- NOVEL METHOD FOR OXIDATION OF SECONDARY ALCOHOLS INTO KETONES WITH MOLECULAR OXIGEN BY USING COBALT(II) COMPLEX CATALYST
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The oxidation of secondary alcohols into the corresponding ketones using a catalytic amount of cobalt(II) complex under an oxygen atmosphere is described.The effect of additives shows that Molecular Sieves is effective to improve the yield of ketones.
- Yamada, Tohru,Mukaiyama, Teruaki
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- Sulfonium ion-promoted traceless Schmidt reaction of alkyl azides
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Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction through 1,2-migration of C-H and C-C bonds was accessible to the one-pot substitution reaction.
- Ardiansah, Bayu,Kakiuchi, Kiyomi,Morimoto, Tsumoru,Tanimoto, Hiroki,Tomohiro, Takenori
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p. 8738 - 8741
(2021/09/08)
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- Chemoselective reduction of ?,￠-unsaturated carbonyl and carboxylic compounds by hydrogen iodide
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The selective reduction of ?,￠-unsaturated carbonyl compounds was achieved to produce saturated carbonyl compounds with aqueous HI solution. The introduction of an aryl group at an ? or ￠ position efficiently facilitated the reduction with good yield. The reaction was applicable to compounds bearing carboxylic acids and halogen atoms. Through the investigation of the reaction mechanism, it was found that Michael-type addition of iodide occurred to produce ￠-iodo compounds followed by the reduction of C-I bond via anionic and radical paths.
- Matsumoto, Shoji,Marumoto, Hayato,Akazome, Motohiro,Otani, Yasuhiko,Kaiho, Tatsuo
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p. 590 - 599
(2021/03/29)
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- Scope and Mechanism of the Redox-Active 1,2-Benzoquinone Enabled Ruthenium-Catalyzed Deaminative α-Alkylation of Ketones with Amines
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The catalytic system formed in situ from the reaction of a cationic Ru-H complex with 3,4,5,6-tetrachloro-1,2-benzoquinone was found to mediate a regioselective deaminative coupling reaction of ketones with amines to form the α-alkylated ketone products. Both benzylic and aliphatic primary amines were found to be suitable substrates for the coupling reaction with ketones in forming the α-alkylated ketone products. The coupling reaction of PhCOCD3 with 4-methoxybenzylamine showed an extensive H/D exchange on both α-CH2 (41% D) and β-CH2 (21%) positions on the alkylation product. The Hammett plot obtained from the reaction of acetophenone with para-substituted benzylamines p-X-C6H4CH2NH2 (X = OMe, Me, H, F, Cl, CF3) showed a strong promotional effect by the amine substrates with electron-releasing groups (ρ = -0.49 ± 0.1). The most significant carbon isotope effect was observed on the α-carbon of the alkylation product (Cα = 1.020) from the coupling reaction of acetophenone with 4-methoxybenzylamine. The kinetics of the alkylation reaction from an isolated imine substrate led to the empirical rate law: rate = k[Ru][imine]. A catalytically active Ru-catecholate complex was synthesized from the reaction of the cationic Ru-H complex with 3,5-di-tert-butyl-1,2-benzoquinone and PCy3. The DFT computational study was performed on the alkylation reaction, which revealed a stepwise mechanism of the [1,3]-carbon migration step via the formation of a Ru(IV)-alkyl species with a moderate energy of activation (ΔG? = 32-42 kcal/mol). A plausible mechanism of the catalytic alkylation reaction via an intramolecular [1,3]-alkyl migration of an Ru-enamine intermediate has been compiled on the basis of these experimental and computational data.
- Kirinde Arachchige, Pandula T.,Handunneththige, Suhashini,Talipov, Marat R.,Kalutharage, Nishantha,Yi, Chae S.
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p. 13962 - 13972
(2021/11/20)
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- Cobalt-Catalyzed Asymmetric 1,4-Reduction of β,β-Dialkyl α,β-Unsaturated Esters with PMHS
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A cobalt-catalyzed asymmetric reduction of β,β-dialkyl α,β-unsaturated esters with polymethylhydrosiloxane (PMHS) was reported to deliver the corresponding esters containing a chiral trialkyl carbon center at β-position with up to 97 % yield and 98 % ee. The chiral tridentate ligand oxazoline iminopyridine (OIP) could perform well for the asymmetric reduction instead of chiral bidentate ligands. This operationally simple protocol shows a broad scope of substrates using one equivalent of readily available PMHS as a cheap and easy-to-handle reductive reagent.
