- Expeditious and practical synthesis of tertiary alcohols from esters enabled by highly polarized organometallic compounds under aerobic conditions in Deep Eutectic Solvents or bulk water
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An efficient protocol was developed for the synthesis of tertiary alcohols via nucleophilic addition of organometallic compounds of s-block elements (Grignard and organolithium reagents) to esters performed in the biodegradable choline chloride/urea eutectic mixture or in water. This approach displays a broad substrate scope, with the addition reaction proceeding quickly (20 s reaction time) and cleanly, at ambient temperature and under air, straightforwardly furnishing the expected tertiary alcohols in yields of up to 98%. The practicability of the method is exemplified by the sustainable synthesis of some representative S-trityl-L-cysteine derivatives, which are a potent class of Eg5 inhibitors, also via telescoped one-pot processes.
- Quivelli, Andrea F.,D'Addato, Giovanna,Vitale, Paola,García-álvarez, Joaquín,Perna, Filippo M.,Capriati, Vito
-
-
- Copper-Catalyzed Enantioselective Hydroalkoxylation of Alkenols for the Synthesis of Cyclic Ethers
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The copper-catalyzed enantioselective intramolecular hydroalkoxylation of unactivated alkenes for the synthesis of tetrahydrofurans, phthalans, isochromans, and morpholines from 4- and 5-alkenols is reported. The substrate scope is complementary to existing enantioselective alkene hydroalkoxylations and is broad with respect to substrate backbone and alkene substitution. The asymmetric induction and isotopic labeling studies support a polar/radical mechanism involving enantioselective oxycupration followed by C-[Cu] homolysis and hydrogen atom transfer. Synthesis of the antifungal insecticide furametpyr was accomplished.
- Chen, Dake,Berhane, Ilyas A.,Chemler, Sherry R.
-
supporting information
p. 7409 - 7414
(2020/06/29)
-
- Synergistic Relay Reactions To Achieve Redox-Neutral α-Alkylations of Olefinic Alcohols with Ruthenium(II) Catalysis
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Herein, we report a ruthenium-catalyzed redox-neutral α-alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone-type “carbanions” and active protons in a one-pot reaction, and at the same time achieves the first Grignard-type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols.
- Kan, Jian,Li, Chao-Jun,Li, Chen-Chen,Li, Jianbin,Lv, Leiyang,Qiu, Zihang
-
p. 4544 - 4549
(2020/02/04)
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- Reactivity and Product Analysis of a Pair of Cumyloxyl and tert-Butoxyl Radicals Generated in Photolysis of tert-Butyl Cumyl Peroxide
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Alkoxyl radicals play important roles in various fields of chemistry. Understanding their reactivity is essential to applying their chemistry for industrial and biological purposes. Hydrogen-atom transfer and C-C β-scission reactions have been reported from alkoxyl radicals. The ratios of these two processes were investigated using cumyloxyl (CumO?) and tert-butoxyl radicals (t-BuO?), respectively. However, the products generated from the pair of radicals have not been investigated in detail. In this study, CumO? and t-BuO? were simultaneously generated from the photolysis of tert-butyl cumyl peroxide to understand the chemical behavior of the pair of radicals by analyzing the products and their distribution. Electron paramagnetic resonance and/or transient absorption spectroscopy analyses of radicals, including CumO? and t-BuO?, provide more information about the radicals generated during the photolysis of tert-butyl cumyl peroxide. Furthermore, the photoproducts of (3-(tert-butylperoxy)pentane-3-yl)benzene demonstrated that the ether products were formed in in-cage reactions. The triplet-sensitized reaction induced by acetophenone, which is produced from CumO?, clarified that the spin state did not affect the product distribution.
- Oyama, Ryoko,Abe, Manabu
-
p. 8627 - 8638
(2020/07/21)
-
- Triphosgene and DMAP as Mild Reagents for Chemoselective Dehydration of Tertiary Alcohols
-
The utility of triphosgene and DMAP as mild reagents for chemoselective dehydration of tertiary alcohols is reported. Performed in dichloromethane at room temperature, this reaction is readily tolerated by a broad scope of substrates, yielding alkenes preferentially with the (E)-geometry. While formation of the Hofmann products is generally favored, a dramatic change in alkene selectivity toward the Zaitzev products is observed when the reaction is carried out in dichloroethane at reflux.
