- Iridium-Catalyzed α-Methylation of α-Aryl Esters Using Methanol as the C1 Source
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IrCl(cod)2]/dppe-catalyzed α-methylation of aryl esters using methanol as the C1 source was developed. This methylation process is useful in several fields including organic chemistry, biochemistry, and medicinal chemistry. Readily available methanol as methylation reagent was successfully adapted. The reaction processed high atom economy and efficient. By applying the reaction system, the synthesis method of naproxen was provided.
- Tsukamoto, Yuya,Itoh, Satoshi,Kobayashi, Masaki,Obora, Yasushi
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supporting information
p. 3299 - 3303
(2019/05/10)
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- Palladium-Catalyzed Carbonylation of sec- and tert-Alcohols
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A general palladium-catalyzed synthesis of linear esters directly from sec- and tert-alcohols is described. Compared to the classic Koch–Haaf reaction, which leads to branched products, this new transformation gives the corresponding linear esters in high yields and selectivity. Key for this protocol is the use of an advanced palladium catalyst system with L2 (pytbpx) as the ligand. A variety of aliphatic and benzylic alcohols can be directly used and the catalyst efficiency for the benchmark reaction is outstanding (turnover number up to 89 000).
- Dong, Kaiwu,Sang, Rui,Liu, Jie,Razzaq, Rauf,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 6203 - 6207
(2017/05/22)
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- Highly Selective Hydrogenation of Aromatic Ketones and Phenols Enabled by Cyclic (Amino)(alkyl)carbene Rhodium Complexes
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Air-stable Rh complexes ligated by strongly σ-donating cyclic (amino)(alkyl)carbenes (CAACs) show unique catalytic activity for the selective hydrogenation of aromatic ketones and phenols by reducing the aryl groups. The use of CAAC ligands is essential for achieving high selectivity and conversion. This method is characterized by its good compatibility with unsaturated ketones, esters, carboxylic acids, amides, and amino acids and is scalable without detriment to its efficiency.
- Wei, Yu,Rao, Bin,Cong, Xuefeng,Zeng, Xiaoming
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supporting information
p. 9250 - 9253
(2015/08/11)
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- Efficient microwave-assisted esterification reaction employing methanesulfonic acid supported on alumina as catalyst
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A rapid and efficient protocol assisted by microwave irradiation for the synthesis of esters using methanesulfonic acid (CH3SO3H) supported on Al2O3 (AMA) as catalyst and free of solvent is described. The products were obtained in good yields and purity, with reduced reaction time, and the process is simple and environmentally benign. Copyright
- Fabian, Lucas,Gomez, Matias,Kuran, Juan A. Caturelli,Moltrasio, Graciela,Moglioni, Albertina
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p. 2386 - 2392
(2014/07/22)
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- Rhodium-catalyzed oxygenative addition to terminal alkynes for the synthesis of esters, amides, and carboxylic acids
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A gem of a couple: The title reaction of terminal alkynes with O and Nnucleophiles proceeds in the presence of [Rh(cod)Cl}2], P(4-FC 6H4)3, and 4-picoline N-oxide. Alcohols, amines, and water add to the terminal alkynes to give esters, amides, and carboxylic acids, respectively. The reaction involves formation of a rhodium vinylidene, oxidation to a ketene by oxygen transfer, and nucleophilic addition.
- Kim, Insu,Lee, Chulbom
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supporting information
p. 10023 - 10026
(2013/10/01)
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- Microwave-assisted synthesis of 5-substituted 2-aminothiophenes starting from arylacetaldehydes
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An easy three-step pathway for the synthesis of arylacet-aldehydes from the corresponding carboxylic acids in very high yields is described. Their use as precursors of 5-substituted-2-aminothiophenes is illustrated via a microwave-assisted Gewald reaction. This method allows obtaining the expected compounds in a shorter time and with better yields and purities than the classical procedures. Georg Thieme Verlag Stuttgart - New York.