- Lu, Dongpo,Lu, Peng,Lu, Zhan
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supporting information
p. 4861 - 4864
(2021/09/22)
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- Visible-Light-Promoted Catalytic Ring-Opening Isomerization of 1,2-Disubstituted Cyclopropanols to Linear Ketones
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Isomerization to linear ketones is a valuable transformation of 1,2-disubstituted cyclopropanols proceeding through radical intermediates. Despite simplicity of this reaction, the known protocol required stoichiometric amounts of both an oxidant and a reducing agent. In this article, we report a catalytic isomerization of 1,2-disubstituted cyclopropanols to linear ketones enabled by the photoredox catalytic system consisting of an acridinium photocatalyst and diphenyl disulfide under irradiation with blue LEDs.
- Laktsevich-Iskryk, Marharyta V.,Varabyeva, Nastassia A.,Kazlova, Volha V.,Zhabinskii, Vladimir N.,Khripach, Vladimir A.,Hurski, Alaksiej L.
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p. 2431 - 2434
(2020/04/20)
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- Ligand-Controlled Regiodivergent Silylation of Allylic Alcohols by Ni/Cu Catalysis for the Synthesis of Functionalized Allylsilanes
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The first Ni/Cu-catalyzed regiodivergent synthesis of allylsilanes directly from allylic alcohols through modulating the steric and electronic properties of the ligands on the nickel catalyst has been developed. Good yields and excellent selectivity were obtained regardless of whether linear or α-branched allylic alcohols were utilized. Mechanistic studies indicate that an allyloxyboronate species is formed during the reaction, which likely serves as an activated intermediate toward the oxidative addition of the C(allyl)-O bond.
- Gan, Yi,Xu, Wei,Liu, Yuanhong
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supporting information
p. 9652 - 9657
(2019/11/28)
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- Isomerization of Allylic Alcohols to Ketones Catalyzed by Well-Defined Iron PNP Pincer Catalysts
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[Fe(PNP)(CO)HCl] (PNP=di-(2-diisopropylphosphanyl-ethyl)amine), activated in situ with KOtBu, is a highly active catalyst for the isomerization of allylic alcohols to ketones without an external hydrogen supply. High reaction rates were obtained at 80 °C, but the catalyst is also sufficiently active at room temperature with most substrates. The reaction follows a self-hydrogen-borrowing mechanism, as verified by DFT calculations. An alternative isomerization through alkene insertion and β-hydride elimination could be excluded on the basis of a much higher barrier. In alcoholic solvents, the ketone product is further reduced to the saturated alcohol.
- Xia, Tian,Wei, Zhihong,Spiegelberg, Brian,Jiao, Haijun,Hinze, Sandra,de Vries, Johannes G.
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supporting information
p. 4043 - 4049
(2018/01/27)
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- Two efficient pathways for the synthesis of aryl ketones catalyzed by phosphorus-free palladium catalysts
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Allylic alcohols, 1-buten-3-ol, 1-penten-3-ol and 1-octen-3-ol, reacted with aryl iodides (iodotoluene, 4-iodotoluene, 4-iodophenol and 4-iodanisole) under Heck reaction conditions to form corresponding saturated aryl ketones in one step. The same products were obtained in a two-step tandem reaction consisted of the Heck coupling of allylic alcohols with aryl iodides, followed by hydrogenation. Reactions were catalyzed by phosphorus-free palladium precursors modified with the menthol-substituted imidazolium chlorides. Formation of crystalline palladium nanoparticles, of the diameter up to 65 nm, in the reaction mixture was evidenced by TEM.
- Wirwis,Feder-Kubis,Trzeciak
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- Palladium-catalyzed room temperature acylative cross-coupling of activated amides with trialkylboranes
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A highly efficient acylative cross-coupling of trialkylboranes with activated amides has been effected at room temperature to give the corresponding alkyl ketones in good to excellent yields by using 1,3-bis(2,6-diisopropyl)phenylimidazolylidene and 3-chloropyridine co-supported palladium chloride, the PEPPSI catalyst, in the presence of K2CO3 in methyl tert-butyl ether. The scope and limitations of the protocol were investigated, showing good tolerance of acyl, cyano, and ester functional groups in the amide counterpart while halo group competed via the classical Suzuki coupling. The trialkylboranes generated in situ by hydroboration of olefins with BH3 or 9-BBN performed similarly to those separately prepared, making this protocol more practical.
