- Temperature Dependence of the Photochemistry of Aryl Alkyl Ketones
-
The photochemistry of several phenyl alkyl and p-anisyl alkyl ketones has been examined using laser flash photolysis and conventional quantum yield techniques.The methoxy-substituted ketones show higher activation energies (ΔEa ca. 3 kcal mol-1) for the Norrish type I and type II processes.It is concluded that both reactions are adiabatic processes occurring from the triplet n? surface.In the case of p-methoxy-substituted ketones the upper n? surface is reached from the low-lying ?? triplet, with the energy gap between both states reflected as an increase in the activation energy.
- Encina, M. V.,Lissi, E. A.,Lemp, Else,Zanocco, A.,Scaiano, J. C.
-
-
Read Online
- Palladium-Catalyzed Synthesis of α-Methyl Ketones from Allylic Alcohols and Methanol
-
One-pot synthesis of α-methyl ketones starting from 1,3-diaryl propenols or 1-aryl propenols and methanol as a C1 source is demonstrated. This one-pot isomerization-methylation is catalyzed by commercially available Pd(OAc)2 with H2O as the only by-product. Mechanistic studies and deuterium labelling experiments indicate the involvement of isomerization of allyl alcohol followed by methylation through a hydrogen-borrowing pathway in these isomerization-methylation reactions.
- Biswal, Priyabrata,Samser, Shaikh,Meher, Sushanta Kumar,Chandrasekhar, Vadapalli,Venkatasubbaiah, Krishnan
-
supporting information
p. 413 - 419
(2021/11/01)
-
- 1,3-Alkyl Transposition in Allylic Alcohols Enabled by Proton-Coupled Electron Transfer
-
A method is described for the isomerization of acyclic allylic alcohols into β-functionalized ketones via 1,3-alkyl transposition. This reaction proceeds via light-driven proton-coupled electron transfer (PCET) activation of the O?H bond in the allylic al
- Knowles, Robert R.,Seidler, Gesa,Zhao, Kuo
-
supporting information
p. 20190 - 20195
(2021/08/13)
-
- Experimental and Computational Studies of Palladium-Catalyzed Spirocyclization via a Narasaka-Heck/C(sp3or sp2)-H Activation Cascade Reaction
-
The first synthesis of highly strained spirocyclobutane-pyrrolines via a palladium-catalyzed tandem Narasaka-Heck/C(sp3 or sp2)-H activation reaction is reported here. The key step in this transformation is the activation of a δ-C-H bond via an in situ generated σ-alkyl-Pd(II) species to form a five-membered spiro-palladacycle intermediate. The concerted metalation-deprotonation (CMD) process, rate-determining step, and energy barrier of the entire reaction were explored by density functional theory (DFT) calculations. Moreover, a series of control experiments was conducted to probe the rate-determining step and reversibility of the C(sp3)-H activation step.
- Wei, Wan-Xu,Li, Yuke,Wen, Ya-Ting,Li, Ming,Li, Xue-Song,Wang, Cui-Tian,Liu, Hong-Chao,Xia, Yu,Zhang, Bo-Sheng,Jiao, Rui-Qiang,Liang, Yong-Min
-
supporting information
p. 7868 - 7875
(2021/05/27)
-
- Rhenium(I)-Catalyzed C-Methylation of Ketones, Indoles, and Arylacetonitriles Using Methanol
-
A ReCl(CO)5/MeC(CH2PPh2)3 (L2) system was developed for the C-methylation reactions utilizing methanol and base, following the borrowing hydrogen strategy. Diverse ketones, indoles, and arylacetonitriles underwent mono-and dimethylation selectively up to 99% yield. Remarkably, tandem multiple methylations were also achieved by employing this catalytic system.
- Shee, Sujan,Kundu, Sabuj
-
p. 6943 - 6951
(2021/05/29)
-
- Facile preparation of 5-alkyl-1-aryltetrazoles with arenes, acyl chlorides, hydroxylamine, and diphenylphosphoryl azide
-
Successive treatment of arenes with acyl chlorides and AlCl3, the addition of water and removal of solvent, the reaction with NH2OH?HCl and K2CO3, and the reaction with diphenylphosphoryl azide and DBU under warming conditions gave the corresponding 5-alkyl-1-aryltetrazoles efficiently in good to moderate yields. The present method is one-pot transformation of arenes into 5-alkyl-1-aryltetrazoles using the Friedel-Crafts acylation and the Beckmann rearrangement under transition-metal-free conditions.