- Revelant, Germain,Dunand, Sandrine,Hesse, Stephanie,Kirsch, Gilbert
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experimental part
p. 2935 - 2940
(2011/11/01)
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- SOLUBLE EPOXIDE HYDROLASE INHIBITORS
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Disclosed are alpha keto amide and alpha hydroxy amide compounds and compositions that inhibit soluble epoxide hydrolase (sEH), methods for preparing the compounds and compositions, and methods for treating patients with such compounds and compositions. The compounds, compositions, and methods are useful for treating a variety of sEH mediated diseases, including hypertensive, cardiovascular, inflammatory, pulmonary, and diabetic-related diseases.
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Page/Page column 93
(2008/12/06)
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- Investigation on the regioselectivities of intramolecular oxidation of unactivated C-H bonds by dioxiranes generated in Situ
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We found that dioxiranes generated in situ from ketones 1-6 and Oxone underwent intramolecular oxidation of unactivated C-H bonds at δ sites of ketones to yield tetrahydropyrans. From the trans/cis ratio of oxidation products 1a and 2a as well as the retention of the configuration at the δ site of ketone 5, we proposed that the oxidation reaction proceeds through a concerted pathway under a spiro transition state. The intramolecular oxidation of ketone 6 showed the preference for a tertiary δ C-H bond over a secondary one. This intramolecular oxidation method can be extended to the oxidation of the tertiary γ′ C-H bond of ketones 9 and 10. For ketone 11 with two δ C-H bonds and one γ′ C-H bond linked respectively by a sp3 hydrocarbon tether and a sp2 ester tether, the oxidation took place exclusively at the δ C-H bonds. Finally, by introducing proper tethers, regioselective hydroxylation of steroid ketones 12-14 have been achieved at the C-17, C-16, C-3, and C-5 positions.
- Wong, Man-Kin,Chung, Nga-Wai,He, Lan,Wang, Xue-Chao,Yan, Zheng,Tang, Yeung-Chiu,Yang, Dan
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p. 6321 - 6328
(2007/10/03)
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- Novel Preparation of α,β-Unsaturated Aldehydes. Benzeneselenolate Promotes Elimination of HBr from α-Bromoacetals
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Acetalization, α-bromination, nucleophilic phenylselenenylation, oxidative elimination/hydrolysis was investigated as a novel protocol for the α,β-dehydrogenation of aldehydes. Treatment of acetals with bromine in methylene chloride afforded the corresponding α-bromoacetals in 80-90% yields. Nucleophilic phenylselenenylation was then conveniently effected by treatment with benzenese-lenolate generated in situ in dimethyl sulfoxide from diphenyl diselenide, hydrazine and potassium carbonate. Unbranched α-bromoacetals cleanly afforded substitution products whereas β- and γ-branched ones gave substantial amounts of α,β-unsaturated acetals via formal loss of hydrogen bromide. Oxidative elimination/hydrolysis of these mixtures afforded α,β-unsaturated aldehydes in 50-80% overall yields. In the case of tertiary α-bromoacetals, treatment with benzeneselenolate afforded only dehydrobromination products as mixtures of isomers. The presence of at least a catalytic amount of the organoselenium reagent was found to be crucial for olefin formation. A SET-mechanism, involving benzeneselenolate-induced electron transfer to the halide, loss of bromide ion, and hydrogen atom or proton/electron was proposed for the benzenselenolate-promoted elimination reaction. Experiments designed to trap carbon-centered radicals in intramolecular cyclization or ring-opening reactions failed to provide any evidence for free-radical intermediates.
- Vasil'ev, Andrei,Engman, Lars
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p. 2151 - 2162
(2007/10/03)
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- Electrochemical deacetylation of 1,3-dicarbonyl compounds
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Mild deacetylation of 1,3-dicarbonyl compounds was achieved by halonium-ion mediated electrolysis. In this reaction, the supporting electrolyte including sodium halide NaX (X = Cl or Br) was essential since the reaction proceeded through substitution by a halonium ion, generated electrochemically at anode, on active methine carbons followed by base-aitalyzed deacctylation, and was terminated by reductive dehalogenation of the formed α-halo carbonyl compounds at cathode.
