- THE REACTION OF PHENYLLITHIUM WITH CARBON MONOXIDE
-
Three main products are obtained from the reaction between phenyllithium and carbon monoxide, namely: benzophenone (I), benzoin (II) and α,α-diphenylacetophenone (III).Evidence is given for the existence of benzoyllithium as the first intermediate of the reaction and for the subsequent intermediates in the production of I, II and III.The basic sequences followed in the formation of those and of other minor products are outlined in the Scheme.Reaction conditions can be adjusted to obtain III in a high yield or to prevent further reaction of the first intermediate and obtain diarylalkylcarbinols, or substituted tetrahydrofurans.
- Nudelman, N. Sbarbati,Vitale, Arturo A.
-
-
Read Online
- Photocatalytic Coproduction of Deoxybenzoin and H2 through Tandem Redox Reactions
-
Photocatalytic H2 evolution from organic feedstocks with simultaneous utilization of photogenerated holes achieves solar energy storage and coproduces value-Added chemicals. Here we show visible-light H2 production from benzyl alcohol (BAL) with controllable generation of deoxybenzoin (DOB) or benzoin (BZ) through tandem redox reactions. Particularly, DOB synthesis circumvents the use of expensive feedstocks and environmentally unfriendly catalysts that are required previously. Under the irradiation of blue LEDs, the key of steering the major product to DOB rather than BZ is to decrease the conduction band bottom potentials of the ZnIn sulfide catalysts by increasing the Zn/In ratio, which results in the dehydration of intermediate hydrobenzoin (HB) to DOB proceeding in a redox-neutral mechanism and consuming an electron-hole pair. As a proof of concept, this method is used to synthesize DOB derivatives in gram scale.
- Luo, Nengchao,Hou, Tingting,Liu, Shiyang,Zeng, Bin,Lu, Jianmin,Zhang, Jian,Li, Hongji,Wang, Feng
-
-
Read Online
- α-Hydroxy ketones in high enantiomeric purity from asymmetric oxidation of enol phosphates with (salen) manganese(III) complex
-
Optically active α-hydroxy ketones 4 have been prepared in high enantioselectivity by the catalytic, enantioselective oxidation of easily available and stable (E)-enol phosphates 2 by (salen) Mn(III) complex.
- Krawczyk, Ewa,Koprowski, Marek,Skowronska, Aleksandra,Luczak, Jerzy
-
-
Read Online
- Iron borohydride pincer complexes for the efficient hydrogenation of ketones under mild, base-free conditions: Synthesis and mechanistic insight
-
The new, structurally characterized hydrido carbonyl tetrahydridoborate iron pincer complex [(iPr-PNP)Fe(H)(CO)(I·1-BH 4)] (1) catalyzes the base-free hydrogenation of ketones to their corresponding alcohols employing only 4.1atm hydrogen pressure. Turnover numbers up to 1980 at complete conversion of ketone were reached with this system. Treatment of 1 with aniline (as a BH3 scavenger) resulted in a mixture of trans-[(iPr-PNP)Fe(H)2(CO)] (4a) and cis-[(iPr-PNP)Fe(H) 2(CO)] (4b). The dihydrido complexes 4a and 4b do not react with acetophenone or benzaldehyde, indicating that these complexes are not intermediates in the catalytic reduction of ketones. NMR studies indicate that the tetrahydridoborate ligand in 1 dissociates prior to ketone reduction. DFT calculations show that the mechanism of the iron-catalyzed hydrogenation of ketones involves alcohol-assisted aromatization of the dearomatized complex [(iPr-PNP*)Fe(H)(CO)] (7) to initially give the Fe0 complex [(iPr-PNP)Fe(CO)] (21) and subsequently [(iPr-PNP)Fe(CO)(EtOH)] (38). Concerted coordination of acetophenone and dual hydrogen-atom transfer from the PNP arm and the coordinated ethanol to, respectively, the carbonyl carbon and oxygen atoms, leads to the dearomatized complex [(iPr-PNP*)Fe(CO)(EtO)(MeCH(OH) Ph)] (32). The catalyst is regenerated by release of 1-phenylethanol, followed by dihydrogen coordination and proton transfer to the coordinated ethoxide ligand.
- Langer, Robert,Iron, Mark A.,Konstantinovski, Leonid,Diskin-Posner, Yael,Leitus, Gregory,Ben-David, Yehoshoa,Milstein, David
-
-
Read Online
- Influence of magnesium(II) ions on cathodic reactions in aprotic solvents: the reduction of benzoate esters
-
The use of an Mg anode in an undivided cell alters the products from many electrosynthetic reactions.In an attempt to understand this phenomenon, the influence of MgII ions on the mechanism for the reduction of benzoate esters in DMF has been investigated.It is confirmed that the presence of MgII in solution leads to a change in the major reaction pathway from cleavage of the ester linkage (to give benzoate ion) to dimerisation (to a diketone).The dimer is then reduced further at the same potential.Cyclic voltammetry shows that in the absence of MgII, the ester radical anion is stable, while in the presence of MgII, the radical anion dimerises rapidly and the MgII also catalyses further reduction.Voltammmetry within the synthesis cell, however, shows that much of the MgII formed by dissolution of the anode is tied up by anionic products and that the dimerisation of the radical anion must occur well away from the cathode surface.