- Shibasaki, Kaho,Togo, Hideo
-
p. 1816 - 1830
(2020/11/19)
-
- Iron-Catalyzed Cleavage Reaction of Keto Acids with Aliphatic Aldehydes for the Synthesis of Ketones and Ketone Esters
-
The radical–radical coupling reaction is an important synthetic strategy. In this study, the iron-catalyzed radical–radical cross-coupling reaction based on the decarboxylation of keto acids and decarbonylation of aliphatic aldehydes to obtain valuable aryl ketones is reported for the first time. Remarkably, when tertiary aldehydes were used as carbonyl sources, ketone esters were selectively obtained instead of ketones. The gram-scale preparation of aryl ketone through this strategy was easily achieved by using only 3 mol % of the iron catalyst. As a proof-of-concept, the bioactive molecule flurprimidol was synthesized in two steps by using this strategy.
- Zhou, Fangyuan,Li, Lesong,Lin, Kao,Zhang, Feng,Deng, Guo-Jun,Gong, Hang
-
supporting information
p. 4246 - 4250
(2020/03/11)
-
- Method for preparing aryl ketone based on iron-catalyzed free radical-free radical coupling reaction such as ketonic acid decarboxylation and fatty aldehyde de-carbonylation
-
The invention discloses a method for preparing an aryl ketone derivative based on a free radical-free radical cross-coupling reaction such as ketonic acid decarboxylation and fatty aldehyde de-carbonylation. The method comprises the following steps: reacting aryl-substituted ketonic acid with fatty aldehyde under the catalytic action of ferric triacetylacetonate to generate an aryl ketone derivative; the gram-grade reaction can be realized by the method only by using 3mol% of an iron catalyst; and the method has the advantages of no need of consumption of a large amount of a Lewis acid catalyst or a stoichiometric organic metal reagent, mild reaction conditions, one-step reaction, few by-products, wide substrate application range and scalable reaction, and overcomes the defects of large catalyst consumption, insufficient functional group tolerance, many by-products and the like in the prior art.
- -
-
Paragraph 0055-0056
(2020/05/05)
-
- Electrochemical [4+2] Annulation-Rearrangement-Aromatization of Styrenes: Synthesis of Naphthalene Derivatives
-
We report the first electrochemical strategy to synthesize functionalized naphthalene derivatives through [4+2] annulation—rearrangement–aromatization from styrenes under mild conditions. The electrolysis does not require metals, oxidants and high valence substrates, indicating the atom and step-economy ideals. The dehydrodimer produced through [4+2] cycloaddition of 4-methoxy α-methyl styrene is isolated and proved to be the key intermediate for the following oxydehydrogenation to form carbon cation, which undergoes rearrangement–aromatization to afford the final products. This reaction represents a powerful access to construct multi-substituted naphthalene blocks in a single step.
- Ma, Yueyue,Lv, Jufeng,Liu, Chengyu,Yao, Xiantong,Yan, Guoming,Yu, Wei,Ye, Jinxing
-
supporting information
p. 6756 - 6760
(2019/04/17)
-
- One-Pot Conversion of Allylic Alcohols to α-Methyl Ketones via Iron-Catalyzed Isomerization-Methylation
-
A one-pot iron-catalyzed conversion of allylic alcohols to α-methyl ketones has been developed. This isomerization-methylation strategy utilized a (cyclopentadienone)iron(0) carbonyl complex as precatalyst and methanol as the C1 source. A diverse range of allylic alcohols undergoes isomerization-methylation to form α-methyl ketones in good isolated yields (up to 84% isolated yield).
- Latham, Daniel E.,Polidano, Kurt,Williams, Jonathan M. J.,Morrill, Louis C.
-
supporting information
p. 7914 - 7918
(2019/10/16)
-
- Iron-Catalyzed Tandem Three-Component Alkylation: Access to α-Methylated Substituted Ketones
-
The borrowing hydrogen strategy has been applied in the synthesis of α-branched methylated ketones via a tandem three-component reaction catalyzed by a diaminocyclopentadienone iron tricarbonyl complex. Various alkyl and aromatic methyl ketones underwent dialkylation with various primary alcohols and methanol as alkylating agents in mild reaction conditions and good yields. Deuterium labeling experiments suggested that the benzylic alcohol was the hydrogen source in this tandem process.
- Bettoni, Léo,Seck, Charlotte,Mbaye, Mbaye DIagne,Gaillard, Sylvain,Renaud, Jean-Luc
-
supporting information
p. 3057 - 3061
(2019/05/10)
-
- Enamines as Surrogates of Alkyl Carbanions for the Direct Conversion of Secondary Amides to α-Branched Ketones
-
A direct transformation of secondary amides into α-branched ketones with enamines as soft alkylation reagents was developed. In this reaction, enamines serve as surrogates of alkyl carbanions, rather than the conventional enolates equivalents in the Stork's reactions, which allowed for the easy introduction of alkyl groups with electrophilic functional groups. In the presence of 4 ? molecular sieves, the method can be extended to the one-pot coupling of secondary amides with aldehydes to yield ketones. (Figure presented.).