- Shi, Weijia,Zou, Gang
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- Selective Synthesis of Unsymmetrical Aliphatic Acyloins through Oxidation of Iridium Enolates
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The first method to access unsymmetrical aliphatic acyloins is presented. The method relies on a fast 1,3-hydride shift mediated by an IrIII complex in allylic alcohols followed by oxidation with TEMPO+. The direct conversion of allylic alcohols into acyloins is achieved in a one-pot procedure. Further functionalization of the Cα′ of the α-amino-oxylated ketone products gives access to highly functionalized unsymmetrical aliphatic ketones, which further highlights the utility of this transformation.
- Sanz-Marco, Amparo,Martinez-Erro, Samuel,Martín-Matute, Belén
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p. 11564 - 11567
(2018/07/31)
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- Chelation-Assisted C-H and C-C Bond Activation of Allylic Alcohols by a Rh(I) Catalyst under Microwave Irradiation
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Chelation-assisted Rh(I)-catalyzed ketone synthesis from allylic alcohols and alkenes through C-H and C-C bond activations under microwave irradiation was developed. Aldimine is formed via olefin isomerization of allyl alcohol under Rh(I) catalysis and condensation with 2-amino-3-picoline, followed by continuous C-H and C-C bond activations to produce a dialkyl ketone. The addition of piperidine accelerates the reaction rate by promoting aldimine formation under microwave conditions.
- Lee, Chang-Hee,Jun, Chul-Ho
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p. 736 - 741
(2017/11/27)
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- Dinuclear Pathways for the Activation of Strained Three-Membered Rings
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Dinuclear, strain-induced ring-opening reactions of vinylaziridines and vinylcyclopropanes are described. The previously reported [NDI]Ni2(C6H6) complex (NDI = naphthyridine-diimine) reacts with N-tosyl-2-vinylaziridine via C-N oxidative addition to generate a dinickel metallacyclic product. On the basis of this stoichiometric reactivity, the [NDI]Ni2(C6H6) complex is shown to be a highly active catalyst for the rearrangement of vinylcyclopropane to cyclopentene. Notably, 2-phenyl-1-vinylcyclopropane undergoes regioselective activation at the less hindered C-C bond in contrast to the noncatalytic thermal rearrangement. DFT calculations provide insight into the ability of the Ni-Ni bond to stabilize key intermediates and transition states along the catalytic pathway.
- Rounds, Heather R.,Zeller, Matthias,Uyeda, Christopher
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p. 545 - 550
(2018/03/08)
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- General, Simple, and Chemoselective Catalysts for the Isomerization of Allylic Alcohols: The Importance of the Halide Ligand
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Remarkably simple IrIIIcatalysts enable the isomerization of primary and sec-allylic alcohols under very mild reaction conditions. X-ray absorption spectroscopy (XAS) and mass spectrometry (MS) studies indicate that the catalysts, with the general formula [Cp*IrIII], require a halide ligand for catalytic activity, but no additives or additional ligands are needed.
- Erbing, Elis,Vázquez-Romero, Ana,Bermejo Gómez, Antonio,Platero-Prats, Ana E.,Carson, Fabian,Zou, Xiaodong,Tolstoy, P?ivi,Martín-Matute, Belén
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supporting information
p. 15659 - 15663
(2016/10/25)
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- Mild N-deacylation of secondary amides by alkylation with organocerium reagents
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Secondary amides are a class of highly stable compounds serving as versatile starting materials, intermediates and directing groups (amido groups) in organic synthesis. The direct deacylation of secondary amides to release amines is an important transformation in organic synthesis. Here, we report a protocol for the deacylation of secondary amides and isolation of amines. The method is based on the activation of amides with Tf2O, followed by addition of organocerium reagents, and acidic work-up. The reaction proceeded under mild conditions and afforded the corresponding amines, isolated as their hydrochloride salts, in good yields. In combination with the C-H activation functionalization methodology, the method is applicable to the functionalization of aniline as well as conversion of carboxylic derivatives to functionalized ketones.
- Wang, Ai-E.,Chang, Zong,Liu, Yong-Peng,Huang, Pei-Qiang
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supporting information
p. 1055 - 1058
(2015/09/01)
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- Michael Addition of Soft Carbon Nucleophiles to Alkylidene Isoxazol-5-ones: A Divergent Entry to β-Branched Carbonyl Compounds
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A novel, divergent strategy toward the synthesis of β-branched (and linear) carbonyl compounds is developed by taking advantage of alkylidene isoxazol-5-ones as key building blocks. The yields obtained range from good to excellent, therefore making the described methods attractive options for building such molecules. (Chemical Equation).
- Capreti, Naylil M. R.,Jurberg, Igor D.
