 2-aminoethanol and phenols with 2-benzoylthio-1-methylpyridinium chloride were also investigated.
- Sakakibara, Tohru,Watabe, Yukie,Yamada, Masahide,Sudoh, Rokuro
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p. 247 - 254
(2007/10/02)
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- A Simple and Mild Esterification Method for Carboxylic Acids Using Mixed Carboxylic-Carbonic Anhydrides
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A simple and mild esterification method using mixed carboxylic-carbonic anhydrides has been developed.Simple aliphatic carboxylic esters are prepared in high yields by the reaction of acids with equimolar amounts of chloroformates (2,2,2-trichloroethyl chloroformate is an exception) and triethylamine in the presence of a catalytic amount of 4-(dimethylamino)pyridine.Although aromatic acids give a mixture of the ester, the acid anhydride, and the carbonate under normal conditions utilized in this study, it is found that increasing the amount of 4-(dimethylamino)pyridine drastically decreases the formation of the acid anhydride and the carbonate, affording a satisfactory yield of the ester.This method reaches a limit with sterically hindered acids and the formation of the acid anhydride and the carbonate is favored.
- Kim, Sunggak,Lee, Jae In,Kim, Youn Chul
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p. 560 - 565
(2007/10/02)
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