- Liu, Yong-Peng,Wang, Shu-Ren,Chen, Ting-Ting,Yu, Cun-Cun,Wang, Ai-E,Huang, Pei-Qiang
-
supporting information
p. 971 - 975
(2019/01/25)
-
- Silver-promoted cascade radical cyclization of γ,δ-unsaturated oxime esters with P(O)H compounds: synthesis of phosphorylated pyrrolines
-
A cascade radical cyclization was realized for the first silver-promoted imino-phosphorylation of γ,δ-unsaturated oxime esters, which provided a step-economical and redox-neutral route to access a variety of phosphorylated pyrrolines in good to excellent yields. Moreover, a new bulky trivalent phosphine ligand with a pyrroline motif was obtained through a deoxidation process.
- Chen, Chen,Bao, Yinwei,Zhao, Jinghui,Zhu, Bolin
-
supporting information
p. 14697 - 14700
(2019/12/11)
-
- α-Methylation of Ketones with Methanol Catalyzed by Ni/SiO2-Al2O3
-
α-Methylation of ketones with methanol catalyzed by a cheap and easy to handle Ni/SiO2-Al2O3 was explored. After optimization of the reaction between propiophenone and methanol, the desired product was obtained in 95 % isolated yield. A wide range of ketones was methylated under the optimized conditions (16 examples). This procedure was extended to a three-component cross-benzylation-methylation of acetophenone.
- Charvieux, Aubin,Duguet, Nicolas,Métay, Estelle
-
supporting information
p. 3694 - 3698
(2019/06/13)
-
- Catalytic C1 Alkylation with Methanol and Isotope-Labeled Methanol
-
A metal-catalyzed methylation process has been developed. By employing an air- and moisture-stable manganese catalyst together with isotopically labeled methanol, a series of D-, CD3-, and 13C-labeled products were obtained in good yields under mild reaction conditions with water as the only byproduct.
- Sklyaruk, Jan,Borghs, Jannik C.,El-Sepelgy, Osama,Rueping, Magnus
-
supporting information
p. 775 - 779
(2019/01/04)
-
- Naphthyridine-based iridium complexes: Structures and catalytic activity on alkylation of aryl ketones
-
Iridium(III) complexes containing a designed ligand, 2-amino-7-(2-pyridinyl)-1,8-naphthyridine derivative, were prepared and all complexes were characterized using spectroscopic and crystallographic methods. These new Ir(III) complexes are able to act as catalysts for the C-alkylation of aryl alkyl ketones with the use of alcohols as the alkylating agent. Typically, acetophenone undergoes alkylation with methanol and ethanol to yield isobutyrophenone and butyrophenone, respectively.
- Chen, Po-Hao,Liu, Yi-Hung,Liu, Shiuh-Tzung
-
p. 972 - 981
(2019/05/24)
-
- Organic Superbase t-Bu-P4 Catalyzes Amination of Methoxy(hetero)arenes
-
We report that the organic superbase t-Bu-P4 efficiently catalyzes the amination of methoxy(hetero)arenes with amine nucleophiles such as aniline, indoline, and aminopyridine derivatives. This catalytic reaction is effective for the transformation of elec
- Shigeno, Masanori,Hayashi, Kazutoshi,Nozawa-Kumada, Kanako,Kondo, Yoshinori
-
p. 5505 - 5508
(2019/08/01)
-
- Palladacycle-Phosphine Catalyzed Methylation of Amines and Ketones Using Methanol
-
Methylation of amines and ketones with palladacycle precatalyst has been performed using methanol as an environmentally benign reagent. Various ketones and amines undergo methylation reaction to yield monomethylated amines or ketones in moderate to good isolated yields. Moreover, this protocol was tested for the chemoselective methylation of 4-aminobenzenesulfonamide. The scope of the reaction was further extended to the deuteromethylation of ketones.
- Mamidala, Ramesh,Biswal, Priyabrata,Subramani, M. Siva,Samser, Shaikh,Venkatasubbaiah, Krishnan
-
p. 10472 - 10480
(2019/08/20)
-
- Pd-catalyzed Oxidative Cross-coupling of Alkyl Chromium(0) Fischer Carbene Complexes with Organoboronic Acids
-
Alkyl chromium(0) carbene complexes have been explored as the cross-coupling partners in the palladium-catalyzed reaction with aryl or alkenyl boronic acids. This coupling reaction displays the versatile reactivities of alkyl chromium(0) carbenes under palladium catalysis. Mechanistically, this transformation is proposed to involve deprotonation of the alkyl chromium carbene substrate to generate a vinyl chromium anion intermediate that undergoes transmetalation to organopalladium species and reductive elimination.
