- Gold N-Heterocyclic Carbene Catalysts for the Hydrofluorination of Alkynes Using Hydrofluoric Acid: Reaction Scope, Mechanistic Studies and the Tracking of Elusive Intermediates
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An efficient and chemoselective methodology deploying gold-N-heterocyclic carbene (NHC) complexes as catalysts in the hydrofluorination of terminal alkynes using aqueous HF has been developed. Mechanistic studies shed light on an in situ generated catalyst, formed by the reaction of Br?nsted basic gold pre-catalysts with HF in water, which exhibits the highest reactivity and chemoselectivity. The catalytic system has a wide alkyl substituted-substrate scope, and stoichiometric as well as catalytic reactions with tailor-designed gold pre-catalysts enable the identification of various gold species involved along the catalytic cycle. Computational studies aid in understanding the chemoselectivity observed through examination of key mechanistic steps for phosphine- and NHC-coordinated gold species bearing the triflate counterion and the elusive key complex bearing a bifluoride counterion.
- Bédard, Sandrine,Cavallo, Luigi,Falivene, Laura,Gauthier, Rapha?l,Nolan, Steven P.,Paquin, Jean-Fran?ois,Saab, Marina,Tzouras, Nikolaos V.,Van Hecke, Kristof,Zhang, Ziyun
-
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- Oxidative Cleavage of Alkenes by O2with a Non-Heme Manganese Catalyst
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The oxidative cleavage of C═C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O2 and oxidatively cleave C═C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O2, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O2. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn-oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O2 activation that leads to the formation of the oxo species.
- Bennett, Elliot L.,Brookfield, Adam,Guan, Renpeng,Huang, Zhiliang,Mcinnes, Eric J. L.,Robertson, Craig M.,Shanmugam, Muralidharan,Xiao, Jianliang
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supporting information
p. 10005 - 10013
(2021/07/19)
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- Method for synthesizing 2, 4-dimethyl pyrimidine-5-alcohol serving as intermediate of Leibolifera
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The invention discloses a method for synthesizing 2, 4-dimethyl pyrimidine-5-alcohol serving as an intermediate of Lemborexant , and aims to solve the problems of safety risk and heavy environmental pollution of the 2, 4-dimethyl pyrimidine-5-alcohol in i
- -
-
Paragraph 0036-0039; 0044-0046
(2021/08/07)
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- Oxidative C-H Acyloxylation of Acetone with Carboxylic Acids under Iodine Catalysis
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Iodine-catalyzed oxidative C(sp 3)-H acyloxylation of acetone with carboxylic acids has been developed. The method employs iodide as catalyst and sodium chlorite as oxidant. Substituted benzoic acids, naphthoic acids and heteroaromatic carboxyl
- Zhou, Xiao-Yu,Chen, Xia
-
supporting information
p. 1654 - 1662
(2021/01/21)
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- KI catalyzed C–H functionalization of acetone for the synthesis of 2-oxopropyl hetero-aromatic carboxylates
-
KI catalyzed C–H functionalization of acetone with hetero-aromatic carboxylic acids has been developed. With potassium iodide as catalyst and sodium chlorite as oxidant, cascade reaction including α-H electrophilic substitution of acetone and nucleophilic
- Zhou, Xiao-Yu,Chen, Xia,Liu, Hai-Long
-
supporting information
p. 1556 - 1563
(2021/03/15)
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- 1,2-Dibromoethane and KI mediated α-acyloxylation of ketones with carboxylic acids
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The 1,2-dibromoethane- and KI-mediated α-acyloxylation of ketones is reported in moderate to good yield without the use of transition metals and strong oxidants. Various acids are well tolerated with wide functional group compatibility. An 1,2-dibromoethane- and KI-catalysed reaction mechanism is proposed based on the results of control experiments.
- Wang, Xujie,Li, Gangsheng,Yang, Yanan,Jiang, Jianshuang,Feng, Ziming,Zhang, Peicheng
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p. 711 - 714
(2019/09/30)
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- Microwave-Enhanced Coupling of Carboxylic Acids with Liquid Ketones and Cyclic Ethers Using Tetrabutylammonium Iodide/ t-Butyl Hydroperoxide
-
The oxidative coupling of carboxylic acids with liquid ketones and cyclic ethers has been accomplished in minutes using t-butyl hydroperoxide in the presence of tetrabutylammonium iodide under microwave irradiation in the absence of a solvent. In addition to drastically shortening the reaction times, the use of microwaves resulted, in general, in yields equal to or higher than those obtained by conventional heating.