- Ganiu, Moshood O.,Cleveland, Alexander H.,Paul, Jarrod L.,Kartika, Rendy
-
supporting information
p. 5611 - 5615
(2019/08/01)
-
- One-pot sustainable synthesis of tertiary alcohols by combining ruthenium-catalysed isomerisation of allylic alcohols and chemoselective addition of polar organometallic reagents in deep eutectic solvents
-
Ru(iv)-Catalysed redox isomerisation of allylic alcohols has, for the first time, been successfully assembled with the chemoselective addition of organolithium or organomagnesium reagents to the in situ formed ketones, en route to tertiary alcohols, employing deep eutectic solvents as environmentally friendly reaction media. The overall transformation, which formally involves three consecutive and different steps such as (i) the reduction of a C-C double bond, (ii) the oxidation of a secondary carbinol moiety, and (iii) a chemoselective C-C bond formation, takes place in protic and biorenewable eutectic mixtures in a sequential one-pot fashion using a commercially and easily available catalytic system, with excellent conversions (up to 99% yield), at room temperature and under air in the last step, with no concomitant reduction or enolisation processes, and with high atom economy, in agreement with the principles of the so-called green chemistry.
- Cicco, Luciana,Rodríguez-álvarez, María J.,Perna, Filippo M.,García-álvarez, Joaquín,Capriati, Vito
-
p. 3069 - 3077
(2017/07/24)
-
- A Short Access to Symmetrically α,α-Disubstituted α-Amino Acids from Acyl Cyanohydrins
-
A straightforward synthesis of symmetrically α,α-disubstituted α-amino acids is presented. The key step of this process relies on the efficient double addition of Grignard reagents to acyl cyanohydrins to provide N-acyl amino alcohols selectively in good yields. The chemoselectivity of the reaction was modulated by the nature of the acyl moiety. Eleven amino acids were prepared, including the particularly simple divinylglycine, which is not easily accessible by using conventional methods.
- Boukattaya, Fatma,Caillé, Julien,Ammar, Houcine,Rouzier, Florian,Boeda, Fabien,Pearson-Long, Morwenna S. M.,Bertus, Philippe
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p. 906 - 916
(2016/03/12)
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- The Barbier-Grignard-Type Arylation of Ketones and Unexpected Cross-Coupling of Phenolic Ketones using Unactivated Aryl Bromides
-
A novel, highly versatile and efficient method has been developed for the Barbier-Grignard-type arylation of ketones and an unexpected cross-coupling of phenolic ketones was observed using unactivated bromides and magnesium in tetrahydrofuran/toluene at 96°C promoted by multicatalysts of cupric bromide (15 mol%), bismuth chloride (5 mol%) and silver bromide (10 mol%). The substituent and electronic effects on the reaction have been discussed. High yields of arylation and cross-coupling have been attained under mild conditions. A novel reasonable mechanism involving a quinone intermediate is proposed. The high chemical selectivity in the cross-coupling to the hydroxy group of phenolic ketones should help ketones find new applications.