- Fujimoto, Kazuo,Maekawa, Hirofumi,Matsubara, Yoshiharu,Nishiguchi, Ikuzo
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p. 143 - 144
(2007/10/03)
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- The photochemistry of acetylenic ethers. A novel carbon-oxygen to carbon-carbon bond conversion
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Irradiation of acetylenic ethers in methanol gives homologated esters via a formal [1,3]-oxygen-to-carbon migration involving a ketene intermediate.
- Smith, Bradley A.,Callinan, Andrew J.,Swenton, John S.
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p. 2283 - 2286
(2007/10/02)
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- Electron transfer induced reductive cleavage of γ-lactones to carboxylic acids by sodium-hexamethylphosphoric triamide (HMPA)
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Sodium-hexamethylphosphoric triamide (HMPA) mediated electron transfer induced reductive cleavage of 1 -> 3 and 1 -> 2 γ-lactones fused in cyclohexane ring gives the corresponding carboxylic acids in good yields.
- Mukhopadhyaya, Jayanta K.,Mukhopadhyay, Chhanda,Ghatak, Usha Ranjan
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p. 132 - 136
(2007/10/02)
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- Electroreductive Deoxygenation of Methanesulfonates of α-Hydroxy Esters via a Catalytic Selenation-Deselenation Sequence
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The methanesulfonates of α-hydroxy esters were converted to the corresponding deoxygenated esters in 70-88percent yields by the indirect electrolysis with diphenyl diselenide as a recyclable reagent in a divided cell.This deoxygenation method may involve the formation of α-phenylselenoester by replacement of α-methylsulfonyloxy group with phenylselenide anion followed by capture of the α-phenylseleno group with phenylselenide anion.
- Inokuchi, Tsutomu,Sugimoto, Tatsuya,Kusumoto, Masahiko,Torii, Sigeru
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p. 3200 - 3202
(2007/10/02)
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- Electrochemical Oxidation of Acylsilanes and Their Tosylhydrazones
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Oxidation potentials of acylsilanes were found to be much less positive than those of ketones and aldehydes.The effect of silicon is attributed to the rise of the HOMO level by the interaction between the C-Si ? orbital and the nonbonding p orbital of the carbonyl oxygen which in turn favors the electron transfer.Preparative electrochemical oxidation of acylsilanes proceeded smoothly, giving rise to facile cleavage of the C-Si bond and the introduction of nucleophiles such as alcohols, water, and carbamates onto the carbonyl carbon.Electrochemical properties of tosylhydrazones of acylsilanes were also investigated.A decrease in oxidation potential of tosylhydrazones caused by silyl substitution was found to be smaller than that for carbonyl compounds.Preparative electrochemical oxidation of tosylhydrazones of acylsilanes gave the corresponding nitriles with consumption of a catalytic amount of electricity.
- Yoshida, Jun-ichi,Itoh, Masanori,Matsunaga, Shin-ichiro,Isoe, Sachihiko
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p. 4877 - 4882
(2007/10/02)
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- ELECTROCHEMICAL OXIDATION OF ACYLSILANES
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Oxidation potentials of acylsilanes were found to be much less than those of the corresponding ketones and aldehydes.Electrochemical oxidation of acylsilanes resulted in facile cleavage of the carbon-silicon bond and introduction of oxygen and nitrogen nucleophiles at the carbonyl carbon.Therefore acylsilanes serve as a synthetic equivalent of acyl cations.
- Yoshida, Jun-ichi,Matsunaga, Shin-ichiro,Isoe, Sachihiko
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p. 5293 - 5296
(2007/10/02)
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- RHODIUM CATALYZED REDUCTIVE ESTERIFICATION REACTIONS
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Reductive esterification occurs when unsaturated acids are treated with hydrogen in alcohol using either rhodium trichloride or the dimer of chloro(1,5-hexadiene)rhodium(I) as the catalyst.Saturated acids containing appropriate functional groups are also esterified under the same conditions.