- Macías-Benítez, Pablo,Moreno-Dorado, F. Javier,Guerra, Francisco M.
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p. 6027 - 6043
(2020/05/22)
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- Catalytic Wacker-type Oxidations Using Visible Light Photoredox Catalysis
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A combined palladium/photoredox catalytic system for the efficient oxidation of terminal olefins to the corresponding methyl ketones is presented. The interplay of air, water, and light leads to a protocol in which the stoichiometric oxidants required for oxidative palladium catalysis are substituted with catalytic, single-electron transfer processes. Detailed mechanistic investigations revealed the role of the key components, in situ generated species, and catalysts. A broad range of substrates was examined in homogeneous as well as heterogeneous photoredox protocols, delivering the desired products in good yields.
- Ho, Yee Ann,Paffenholz, Eva,Kim, Hyun Jin,Orgis, Benjamin,Rueping, Magnus,Fabry, David C.
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p. 1889 - 1892
(2019/03/17)
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- Group VIII carbamoyl complexes as catalysts for alkyne hydrocarboxylation and electrochemical proton reduction
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A series of group VIII carbamoyl complexes, [M(2-NHC(O)C5H4N)(CO)2(2-SC5H4N)] [where M = Fe, Ru and Os], was found to be efficient and regioselective catalysts for the intramolecular hydroxycarboxylat
- Barik, Chandan Kr,Tessensohn, Malcolm E.,Webster, Richard D.,Leong, Weng Kee
-
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- TBAI/TBHP mediated oxidative cross coupling of ketones with phenols and carboxylic acids: Direct access to benzofurans
-
TBAI/TBHP mediated oxidative cross coupling of phenols and carboxylic acids with ketones has been reported under metal-free, base free, solvent free conditions enabling environmentally benign synthesis of aryloxyketones, acyloxy ketones and benzofurans. Phenoxyketones and acyloxylcarbonyl compounds were synthesized in good to high yields, where as benzofurans were synthesized in moderate yields. This method is operationally simple, works under mild conditions, using commercially available as well as inexpensive TBAI and an oxidant TBHP.
- Santhosh Kumar,Ravikumar,Chinna Ashalu,Rajender Reddy
-
supporting information
p. 33 - 37
(2017/12/11)
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- Wacker-Type Oxidation Using an Iron Catalyst and Ambient Air: Application to Late-Stage Oxidation of Complex Molecules
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A practical and general iron-catalyzed Wacker-type oxidation of olefins to ketones is presented, and it uses ambient air as the sole oxidant. The mild oxidation conditions enable exceptional functional-group tolerance, which has not been demonstrated for any other Wacker-type reaction to date. The inexpensive and nontoxic reagents [iron(II) chloride, polymethylhydrosiloxane, and air] can, therefore, also be employed to oxidize complex natural-product-derived and polyfunctionalized molecules.
- Liu, Binbin,Jin, Fengli,Wang, Tianjiao,Yuan, Xiaorong,Han, Wei
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p. 12712 - 12717
(2017/09/11)
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- A Combination System of p -Toluenesulfonic Acid and Acetic Acid for the Hydration of Alkynes
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A simple combination system of p-toluenesulfonic acid/acetic acid has been developed for efficient hydration of alkynes. The corresponding ketones can be obtained in good to excellent yields under mild conditions. The mechanism of the reaction was disclosed unambiguously which was a stepwise process (addition and then hydrolysis). Furthermore, this system was proved to be powerful that has the potential to be used to synthesize vinyl 4-methylbenzenesulfonates.
- Liu, Haixuan,Wei, Yunyang,Cai, Chun
-
supporting information
p. 2378 - 2383
(2016/09/28)
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- Tert-Butyl Nitrite: Organic Redox Cocatalyst for Aerobic Aldehyde-Selective Wacker-Tsuji Oxidation
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An aldehyde-selective aerobic Wacker-Tsuji oxidation is developed. Using tert-butyl nitrite as a simple organic redox cocatalyst instead of copper or silver salts, a variety of aldehydes were achieved as major products in up to 30/1 regioselectivity as well as good to high yields at room temperature.