- Wen, Yunming,Chen, Guifang,Huang, Shiqiang,Tang, Yu,Yang, Jun,Zhang, Yuanming
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p. 947 - 957
(2016/04/05)
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- Titanium-mediated addition of grignard reagents to acyl cyanohydrins: Aminocyclopropane versus 1,4-diketone formation
-
The 1,2-dianion reactivity of the reagent generated from EtMgBr and titanium isopropoxide was illustrated when N-acyl cyanohydrins were used as substrates (>20 examples), giving both aminocyclopropane derivatives and 1,4-dicarbonyl compounds. When the reaction was performed in diethyl ether, 5-hydroxy-1,4-diketones were the main product. Under specific conditions (use of tetrahydrofuran and a bulky carboxylic moiety), the cyclopropane derivatives were obtained in good yields. The observed dichotomy may be explained by a ring-opening of the five-membered titanacycle intermediate followed by a nonselective acyl addition. The 1,2-dianion reactivity of the reagent generated from EtMgBr and Ti(OiPr)4 was illustrated when N-acyl cyanohydrins were used as substrates (>20 examples). When the reaction was performed in diethyl ether, 1,4-diketones were mainly isolated. Under certain conditions, cyclopropane derivatives were also obtained in good yields. A mechanism rationalizing this dichotomy is presented. Copyright
- Setzer, Paul,Forcher, Gwenael,Boeda, Fabien,Pearson-Long, Morwenna S. M.,Bertus, Philippe
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p. 171 - 180
(2014/01/06)
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- Simple and convenient access to α,α,α-trisubstituted amides by double addition of Grignard reagents to acyl cyanohydrins
-
The double addition of Grignard (alkyl, aryl, alkenyl, alkynyl) reagents to acyl cyanohydrins was performed under unusually smooth conditions with a concomitant O-N acyl transfer, providing a very simple and general access to α,α,α-trisubstituted amides.
- Boukattaya, Fatma,Stanovych, Andrii,Setzer, Paul,Abid, Souhir,Ammar, Houcine,Pearson-Long, Morwenna S. M.,Bertus, Philippe
-
scheme or table
p. 8655 - 8657
(2012/10/08)
-
- Synthesis and pharmacological evaluation of 1-Alkyl-N-[(1R)-1-(4- fluorophenyl)-2-methylpropyl]piperidine-4-carboxamide derivatives as novel antihypertensive agents
-
We synthesized and evaluated inhibitory activity against T-type Ca 2+ channels for a series of 1-alkyl-N- [(1R)-1-(4-fluorophenyl)-2- methylpropyl]piperidine-4-carboxamide derivatives. Structure-activity relationship studies have revealed that the isopropyl substituent at the benzylic position plays an important role in exerting potent inhibitory activity, and the absolute configuration of the benzylic position was found to be opposite that of mibefradil, which was first launched as a new class of T-type Ca2+ channel blocker. Oral administration of N- [(1R)-1-(4-fluorophenyl)-2-methylpropyl]-1-[2-(3-methoxyphenyl)ethyl] piperidine-4-carboxamide (17f) lowered blood pressure in spontaneously hypertensive rats without inducing reflex tachycardia, an adverse effect often caused by traditional L-type Ca2+ channel blockers.
- Watanuki, Susumu,Matsuura, Keisuke,Tomura, Yuichi,Okada, Minoru,Okazaki, Toshio,Ohta, Mitsuaki,Tsukamoto, Shin-Ichi
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experimental part
p. 1376 - 1385
(2012/01/05)
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- Alternative method for alkylation of arylpolyhalomethanes with trialkylborane in the presence of magnesium
-
Reduction of benzal halide derivatives and α,α,α,-trichloromethylbenzene by magnesium powder in DMAc affords α-halocarbanions which then react with triethylborane to give alkylated products. After oxidation with H2O2-NaOH, secondary
- Condon, Sylvie,Nédélec, Jean-Yves
-
supporting information; experimental part
p. 32 - 35
(2010/09/18)
-
- Enantioselective nitroaldol reaction catalyzed by sterically modified salen-chromium complexes
-
A group of modified (salen)Cr(III)Cl complexes with bulky benzylic substituents in the 3,3'-position of the salicylidene moiety have been successfully applied for the asymmetric nitroaldol reaction. The readily accessible complex bearing 3-phenylpent-3-yl groups (2 mol %) leads to β-nitro alcohols in up to 92% yield and 94% ee.
- Kowalczyk, Rafal,Kwiatkowski, Piotr,Skarzewski, Jacek,Jurczak, Janusz
-
supporting information; experimental part
p. 753 - 756
(2009/06/28)
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- Organocatalytic peroxy-asymmetric allylic alkylation
-
The peroxy-asymmetric allylic alkylation of hydroperoxyalkanes with Morita-Baylis-Hillman carbonates was catalysed by modified cinchona alkaloids (up to 93% ee), from which chiral α-methylene-β-hydroxy esters could be efficiently derived.