- Lin, Ivan J. B.,Zahalka, Hayder A.,Alper, Howard
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p. 1759 - 1762
(2007/10/02)
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- 2,5,6,7-tetranor-4,8-inter-m-phenylene PGI2 derivatives
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Disclosed herein are novel prostaglandin I2 (PGI2) derivatives exhibiting excellent in vivo duration and activities, said derivatives being represented by the general formula: STR1 wherein R1, X, R2 and R3 are as defined herein.
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- Synthesis of carbocycles from ω-substituted α,β-unsaturated esters via radical-induced cyclizations
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The intramolecular radical cyclization of ω-bromo α,β-unsaturated esters for the synthesis of carbocyclic compounds is described.The effect of carbon chain substituents, the bulk of the ester group, and the olefin geometry were examined.The highest level of stereoselectivity (trans/cis:9/1) was achieved with the Z ester via an exo cyclization.The sequential radical cyclization of a dihalodienoate to give a cis-fused bicyclic structure is also described.
- Hanessian, Stephen,Dhanoa, Daljit S.,Beaulieu, Pierre L.
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p. 1859 - 1866
(2007/10/02)
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- A + + 4> Polar Cycloaddition of α-Thiocarbocations with 1,3-Dienes: Synthesis and Thermal Reaction of 1-Acyl-1-methylthio-2-vinylcyclopropanes
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Treatment of methyl 2-chloro-2-(methylthio)acetate, 1-chloro-1-(methylthio)propan-2-one, chloro(methylthio)methyl phenyl ketone, or 2-chloro-2-(methylthio)acetonitrile with 1,3-dienes in the presence of stannic chloride followed by addition of triethylamine gave 1-acyl- or 1-cyano-1-(methylthio)-2-vinylcyclopropanes.A mechanistic interpretation of this reaction is presented.Thermal behaviour of the vinylcyclopropanes is also described.
- Ishibashi, Hiroyuki,Okada, Motofumi,Nakatani, Hiroshi,Ikeda, Masazumi,Tamura, Yasumitsu
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p. 1763 - 1768
(2007/10/02)
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- SYNTHESIS OF CYCLOHEXYLALIPHATIC ACIDS AND THEIR PHARMACOLOGICAL PROPERTIES
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A series of substituted cyclohexylacetic acids I has been obtained by hydrogenation of the unsaturated analogues II and III.Esters of these analogues were prepared by the Horner-Wittig reaction of the corresponding cyclohexanones IV and/or 2-cyclohexenones V with triethyl phosphonoacetate.These esters were obtained in two isomeric forms (Z and E), differing in the double bond in the exo-position.The derivatives with a substituent in the 2-position exhibited a partial shift of the double bond to the cyclohexane ring; this shift was especially marked in the 2-phenyl derivative.With the acids I-III, activation of fibrinolysis was assessed by the hanging clot method; the anti-inflammatory effect was assessed by inhibition of two experimental model inflammations.The regression equation relating fibrinolytic capacity to lipophilicity was a quadratic one, the logarithm of optimum lipophilicity being log Popt = 5.55.A qualitative assessment of the anti-inflammatory effect in relation to lipophilicity suggests that log Popt is probably higher than with arylaliphatic acids.These acids seem to have an active site different from that of the acids I-III.
- Kuchar, Miroslav,Brunova, Bohumila,Grimova, Jaroslava,Vanecek, Stanislav,Holubek, Jiri
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p. 2896 - 2908
(2007/10/02)
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- O-SILYLATED ENOLATES IN ORGANIC SYNTHESIS: SULPHUR-MEDIATED ALKYLATION OF ESTERS WITH ALKENES.
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O-Silylated ester enolates can be alkylated, under ZnBr2-catalysis, by the PhSCl-adducts of mono- and di-substituted alkenes to give γ-phenylthioesters, from which sulphur can be removed both reductively and oxidatively.This alkene carbosulphenylation rea
- Patel, Shailesh K.,Paterson, Ian
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p. 1315 - 1318
(2007/10/02)
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