- Ning, Xiao-Shan,Wang, Mei-Mei,Yao, Chuan-Zhi,Chen, Xian-Min,Kang, Yan-Biao
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supporting information
p. 2700 - 2703
(2016/06/15)
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- KI-catalyzed α-acyloxylation of acetone with carboxylic acids
-
The KI-catalyzed reaction of acetone with aromatic carboxylic acids is achieved, leading to α-acyloxycarbonyl compounds in good to excellent yields under mild reaction conditions. The present method exhibits good functional-group compatibility. Notably, t
- Wu, Ya-Dong,Huang, Bei,Zhang, Yue-Xin,Wang, Xiao-Xu,Dai, Jian-Jun,Xu, Jun,Xu, Hua-Jian
-
supporting information
p. 5936 - 5939
(2016/07/06)
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- Alkene-directed N-attack chemoselectivity in the gold-catalyzed [2+2+1]-annulations of 1,6-enynes with N-hydroxyanilines
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Kinetically unstable nitrones are generated from gold-catalyzed reactions of 1,6-enynes with N-hydroxyanilines, and subsequently trapped by tethered alkenes to furnish [2+2+1]-annulations. Our experimental data reveal that such nitrones arise from atypical N-attack chemoselectivity that is triggered by tethered alkenes to facilitate the key protodeauration reaction. Kinetically unstable nitrones are generated from gold-catalyzed reactions of 1,6-enynes with N-hydroxyanilines, and subsequently trapped by tethered alkenes to furnish [2+2+1]-annulations. These findings open the door to new ways to access ketone nitrones with good stereoselectivity.
- Huple, Deepak B.,Mokar, Bhanudas D.,Liu, Rai-Shung
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p. 14924 - 14928
(2016/02/05)
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- Catalytic activity assessment of [RuCl2 (p-cymene) (PTA)] in the synthesis of enol esters
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The addition of carboxylic acids onto 1-hexyne was catalyzed by [RuCl2 (p-cymene) (PTA)] complex to give enol esters. Accordingly, the Markovnikov addition-type product was selectively obtained. The microwave-assisted reactions at 160 °C confir
- Musengimana, Eric,Fatakanwa, Claver
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p. 253 - 259
(2016/01/09)
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- Ruthenium Carboxylate Complexes as Efficient Catalysts for the Addition of Carboxylic Acids to Propargylic Alcohols
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Ruthenium complexes [Ru(CO)2(PPh3)2(O2CR)2] - 3a (R = CH2OCH3), 3b (R = iPr), 3c (R = tBu), 3d (R = 2-cC4H3O), and 3e (R = Ph) - were synthesized
- Jeschke, Janine,G?bler, Christian,Korb, Marcus,Rüffer, Tobias,Lang, Heinrich
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p. 2939 - 2947
(2015/06/30)
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- Carbosilane-supported (p-cymene) ruthenium ferrocenyl phosphines in the β-oxopropyl ester synthesis
-
The synthesis and characterization of a series of carbosilane-supported ferrocenyl phosphine ruthenium complexes of type SiMe4-n(Fe(η5-C5H4SiMe2(CH2)3)((η5-C5/su
- Schreiner, Claus,Jeschke, Janine,Milde, Bianca,Schaarschmidt, Dieter,Lang, Heinrich
-
-
- Atom Economic Ruthenium-Catalyzed Synthesis of Bulky β-Oxo Esters
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Ruthenium complexes with the formulae Ru(CO)2(PR3)2(O2CPh)2 [6a-h; R=n-Bu, p-MeO-C6H4, p-Me-C6H4, Ph, p-Cl-C6H4, m-Cl-C6H4, p-CF3-C6H4, m,m′-(CF3)2C6H3] were prepared by treatment of triruthenium dodecacarbonyl [Ru3(CO)12] with the respective phosphine and benzoic acid or by the conversion of Ru(CO)3(PR3)2 (8e-h) with benzoic acid. During the preparation of 8, ruthenium hydride complexes of type Ru(CO)(PR3)3(H)2 (9g, h) could be isolated as side products. The molecular structures of the newly synthesized complexes in the solid state are discussed. Compounds 6a-h were found to be highly effective catalysts in the addition of carboxylic acids to propargylic alcohols to give valuable β-oxo esters. The catalyst screening revealed a considerably influence of the phosphine′s electronic nature on the resulting activities. The best performances were obtained with complexes 6g and 6h, featuring electron-withdrawing phosphine ligands. Additionally, catalyst 6g is very active in the conversion of sterically demanding substrates, leading to a broad substrate scope. The catalytic preparation of simple as well as challenging substrates succeeds with catalyst 6g in yields that often exceed those of established literature systems. Furthermore, the reactions can be carried out with catalyst loadings down to 0.1mol% and reaction temperatures down to 50 C.