- Wang, Kang,Yang, Jinghui,Yao, Xingqi,Wang, Jianbo
-
supporting information
p. 3165 - 3168
(2018/10/15)
-
- C -Methylation of Alcohols, Ketones, and Indoles with Methanol Using Heterogeneous Platinum Catalysts
-
A versatile, selective, and recyclable heterogeneous catalytic method for the methylation of C-H bonds in alcohols, ketones, and indoles with methanol under oxidant-free conditions using a Pt-loaded carbon (Pt/C) catalyst in the presence of NaOH is reported. This catalytic system is effective for various methylation reactions: (1) the β-methylation of primary alcohols, including aryl, aliphatic, and heterocyclic alcohols, (2) the α-methylation of ketones, and (3) the selective C3-methylation of indoles. The reactions are driven by a borrowing-hydrogen mechanism. The reaction begins with the dehydrogenation of the alcohol(s) to afford aldehydes, which subsequently undergo a condensation reaction with the nucleophile (aldehyde, ketone, or indole), followed by hydrogenation of the condensation product by Pt-H species to yield the desired product. In all of the methylation reactions explored in this study, the Pt/C catalyst exhibits a significantly higher turnover number than other previously reported homogeneous catalytic systems. Moreover, it is demonstrated that the high catalytic activity of Pt can be rationalized in terms of the adsorption energy of hydrogen on the metal surface, as revealed by density functional theory calculations on different metal surfaces.
- Siddiki, S. M. A. Hakim,Touchy, Abeda S.,Jamil, Md. A. R.,Toyao, Takashi,Shimizu, Ken-Ichi
-
p. 3091 - 3103
(2018/04/14)
-
- Iron-Catalyzed Methylation Using the Borrowing Hydrogen Approach
-
A general iron-catalyzed methylation has been developed using methanol as a C1 building block. This borrowing hydrogen approach employs a Kn?lker-type (cyclopentadienone)iron carbonyl complex as catalyst (2 mol %) and exhibits a broad reaction scope. A variety of ketones, indoles, oxindoles, amines, and sulfonamides undergo mono- or dimethylation in excellent isolated yields (>60 examples, 79% average yield).
- Polidano, Kurt,Allen, Benjamin D. W.,Williams, Jonathan M. J.,Morrill, Louis C.
-
p. 6440 - 6445
(2018/07/25)
-
- Synthesis of Halomethyl Isoxazoles/Cyclic Nitrones via Cascade Sequence: 1,2-Halogen Radical Shift as a Key Link
-
A novel iminoxyl radical-promoted dichotomous regioselective 5-exo-trig cyclization onto vinylic halogen/1,2-halogen radical shift sequence is developed for the synthesis of halomethyl isoxazoles/cyclic nitrones using β-halo-β,?- and ?-halo-?,?-unsaturated ketoximes as the substrates and PhI(OAc)2/TEMPO as the oxidation system. DFT calculations reveal that a halogen-bridged three-membered ring transition state is involved in the 1,2-Cl-/Br-atom shift, while the 1,2-I atom migration can be taken into account with an elimination/readdition mechanism. The migration ability was indicated to be ranked in the following order: I > Br > Cl.
- Chen, Hong-Lei,Wei, Dian,Zhang, Jian-Wu,Li, Cheng-Lin,Yu, Wei,Han, Bing
-
p. 2906 - 2910
(2018/05/28)
-
- Methylation of Amines and Ketones with Methanol Catalyzed by an Iridium Complex Bearing a 2-Hydroxypyridylmethylene Fragment
-
Reaction of complex [Cp?Ir(HOC5H3CH2C5H3OH)Cl][Cl] (1) with AgOTf generated the product [Cp?Ir(HOC5H3CH2C5H3OH)(H2O)][OTf]2 (2), which was further transformed to the complex [Cp?Ir(OC5H3CH2C5H3O)(H2O)] (3) in the presence of t-BuONa via -OH deprotonation. Complexes 1-3 exhibited high activity for the methylation of amines and ketones. These C-C and C-N coupling reactions proceeded in air with 1 mol % catalyst loading in the presence of K2CO3.
- Deng, Danfeng,Hu, Bowen,Yang, Min,Chen, Dafa
-
p. 3353 - 3359
(2018/09/25)
-
- Rhodium-Catalyzed Direct Ortho C-H Arylation Using Ketone as Directing Group with Boron Reagent
-
A general method for selective ortho C-H arylation of ketone, with boron reagent enabled by rhodium complexes with excellent yields, is developed. The transformation is characterized by the use of air-stable Rh catalyst, high monoarylation selectivity, and excellent yields of most of the substrates.
- Zhang, Bing,Wang, Huai-Wei,Kang, Yan-Shang,Zhang, Ping,Xu, Hua-Jin,Lu, Yi,Sun, Wei-Yin
-
supporting information
p. 5940 - 5943
(2017/11/10)
-
- Iminoxyl Radical-Promoted Oxycyanation and Aminocyanation of Unactivated Alkenes: Synthesis of Cyano-Featured Isoxazolines and Cyclic Nitrones
-
A novel and facile approach to vicinal oxycyanation and aminocyanation of internal unactivated alkenes is developed. This method utilizes the dichotomous reactivity of iminoxyl radical derived from the initiation of β,γ- and γ,δ-unsaturated ketoximes to provide the general difunctionalization of internal alkenes using tert-butyl hydroperoxide (TBHP) as the environmentally friendly oxidant, CuCN as the commercially available cyanating reagent, and pentamethyldiethylenetriamine (PMDETA) as the ligand. By using this protocol, a series of useful cyano-featured isoxazolines and cyclic nitrones were efficiently prepared.