- Feng, Xin,Yuan, Yu-Qing,Cui, Hai-Lei,Jiang, Kun,Chen, Ying-Chun
-
supporting information; experimental part
p. 3660 - 3662
(2009/10/23)
-
- Application of a 3,3-diphenylpentane skeleton as a multi-template for creation of HMG-CoA reductase inhibitors
-
Based on our hypothesis that the 3,3-diphenylpentane (DPP) skeleton is useful as a multi-template for creation of various biologically active compounds and acts as a steroid skeleton substitute, we designed and synthesized novel HMG-CoA reductase inhibitors with a DPP skeleton. Among them, sodium (E,3R,5S)-7-(2-(4-fluorophenyl)-4-(3-phenylpentan-3-yl)phenyl)-3,5-dihydroxy-hept-6-enoate showed potent HMG-CoA reductase-inhibitory activity comparable with that of clinically useful mevastatin.
- Hosoda, Shinnosuke,Matsuda, Daisuke,Tomoda, Hiroshi,Hashimoto, Mariko,Aoyama, Hiroshi,Hashimoto, Yuichi
-
scheme or table
p. 4228 - 4231
(2010/05/02)
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- DIPHENYLMETHANE DERIVATIVES AS INHIBITORS OF LEUKOTRIENE BIOSYNTHESIS
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The instant invention provides compounds of Formula I which are 5-lipoxygenase activating protein inhibitors. Compounds of Formula I are useful as anti-atherosclerotic, anti-asthmatic, anti-allergic, anti-inflammatory, and cytoprotective agents.
- -
-
Page/Page column 51
(2008/06/13)
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- The chemistry of alkylstrontium halide analogues, Part 2: Barbier-type dialkylation of esters with alkyl halides
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The chemistry of an alkylstrontium halide analogue was examined. In the presence of metallic strontium, the Barbier-type alkylation of esters with alkyl iodides proceeded smoothly at room temperature, under argon, to afford the corresponding dialkylated alcohols in good yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Miyoshi, Norikazu,Matsuo, Tsuyoshi,Wada, Makoto
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p. 4253 - 4255
(2007/10/03)
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- Highly alkyl-selective addition to ketones with magnesium ate complexes derived from Gignard reagents
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(Chemical Equation Presented) A highly efficient alkyl-selective addition to ketones with magnesium ate complexes derived from Grignard reagents and alkyllithiums is described. The nucleophilicity of R in R3MgLi is remarkably increased compared to that of the original RLi or RMgX, while the basicity of R3MgLi is decreased. Furthermore, a highly R-selective addition to ketones is demonstrated using RMe2MgLi in place of R 3MgLi.
- Hatano, Manabu,Matsumura, Tokihiko,Ishihara, Kazuaki
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p. 573 - 576
(2007/10/03)
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- A sterically modified (salen)chromium(III) complex - An efficient catalyst for high-pressure asymmetric allylation of aldehydes
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A novel (salen)chromium(III) catalyst with a modified salen ligand was synthesised in a simple way starting from readily available precursors. High-pressure allylation reaction of aromatic and aliphatic aldehydes with allyltributyltin upon application of
- Kwiatkowski, Piotr,Cha?adaj, Wojciech,Jurczak, Janusz
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p. 2301 - 2304
(2007/10/03)
-
- Generation of allylic and benzylic organolithium compounds by fluorine-lithium exchange: Reaction with electrophiles
-
The application of the naphthalene-catalysed lithiation methodology to allylic and benzylic fluorides 1 led to the corresponding allylic and benzylic organolithium reagents, which, in the presence of different electrophiles (Barbier-type reaction conditions), afforded the expected products 2 in moderate yields. The procedure was useful for the transformation of primary, secondary and tertiary benzylic fluorides into the corresponding lithium derivatives. When a two-step lithiation process was used (treatment of fluoride 1 with lithium and a catalytic amount of naphthalene, followed by addition of the electrophilic reagent), only Wurtz-type coupling products were formed.