- Pletcher, Derek,Slevin, Louise
-
-
Read Online
- Pyridinium dichromate-assisted oxidative cleavage of α-functionalized benzylic alcohols by sodium percarbonate under phase-transfer conditions
-
The course and the efficacy of the oxidation by sodium percarbonate of benzylic alcohols, α-substituted by a keto, hydroxy, ester or acid group, are dependent on the nature of both α-group and the solvent, and yields are usually improved by the presence of catalytic amounts of Cr(VI) species. The oxidative cleavage of the C(OH)-C(α) bond is the main process observed.
- Mohand,Levina,Muzart
-
-
Read Online
- Azolium salts as effective catalysts for benzoin condensation and related reactions
-
A catalytic ability of several azolium salts for benzoin condensation, the benzoylation of 4-chloro-1-phenyl-1H-pyrazolo[3,4-d]pyrimidine, and oxidative aroylation was examined. We found that azolium salts having an imidazolium moiety, such as 1,4-dimethy
- Miyashita, Akira,Suzuki, Yumiko,Kobayashi, Motoi,Kuriyama, Naomi,Higashino, Takeo
-
-
Read Online
- Postulation of Bis(thiazolin-2-ylidene)s as the Catalytic Species in the Benzoin Condensation Catalyzed by a Thiazolium Salt plus Base
-
Thiazolin-2-ylidenes generated by desilylation of 2-(trimethylsilyl)thiazolium ions are used as catalysts for the benzoin condensation.The experimental results together with theoretical calculations lead the postulate that bis(thiazolin-2-ylidene)s, and n
- Castells, J.,Lopez-Calahorra, F.,Domingo, L.
-
-
Read Online
- Mechanistic studies of the O2-dependent aliphatic carbon-carbon bond cleavage reaction of a nickel enolate complex
-
The mononuclear nickel(II) enolate complex [(6-Ph2TPA)Ni(PhC(O)C(OH)C(O)Ph] ClO4 (I) was the first reactive model complex for the enzyme/substrate (ES) adduct in nickel(II)-containing acireductone dioxygenases (ARDs) to be reported. In this contribution, the mechanism of its O 2-dependent aliphatic carbon-carbon bond cleavage reactivity was further investigated. Stopped-flow kinetic studies revealed that the reaction of I with O2 is second-order overall and is ～ 80 times slower at 25 °C than the reaction involving the enolate salt [Me4N][PhC(O) C(OH)C(O)Ph]. Computational studies of the reaction of the anion [PhC(O)C(OH)C(O)Ph]- with O2 support a hydroperoxide mechanism wherein the first step is a redox process that results in the formation of 1,3-diphenylpropanetrione and HOO-. Independent experiments indicate that the reaction between 1,3-diphenylpropanetrione and HOO- results in oxidative aliphatic carbon-carbon bond cleavage and the formation of benzoic acid, benzoate, and CO:CO2 ( ～ 12:1). Experiments in the presence of a nickel(II) complex gave a similar product distribution, albeit benzil [PhC(O)C(O)Ph] is also formed, and the CO:CO2 ratio is ～ 1.5:1. The results for the nickel(II)-containing reaction match those found for the reaction of I with O2 and provide support for a trione/HOO- pathway for aliphatic carbon-carbon bond cleavage. Overall, I is a reasonable structural model for the ES adduct formed in the active site of Ni"ARD. However, the presence of phenyl appendages at both C(1) and C(3) in the [PhC(O)C(OH)C(O)Ph]- anion results in a reaction pathway for O2-dependent aliphatic carbon-carbon bond cleavage (via a trione intermediate) that differs from that accessible to C(1)- H acireductone species. This study, as the first detailed investigation of the O2 reactivity of a nickel(II) enolate complex of relevance to Ni"ARD, provides insight toward understanding the chemical factors involved in the O2 reactivity of metal acireductone species.
- Berreau, Lisa M.,Borowski, Tomasz,Grubel, Katarzyna,Allpress, Caleb J.,Wikstrom, Jeffrey P.,Germain, Meaghan E.,Rybak-Akimova, Elena V.,Tierney, David L.
-
-
Read Online
- On the reactivity and stability of electrogenerated N-heterocyclic carbene in parent 1-butyl-3-methyl-1H-imidazolium tetrafluoroborate: Formation and use of N-heterocyclic carbene-CO2 adduct as latent catalyst
-
A simple electrolysis (under galvanostatic conditions) of the room temperature ionic liquid 1-butyl-3-methyl-1H-imidazolium tetrafluoroborate, BMIm-BF4, yields, after bubbling CO2 into the catholyte, theadduct NHC-CO2. The considerable stability of this NHC-CO 2 adduct, at room temperature, in the parentionic liquid as solvent, has been compared with the one of free NHC in the same BMIm-BF4. The BMIm-BF4solution containing NHC-CO2 adduct, suitably triggered (US irradiation or 120 °C), is able to releasefree NHC. The NHC-CO2 adduct usefulness has been demonstrated using it as efficient latent catalyst, inBMIm-BF4as solvent, in the benzoin condensation and in the oxidative esterification of cinnamaldehydewith benzyl alcohol.