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supporting information
p. 2490 - 2493
(2015/05/27)
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- A general method for the direct transformation of common tertiary amides into ketones and amines by addition of Grignard reagents
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The direct transformation of amides into ketones by addition of organometallic reagents has attracted the attention of organic chemists for a long time. However limited methods are reliable for common amides and have found synthetic applications. Here we report a method featuring in situ activation of tertiary amides with triflic anhydride (Tf2O) followed by addition of Grignard reagents. The method displays a good generality in scope for both amides and Grignard reagents, and it can be viewed as the acylation of Grignard reagents using amides as stable and selective acylating agents. Moreover, this deaminative alkylation reaction provides a mild method for the N-Deacylation of amides to give free amines.
- Huang, Pei-Qiang,Wang, Yu,Xiao, Kai-Jiong,Huang, Ying-Hong
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p. 4248 - 4254
(2015/06/02)
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- DMF as carbon source: Rh-catalyzed α-methylation of ketones
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An unprecedented Rh-catalyzed direct methylation of ketones with N,N-dimethylformamide (DMF) is disclosed. The reaction shows a broad substrate scope, tolerating both aryl and alkyl ketones with various substituents. Mechanistic studies suggest that DMF delivers a methylene fragment followed by a hydride in the methylation process.
- Li, Yang,Xue, Dong,Lu, Wei,Wang, Chao,Liu, Zhao-Tie,Xiao, Jianliang
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supporting information
p. 66 - 69
(2014/01/23)
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- Deaminative and decarboxylative catalytic alkylation of amino acids with ketones
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It cuts two ways: The cationic [Ru-H] complex catalyzes selective coupling of α- and β-amino acids with ketones to form α-alkylated ketone products. The reaction involves C-C and C-N bond cleavage which result in regio- and stereoselective alkylation using amino acids. A broad substrate scope and high functional-group tolerance is demonstrated. Copyright
- Kalutharage, Nishantha,Yi, Chae S.
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supporting information
p. 13651 - 13655
(2014/01/06)
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- Palladium-Based Nanocatalyst for One-Pot Synthesis of Polysubstituted Quinolines
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The synthesis of quinolines has been achieved through a one-pot, two-step tandem reaction catalyzed with Ag-Pd alloy nanoparticles supported on carbon. Ag-Pd alloy nanoparticles catalyzed the coupling of a ketone with a primary alcohol through a hydrogen autotransfer process, which yields α-alkylated ketones under an Ar flow. These are reacted with 2-aminobenzyl alcohols in a modified Friedlaender synthesis to give polysubstituted quinolines in moderate to good yields.
- Chen, Benjamin Wei Jie,Chng, Leng Leng,Yang, Jun,Wei, Yifeng,Yang, Jinhua,Ying, Jackie Y.
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p. 277 - 283
(2013/03/13)
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- 2-catalyzed conjugate addition of arylboronic acids to α,β-unsaturated ketones under ligand-free and neutral conditions
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A simple and efficient Ru-catalyzed conjugate addition reaction of arylboronic acids to α,β-unsaturated ketones under neutral conditions without any additional ligands has been developed. This Ru(II)-catalytic system both fulfilled the inhibition of the β-hydride elimination in the catalytic cycle and minimized the protonolysis of arylboronic acids.
- Zhang, Lei,Xie, Xiaomin,Fu, Lei,Zhang, Zhaoguo
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p. 3434 - 3437
(2013/06/26)
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- New Pd(II) binuclear complexes as effective catalysts in oxidative-heck reaction using arylboronic acid derivatives
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A series of new binuclear Pd(II) complexes based on chelating diimines and bridging diphosphine or diimine ligands have been synthesized and characterized successfully. The formula of the new complexes are [Pd2(mbyp) 2(DPA)2](PF6)4 (1), [Pd 2(mbyp)2(DPE)2] (PF6)4 (2), [Pd2(mbyp)2(4,4-byp)2] (PF 6)4 (3), [Pd2(mbyp)2(t-pye) 2] (PF6)4 (4) [mbyp= 4,4-dimethyl-2,2- bipyridine, DPA= 1,2-bis(diphenylphosphino)acetylene, DPE= 1,2- bis(diphenylphosphino)ethylene, 4,4-byp= 4,4-bipyridine, and t-ype= trans 1,2-bis(4-pyridyl)ethylene)]. The catalytic activities of the new complexes have been investigated in the coupling of arylboronic acid derivatives to various olefins. Results obtained showed interesting catalytic activities and chemoselectivities for the new complexes in the coupling reactions to produce the conjugate addition and heck coupling products under free base or oxidant conditions.