- Jeschke, Janine,Korb, Marcus,Rüffer, Tobias,G?bler, Christian,Lang, Heinrich
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supporting information
p. 4069 - 4081
(2016/01/25)
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- N-Isocyanimino-Triphenylphosphorane (Ph 3Pnnc) as an Efficient Reagent for the Preparation of Fully Substituted 1,3,4-Oxadiazoles via Intramolecular Aza-Wittig Reaction in Water
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An efficient green protocol for the synthesis of 1,3,4-oxadiazoles derivatives via a one-pot three-component reaction of aromatic carboxylic acids, N-isocyanimino-Triphenylphosphorane and ester derivatives of 2-oxopropyl alcohol (2-oxopropyl benzoate, 2-oxopropyl-4-bromobenzoate and 2-oxopropyl acetate) in water at room temperature have been developed. The present methodology offers several advantages such as a simple procedure, high yields, environmental friendliness and the absence of any volatile and hazardous organic solvents.
- Jafari, Ali,Ramazani, Ali,Asiabi, Pegah Azimzadeh,Sadri, Fariba,Joo, Sang Woo
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p. 2246 - 2254
(2015/12/20)
-
- NOVEL INHIBITORS
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The invention relates to a compound of formula (I) or a pharmaceutically acceptable salt, solvate or polymorph thereof, including all tautomers and stereoisomers thereof, wherein R1, R2, R3, R4 and R5 are as defined herein, as inhibitors of glutaminyl cyclase (QC, EC 2.3.2.5). QC catalyzes the intramolecular cyclization of N- terminal glutamine residues into pyroglutamic acid (5-oxo-prolyl, pGlu*) under liberation of ammonia and the intramolecular cyclization of N-terminal glutamate residues into pyroglutamic acid under liberation of water.
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Page/Page column 69; 125
(2014/09/29)
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- Greening the Wacker process
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Wacker oxidation of various terminal olefins with Pd0/C- KBrO3, a nontoxic, environmentally benign, and easy to handle catalyst system, was achieved in high isolated yields. The described protocol offers an alternative to the traditional Wacker system which uses CuCl 2 as co-catalyst. The catalyst is reusable while maintaining high activity and selectivity.
- Kulkarni, Mukund G.,Shaikh, Yunnus B.,Borhade, Ajit S.,Chavhan, Sanjay W.,Dhondge, Attrimuni P.,Gaikwad, Dnyaneshwar D.,Desai, Mayur P.,Birhade, Deekshaputra R.,Dhatrak, Nagorao R.
-
supporting information
p. 2293 - 2295
(2013/06/26)
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- The reaction of N-isocyaniminotriphenylphosphorane with 2-oxopropylbenzoate (or 4-bromobenzoate) and a primary amine in the presence of (E)-cinnamic acid derivatives: A one-pot efficient four-component reaction for the synthesis of 2-(arylamino)-2-(5-aryl-1-ethenyl-1,3,4-oxadiazol-2-yl) propyl benzoate (or 4-bromobenzoate) derivatives
-
Reactions of N-isocyaniminotriphenylphosphorane with 2-oxopropylbenzoate (or 2-oxopropyl 4-bromobenzoate) in the presence of (E)-cinnamic acids and primary amines proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions and no side reactions were observed.
- Ramazani, Ali,Ahmadi, Yavar,Nasrabadi, Fatemeh Zeinali,Rouhani, Morteza
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p. 1294 - 1298
(2014/01/06)
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- (Ethynylferrocenyl)phosphine ruthenium complexes in catalytic β-oxopropyl benzoate formation
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The synthesis of a series of (ethynylferrocenyl)phosphino ruthenium compounds of type (FcCC)R2P(RuCl2(η6-p- cymene)) (3a, R = C6H5; 3b, R = 2-CH3C 6H4; 3c, R = c
- Milde, Bianca,Rueffer, Tobias,Lang, Heinrich
-
experimental part
p. 338 - 345
(2012/06/30)
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- The reaction of N-isocyaniminotriphenylphosphorane with ester derivatives of 2-oxopropyl alcohol (2-Oxopropyl 4-Bromobenzoate, 2-Oxopropyl Benzoate, and 2-Oxopropyl Acetate) in the presence of aromatic carboxylic acids: A one-pot efficient three-component reaction for the synthesis of fully substituted 1,3,4-oxadiazole derivatives
-
Reactions of N-isocyaniminotriphenylphosphorane with ester derivatives of 2-oxopropyl alcohol (2-oxopropyl 4-bromobenzoate, 2-oxopropyl benzoate, and 2-oxopropyl acetate) in the presence of aromatic carboxylic acids proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions and no side reactions were observed.