- Feroci, Marta,Chiarotto, Isabella,Vecchio Ciprioti, Stefano,Inesi, Achille
-
-
Read Online
- ANODIC GENERATION OF POLYBROMOCHLORIDE IONS AND THEIR UTILIZATION AS PRECISELY-CONTROLLED OXIDIZING REAGENTS FOR EX-CELL INDIRECT ELECTROOXIDATION OF ALCOHOLS
-
Polybromochloride ions (BrxCly(1-) were generated by anodic oxidation of mixtures of Br(1-) and Cl(1-) in dichloromethane, and they could be used as precisely-controlled oxidizing reagents, of which oxidizing powers depended on the x- and y-values, for ex-cell indirect electrooxidation of a variety of alcohols
- Konno, Akinori,Fukui, Kouta,Fuchigami, Toshio,Nonaka, Tsutomu
-
-
Read Online
- Reduction of Sulfur Dioxide and Carbon Dioxide with Benzoin Carbanion. Oxygen Transfer from Products Formed by the Reduction of Sulfur Dioxide to 7,7,8,8-Tetracyanoquinodimethane
-
A reaction of sulfur dioxide (SO2) with benzoin carbanion (the lithium salt of benzoin dianion, 1) in tetrahydrofuran (THF) gave a mixture of benzyl (2) and benzoin (3) in yields of 83 and 17 percent, respectively, irrespective of the reaction temperature between -78 and 25 deg C.The reaction of carbon dioxide (CO2) with 1 in THF gave a mixture of 2 and 3 accompanied by the formation of a small amount of lithium benzoate (4).The proportion of 2 in a mixture of 2 and 3 formed in the reaction of CO2 with 1 were 49, 30, and 20percent at -78, -22, and 25 deg C, respectively.The reaction of SO2 with 1 in the presence of 7,7,8,8-tetracyanoquinodimethane (TCNQ) gave oligomers of TCNQ with a yield of 60percent, in which some parts of the cyano groups were transformed to carboxylato groups.
- Akiyama, Fuminori
-
-
Read Online
- Boronic acid-catalyzed selective oxidation of 1,2-diols to α-hydroxy ketones in water
-
The activation of 1,2-diols through formation of boronate esters was found to enhance the selective oxidation of 1,2-diols to their corresponding α-hydroxy ketones in aqueous medium. The oxidation step was accomplished using dibromoisocyanuric acid (DBI) as a terminal chemical oxidant or an electrochemical process. The electrochemical process was based on the use of platinum electrodes, methylboronic acid [MeB(OH)2] as a catalyst and bromide ion as a mediator. Electro-generated OH- ions (EGB) at the cathode acted as a base and "Br+" ion generated at the anode acted as an oxidant. Various cyclic and acyclic 1,2-diols as substrates were selectively oxidized to the corresponding α-hydroxy ketones via their boronate esters by the two oxidative methods in good to excellent yields.
- William, Julius M.,Kuriyama, Masami,Onomura, Osamu
-
-
Read Online
- Thiazolium salt immobilized on ionic liquid: An efficient catalyst and solvent for preparation of α-hydroxyketones
-
Aldehydes were efficiently converted to acyloins and benzoins using a new ionic liquid, 3-[2-(1-butyl-1H-imidazol-1,3-ium-3-yl)ethyl]-4,5-dimethyl-1,3- thiazol-3-ium dibromide 1. This ionic liquid is introduced as a catalyst and a solvent. Acyloins and benzoins were easily isolated from the reaction mixture via simple extraction, and the ionic liquid could be recycled for further use. Also, -hydroxy ketones with an aromatic and aliphatic substituent were prepared starting from aromatic and aliphatic aldehydes in the presence of ionic liquid 1.
- Mohanazadeh, Farajollah,Aghvami, Majid
-
-
Read Online
- Polarity reversal induced by electrochemically generated thiazol-2-ylidenes: The Stetter reaction
-
The inversion of the normal reactivity (umpolung) of aldehydes has been induced via N-heterocyclic carbenes (NHCs) thiazol-2-ylidenes 2a or 3a, generated by simple electrolyses of solutions containing thiazolium salt 2 or 3. Accordingly, 1,4-dicarbonyl compounds have been obtained, in mild conditions and in moderate to very high yields, via 1,4-addition of the Breslow intermediates to the suitable Michael acceptor. The procedure has been performed in classical organic solvents (VOCs) as well as in room temperature ionic liquids (RTILs). The different reactivity of aliphatic aldehydes vs the one of aromatic and heteroaromatic aldehydes has been emphasized.
- Orsini, Monica,Chiarotto, Isabella,Sotgiu, Giovanni,Inesi, Achille
-
-
Read Online
- Organocatalysis in polysiloxane gels: A magnetic-stir-bar encapsulated catalyst system prepared by thiol-ene photo-click immobilization
-
This manuscript presents a facile thiol-ene photo-click chemistry method to prepare magnetic stir bar-encapsulated polysiloxane-based organocatalyst gels under benign conditions, and develops a Stir Bar-Encapsulated Catalysis (SBEC) technique. Through thiol-ene addition chemistry, we graft olefin-terminated organocatalysts (i.e. MacMillan catalyst, proline catalyst, and N-heterocyclic carbene catalyst) onto poly[3-mercaptopropylmethylsiloxane], which is further photo-crosslinked to coat the embedded magnetic stir bar. The prepared magnetic stir bar-encapsulated polysiloxane-based organocatalyst gels can be put into reaction flasks to perform stirring and catalysis functions at the same time. The most important benefit of SBEC technique is to infinitely simplify the catalyst/product separation procedure by using a simple stir-bar-retriever, even without any precipitation/filtration steps. The catalytic performances of three different organocatalyst gels applied in asymmetric Diels-Alder reaction, asymmetric aldol reaction and benzoin condensation reaction respectively are also examined herein.
