- Traceless directing group for stereospecific nickel-catalyzed alkyl-alkyl cross-coupling reactions
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Stereospecific nickel-catalyzed cross-coupling reactions of benzylic 2-methoxyethyl ethers are reported for the preparation of enantioenriched 1,1-diarylethanes. The 2-methoxyethyl ether serves as a traceless directing group that accelerates cross-coupling. Chelation of magnesium ions is proposed to activate the benzylic C-O bond for oxidative addition.
- Greene, Margaret A.,Yonova, Ivelina M.,Williams, Florence J.,Jarvo, Elizabeth R.
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supporting information; experimental part
p. 4293 - 4296
(2012/09/22)
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- Tuning the reducing properties of 1,2-diaryl-1,2-disodiumethanes
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(Chemical Equation Presented) We investigated the reducing properties of a series of 1,2-diaryl-1,2-disodiumethanes by means of equilibration reactions. The electron-donor power of these vic-diorganometals is strongly affected by the nature of substituents present either on the aromatic ring(s) or on the carbanionic centers, and it can be correlated with their ability to delocalize the arylmethyl carbanions. These findings are supported by electrochemical analysis of the reduction behavior of the parent 1,2-diarylalkene. Applications of these results to the reduction of selected substrates are described. 2009 American Chemical Society.
- Azzena, Ugo,Pisano, Luisa,Antonello, Sabrina,Maran, Flavio
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supporting information; experimental part
p. 8064 - 8070
(2010/03/02)
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- Halogen-magnesium exchange on unprotected aromatic and heteroaromatic carboxylic acids
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The magnesiation of halogenated aromatic and heteroaromatic carboxylic acids is accomplished by their treatment with MeMgCl in the presence of LiCl and subsequent reaction with i-PrMgCl·LiCl; the resulting double-magnesiated species react with a variety of electrophiles in up to 97% yield. The Royal Society of Chemistry.
- Kopp, Felix,Wunderlich, Stefan,Knochel, Paul
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p. 2075 - 2077
(2008/02/09)
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- t-Bu-Amphos-RhCl3·3H2O: A highly recyclable catalyst system for the cross-coupling of aldehydes and aryl- and alkenylboronic acids in aqueous solvents
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The combination of t-Bu-Amphos and RhCl3·3H2O gave the first highly recyclable catalyst for the coupling of aryl- and vinylboronic acids with aldehydes in aqueous solvents. The Royal Society of Chemistry 2005.
- Huang, Rongcai,Shaughnessy, Kevin H.
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p. 4484 - 4486
(2007/10/03)
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- Method for producing Grignard compounds
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The invention relates to a process for preparing Grignard compounds of the formula I. The invention additionally relates to compounds of the formula I and to polymer-bound compounds of the formula Ia. The invention further relates to the use of the process for preparing substance libraries and to the use of the compounds of the formulae I and Ia in chemical synthesis.
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Page/Page column 13-14
(2008/06/13)
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- METHOD OF SUBSTITUENT INTRODUCTION THROUGH HALOGEN-METAL EXCHANGE REACTION
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A method of exchanging a halogen atom of a halide, which has a group containing an acidic proton and in which one or more halogen atom(s) is/are substituted on a carbon atom of the carbon-carbon double bond, with a metal atom by halogen-metal-exchange reaction and introducing an electrophilic reagent into the carbon atom to which the metal atom is attached. The above method is an industrially excellent method of introducing a substituent by halogen-metal exchange reaction.
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Page/Page column 19
(2010/02/10)
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- CATHEPSIN CYSTEINE PROTEASE INHIBITORS
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This invention relates to class of compounds which are cysteine protease inhibitors, including but not limited to, inhibitors of cathepsins K, L, S and B. These compounds are useful for treating diseases in which inhibition of bone resorption is indicated, such as osteoporosis. They have the following structure: Formula (I).
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- Non-cryogenic metalation of aryl bromides bearing proton donating groups: Formation of a stable magnesio-intermediate
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Bromine-metal exchange of o-bromobenzoic acid (1) with Bu2Mg followed by n-BuLi was successfully carried out at non-cryogenic temperature (>-20°C), and gave a stabilized metal species which smoothly reacted with several electrophiles. This methodology expanded to several other bromides bearing proton donating groups (PDGs).
- Kato, Shinji,Nonoyama, Nobuaki,Tomimoto, Koji,Mase, Toshiaki
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p. 7315 - 7317
(2007/10/03)
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- Synthesis of novel analogues of the delta opioid ligand SNC-80 using REM resin
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Focused libraries of delta opioid ligands were synthesised using REM resin methodology. Several high affinity compounds were identified with good selectivity over the g opioid receptor. Automated REM resin recycling was used to synthesise larger amounts o
- Cottney,Rankovic,Morphy
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p. 1323 - 1328
(2007/10/03)
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- Synthesis of novel analogues of the delta opioid ligand SNC-80 using AlCl3-promoted aminolysis
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Two focused libraries of delta opioid ligands were synthesised using AlCl3 facilitated aminolysis. Several compounds were identified with DOR binding affinities higher or similar to SNC-80. A novel acyclic derivative of SNC-80 produced antinoci
- Barn,Bom,Cottney,Caulfield,Morphy
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p. 1329 - 1334
(2007/10/03)
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- Preparation of highly functionalized Grignard reagents by an iodine-magnesium exchange reaction and its application in solid-phase synthesis
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At -40°C aryl iodides that contain other functional groups can be selectively converted into Grignard reagents, which react with electrophiles such as benzaldehyde in the usual manner [Eq. (a)]. Aryl bromides and iodides that are immobilized as esters on a Wang resin behave analogously.