- Chen, Fei,Zhu, Fei-Fei,Zhang, Man,Liu, Rui-Hua,Yu, Wei,Han, Bing
-
supporting information
p. 3255 - 3258
(2017/06/23)
-
- Why are vinyl cations sluggish electrophiles?
-
The kinetics of the reactions of the vinyl cations 2 [Ph2C=C+-(4-MeO-C6H4)] and 3 [Me2C=C+-(4-MeO-C6H4)] (generated by laser flash photolysis) with diverse nucleophile
- Byrne, Peter A.,Kobayashi, Shinjiro,Würthwein, Ernst-Urich,Ammer, Johannes,Mayr, Herbert
-
supporting information
p. 1499 - 1511
(2017/02/10)
-
- Preparation and use of DMF-stabilized iridium nanoclusters as methylation catalysts using methanol as the C1 source
-
We report methylations of alcohols and anilines catalyzed by DMF-stabilized Ir nanoclusters using methanol as the C1 source. The DMF-stabilized Ir nanoclusters were prepared in one step and have diameters of 1-1.5 nm. They react in a borrowing-hydrogen reaction and are efficient methylation catalysts (TON up to 310?000).
- Oikawa, Kei,Itoh, Satoshi,Yano, Hiroki,Kawasaki, Hideya,Obora, Yasushi
-
p. 1080 - 1083
(2017/02/05)
-
- Methylation of C(sp3)-H/C(sp2)-H bonds with methanol catalyzed by cobalt system
-
A highly efficient Co-based catalytic system, composed of a commercially available Co salt, a tetradentate phosphine ligand P-(CH2CH2PPh2)3(PP3), and a base (denoted as [Co]/PP3/base), is developed for the methylation of C(sp3)-H and C(sp2)-H bonds using methanol as a methylating reagent. The Co(BF4)2.6H2O/PP3/K2CO3 catalytic system showed high catalytic activity for the methylation of C-H bonds in aryl alkyl ketones, aryl acetonitriles, and indoles, with wide substrate scope and good functional group tolerance, and methylsubstituted products were obtained in good to excellent yields at 100 °C. This cheap, readily available, and highly efficient Co-based catalytic system may have promising applications in methylation reaction using methanol.
- Liu, Zhenghui,Yang, Zhenzhen,Yu, Xiaoxiao,Zhang, Hongye,Yu, Bo,Zhao, Yanfei,Liu, Zhimin
-
supporting information
p. 5228 - 5231
(2017/11/06)
-
- Syndiotactic Poly(aminostyrene)-Supported Palladium Catalyst for Ketone Methylation with Methanol
-
Palladium nanoparticles immobilized on an amino-functionalized syndiotactic polystyrene (sPS-N) served as a novel recyclable catalyst for the dimethylation and cross methyl alkylation of a wide range of ketones with methanol as the methylation agent. This heterogeneous catalyst (Pd@sPS-N) was highly robust and showed excellent thermal stability and chemical resistance. It not only showed remarkably high activity, but it could also be easily recovered by filtration without loss of activity.
- Jiang, Lei,Guo, Fang,Shi, Zhenghai,Li, Yang,Hou, Zhaomin
-
p. 3827 - 3832
(2017/09/25)
-
- Utilization of MeOH as a C1 Building Block in Tandem Three-Component Coupling Reaction
-
Ru(II) catalyzed tandem synthesis of α-branched methylated ketones via multicomponent reactions following the hydrogen borrowing process is described. This nonphosphine-based air and moisture stable catalyst efficiently produced various methylated ketones using methanol as a methylating agent. This system was found to be highly effective in three-component coupling between methanol, primary alcohols, and methyl ketones. A proposed catalytic cycle for the α-methylation is supported by DFT calculations as well as kinetic experiments.
- Chakrabarti, Kaushik,Maji, Milan,Panja, Dibyajyoti,Paul, Bhaskar,Shee, Sujan,Das, Gourab Kanti,Kundu, Sabuj
-
supporting information
p. 4750 - 4753
(2017/09/22)
-
- C-C coupling of ketones with methanol catalyzed by a N-heterocyclic carbene-phosphine iridium complex
-
An N-heterocyclic carbene-phosphine iridium complex system was found to be a very efficient catalyst for the methylation of ketone via a hydrogen transfer reaction. Mild conditions together with low catalyst loading (1 mol%) were used for a tandem process which involves the dehydrogenation of methanol, C=C bond formation with a ketone, and hydrogenation of the new generated double bond by iridium hydride to give the alkylated product. Using this iridium catalyst system, a number of branched ketones were synthesized with good to excellent conversions and yields.