- Ramazani, Ali,Ahmadi, Yavar,Karimi, Zahra,Rezaei, Aram
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p. 1447 - 1451
(2013/02/23)
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- A one-pot efficient four-component reaction for the synthesis of 2-(arylamino)-2-(5-aryl-1-ethenyl-1,3,4-oxadiazol-2-yl)propyl benzoate (or 4-bromobenzoate) derivatives
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Reactions of N-isocyaniminotriphenylphosphorane with 2-oxopropyl benzoate (or 2-oxopropyl 4-bromobenzoate) in the presence of 3-phenyl-2-propynoic acid and primary amines proceeded smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeded smoothly and cleanly under mild conditions and no side reactions were observed. TUeBITAK, 2012.
- Holagh, Mohsen Valizadeh,Maharramov, Abel Mohammadalioglu,Allahverdiyev, Mirza Aliakbaroglu,Ramazani, Ali,Ahmadi, Yavar,Nasrabadi, Fatemeh Zeinali,Souldozi, Ali
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p. 671 - 681
(2013/02/25)
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- Ruthenium carboxylate complexes as easily prepared and efficient catalysts for the synthesis of β-oxopropyl esters
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The easily prepared complex cis-[Ru(κ2-O 2CMe)2(PPh3)2] is an effective catalyst for the addition of carboxylic acids to propargyl alcohols to afford β-oxopropyl esters. The reaction is tolerant to a
- Hiett, Nicholas P.,Lynam, Jason M.,Welby, Christine E.,Whitwood, Adrian C.
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experimental part
p. 378 - 387
(2011/02/16)
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- Ruthenium(IV)-catalyzed markovnikov addition of carboxylic acids to terminal alkynes in aqueous medium
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The dimeric bis(allyl)ruthenium(IV) complex [{RuCl(μ-Cl)( η3:η3-C10H16)}2] (C10H16 = 2,7-dimethylocta-2,6-diene-1,8-diyl) (5) and several mononuclear species trans-[RuCl2(η3: η3-C10H16)(L)] (L = two-electron-donor ligand) (6) derived from 5 have been checked as catalysts for the addition of carboxylic acids onto terminal alkynes using water as a green reaction medium. The best results in terms of activity and regioselectivity were obtained with the mononuclear derivative trans-[RuCl2(η3: η3-C10H16)(PPh3)] (6a), which was able to promote the selective Markovnikov addition of both aromatic and aliphatic carboxylic acids to a large variety of terminal alkynes, enynes, and diynes as well as propargylic alcohols. In this way, a wide number of enol esters and β-oxo esters could be synthesized in moderate to good yields under mild conditions (60 °C) in an aqueous medium.
- Cadierno, Victorio,Francos, Javier,Gimeno, Jose
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experimental part
p. 852 - 862
(2011/04/15)
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- A one-pot efficient four-component reaction for the synthesis of 2-(arylamino)-2-(5-aryl-1,3,4-oxadiazol-2-yl)propyl benzoate (or acetate) derivatives
-
Reactions of (N-isocyanimino) triphenylphosphorane with 2-oxopropylbenzoate (or acetate) in the presence of aromatic carboxylic acids and primary amines proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions, and no side reactions were observed.