- Yang, Hong,Xu, Ming,Guo, Ling-Xiang,Ji, Hao-Fan,Wang, Jun-Yu,Lin, Bao-Ping,Zhang, Xue-Qin,Sun, Ying
-
-
Read Online
- A self-assembled nanoprobe for long-term cancer cell nucleus-specific staining and two-photon breast cancer imaging
-
Herein, a novel self-assembled nanoprobe for the long-term tracking of the nucleoli of cancer cells and for differentiating between clinical breast cancer tissues and para-carcinoma tissues has been developed.
- Gao, Tang,Wang, Shuanglian,Lv, Wuwu,Liu, Mian,Zeng, Hongliang,Chen, Zhu,Dong, Jie,Wu, Ziping,Feng, Xueping,Zeng, Wenbin
-
-
Read Online
- Selective Aerobic Oxidation of Benzyl Alcohols with Palladium(0) Nanoparticles Suspension in Water
-
Abstract: This study concerns one of the rare applications of a suspension of palladium nanoparticles in water for oxidation reactions. The aqueous suspension containing well dispersed nanoparticles of 3.85?nm was obtained following a straightforward procedure involving the reduction of Na2PdCl4 with NaBH4 in the presence of PVP as stabilizing agent. In the way of oxidative catalytic valorisation of lignin, the aqueous suspension was directly applied as catalytic medium for the selective oxidation of vanillic alcohol into vanillin (80?°C, O2, 1?h) with more than 90% yield. Reusability of the catalytic medium has been demonstrated, acting as “quasi-homogeneous catalyst”. More sophisticated lignin-derived substrates like veratryl alcohol and hydrobenzoin gave yields of 50–80% to the respective aldehyde and ketone. In parallel, this as-synthesized suspension was directly used to prepare a Pd/TiO2 catalyst, the latter showing less efficiency for the catalytic transformations. Graphic Abstract: [Figure not available: see fulltext.]
- Bourbiaux, Dolorès,Mangematin, Stéphane,Djakovitch, Laurent,Rataboul, Franck
-
-
Read Online
- An organocatalytic ionic liquid
-
The carbene concentration in 1-ethyl-3-methylimidazolium-acetate ionic liquid is sufficiently high to act as a catalyst in benzoin condensation, hydroacylation and also in oxidation of an alcohol by using CO2 and air. This observation reveals the potential of ionic liquid organocatalysts, uniting the beneficial properties of these two families of compounds.
- Kelemen, Zsolt,Holloczki, Oldamur,Nagy, Jozsef,Nyulaszi, Laszlo
-
-
Read Online
- Photochemical Transformations of 1,2-Diketones and Benzhydrylamine
-
Photolysis of a mixture of substituted 1,2-diketones and benzhydrylamine (in 1:2 mole ratio) in benzene gave N-benzhydrylidenebenzhydrylamine, N-(diarylmethyl)benzamides, acyloins (3), N-(arylmethylene)benzhydrylamines, and benzophenone separated by fractional crystallization and column chromatogaphy.The products have been characterised by analytical and spectral (IR, UV, and NMR) data and the structural assignments confirmed by the comparison (IR spectra and undepressed mixed mp) with authentic samples.Acyloins (3) are precursors for N-(diarylmethyl)benzamides and N-(arylmethylene)benzhydrylamines.A tentative mechanistic route for the formation of products has been suggested.
- Mehrotra, Kailash Nath,Pandey, Ganesh Prasad
-
-
Read Online
- Reductive formation and transformation of epoxides in neutral aqueous medium
-
Stoichiometrically controlled reductive epoxidation could be elaborated to transform α,β-diketones or α-hydroxy ketones to epoxides in a very good yields in neutral aqueous medium using chromium(II)acetate. Modification of the coordination sphere of Cr(II) ion with the added ligand makes the reductive ring-opening possible.
- Kovacs, Gabor,Micskei, Karoly
-
-
Read Online
- Structural Aspects of Catalytic Activities of Thiazolium Salts in Benzoin Condensation Reaction in Methanol
-
The rates of benzoin condensation catalyzed by thiazolium salts of varying structures have been determined in methanol containing triethylamine as the base by the method of gas chromatography.The condensation activity was observed not to be linearly corre
- Yano, Yumihiko,Tamura, Yoshiharu,Tagaki, Waichiro
-
-
Read Online
- Samarium diiodide promoted formation of 1,2-diketones and 1-acylamido-2-substituted benzimidazoles from N-acylbenzotriazoles
-
N-Acylbenzotriazoles, when treated with samarium diiodide in THF, undergo self-coupling reaction to afford 1,2-diketones in good to excellent yields; while when treated with samarium diiodide in CH3CN, they undergo ring-opening reaction to afford 1-acylamido-2-alkyl (or aryl) benzimidazoles in reasonable to good yields. A plausible mechanism was suggested.