- Suleiman, Rami,Shakil Hussain,Fettouhi, Mohammed,El Ali, Bassam
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scheme or table
p. 850 - 856
(2012/09/22)
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- Chemoselective synthesis of ketones and ketimines by addition of organometallic reagents to secondary amides
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The development of efficient and selective transformations is crucial in synthetic chemistry as it opens new possibilities in the total synthesis of complex molecules. Applying such reactions to the synthesis of ketones is of great importance, as this motif serves as a synthetic handle for the elaboration of numerous organic functionalities. In this context, we report a general and chemoselective method based on an activation/addition sequence on secondary amides allowing the controlled isolation of structurally diverse ketones and ketimines. The generation of a highly electrophilic imidoyl triflate intermediate was found to be pivotal in the observed exceptional functional group tolerance, allowing the facile addition of readily available Grignard and diorganozinc reagents to amides, and avoiding commonly observed over-addition or reduction side reactions. The methodology has been applied to the formal synthesis of analogues of the antineoplastic agent Bexarotene and to the rapid and efficient synthesis of unsymmetrical diketones in a one-pot procedure. Macmillan Publishers Limited. All rights reserved.
- Bechara, William S.,Pelletier, Guillaume,Charette, Andre B.
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experimental part
p. 228 - 234
(2012/06/01)
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- C-X (X=Br, I) bond-tolerant aerobic oxidative cross-coupling: A strategy to selectively construct β-aryl ketones and aldehydes
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Using moelcular oxygen as the terminal oxidant, various aryl halide-containing β-aryl ketones and aldehydes can be synthesized directly from readily available allyic alcohols and boronic acids via palladium-catalyzed oxidative cross-coupling reactions. The dual roles of copper, including electron-carrier and Lewis acid functions, are supposed to be critical for the high reactivity and selectivity of this aerobic oxidative coupling transformation. Copyright
- Chen, Mao,Wang, Jie,Chai, Ziyi,You, Cai,Lei, Aiwen
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supporting information; scheme or table
p. 341 - 346
(2012/05/04)
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- Rhodium-catalyzed asymmetric 1,4-addition of sodium tetraarylborates to β,β-disubstituted α,β-unsaturated esters
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A rhodium-catalyzed 1,4-addition of sodium tetraarylborates to β,β-disubstituted α,β-unsaturated esters has been developed. Highly efficient asymmetric catalysis has also been described to create quaternary carbon stereocenters at the β-position of esters by tuning the ester group of substrates and employing a readily available chiral diene ligand.
- Shintani, Ryo,Hayashi, Tamio
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supporting information; experimental part
p. 350 - 352
(2011/03/22)
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- Chemoselective conjugate reduction of α,β-unsaturated ketones catalyzed by rhodium amido complexes in aqueous media
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Although a notable feature of Noyori's Ru-TsDPEN complex is that the transfer hydrogenation reaction is highly chemoselective for the C-O functional group and tolerant of alkenes, our early report indicated that the chemoselectivity could be switched from C-O to C-C bonds in the transfer hydrogenation of activated α,β-unsaturated ketones. Now we have found that a variety of α,β-unsaturated ketones, even without other electron-withdrawing functional groups, could be reduced on the alkenic double bonds with high selectivities employing amido-rhodium hydride complex in aqueous media, and up to 100% chemoselectivity has been achieved. It is notable that the chemoselectivity was improved significantly on going from organic solvent to water. Moreover, a 1,4-addition mechanism has been proposed on the basis of the corresponding experimental details and computational analysis.
- Li, Xuefeng,Li, Liangchun,Tang, Yuanfu,Zhong, Ling,Cun, Linfeng,Zhu, Jin,Liao, Jian,Deng, Jingen
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supporting information; experimental part
p. 2981 - 2988
(2010/07/05)
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- Regioselective tandem ring closing/cross metathesis of 1,5-hexadien-3-ol derivatives: Application to the total synthesis of rugulactone
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A tandem ring-closing metathesis/cross-metathesis procedure was devised for the synthesis of various pyrones. The reaction occurred with high regioselectivity and E stereocon-trol of the lateral unsaturated chain. This process was applied to the synthesis of rugulactone, an inhibitor of the nuclear factor NF-?B according to a four-step sequence.