- Ramazani, Ali,Ahmadi, Yavar,Malekzadeh, Asemeh Mashhadi,Rezaei, Aram
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scheme or table
p. 692 - 698
(2012/01/03)
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- Ruthenium-catalyzed synthesis of β-oxo esters in aqueous medium: Scope and limitations
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The ability of the hydrosoluble ruthenium(ii) complexes [RuCl 2(η6-arene)(PTA)] 3a-d, [RuCl2(η 6-arene)(PTA-Bn)] 4a-d, [RuCl2(η6-arene) (DAPTA)] 5a-d, [RuCl2(η6-arene)(TPPMS)] 6a-d (arene = C6H6, p-cymene, 1,3,5-C6H3Me 3, C6Me6) to promote the atom-economic formation of β-oxo esters, by addition of carboxylic acids to terminal propargylic alcohols in water has been explored. Scope, limitations and catalyst recycling have been evaluated using the most active catalyst [RuCl 2(η6-C6H6)(TPPMS)], 6a.
- Cadierno, Victorio,Francos, Javier,Gimeno, Jose
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experimental part
p. 135 - 143
(2010/05/18)
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- Pd(0)/C catalyzed efficient Wacker oxidation of functionalized terminal olefins
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Wacker oxidation of terminal olefins was carried out at room temperature and atmospheric pressure by using Pd(0)/C in THF/H2O (9:1). Palladium(0)/C was proven to be highly efficient catalyst for the Wacker oxidation of terminal olefins to the corresponding methyl ketones. The catalyst was reusable while maintaining its activity and selectivity to a high degree.
- Kulkarni, Mukund G.,Bagale, Sharanappa M.,Shinde, Mahadev P.,Gaikwad, Dnyaneshwar D.,Borhade, Ajit S.,Dhondge, Attrimuni P.,Chavhan, Sanjay W.,Shaikh, Yunnus B.,Ningdale, Vijay B.,Desai, Mayur P.,Birhade, Deekshaputra R.
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experimental part
p. 2893 - 2894
(2009/09/06)
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- Conversion of propargylic alcohols to β-oxo esters catalyzed by novel ruthenium-phosphoramidite complexes
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A series of half-sandwich phosphoramidite complexes of ruthenium were synthesized and employed as catalysts in the atom-economical formation of β-oxo esters from carboxylic acids and propargylic alcohols. Reaction of the phosphoramidites (R)-BINOL-PNR2 (R=Me, 1a; i-Pr, 1b; benzyl, 1c) and (rac)-6,6′-dibromo-BINOL-PNMe2 (1d) with the dimeric p-cymene-ruthenium dichloride complex, [RuCl2(p-cymene)]2, gave the complexes [RuCl2(p-cymene)(L)] (L=1a, 7a; 1b, 7b; 1c, 7c; 1d, 7d) in 96-66% yield. Accordingly, reaction of (R)-BINOL(8H)-PNMe2 (2a) and (R)-BINOL(8H)-PN-(benzyl)2 (2b) with [RuCl2(p-cymene)] 2 afforded the complexes [RuCl2(p-cymene)(L)] (L=2a, 8a; 2b, 8b) in 82% and 86% yield. In a similar reaction, treatment of (R)-BIPHEN-PNMe2 (9) with [RuCl2(p-cymene)] 2 gave the complex [RuCl2(p-cymene)(9)] (11) in 60% yield. Finally, phosphoramidite 1b reacted with [RuCl2(C6Me 6)]2 to give [RuCl2(C6Me 6)(1b)] (12) in 78% yield. All novel complexes are catalytically active in the formation of β-oxo esters from propargylic alcohols and carboxylic acids. Standard conditions involve cyclohexane solvent, propargylic alcohol (1.0 equiv.), carboxylic acid (1.0 equiv.), ruthenium catalyst (1.5 mol%), and 90°C for 5-18 h. Isolated yields of the β-oxo esters range from 87 to 16% and show broad substrate generality. The reaction proceeds without racemization if a chiral propargylic alcohol is employed. The method is practical as no additives are required and the exclusion of oxygen and moisture is not needed. Complex 7c turned out to be the most effective catalyst (5 h reaction time), showing that the ligand structure has a profound impact on the catalytic performance. The crystal structure of 7a was determined, confirming an octahedral coordination geometry about the ruthenium center.
- Costin, Stephen,Rath, Nigam P.,Bauer, Eike B.
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supporting information; experimental part
p. 2414 - 2424
(2009/11/30)
-
- Low pressure carbonylation of heterocycles
-
Heterocycles, e.g., epoxides, are carbonylated at low pressure with high percentage conversion to cyclic, ring expanded products using the catalyst where L is tetrahydrofuran (THF).