- Wang, Xiaoxia,Zhang, Yongmin
-
-
Read Online
- Medium and reaction engineering for the establishment of a chemo-enzymatic dynamic kinetic resolution of rac-benzoin in batch and continuous mode
-
The effect of the reaction parameters water activity and reaction solvent was investigated for the dynamic kinetic resolution (DKR) of rac-benzoin with immobilized Lipase TL as biocatalyst for transesterification and the heterogeneous chemo-catalyst Zr-TUD-1 (Si/Zr = 25) for in situ racemization. Overall dry reaction conditions led to the best results for both catalysts. The immobilized lipase in a more environmentally benign solvent like cyclopentyl methyl ether (CPME) exhibited a 1.6-fold higher activity and an up to 1.5-fold higher half-life time than in the standard solvents such as toluene and 2-methyltetrahydrofuran (2-MeTHF). Among a variety of deep eutectic solvents (DESs) choline chloride:isosorbide (ChCl:Iso) was found to be suitable for the reaction system. The activity was lower than in the aforementioned solvents, but the very low solubility of the product (S)-benzoin butyrate in ChCl:Iso compared to the investigated organic solvents possesses great potential with respect to downstream processing. Optimized reaction parameters (dry CPME) were applied for DKR in batch and continuous mode yielding comparable or slightly better results than in toluene or 2-MeTHF.
- Petrenz, Annika,María, Pablo Domínguez De,Ramanathan, Anand,Hanefeld, Ulf,Ansorge-Schumacher, Marion B.,Kara, Selin
-
-
Read Online
- A γ-CYCLODEXTRIN THIAZOLIUM SALT HOLOENZYME MIMIC FOR THE BENZOIN CONDENSATION
-
Several thiazolium salts have been attached to a C-6 carbon of γ-cyclodextrin.They catalyze the benzoin condensation of benzaldehyde very effectively.
- Breslow, Ronald,Kool, Eric
-
-
Read Online
- The Hydrogenation of Benzyl Catalyzed by Cobalt(II) Dimethylglyoxime Complex
-
Kinetic studies on the catalytic hydrogenation of benzil to benzoin by bis(dimethylglyoximato)cobalt(II), Co(Hdmg)2, were carried out by varying the concentration of Co(Hdmg)2 and pyridine.The initial rate of the hydrogenation reaction was first order with respect to the overall cobalt concentration at a constant overall pyridine concentration.On the other hand, the rate passed through a peak as the overall pyridine concentration was increased at a constant overall cobalt concentration.The peak was observed at T=130 mmol dm-3, where the square bracket denotes the concentration in the liquid phase.These results show that the initial reaction rate, Vin, can be expressed by the following rate equation, where k=1.1 min-1.
- MITA, Keisuke
-
-
Read Online
- Solid-support-bound 1-aminoimidazolium chlorochromate: A selective, efficient and recyclable oxidant
-
A series of polymer-bound imidazolium chlorochromates have been synthesised and used as selective oxidants for benzylic and cinnamylic alcohols. Solid-support-bound 1-amino-imidazolium chlorochromate proved to be the most convenient system due to its efficiency, selectivity and ease of recycling the material.
- Linares,Sánchez,Alajarín,Vaquero,Alvarez-Builla
-
-
Read Online
- N-Heterocyclic olefins as ancillary ligands in catalysis: A study of their behaviour in transfer hydrogenation reactions
-
The Ir(i) complexes [Ir(cod)(κP,C,P′-NHOPPh2)]PF6 and [IrCl(cod)(κC-NHOOMe)] (cod = 1,5-cyclooctadiene, NHOPPh2 = 1,3-bis(2-(diphenylphosphanyl)ethyl)-2-methyleneimidazoline) and NHOOMe = 1,3-bis(2-(methoxyethyl)-2-methyleneimidazoline), both featuring an N-heterocyclic olefin ligand (NHO), have been tested in the transfer hydrogenation reaction; this representing the first example of the use of NHOs as ancillary ligands in catalysis. The pre-catalyst [Ir(cod)(κP,C,P′-NHOPPh2)]PF6 has shown excellent activities in the transfer hydrogenation of aldehydes, ketones and imines using iPrOH as a hydrogen source, while [IrCl(cod)(κC-NHOOMe)] decomposes throughout the reaction to give low yields of the hydrogenated product. Addition of one or two equivalents of a phosphine ligand to the latter avoids catalyst decomposition and significantly improves the reaction yields. The reaction mechanism has been investigated by means of stoichiometric studies and theoretical calculations. The formation of the active species ([Ir(κP,C,P′-NHOPPh2)(iPrO)]) has been proposed to occur via isopropoxide coordination and concomitant COD dissociation. Moreover, throughout the catalytic cycle the NHO moiety behaves as a hemilabile ligand, thus allowing the catalyst to adopt stable square planar geometries in the transition states, which reduces the energetic barrier of the process.
- Iturmendi, Amaia,García, Nestor,Jaseer,Munárriz, Julen,Sanz Miguel, Pablo J.,Polo, Victor,Iglesias, Manuel,Oro, Luis A.
-
-
Read Online
- VIOLOGENS THAT PLUNDER ELECTRON FROM SOLID REDUCING AGENT. REDUCTION OF ARYL KETONES BY ZINC POWDER IN THE PRESENCE OF PROPYL VIOLOGEN AS AN ELECTRON TRANSFER CATALYST
-
It was found that viologen (propyl viologen) acted as an Electron Transfer Catalyst (ETC) in the reduction of aryl ketones with zinc powder. α-Diketones undertook the two-electron reduction to obtain the corresponding benzoins in good yields and aromatic ketones could one-electron reduced selectively to give the corresponding pinacols.