- Guijarro, David,Yus, Miguel
-
-
- Reactions of Et3ZnLi with ketones: Electronic and steric effects
-
Toluene solutions of composition Et3ZnLi react rapidly with aldehydes and ketones to form addition products. Et3ZnNa and Et3ZnK solutions react readily with the same substrates although metalation, as well as addition, is significant with substrates having α-hydrogens. The Et3ZnM solutions react with 2-cyclohexenone to give mainly the 1,4-addition product. Relative rates of addition of Et3ZnLi to substituted acetophenones give a Hammett ρ of 2.78. Addition of Et3ZnLi to acetophenone is slowed significantly by α and ortho methyl substituents; relative rates of addition to acetophenone, o-methylacetophenone, and tert-butyl phenyl ketone are 1.00, 0.012, and 0.003.
- Musser,Richey Jr.
-
p. 7750 - 7756
(2007/10/03)
-
- Arene-catalysed lithiation of fluoroarenes
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The reaction of different fluoroarenes 1 with lithium and a catalytic amount (7%) of naphthalene in THF at -30°C affords the corresponding aryllithium intermediates which, by reaction with several electrophiles at temperatures ranging between -30 and 0°C, lead to the expected products 2, after hydrolysis. (C) 2000 Elsevier Science Ltd.
- Guijarro, David,Yus, Miguel
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p. 1135 - 1138
(2007/10/03)
-
- A Novel C-C Single-Bond Formation Accompanying C-O Bond Cleavage by Use of a Ketone, an Alkylating Reagent, and a Low-Valent Vanadium Complex in the Presence of a Catalytic Amount of Molecular Oxygen
-
A C-C single-bond-forming reaction from ketones with accompanying C-O bond cleavage mediated by a RMgBr or RLi-vanadium(II)-O2 system has been accomplished. Different from conventional reductive coupling reactions of ketones such as the McMurry coupling, the present method forms a C-C single (instead of a double) bond and yields a product that contains components derived from the ketone and the alkylating reagent in a one-pot reaction. Collaboration of both a low-valent vanadium(II) species and a higher-valent vanadium species produced from vanadium(II) and a catalytic amount of O2 effects the abstraction of the oxygen atom from a C-O bond.
- Kataoka, Yasutaka,Akiyama, Hiroaki,Makihira, Isamu,Tani, Kazuhide
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p. 8109 - 8113
(2007/10/03)
-
- 13C NMR spectroscopic comparison of sterically stabilized meta and para-substituted o-tolyldi(adamant-l-yl)methyl cations with conjugatively stabilized benzyl cations
-
A series of meta- and para-substituted anti-o-tolyldi(adamant-1-yl)methyl cations has been generated by reaction of anti-o-tolyldi(adamant-1-yl)methanols with trifluoroacetic acid in chloroform. 13C NMR spectroscopy indicates small but significant variations in the chemical shifts of the charged carbon and its nearest neighbours on the adamantyl groups, and departures from additivity of substituent effects on the shifts of the aromatic carbons. Previous work on the closely related di(adamant-1-yl)benzyl cations is discussed. Comparison with data on aryl-substituted carbocations in superacid media reveals marked differences in the aromatic carbon shifts in the two types of carbocation. The dihedral angle between aryl and carbocation planes in aryldi(adamant-1-yl)methyl cations is estimated to be about 60°.
- Lomas, John S.
-
p. 2601 - 2609
(2007/10/03)
-
- Chemoselective Preparation of Ketones by the Grignard Reaction of N-Acylpyrazoles
-
N-Acylpyrazoles afford chemoselectively the corresponding ketones in good yields by the use of equimolar amounts of Grignard reagent.In the case of an optically active N-acylpyrazole, optical asymmetry was retained in comparable optical yield.Ketone formation by the Grignard reactions can be regarded as an important functionalization in a synthetic loop using pyrazoles as the auxiliary compound.