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Page/Page column 4
(2008/06/13)
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- Benzimidazole compound
-
An object of the present invention is to provide a novel chemical compound useful as a therapeutic or prophylactic agent for acid-related diseases, having an excellent inhibitory effect against gastric acid secretion, an excellent effect of maintaining the inhibitory effect against gastric acid secretion, thereby maintaining intragastric pH high for a long time, and having more safety and appropriate physicochemical stability. Provided is a compound represented by where R1 and R3 may be the same or different and each represent a hydrogen atom or a C1-C6 alkyl group; R2 represents (5,5-dimethyl-1,3-dioxan-2-yl)methoxy group, 5,7-dioxaspiro[2.5]oct-6-ylmethoxy group, 1,5,9-trioxaspiro[5.5]undec-3-ylmethoxy group, or (2,2-dimethyl-1,3-dioxan-5-yl)methoxy group; R4, R5, R6 and R7 represent a hydrogen atom, halogen atom, C1-C6 alkyl group, C1-C6 haloalkyl group, C1-C6 alkoxy group or C1-C6 haloalkoxy group; and W1 represents a single bond, methylene or ethylene group, a salt thereof or a solvate of these.
- -
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Page/Page column 25
(2008/06/13)
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- Practical β-lactone synthesis: Epoxide carbonylation at 1 atm
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A readily prepared bimetallic catalyst is capable of effecting epoxide carbonylation to produce β-lactones at substantially lower CO pressures than previously reported catalyst systems. A functionally diverse array of β-lactones is produced in excellent yields at CO pressures as low as 1 atm. This procedure allows for epoxide carbonylation on a multigram scale without the requirement of specialized, high-pressure equipment.
- Kramer, John W.,Lobkovsky, Emil B.,Coates, Geoffrey W.
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p. 3709 - 3712
(2007/10/03)
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- Oxidative ring cleavage of cyclic acetals with hypervalent tert-butylperoxy-λ3-iodanes
-
(matrix presented) Exposure of cyclic acetals to 1-tert-butylperoxy-1,2-benziodoxol-3(1H)-one in the presence of tert-butyl hydroperoxide and potassium carbonate in benzene at room temperature results in oxidative ring cleavage to glycol monoesters via intermediate tert-butylperoxy ortho esters.
- Sueda, Takuya,Fukuda, Sonoko,Ochiai, Masahito
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p. 2387 - 2390
(2007/10/03)
-
- Short synthesis of 2,4-disubstituted 1,3-oxathiolane and 1,3-dithiolane cytosine nucleosides: Facile introduction of a 4-benzoate group using benzoyl peroxide
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Introduction of a benzoate group at position 4 in 2-substituted 1,3- oxathiolane and 1,3-dithiolane using benzoyl peroxide is described. The coupling reaction between 1,3-oxathiolane derivatives 3 and pyrimidine bases in the presence of TMSI produced cis
- Nguyen-Ba, Nghe,Brown, William,Lee, Nola,Zacharie, Boulos
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p. 759 - 762
(2007/10/03)
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- Polymer supported reagents: Facile synthesis of β-oxalkyl (acetonyl) esters of carboxylic acids
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β-Oxoalkyl (acetonyl) esters have been synthesised in high yields and in a state of purity by reaction of chloroacetone with insoluble polymer supported carboxylate ions at room temperature.
- Salunkhe, Manikrao M.,Sande, Amirhamja R.,Kanade, Annappa S.,Wadgaonkar, Prakash P.