- Endo, Takeshi,Saotome, Yasushi,Okawara, Makoto
-
-
Read Online
- Origin of chemoselectivity in N-heterocyclic carbene catalyzed cross-benzoin reactions: DFT and experimental insights
-
An exploration into the origin of chemoselectivity in the NHC-catalyzed cross-benzoin reaction reveals several key factors governing the preferred pathway. In the first computational study to explore the cross-benzoin reaction, a piperidinone-derived triazolium catalyst produces kinetically controlled chemoselectivity. This is supported by 1H NMR studies as well as a series of crossover experiments. Major contributors include the rapid and preferential formation of an NHC adduct with alkyl aldehydes, a rate-limiting carbon-carbon bond formation step benefiting from a stabilizing π-stacking/π-cation interaction, and steric penalties paid by competing pathways. The energy profile for the analogous pyrrolidinone-derived catalyst was found to be remarkably similar, despite experimental data showing that it is less chemoselective. The chemoselectivity could not be improved through kinetic control; however, equilibrating conditions show substantial preference for the same cross-benzoin product kinetically favored by the piperidinone-derived catalyst.
- Langdon, Steven M.,Legault, Claude Y.,Gravel, Michel
-
-
Read Online
- De Novo Synthesis of α-Hydroxy Ketones by Gallic Acid-Promoted Aerobic Coupling of Terminal Alkynes with Diazonium Salts
-
An unprecedented metal-free direct preparation of unprotected α-hydroxy ketones from terminal alkynes under mild conditions with diazonium salts as the arene source and without the requirement of irradiation is described. The process is general and fully compatible with a wide variety of substitution in both reactants. Experimental and computational evidence strongly suggest the involvement of radical species in the transformation.
- Alcaide, Benito,Almendros, Pedro,Fernández, Israel,Herrera, Fernando,Luna, Amparo
-
-
Read Online
- On the paradox of TiCl4 reducing power: Pinacol coupling and two-carbon homologation of carbonyl compounds
-
TiCl4/DIPEA/CH2Cl2 reducing system promotes pinacol coupling and/or reduction to alcohol of aromatic aldehydes and carbonyl compounds activated towards reduction by an electron withdrawing group. In addition, bis homologation of these substrates is observed. An inner-sphere electron transfer from TiCl4 to DIPEA accounts for the products distribution.
- Clerici, Angelo,Pastori, Nadia,Porta, Ombretta
-
-
Read Online
- Reactions of Bezaldehyde with Thiazolium Salts in Me2SO: Evidence for Initial Formation of 2-(α-Hydroxybenzyl)thiazolium by Nucleophilic Addition and for Dramatic Solvent Effects on Benzoin Formation
-
The mechanism of benzoin condensation from benzaldehyde catalyzed by -labeled 3-benzyl- and 3-methylthiazolium salts was examined under a variety of conditions.At ambient temperatures in dry Me2SO, employing t-BuOK as the base, several different co
- Chen, Yao-Tsung,Barletta, Gabriel L.,Haghjoo, Khadijah,Cheng, Jung Tsang,Jordan, Frank
-
-
Read Online
- One-pot synthesis benzils from aldehydes via nhc-catalyzed benzoin dimerization under metal-free conditions in water
-
A simple and convenient one-pot procedure is reported for the synthesis of 1,2-diketones from corresponding benzoin-type condensation reaction of aromatic aldehydes in water with N,N-dialkylbenzimidazolium salt as condensation catalyst and air as oxidizing reagent.
- Bi, Xiaoxin,Wu, Lintao,Yan, Chaoguo,Jing, Xiaobi,Zhu, Hongxiang
-
-
Read Online
- An efficient method for selective oxidation of 1,2-diols in water catalyzed by Me2SnCl2
-
Dimethyltin(iv)dichloride-catalyzed selective oxidation of 1,2-diols in water was achieved using dibromoisocyanuric acid (DBI) or Br2 as oxidants. The catalyst activates the 1,2-diol moiety through the formation of stannylene acetal in addition to enhancing selectivity. Various cyclic and acyclic 1,2-diol substrates have been selectively oxidized affording α-hydroxyketones in good to excellent yields. This method is safe and simple in operation.
- William, Julius M.,Kuriyama, Masami,Onomura, Osamu
-
-
Read Online
- Metal-free porous phosphorus-doped g-C3N4photocatalyst achieving efficient synthesis of benzoin
-
Photocatalytic organic synthesis is mostly limited by the shortcomings of insufficient light absorption, high photogenerated electron-hole recombination rate and inadequate reactive sites of photocatalysts. To solve these problems, phosphorus-doped g-C3N4with a porous structure was constructed. Benefiting from enhanced light absorption and electron-hole separation efficiency, PCNT has intensive oxygen activation ability to generate superoxide radicals, and is highly active in organic synthesis. In addition, PCNT has enhanced surface nucleophilicity, which is conducive to the carbon-carbon coupling process of the intermediate product benzaldehyde molecules and benzyl alcohol molecules in the benzoin condensation reaction. Metal-free PCNT is expected to replace the previously used highly toxic cyanide catalysts and provide a new way for the low-cost and efficient photocatalytic synthesis of benzoin.