- Kashima, Choji,Kita, Isanobu,Takahashi, Katsumi,Hosomi, Akira
-
-
- Direct Transformation of Trialkyl Phosphates into Organolithium Compounds by a DTBB-Catalysed Lithiation
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The reaction of different alkylic or phenylic phosphates 1 with an excess of lithium powder and a catalytic amount of DTBB (5 mol percent) in the presence of an electrophile -Barbier-type reaction conditions- in THF at -30 deg C leads to the formation of the expected products 2, resulting from the reaction of the in situ generated organolithium compound with the corresponding electrophile.
- Guijarro, David,Mancheno, Balbino,Yus, Miguel
-
p. 8551 - 8558
(2007/10/02)
-
- Organolithium reagents by reductive decyanation of nitriles with lithium and a catalytic amount of 4,4'-di-tert-butyl-biphenyl in a Barbier-type reaction
-
The reaction of different nitriles 1 with an excess of lithium powder (1:14 molar ratio) and a catalytic amount of 4,4'-di-tert-butylbiphenyl (5 mol %) in the presence of a carbonyl compound (Barbier-type conditions) in THF at low temperature (-30 or -78°C) leads to the corresponding compounds 2 resulting from the coupling between the electrophile and the organolithium intermediate arising from a reductive decyanation of the starting nitrile 1. This new reaction can be also applied to the use of trimethylchlorosilane as electrophile at 0°C.
- Guijarro,Yus
-
p. 3447 - 3452
(2007/10/02)
-
- Diorganomagnesium Compounds from Magnesium, Hydrogen, and 1-Alkenes and Their Application in Synthesis
-
1-Alkenes are converted in high yields to the corresponding primary diorganomagnesium compounds by transition metal-catalyzed hydromagnesation reaction using catalytically prepared suspended (MgH2*) or dissolved magnesium hydride (MgH2').The most active hydromagnesation catalysts have been found to be combinations of zirconium tetrahalides with MgH2* or MgH2'.The reaction is highly regio- and chemoselective.The diorganomagnesium compounds prepared in situ from magnesium, hydrogen, and 1-alkenes can be applied to the synthesis of organic and organometallic compounds just as Grignard compounds (Scheme 3, reactions 3-11).Dioctylmagnesium undergoes the growth reaction with ethene in the presence of quinuclidine and is oxidized by molecular oxygen in high yield to 1-octanol. Key Words: Magnesium hydride, catalytically prepared / Hydromagnesation reactions / Magnesium, diorgano compounds, preparation from magnesium, hydrogen and 1-alkenes / Magnesium, diorgano compounds, application in syntheses / Magnesium, diorgano compounds, oxidation of
- Bogdanovic, Borislav,Bons, Peter,Konstantinovic, Stanimir,Schwickardi, Manfred,Westeppe, Uwe
-
p. 1371 - 1384
(2007/10/02)
-
- Synthesis and Anticonvulsant Activity of 1-Phenylcyclohexylamine Analogues
-
Thirty-eight analogues of 1-phenylcyclohexylamine (PCA), a phencyclidine (PCP) derivative, were examined for their activities in the mouse maximal electroshock (MES) seizure test and in a motor-toxicity assay.In addition, we determined the binding affinities of the compounds for PCP acceptor sites in rat brain membranes labeled with -1-piperidine.Many of the analogues were protective against MES seizures (ED50s of 4-41 mg/kg, ip) and all of these compounds caused motor toxicity.The potencies in the motor toxicity and MES seizure tests showed a moderate correlation with the affinities for PCP sites.Several analogues exhibited a greater separation of potencies in the motor toxicity and MES seizure tests than did the parent compound PCA.These were obtained by (i) 3-methylation of the cyclohexyl ring trans to the phenyl ring, (ii) methoxylation at the ortho position on the phenyl ring, and (iii) contraction of the cyclohexane ring to form the corresponding cyclopentane.
- Thurkauf, Andrew,Costa, Brian de,Yamaguchi, Shun-ichi,Mattson, Mariena V.,Jacobson, Arthur E.,et al.