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p. 2885 - 2891
(2007/10/03)
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- Synthesis, NMR spectroscopy study, and antimuscarinic activity of a series of 2-(acyloxymethyl)-1,3-dioxolanes
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A series of 19-dioxolane-based ligands, bearing hydroxymethyl or ester functionalities, was synthesized and tested as potential muscarinic antagonists. The compounds display moderate to low affinity for the three receptor subtypes M1-M3/s
- Malmusi, Luca,Mucci, Adele,Schenetti, Luisa,Gulini, Ugo,Marucci, Gabriella,Brasili, Livio
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p. 2071 - 2080
(2007/10/03)
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- A Systematic Study on the Bakers'Yeast Reduction of 2-Oxoalkyl Benzoates and 1-Chloro-2-alkanones
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The bakers' yeast reduction of a series of 2-oxoalkyl arenecarboxylates (1a-f) (R=CH3 to n-C6H13; X=H) and the phenyl-modified derivatives (1g-l) (R=n-C5H11, X=OH, CH3, F, Cl, Br, or I) as well as 1-chloro-2-alkanones R(C=O)CH2Cl (6a-f) (R=CH3 to n-C6H13) were systematically investigated.The substrate specificities, configuration and percentee of the reduction products were found to be highly dependent on the length of the alkyl group (R) and the α substituent.Thus, the benzoates 1a-f gave optically active 2-hydroxyalkyl benzoates (2a-f) (R, configuration, percentee) (a: CH3, S, 99; b: C2H5, S, 98; c: C3H7, S, 26; d: n-C4H9, R, 55; e: n-C5H11, S, 15; f: n-C6H13, S, 63) in 11-91percent yields.Among the modification experiments of the phenyl group, 1g-l, the p-iodo substituent markedly increased the ee from 15 to 71percent, although the yield was rather lowered (22percent yield).The reduction of α-chloro ketones 6a-f also gave optically active 1-chloro-2-alkanols (7a-f) in 16-69percent yields.
- Sakai, Takashi,Wada, Kou,Murakami, Takahiko,Kohra, Kiichiro,Imajo, Norihisa,et al.
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p. 631 - 638
(2007/10/02)
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- Cyclization of alkynyl benzoates and generation of dioxolenylium ions
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Reactions of l-ethynyl benzoates RC≡CO2CC6H4X in H2O and CH3OH have been studied. In neutral H2O, reaction rates for CH3C≡CO2CC6H4X depend on σp of X with p of 1.3. Reaction of CH3C≡CO2CPh (1) in 18O-labeled H2O gives CH3CH2CO2H and PhCO2H in 54% relative yield with 90 and 83%, respectively, incorporation of a single 18O in the acids and CH3COCH2O2CPh (2) in 46% relative yield with 100% incorporation of 18O in both carbonyl oxygens. These results arc explained by the hypothesis that at least 46% of 1 reacts by cyclization to an intermediate 2-hydroxy-1,3-dioxolene 18. Mcthanolysis of 1 and other alkynyl benzoates gives 2-methoxy-1,3-dioxolenes, confirming the cyclization pathway. Reaction in 44% H2SO4 of 2-methoxy-2-phenyl-4-tert-butyl-1,3-dioxol-4-ene (8), prepared in this way, gives the 2-phenyl-4-tert-butyl-1,3-dioxol-4-enylium cation (16), directly observable by UV, which hydrolyzes to t-BuCOCH2O2CPh (12).
- Allen, Annette D.,Kitamura, Tsugio,McClelland,Stang, Peter J.,Tidwell, Thomas T.
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p. 8873 - 8878
(2007/10/02)
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- On the Chemistry of Pyrazolylalkines; Pyrazoles II.
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Palladium-catalyzed reactions of 1-benzoyl-4-iodopyrazole (2a) with monosubstituted acetylenes 3a,3b and 3c in triethylamine solution provide convenient access to the cross-coupled products 4a,4b and 4c.The 4-ethinylpyrazoles 5a and 7 obtained after metha
- Heinisch, Gottfried,Holzer, Wolfgang,Obala, Claudia
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p. 253 - 262
(2007/10/02)
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- Synthesis of β-Oxopropyl Esters By Catalytic Addition of Carboxylic Acids and N-Protected Amino Acids to Propargyl Alcohol
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The synthesis of β-oxopropyl esters results from the addition of saturated and unsaturated carboxylic acids or N-protected amino acids to propargyl alcohol in the presence of (arene)(phosphine)ruthenium(II) catalysts.
- Devanne, Dominique,Ruppin, Christophe,Dixneuf, Pierre H.
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p. 925 - 926
(2007/10/02)
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- A Convenient Method for the Hydrolysis of Diethylthioacetals Catalyzed by Trityl Perchlorate
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Treatment of diethylthioacetals with two equivalents of trityl methyl ether in the presence of a catalytic amount of trityl perchlorate, and successive quenching with aqueous sodium hydrogencarbonate gave parent carbonyl compounds, hydrolyzed products, in high yields under mild conditions.According to this method, it is also possible to hydrolyze diethylthioacetals selectively even when another thioacetal, such as 1,3-dithiane, coexisted in the same molecule.
- Ohshima, Masahiro,Murakami, Masahiro,Mukaiyama, Teruaki
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p. 1593 - 1596
(2007/10/02)
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