- Li, Yuanjin,Wang, Shuhui,Wu, Jin,Wang, Qiuyan,Ma, Changqiu,Jiang, Daheng,Hu, Wanglai,Zhu, Lixin,Xu, Xiaoliang
-
-
Read Online
- Synthesis, structure and oxidation of alkynes using a μ-oxo diiron complex with the ligand bis (1-(pyridin-2-ylmethyl)-benzimidazol-2-yl methyl) ether
-
New ligand bis (1-(pyridin-2-ylmethyl)-benzimidazol-2-ylmethyl ether and its μ-oxo diferric complex has been synthesized and characterized. The dimeric [LClFe-O-FeCl3] has been characterized crystallographically, and shows that iron atoms occupy inequivalent coordination sites. One of the Fe (III) atom is coordinated by two benzimidazole nitrogens, one ether oxygen and bridging oxide oxygen, forming the equatorial plane while one Cl- ion and the oxygen atom of a DMF molecule occupy the axial fifth and the sixth coordination positions. The second Fe (III) is tetrahedrally coordinated by three Cl- ions and the bridging oxide oxygen O. The bridging oxide anion is unsymmerically coordinated to the two Iron (III) atoms. Oxidation of aromatic alkynes was investigated using this complex as catalyst with small amount of tert-butyl hydroperoxide (TBHP) and Hydrogen peroxide (H 2O2) as an alternate source of oxygen. Isolated products were characterized by GC-Mass. Solvent, temperature, Stoichiometry and oxidant variation are studied and reaction conditions have been optimized. Dicarbonyl and α,β-acetylenic ketone are the major product and depend on the nature of the alkyne employed.
- Khattar, Raghvi,Hundal,Mathur, Pavan
-
-
Read Online
- Generation and reactivity of phenylhydroxycarbenes in solution
-
We provide evidence for the first successful generation of phenylhydroxycarbene and 4-trifluoromethylphenylhydroxycarbene in solution. The carbene tautomers of the corresponding benzaldehyde derivatives had been prepared under cryogenic matrix-isolation conditions before but their reactivity, apart from a prototypical quantum mechanical tunneling [1,2]-H-shift reaction, had not been studied. Here our strategy is to employ suitable carbene precursors for the McFadyen–Stevens reaction, to generate the parent and the para-CF3-substituted phenylhydroxycarbenes, and to react them with benzaldehyde or acetone in a highly facile, allowed six-electron carbonyl-ene reaction toward the corresponding α-hydroxy ketones. Our findings are supported by computations at the DLPNO-CCSD(T)/cc-pVQZ//B3LYP/def2-TZVP level of theory.
- Keul, Felix,Mardyukov, Artur,Schreiner, Peter R.
-
supporting information
(2022/01/19)
-
- Direct Synthesis of Vinylene Carbonates from Aromatic Aldehydes**
-
Substituted vinylene carbonates were directly prepared from aromatic aldehydes following a one-pot Benzoin condensation/transcarbonation sequence under solvent-free conditions. The combination of a N-phenyl substituted triazolium salt NHC precursor and 4-dimethylaminopyridine (DMAP) was found essential to reach high yield and selectivity. The reaction scope was investigated with a range of aromatic aldehydes and the corresponding vinylene carbonates were obtained with 32–86 % isolated yields (14 examples).
- Duguet, Nicolas,Ibrahimli, Leyli,Onida, Killian
-
supporting information
(2022/04/03)
-
- Zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source
-
The zinc salt-catalyzed reduction of α-aryl imino esters, diketones and phenylacetylenes with water as hydrogen source and zinc as reductant was successfully conducted. The presented method provides a low-cost, environmentally friendly and practical preparation of α-aryl amino esters, α-hydroxyketones and phenylethylenes. By using D2O as deuterium source, the corresponding products were obtained in high efficiency with excellent deuterium incorporation rate, which gives a cheap and safe tool for access to valuable deuterium-labelled compounds. This journal is
- Shen, Guoli,Liu, Haojie,Chen, Jingchao,He, Zhenxiu,Zhou, Yongyun,Wang, Lin,Luo, Yang,Su, Zhimin,Fan, Baomin
-
supporting information
p. 3601 - 3610
(2021/05/04)
-
- Organocatalytic Synthesis of Substituted Vinylene Carbonates
-
The organocatalytic synthesis of substituted vinylene carbonates from benzoins and acyloins was studied using diphenyl carbonate as a carbonyl source. A range of N-Heterocyclic Carbene (NHC) precursors were screened and it was found that imidazolium salts were the most active for this transformation. The reaction occurs at 90 °C under solvent-free conditions. A wide range of substituted vinylene carbonates (symmetrical and unsymmetrical, aromatic or aliphatic), including some derived from natural products, were prepared with 20–99% isolated yields (24 examples). The reaction was also developed using thermomorphic polyethylene-supported organocatalysts as recoverable and recyclable species. The use of such species facilitates the workup and allows the synthesis of vinylene carbonates on the preparative scale (>30 g after 5 runs). (Figure presented.).
- Onida, Killian,Haddleton, Alice J.,Norsic, Sébastien,Boisson, Christophe,D'Agosto, Franck,Duguet, Nicolas
-
supporting information
p. 5129 - 5137
(2021/09/18)
-
- N-PEGylated Thiazolium Salt: A Green and Reusable Homogenous Organocatalyst for the Synthesis of Benzoins and Acyloins
-
N-PEGylated-thiazolium salt is used as efficient catalyst for the benzoin condensation. The catalyst was synthesized by reaction of activated polyethylene glycol 10,000 (PEG-10000) with 4-methyl-5-thiazoleethanol (sulfurol). Reaction mixture undergoes temperature-assisted phase transition and catalyst separated by simple filtration. After reaction course, catalyst can be recycled and reused without any apparent loss of activity which makes this process cost effective and hence ecofriendly. Synthesized benzoins and acyloins by this method have been characterized on the basis of melting point and 1H-NMR spectral studies. Graphic Abstract: [Figure not available: see fulltext.]