-
p. 1452 - 1458
(2007/10/02)
-
- Transition-State Polarization in Cleavage of C-C Bonds in Radical Anions
-
The substituent effect on the rate of C-C bond cleavage in radical anions of 1-(4-nitrophenyl)-2-(substituted-phenyl)-1,1,2,2-tetraethylethanes has been explored.The data provide evidence for two distinctive modes of bond scission.One mode is characterized by a significant negative charge transfer across the scissile bond in the transition state.Such polarization of the transition state is in contradiction to the prediction based on the fragments' stability.The second mode, dominant in cases where the charge shift leads to negative charge accumulation on an already electron-rich fragment, involves a ?* radical anion.Both modes point to a general kinetic preference for a cleavage of radical anions that allows for charge delocalization across the scissile bond.
- Maslak, Przemyslaw,Narvaez, Javier N.,Kula, Jozef,Malinski, David S.
-
p. 4550 - 4559
(2007/10/02)
-
- GRIGNARD REAGENTS AS POWDERS : PREPARATION AND REACTIVITY
-
The TDA-1 chelating agent is able to complex Grignard reagents.This complexation leads to powders.The preparation is general and the complexes "RMgX/TDA-1" are easily prepared from every type of Grignard reagents.These solids are stable under nitrogen and can be titrated and used as Grignard reagents.The study of their chemical reactivity shows a behaviour comparable to that of conventional Grignard reagents, the rate of reactions however being decreased.Selective addition onto a mixture of aldehyde and ketone is possible.Interestingly the reactions can be performed in hydrocarbon solvents (toluene, light petroleum, cyclohexane).
- Boudin, Alain,Cerveau, Genevieve,Chuit, Claude,Corriu, Robert J.P.,Reye, Catherine
-
p. 171 - 180
(2007/10/02)
-
- Collision-induced Dissociations of Substituted Benzyl Negative Ions in the Gas Phase. The Elimination of C4H4
-
The major collision-induced dissociation of PhEt2 involve the losses of H, H2, and CH4.Loss of H occurs from the phenyl ring, H2 is eliminated principally by the process while methane is lost by the stepwise process in which t
- Currie, Graeme J.,Bowie, John H.,Massy-Westropp, Ralph A.,Adams, Gregory W.
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p. 403 - 408
(2007/10/02)
-
- Studies on the Regioselectivities in the Oxidation of Simple Alkyl Aromatic Hydrocarbons by Molecular Oxygen
-
The products of the autoxidation of various simple alkyl aromatic hydrocarbons were reduced by LiAlH4, and the alcohols formed were determined by gas chromatography.In the cases of 2-phenylbutane, 3-phenylpentane, and 2-p-tolylbutane a considerable fragmentation of the intermediate tertiary alkoxy radicals was proved.On the basis of the analytical results relative reaction rates of the various C-H bonds in the hydrocarbons studied were calculated.It is shown that the attack at C-H bonds which are not activated by the aromatic nucleus cannot be neglected and may be of great importance for the kinetics of the oxidation of alkyl aromatic hydrocarbons.
- Pritzkow, Wilhelm,Thomas, Gerda,Willecke, Lothar
-
p. 847 - 851
(2007/10/02)
-
- Determination of Relative Autoxidation Rates of Simple Alkylaromatic Hydrocarbons by Competitive Reactions
-
Relative rates of oxidative attack at the C-H bonds in α-position to the aromatic nucleus were determined for 10 simple alkylaromatic hydrocarbons.The results obtained by competitive oxidations of binary mixtures were shown to be consistent.From these results and the regioselectivity data already published, relative reactivities referring to the tertiary C-H bond of cumene were calculated for all C-H bonds of the hydrocarbons studied.As expected, p-alkyl groups increase the reactivity of C-H bonds in α-position to the aromatic nucleus.On the other hand, large alky l groups, bound to the α-C atoms, decrease the reactivity of the α-C-H bonds.