- Cros, Fanny,Pelotier, Beatrice,Piva, Olivier
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experimental part
p. 5063 - 5070
(2010/10/21)
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- Rhodium-catalyzed conjugate addition of Sb-aryl-1,5-azastibocines to α,β-unsaturated carbonyl compounds
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Rhodium-catalyzed conjugate addition of Sb-aryl-1,5-azastibocines to α,β-unsaturated carbonyl compounds is described. The rhodium-catalyzed reaction was carried out in aqueous N-methy-2-pyrrolidinone (NMP) to give 1,4-conjugate adduct exclusively, while t
- Kakusawa, Naoki,Yasuike, Shuji,Kurita, Jyoji
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experimental part
p. 1269 - 1283
(2010/10/03)
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- Pentamethylcyclopentadienyl ruthenium: an efficient catalyst for the redox isomerization of functionalized allylic alcohols into carbonyl compounds
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The catalytic activity of the ruthenium(II) complex [RuCp*(CH3CN)3][PF6] 1 in the transposition of allylic alcohols into carbonyl compounds, in acetonitrile, is reported. This catalyst has proven to be able to catalyze the transformation of poorly reactive and/or functionalized substrates under smooth conditions.
- Bouziane, Asmae,Carboni, Bertrand,Bruneau, Christian,Carreaux, Fran?ois,Renaud, Jean-Luc
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experimental part
p. 11745 - 11750
(2009/04/11)
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- A new synthetic method for methyl ketones from carboxylic acids using metallic strontium and methyl iodide
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Carboxylic acids reacted with metallic strontium and methyl iodide to give methyl ketones preferentially in moderate to good yields. Copyright
- Miyoshi, Norikazu,Matsuo, Tsuyoshi,Asaoka, Masashi,Matsui, Aki,Wada, Makoto
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- Synthesis and olefination of carbonyl compounds using solid-supported reagents
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The development and application of three new solid-supported reagents for use in the synthesis or olefination of carbonyl compounds are described. The reagents include the Weinreb amide, Mukaiyama's S-2-pyridyl thioate and a Peterson methylenation reagent. As solid-supports p-benzyl alcohol resin, Wang resin and Merrifield resin (1-2% crosslinked polystyrene) have been used. The Royal Society of Chemistry.
- Hansen, Anne-Lene L.,Murray, Anthony,Tanner, David
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p. 4497 - 4505
(2008/09/18)
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- Synthetic scope and mechanistic studies of Ru(OH)x/Al 2O3-catalyzed heterogeneous hydrogen-transfer reactions
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Three kinds of hydrogen-transfer reactions, namely racemization of chiral secondary alcohols, reduction of carbonyl compounds to alcohols using 2-propanol as a hydrogen donor, and isomerization of allylic alcohols to saturated ketones, are efficiently promoted by the easily prepared and inexpensive supported ruthenium catalyst Ru(OH)x/Al2O 3. A wide variety of substrates, such as aromatic, aliphatic, and heterocyclic alcohols or carbonyl compounds, can be converted into the desired products, under anaerobic conditions, in moderate to excellent yields and without the need for additives such as bases. A larger scale, solvent-free reaction is also demonstrated: the isomerization of 1-octen-3-ol with a substrate/catalyst ratio of 20000/1 shows a very high turnover frequency (TOF) of 18400 h 1, with a turnover number (TON) that reaches 17200. The catalysis for these reactions is intrinsically heterogeneous in nature, and the Ru(OH)x/Al2O3 recovered after the reactions can be reused without appreciable loss of catalytic performance. The reaction mechanism of the present Ru(OH)x/Al2O 3-catalyzed hydrogentransfer reactions were examined with monodeuterated substrates. After the racemization of (S)-1-deuterio-1-phenylethanol in the presence of acetophenone was complete, the deuterium content at the α-position of the corresponding racemic alcohol was 91%, whereas no deuterium was incorporated into the α-position during the race mization of (S)-1-phenylethanol-OD. These results show that direct carbon-to-carbon hydrogen transfer occurs via a metal monohydride for the racemization of chiral secondary alcohols and reduction of carbonyl compounds to alcohols. For the isomerization, the α-deuterium of 3-deuterio-1-octen-3-ol was selectively relocated at the β-position of the corresponding ketones (99% D at the β-position), suggesting the involvement of a 1,4-addition of ruthenium monohydride species to the α,β-unsaturated ketone intermediate. The ruthenium monohydride species and the α,β-unsaturated ketone would be formed through alcoholate formation/β-elimination. Kinetic studies and kinetic isotope effects show that the Ru - H bond cleavage (hydride transfer) is included in the rate-determining step.