- Boymond, Laure,Rottlaender, Mario,Cahiez, Gerard,Knochel, Paul
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p. 1701 - 1703
(2007/10/03)
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- The dimerization of radical anions of aromatic carboxylic acids competing with the self-protonation reaction
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Quantum-chemical calculations (CNDO/2) of the theoretical relationship between the rate constants for the dimerization and self-protonation of radical anions show that dimer formation in the one-electron electroreduction of aromatic carboxylic acids (benzoic (1), 1-naphthoic (2), and 9-anthroic (3)) is most probable for 1.It is established that during the constant potential electrolysis (CPE) of 1 a mixture of "head-to-tail" dimers is formed in the presence of 0.1 M Bu4NClO4 (DMF).Their ratio depends on the amount of electricity passed through the solution.The CPE of 2 in the presence of 20 percent H2O affords 1,4-dihydro-1-naphthoic acid in up to 70 percent yield.The high yield ( ca. 70 percent) of 9,10-dihydro-9-anthroic acid during the CPE of 3 can be accounted for the decomposition of the dimeric product followed by protonation of the anionic species. - Key words: dimerization, self-protonation, aromatic carboxylic acids, electroreduction, radical anions.
- Rubinskaya, T. Ya.,Mendkovich, A. S.,Lisitsina, N. K.,Yakovlev, I. P.,Gultyai, V. P.
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p. 1658 - 1661
(2007/10/02)
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- Lanthanoids in Organic Synthesis. I. The Novel Reduction of Carboxylic Acids with Samarium Diiodide-Base System
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Aromatic and aliphatic carboxylic acids were rapidly reduced with samarium diiodide by the addition of base in the presence of protic solvent at room temperature to the corresponding alcohols.Sodium benzoate was similarly reduced with samarium diiodide in the presence of H2O in a good yield.In the similar reactions of benzoic acid derivatives bearing carboxyl, formyl, carbamoyl, methoxyl, and chloro groups, these functional groups were also reduced to the corresponding alcohol or amine derivatives.Interestingly, the carboxyl and formyl groups of benzoic acids were partly reduced into the methyl group.
- Kamochi, Yasuko,Kudo, Tadahiro
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p. 3049 - 3054
(2007/10/02)
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- Regioselective Functionalization of Nonactivated CH-Bonds, 4. -Photoreactions of Amphiphilic Derivatives of Benzophenonecarboxylic Acid and Myristic Acid Derivatives in Micelles and Bilayers
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Amphiphilic derivatives of benzophenonecarboxylic acid and myristic acid in micelles, vesicles, and multilamellar aggregates were photochemically converted into tertiary alcohols, the workup of which yielded mixtures of the isomeric ketomyristic acid methyl esters 5.A slightly increased but none the less low selectivity was found in bilayers in comparison with micelles.Various amphiphilic head groups shifted the center of attack.Low total yields, especially in bilayers, can be attributed to a predominant reaction between the benzophenone substituents.By preparation of the corresponding reference compounds it could be demonstrated that benzhydrols (8a-d) or benzpinacols (9a-c) are not formed in this unexpected reaction.
- Gogoll, Adolf,Schaefer, Hans J.
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p. 597 - 606
(2007/10/02)
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- Quenching, Radical Formation, and Disproportionation in the Photoreduction of 4-Carboxybenzophenone by 4-Carboxybenzhydrol, Hydrazine, and Hydrazinium Ion
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Laser flash and steady irradiation studies have been carried out on the 4-carboxybenzophenone (CB) - 4-carboxybenzhydrol (CBH2) and CB - hydrazine systems over the pH range 5.8-12.In reaction with CBH2, CB triplet is quenched in part by the carboxylate, kq ca. 4 * 106 M-1 s-; total reaction, k4 = 3.0 * 107 M-1 s-1, leads to the ketyl radical CBH., φ = 1.7.Absorption spectra were recorded for CB triplet, λmax = 535 nm (ε = 6600 M-1 cm-1), for CBH., λmax = 570 nm (ε = 5500), and for the radical anion CB-., λmax = 660 (ε = 8100).The pKa of CBH. was determined, 8.2.Rate constants were determined: for combination of CBH. to pinacol, 2k6 = 1.8 * 109 M-1 s-1; for reactions of CBH. with CB-., k7 = 1.1 * 109 M-1 s-; for disproportionation of 2CB-., 2k8 = 9.8 * 106 M-1 s-.Factors to convert observed yields of photoreduction by hydrazine to yields of ketyl radical leading to pinacol and hydrol were determined from effects of pH on quantum yields of reduction of CB by CBH2.Reduction of CB triplet by neutral hydrazine occurs with kir = 6.8 * 108 M-1 s-1, forming ketyl radical with φ = 1.0, measured relative to the CBH2 reaction.The reaction with protonated hydrazine is slower, k'ir = 4.4 * 106 M-1 s-1.Computer simulation, using the measured rate constants, pKa and primary yields, and literature constants for pure hydrazine systems, leads to calculated reduction yields very similar to the observed values, with φketyl ca. 0.0 for reaction of triplet with protonated hydrazine, and ratios of rate constants for ketyl-hydrazyl disproportionations appropriately close to unity.
- Inbar, Shai,Linschitz, Henry,Cohen, Saul G.
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p. 7323 - 7328
(2007/10/02)
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