- Quan, Xu,Kerdphon, Sutthichat,Andersson, Pher G.
-
supporting information
p. 3576 - 3579
(2015/03/04)
-
- DMF as carbon source: Rh-catalyzed α-methylation of ketones
-
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
-
-
- Iridium-catalyzed selective α-methylation of ketones with methanol
-
Iridium-catalyzed selective α-dimethylation and α-methylation of ketones or phenylacetonitriles, using methanol as the methylating agent, were achieved. In addition, three-component cross α-methyl-alkylation was successfully performed using methyl ketones with methanol and primary alcohols with long-chain alkyl groups. This method provides a very convenient direct route to α-methylated ketones, using methanol.
- Ogawa, Shinji,Obora, Yasushi
-
supporting information
p. 2491 - 2493
(2014/03/21)
-
- Iminoxyl radical-promoted dichotomous cyclizations: Efficient oxyoximation and aminooximation of alkenes
-
A novel iminoxyl radical-involved metal-free approach to vicinal oxyoximation and aminooximation of unactivated alkenes is developed. This method utilizes the dichotomous reactivity of the iminoxyl radical to furnish a general difunctionalization on alkenes using simple tert-butyl nitrite (TBN) as the iminoxyl radical initiator as well the carbon radical trap. By using this protocol, oxime featured 4,5-dihydroisoxazoles and cyclic nitrones were facilely prepared from β,γ- and γ,δ-unsaturated ketoximes, respectively.
- Peng, Xie-Xue,Deng, Yun-Jing,Yang, Xiu-Long,Zhang, Lin,Yu, Wei,Han, Bing
-
p. 4650 - 4653
(2015/01/08)
-
- Rhodium-catalyzed ketone methylation using methanol under mild conditions: Formation of α-branched products
-
The rhodium-catalyzed methylation of ketones has been accomplished using methanol as the methylating agent and the hydrogen-borrowing method. The sequence is notable for the relatively low temperatures that are required and for the ability of the reaction system to form α-branched products with ease. Doubly alkylated ketones can be prepared from methyl ketones and two different alcohols by using a sequential one-pot iridium- and rhodium-catalyzed process. Uniquely effective for making branched alkyl products from ketones (see scheme): The scope of the presented reaction includes aromatic and aliphatic ketones and consecutive one-pot double alkylation reactions to provide a convenient route to branched ketones from simple methyl ketones. A brief study into the mechanism of the reaction has given evidence for an aldol-based reaction pathway.
- Chan, Louis K. M.,Poole, Darren L.,Shen, Di,Healy, Mark P.,Donohoe, Timothy J.
-
supporting information
p. 761 - 765
(2014/01/23)
-
- Catalytic Friedel-Crafts acylation: Magnetic nanopowder CuFe 2O4 as an efficient and magnetically separable catalyst
-
Catalytic regioselective Friedel-Crafts acylation of an array of anisoles/arenes with various acid chlorides using 5-20 mol % of magnetic nanopowder CuFe2O4 is reported. Unlike the conventional Friedel-Crafts reactions, which are catalyzed by moisture sensitive homogeneous catalysts/promoters, the nanopowder CuFe2O4 catalyst is moisture insensitive and the product/ketone-catalyst isolation is easily achieved using the magnetic properties of CuFe2O4.
- Parella, Ramarao,Naveen,Kumar, Amit,Babu, Srinivasarao Arulananda
-
p. 1738 - 1742
(2013/03/28)
-
- Efficient and scalable synthesis of ketones via nucleophilic Grignard addition to nitriles using continuous flow chemistry
-
In the present Letter we report the development of efficient continuous flow chemistry conditions for the scalable preparation of ketones. This transformation is achieved via nucleophilic addition of Grignard reagents to the corresponding nitriles and imine hydrolysis by means of in-series plug flow reactors.
- Mateos, Carlos,Rincón, Juan A.,Villanueva, José
-
supporting information
p. 2226 - 2230
(2013/05/08)
-
- A base-promoted deprotection of 1,3-dioxolanes to ketones
-
An effective deprotection methodology of dioxolanes was developed, affording moderate to excellent yield via a LTMP-promoted reaction in THF, which displays admirable chemoselectivity in the presence of dimethylketal, 1,3-dioxane, 1,3-dithiane, or other acid-sensitive protective groups.
- Yuan, Changchun,Yang, Li,Yue, Guizhou,Yu, Tianzi,Zhong, Weiming,Liu, Bo
-
supporting information
p. 6972 - 6976
(2013/01/15)
-
- Mild ketone formation via Ni-catalyzed reductive coupling of unactivated alkyl halides with acid anhydrides
-
Ni-catalyzed ketone formation through mild reductive coupling of a diverse set of unactivated alkyl bromides and iodides with particularly aryl acid anhydrides was successfully developed using zinc as the terminal reductant. These conditions also allow direct coupling of alkyl iodides with aryl acids in the presence of Boc2O and MgCl2. The Royal Society of Chemistry 2012.