- Yamaguchi, Kazuya,Koike, Takeshi,Kotani, Miyuki,Matsushita, Mitsunori,Shinachi, Satoshi,Mizuno, Noritaka
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p. 6574 - 6582
(2007/10/03)
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- Indium(III) acetate-catalyzed 1,4-reduction and reductive aldol reactions of α-enones with phenylsilane
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A catalytic amount of In(OAc)3 smoothly promoted 1,4-reduction of certain α-enones with PhSiH3 in ethanol at ambient temperature. The intermediary enolates could be used for inter- and intramolecular aldol reactions and intramolecular Michael addition.
- Miura, Katsukiyo,Yamada, Yusuke,Tomita, Mitsuru,Hosomi, Akira
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p. 1985 - 1989
(2007/10/03)
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- A hydroacylation-triggered carbon-carbon triple bond cleavage in alkynes via retro-Mannich type fragmentation
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The carbon-carbon triple bond in alkyne is cleaved via hydroacylation followed by retro-Mannich type fragmentation in the presence of aldehyde, which triggers a successive C-C bond cleavage. Copyright
- Lee, Dae-Yon,Hong, Boo-Sun,Cho, Eung-Goo,Lee, Hyuk,Jun, Chul-Ho
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p. 6372 - 6373
(2007/10/03)
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- Arylation of allylic alcohols in ionic liquids catalysed by a Pd-benzothiazole carbene complex
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The reaction of aryl bromides with allylic alcohols catalysed by a Pd-benzothiazole carbene complex, in tetrabutylammonium bromide as solvent, leads principally to β-arylated carbonyl compounds. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Calo, Vincenzo,Nacci, Angelo,Monopoli, Antonio,Spinelli, Michele
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p. 1382 - 1385
(2007/10/03)
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- Substituted 2-amino-4-alkylamino-1,3,5-triazines as herbicides
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The invention relates to novel substituted 2-amino-4-alkylamino-1,3,5-triazines of the formula (I) in which R1represents in each case optionally substituted alkyl having 2 to 6 carbon atoms or cycloalkyl having 3 to 6 carbon atoms, R2represents hydrogen or represents alkyl having 1 to 4 carbon atoms, A represents oxygen or methylene, Ar represents in each case optionally substituted phenyl, naphthyl or heterocyclyl, and Z represents hydrogen, represents halogen or represents in each case optionally substituted alkyl, alkoxy, alkylcarboxyl, alkoxycarbonyl, alkylthio, alkylsulphinyl, alkylsulphonyl, alkenyl or alkinyl, to processes and to novel intermediates for their preparation and to their use as herbicides.
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Page column 62
(2008/06/13)
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- Pd-catalyzed ring opening of cyclopropanols
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Treatment of substituted cyclopropanols with a Pd catalyst in MeCN at 50 °C gave enones in good yields.
- Okumoto, Hiroshi,Jinnai, Takamitsu,Shimizu, Hiroyuki,Harada, Yoshinori,Mishima, Hideki,Suzuki, Akira
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p. 629 - 630
(2007/10/03)
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- Novel and efficient isomerization of allylic alcohols promoted by a etrapropylammonium perruthenate catalyst
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In the absence of an oxidant, tetrapropylammonium perruthenate (TPAP) is reduced by 2-undecanol to a low-valent ruthenium species that efficiently catalyzes the isomerization of a wide range of allylic alcohols into the corresponding saturated carbonyl derivatives [Eq.(1)]. R1, R2, R3, R4 = alkyl, aryl, H.
- Markó, István E.,Gautier, Arnaud,Tsukazaki, Masao,Llobet, Antoni,Plantalech-Mir, Elena,Urch, Christopher J.,Brown, Stephen M.
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p. 1960 - 1962
(2007/10/03)
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- Rhodium promoted isomerisation of allylic alkoxides: A new method for enolate anion formation
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Transition metal mediated isomerisation of allylic alkoxides is presented as a new method for enolate anion generation. The scope and limitations of enolate formation with the catalysts [Rh(dppe)(THF)2]+ClO4- and (Ph3P)3RhCl are explored and the synthetic potential of the methodology demonstrated in the stereoselective formation and reactions of certain ketone and aldehyde enolates.
- Gazzard, Lewis J.,Motherwell, William B.,Sandham, David A.
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p. 979 - 993
(2007/10/03)
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- Facile synthesis of 1, 3-diaryl-propanones through heck reaction
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1,3-diaryl propanones (1a-6a) and 1,3-diaryl-2-carbomethoxypropanones (1b-6b) have been synthesized through facile palladium catalysed arylation of Baylis-Hillman adducts.
- Sundar,Bhat, Sujata V.