- Pritzkow, Wilhelm,Thomas, Gerda,Willecke, Lothar
-
p. 945 - 952
(2007/10/02)
-
- CARBONYLATIVE CROSS-COUPLING REACTION OF ARYL IODIDES WITH ALKYLALUMINUMS BY PALLADIUM COMPLEX CATALYSIS
-
Secondary and/or tertiary alcohols and unsymmetrical ketones have been obtained in moderate to good yields by palladium-catalyzed (5 molpercent) carbonylative coupling of aryl iodides with alkylaluminum compounds under very mild conditions (20-50 deg C, 1 atm of carbon monoxide).The type of th reaction product depended on the aluminum reagent employed.While the selective formation of secondary alcohols was observed in the reaction with i-Bu3Al, the use of Et3Al led to a mixture of a ketone and two alcoholic products.With Et2AlCl predominantly unsymmetrical ketones were produced.In all cases, formation of directly cross-coupled products was not observed.DME and benzene can be used as solvents, but THF is unsuitable.Nickel catalysts were found to be ineffective for this reaction.
- Wakita, Yoshiaki,Yasunaga, Tomoyuki,Kojima, Masaharu
-
p. 261 - 268
(2007/10/02)
-
- REACTIONS OF BENZENE VAPOR-CALCIUM ATOM WITH ORGANIC HALIDES AND CARBONYL COMPOUNDS
-
Reactions of benzene vapor-calcium atom with organic halides and carbonyl compounds were examined.Benzene vapor-calcium atom reacted with organic halides (RX) to give phenyl-substituted products (PhR) and reduced products (RH).The reactions of benzene vapor-calcium atom with ketones (RR'CO) or benzaldehyde gave two kinds of alcohol PhRR'COH and RR'CHOH, or Ph2CHOH and PhCH2OH, respectively
- Mochida, Kunio,Takeuchi, Hidenori,Hiraga, Yoo,Ogawa, Hiroyasu
-
p. 1989 - 1992
(2007/10/02)
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- Thermolabile Hydrocarbons, XX. Synthesis, Structure, and Strain of Sym. Tetraalkyl-1,2-diarylethanes
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The syntheses of 18 1,1,2,2-tetraalkyl-1,2-diarylethanes 1 - 4 by dimerisation procedures starting with 10 - 13 are reported.In the absence of p-substituents X and with increasing alkyl side chains the α,p-dimers 6 or their aromatic counter parts 7 are obtained besides or instead of 1.The relationships between strain enthalpy Hs, bond lengths, bond angles, torsional angles, and rotational barrier are discussed on the basis of force field calculations.They are supported by two additional experimental structure determinations by X-ray diffraction.
- Kratt, Guenter,Beckhaus, Hans-Dieter,Lindner, Hans Joerg,Ruechardt, Christoph
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p. 3235 - 3263
(2007/10/02)
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- COMPLEXES OF TRANSITION METALS IN THE CHEMISTRY OF CONJUGATED SYSTEMS. I. CATALYTIC ADDITION OF ORGANOMAGNESIUM AND ORGANOLITHIUM COMPOUNDS TO ENYNES AND THEIR DERIVATIVES
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Hydrocarbons with a conjugated system of double and triple bonds are capable of catalytic addition of arylmagnesium halides and aryllithiums at the triple bond in the presence of the salts and complexes of transition metals of group VIII.The β-diketonate complexes of Ni(II) and Fe(III) have the greatest activity.In the case of aryllithiums uncatalyzed addition reactions occur as well.Under the same conditions aliphatic Grignard reagents and alkyllithiums give a complex mixture of addition, reduction and oligomerizatin products.The direction of addition is determined solely by the character of substitution in the enyne system.The product yields are also determined by the nature of the metal and of the ligands in the catalyst and by the character of the organomagnesium and organolithium compound.The effect of polar and steric factors of the substituents at the triple bond in the alkyl, aryl, and trialkylsilyl series leads to a change in the direction of coordination and to the formation of the products from addition at the double bond.
- Zubritskii, L. M.,Fomina, T. N.,Bal'yan, Kh. V.
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