- Yin, Hongyu,Zhao, Chenglong,You, Hengzhi,Lin, Kunhua,Gong, Hegui
-
supporting information; experimental part
p. 7034 - 7036
(2012/08/14)
-
- Enantiopure C1-symmetric bis(imino)pyridine cobalt complexes for asymmetric alkene hydrogenation
-
Enantiopure C1-symmetric bis(imino)pyridine cobalt chloride, methyl, hydride, and cyclometalated complexes have been synthesized and characterized. These complexes are active as catalysts for the enantioselective hydrogenation of geminal-disubstituted olefins.
- Monfette, Sebastien,Turner, Zoe R.,Semproni, Scott P.,Chirik, Paul J.
-
supporting information; experimental part
p. 4561 - 4564
(2012/04/23)
-
- Rhodium-catalyzed phenylthiolation reaction of heteroaromatic compounds using α-(phenylthio)isobutyrophenone
-
In the presence of catalytic amounts of RhH(PPh3)4 and 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-benzothiazoles, 1,3-benzoxazoles, and benzothiophene reacted with α-(phenylthio) isobutyrophenone giving 2-phenylthio derivatives. Reactive monocyclic heteroaromatics, 1-methyl-1,2,3,4-tetrazole and 2-cyanothiophene were also converted into the 5-phenylthio derivatives. The use of an appropriate phenylthio transfer reagent is crucial for the efficient catalyzed conversion of heteroaromatic C-H bonds into C-S bonds.
- Arisawa, Mieko,Toriyama, Fumihiko,Yamaguchi, Masahiko
-
supporting information; experimental part
p. 2344 - 2347
(2011/05/16)
-
- Double duty for cyanogen bromide in a cascade synthesis of cyanoepoxides
-
An unprecedented reaction mode of cyanogen bromide has been discovered. Under basic conditions, cyanogen bromide acts as an equivalent of both Br + and CN- to convert enolizable ketones into the corresponding cyanoepoxides in good yields. This unique reaction mode provides new, one-pot access to densely substituted cyanoepoxides from easily available ketones (see scheme). Copyright
- Li, Zhou,Gevorgyan, Vladimir
-
supporting information; experimental part
p. 2808 - 2810
(2011/05/05)
-
- Palladium-catalyzed arylation of vinylic acetates. Phosphine ligand influenced regioselectivity
-
A palladium-catalyzed coupling reaction of aryl bromides with vinylic acetates in the presence of tributyltin methoxide h as been described. The α-arylation aldehyde product and the aryl ketone were obtained in the presence of P(t-Bu)3 and P(o-
- Jean, Micka?l,Renault, Jacques,Van De Weghe, Pierre
-
supporting information; experimental part
p. 6546 - 6548
(2011/02/23)
-
- Unexpected formation of aryl ketones by palladium-catalyzed coupling of aryl bromides with vinylic acetates
-
A palladium-catalyzed coupling reaction of aryl bromides with vinylic acetates in the presence of tributyitin methoxide has been described. Unexpected formation of aryl ketones was obtained. Preliminary mechanistic studies indicated that the reaction proceeded by the addition of the aryl moiety in the coordination sphere of palladium to a ketene.
- Jean, Mickael,Renaulty, Jacques,Uriac, Philippe,Capet, Marc,Van De Weghe, Pierre
-
p. 3623 - 3625
(2008/02/12)
-
- Friedel-Crafts acylation reaction using carboxylic acids as acylating agents
-
Dehydrative Friedel-Crafts acylation reaction of aromatic compounds with carboxylic acids as acylating agents was investigated in the presence of Lewis acid- or Br?nsted acid-catalyst. Various metal triflates and bis(trifluoromethanesulfonyl)amides showed catalytic activity at high temperature, among which Eu(NTf2)3 proved to be the most effective and efficiently catalyzed the acylation reaction of alkyl- and alkoxybenzenes with aliphatic and aromatic carboxylic acids at 250 °C. Bi(NTf2)3 was more effective than Eu(NTf2)3 at lower temperature, but proved to be hydrolyzed in the presence of a small amount of water to give HNTf2 and [Bi6O4(OH)4(H2O)6](NTf2)6. The structure of the latter compound was confirmed by a single crystal X-ray analysis. Among five Br?nsted acids, HOTf, HNTf2, HCTf3, TsOH, and Nafion SAC-13, HNTf2 has proved to be the most efficient catalyst and more effective than Eu(NTf2)3 for the acylation of p-xylene with heptanoic acid at 220 °C or lower temperature. HNTf2 catalyzed the acylation of anisole with carboxylic acids in high yields in refluxing toluene with azeotropic removal of water.