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p. 2311 - 2316
(2007/10/03)
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- Chemoselectivity in the ruthenium-catalyzed redox isomerization of allyl alcohols
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Adjustment of oxidation level by internal hydrogen reorganization represents a highly efficient synthetic protocol. Cyclopentadienylbis(triphenylphosphine)ruthenium chloride in the presence of triethylammonium hexafluorophosphate catalyzes the redox isomerization of allyl alcohols to their saturated aldehydes or ketones. High chemoselectivity is observed since simple primary and secondary alcohols and isolated double bonds are not affected by this catalyst. The reaction is sensitive to the degree of substitution on the double bond and requires relatively unhindered olefins. Switching to indenylbis(triphenylphosphine)ruthenium chloride in the presence of triethylammonium hexafluorophosphate significantly expands the scope of the reaction to substrates bearing more substituted olefinic linkages and to cyclic substrates of rings containing eight or more members. The mechanism is probed by deuterium labeling, which shows that the metal catalyzes an intramolecular 1,3-hydrogen shift of the carbinol hydrogen to the terminal olefinic position.
- Trost, Barry M.,Kulawiec, Robert J.
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p. 2027 - 2036
(2007/10/02)
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- The synthesis of 3-trimethylsilyl-4-dimethyl(phenyl)silyl-but-3-en-2-one, a β-functionalised Michael acceptor
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The title compound 3 has been prepared by silyl-cupration of trimethylsilylacetylene followed by acetylation. The phenyldimethylsilyl group can be removed selectively in a three-step procedure to give 3-trimethylsilylbut-3-ene-2-one 1b. The enone 3 and cyclohexanone can be used in an annelation reaction to make 5-dimethyl(phenyl)silylbicyclo[4.4.0]decan-3-one 20 and hence to make 2-vinylcyclohexylacetic acid 23.
- Fleming,Newton,Sabin,Zammattio
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p. 7793 - 7802
(2007/10/02)
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- A chemoselective internal redox of allyl alcohols to saturated aldehydes or ketones
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Cp(Ph3P)2RuCl efficiently isomerizes allyl alcohols to saturated aldehydes or ketones even in the presence of other olefins and saturated alcohols.
- Trost, Barry M.,Kulawiec, Robert J.
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p. 3039 - 3042
(2007/10/02)
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- HYDROGENATION CATALYTIQUE D'ALDEHYDES; CETONES ET ESTERS α,β-ETHYLENIQUES α-FLUORES ET DE CETONES α,β-ETHYLENIQUES α,β-DIFLUORES
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Reduction of α-fluoro α,β-unsaturated aldehydes, esters and ketones to the corresponding saturated compounds is readily achieved by catalytic hydrogenation on Pd/C.The same reduction with α,β-difluoro α,β-unsaturated ketones gives various results depending on the solvent.
- Martinet, Pascal,Sauvetre, Raymond,Normant, Jean-F.
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p. 419 - 432
(2007/10/02)
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- α-Benzylation of Ketones by Reaction with Benzylamine. Regioselective Reduction of C-C Double Bonds in Cohjugated Enones
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Prolonged reaction of some ketones with benzylamine at reflux converts them into α-benzyl derivatives by a route involving Aldol condensation of the related ketimine with benzaldimine followed by exclusive reduction of the resultant C-C double bond.Reduction does not occur when pure benzylamine is used under oxygen-free nitrogen, however the inclusion of a trace of benzaldehyde restores the efficiency of the reaction.Treatment of several ketones in this manner established the scope of the process.When the reaction was extended to the reduction of α,β-unsaturated enones again using benzylamine, reaction times were shorter and the product yield greater.The possibility that the reductive step was an intramolecular 1,5-hydrogen transfer was studied.
- Armesto, Diego,Esteban, Soledad,Horspool, William M.,Martin, Juan-Antonio F.,Martinez-Alcazar, Paz,Perez-Ossorio, Rafael
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p. 751 - 755
(2007/10/02)
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- Amberlyst 15, a Superior, Mild, and Selective Catalyst for Carbonyl Regeneration from Nitrogeneous Derivatives
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Various tosylhydrazones, oximes, 2,4-dinitrophenylhydrazones, and semicarbazones were converted into the corresponding carbonyl compounds, mostly in quantitive yields, via equilibrium exchange with aqueous acetone, by use of Amberlyst 15 as acidic catalyst.Good results were obtained also with aldehyde derivatives.Groups which are acid-sensitive survive under these reaction conditions.
- Ballini, Roberto,Petrini, Marino
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p. 2563 - 2566
(2007/10/02)
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