- Kawamura, Masato,Cui, Dong-Mei,Shimada, Shigeru
-
p. 9201 - 9209
(2007/10/03)
-
- 9,10-Dicyanoanthracene photosensitized oxidation of aryl alkanols: Evidence for an electron transfer mechanism
-
9,10-Dicyanoanthracene (DCA) photosensitizes the oxidation of a series of para substituted aryl alkanols in oxygen-saturated acetonitrile. Product analysis and Hammett correlations support an electron transfer mechanism for the title reaction.
- Lykakis, Ioannis N.,Lestakis, Stellios,Orfanopoulos, Michael
-
p. 6247 - 6251
(2007/10/03)
-
- BiCl3-catalyzed Friedel-Crafts acylation reactions: Bismuth(III) oxychloride as a water insensitive and recyclable procatalyst
-
The Friedel-Crafts acylation of activated and polycyclic aromatics is efficiently catalyzed by bismuth(III) chloride which is generated in situ from bismuth(III) oxychloride, a water insensitive and eco-friendly material. Bismuth(III) oxychloride is easily recovered in near quantitative yields after an aqueous work-up.
- Répichet, Sigrid,Le Roux, Christophe,Roques, Nicolas,Dubac, Jacques
-
p. 2037 - 2040
(2007/10/03)
-
- Astonishing alkylation and unusual reduction reactions of anionic titanium(II) isopropoxide complexes: Evidence for SET processes in transition-metal oxidative additions
-
A mixture of titanium(II) isopropoxide and lithium isopropoxide (1:2), generated in THF by the treatment of titanium(IV) isopropoxide with two equivalents of n-butyllithium, has been shown to be an unexpected alkylating agent as well as an unusual reducing agent for a wide variety of organic substrates. Since titanium(II) isopropoxide, which is free of any lithium isopropoxide, neither causes alkylation of any of the same substrates nor is such a powerful reductant, it is proposed that the lithium isopropoxide activates titanium(II) isopropoxide for such unusual reactions by the formation of the lithium salt coordination complex Li2Ti[OiPr]4. Illustrative of the unprecedented alkylations are the transformations, after hydrolysis, of various substituted benzonitriles to isopropyl-substituted phenyl ketones, of (dichloromethyl)benzene to, principally, 2-methyl-1-phenyl-1-propene and of (trichloromethyl)benzene to isopropyl phenyl ketone. By comparing the reducing actions of Li2Ti[OiPr]4 and Ti[OiPr]2 individually, it has been shown that, generally, the lithium salt is the more powerful reductant for epoxides, benzylic halides and conjugated olefins. From the reactions of Li2Ti[OiPr]4 with the benzonitriles, styrene, the isomeric stilbene oxides and cis-stilbene, cogent evidence is marshaled for the operation of SET processes, sensitive to steric hindrance, in such alkylations and reductions. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Eisch, John J.,Gitua, John N.
-
p. 3091 - 3096
(2007/10/03)
-
- Method for acylation or sulphonylation of an aromatic compound
-
The present invention relates to a process for the acylation or sulphonylation of an aromatic compound. More particularly, the invention relates to a process for the acylation or sulphonylation of an activated or deactivated aromatic compound. The invention is applied to the preparation of aromatic ketones or sulphones. The process for the acylation or sulphonylation of an aromatic compound which consists in reacting at least one aromatic compound with an acylating or sulphonylating agent, in the presence of a Friedel-Crafts catalyst is characterized in that the acylation or sulphonylation reaction is carried out in liquid phase under microwave irradiation.
- -
-
Page column 15
(2008/06/13)
-
- LiClO4-acyl anhydrides complexes as powerful acylating reagents of aromatic compounds in solvent free conditions
-
The Friedel-Crafts acylation of various activated benzenes is smoothly carried out with acyl anhydrides in the presence of 2 equiv. of LiClO4, as reaction promoter, under solventless conditions.
- Bartoli, Giuseppe,Bosco, Marcella,Marcantoni, Enrico,Massaccesi, Massimo,Rinaldi, Samuele,Sambri, Letizia
-
p. 6331 - 6333
(2007/10/03)
-
- A highly active ytterbium(III) methide complex for truly catalytic Friedel-Crafts acylation reactions
-
The Friedel-Crafts acylation of anisole with acetic anhydride using ytterbium(III) tri[tris(nonafluorobutanesulfonyl)methide] was studied with respect to catalyst loading. A strong inhibitory effect due to the product became apparent from doping experiments and from examination of the kinetic data. This understanding allowed catalyst loadings to be reduced to as little as 0.1 mol% for effective acylation under a suitable temperature and pressure regime.
- Barrett, Anthony G. M.,Bouloc, Nathalie,Braddock, D. Christopher,Chadwick, David,Henderson, David A.
-
p. 1653 - 1656
(2007/10/03)
-