- Haghighi, Ali Javaheri,Mokhtari, Javad,Karimian, Khashayar
-
p. 1646 - 1652
(2020/10/19)
-
- Rapid, chemoselective and mild oxidation protocol for alcohols and ethers with recyclable N-chloro-N-(phenylsulfonyl)benzenesulfonamide
-
Chlorine is the 20th most abundant element on the earth compared to bromine, iodine, and fluorine, a sulfonimide reagent, N-chloro-N-(phenylsulfonyl)benzenesulfonamide (NCBSI) was identified as a mild and selective oxidant. Without activation, the reagent was proved to oxidize primary and secondary alcohols as well as their symmetrical and mixed ethers to corresponding aldehydes and ketones. With recoverable PS-TEMPO catalyst, selective oxidation over chlorination of primary and secondary alcohols and their ethers with electron-donating substituents was achieved. The reagent precursor of NCBSI was recovered quantitatively and can be reused for synthesizing NCBSI.
- Badani, Purav,Chaturbhuj, Ganesh,Ganwir, Prerna,Misal, Balu,Palav, Amey
-
supporting information
(2021/06/03)
-
- Visible Light Enabled Formal Cross Silyl Benzoin Reaction as an Access to α-Hydroxyketones
-
In this work, a visible-light enabled coupling of acylsilanes with aldehydes to give a range of cross-benzoin type products α-hydroxyketones is described. The reaction could proceed at ambient temperature, with the irradiation of low energy visible light, and without addition of photosensitizer or any other additives. (Figure presented.).
- Ma, Liyao,Yu, Yinghua,Xin, Luoting,Zhu, Lei,Xia, Jiajin,Ou, Pengcheng,Huang, Xueliang
-
supporting information
p. 2573 - 2577
(2021/04/05)
-
- Ruthenium(II)-Catalyzed Cross-Coupling of Benzoyl Formic Acids with Toluenes: Synthesis of 2-Phenylacetophenones
-
Herein, we report a direct method to synthesize 2-phenylacetophenone through a ruthenium(II)-catalyzed cross-coupling reaction between acyl and benzyl radical. The various derivatives of 2-phenylacetophenone were prepared easily in moderate to good yields. These reactions provide a straightforward pathway to synthesize a variety of ketones bearing various functional groups.
- Chen, Yujie,Dai, Chenyang,Huang, Zhibin,Jiang, Yaqiqi,Shu, Sai,Yang, Shan,Zhao, Yingsheng
-
p. 2955 - 2961
(2021/07/22)
-
- Palladium-catalyzed synthesis of α-aryl acetophenones from styryl ethers and aryl diazonium saltsviaregioselective Heck arylation at room temperature
-
Preparation of α-aryl acetophenones from styryl ethers and aryldiazonium salts is described. The reaction is catalyzed by palladium acetate at room temperature in the absence of ligand and base. The developed method is highly attractive in terms of reaction conditions, substrate scope, functional group tolerance and yields. Synthetic applications of the present method are demonstrated by preparing α-aryl indoles and 3-aryl isocoumarin from styryl ethers.
- Kandasamy, Jeyakumar,Lee, Yong Rok,Singh, Adesh Kumar,Venkatesh, Rapelly
-
supporting information
p. 7832 - 7837
(2021/09/28)
-
- Enantioselective N-heterocyclic carbene-catalysed intermolecular crossed benzoin condensations: Improved catalyst design and the role of in situ racemisation
-
The enantioselective intermolecular crossed-benzoin condensation mediated by novel chiral N-heterocyclic carbenes derived from pyroglutamic acid has been investigated. A small library of chiral triazolium ions were synthesised. Each possessed a tertiary alcohol H-bond donor and a variable N-aryl substituent. It was found that increasing both the steric requirement and the electron-withdrawing characteristics of the N-aryl ring led to more chemoselective, efficient and enantioselective chemistry, however both quenching the reaction at different times and deuterium incorporation experiments involving the product revealed that this is complicated by product racemisation in situ (except in the case of benzoin itself), which explains the dependence of enantioselectivity on the electrophilicity of the reacting aldehydes common in the literature. Subsequent protocol optimisation, where one reacting partner was an o-substituted benzaldehyde, allowed a range of crossed-benzoins to be synthesised in moderate-good yields with moderate to excellent enantioselectivity.
- Delany, Eoghan G.,Connon, Stephen J.
-
supporting information
p. 248 - 258
(2021/01/14)
-
- Sol-gel synthesis of ceria-zirconia-based high-entropy oxides as high-promotion catalysts for the synthesis of 1,2-diketones from aldehyde
-
Efficient Lewis-acid-catalyzed direct conversion of aldehydes to 1,2-diketones in the liquid phase was enabled by using newly designed and developed ceria–zirconia-based high-entropy oxides (HEOs) as the actual catalysts. The synergistic effect of various cations incorporated in the same oxide structure (framework) was partially responsible for the efficiency of multicationic materials compared to the corresponding single-cation oxide forms. Furthermore, a clear, linear relationship between the Lewis acidity and the catalytic activity of the HEOs was observed. Due to the developed strategy, exclusively diketone-selective, recyclable, versatile heterogeneous catalytic transformation of aldehydes can be realized under mild reaction conditions.
- Dinjar, Kristijan,Djerdj, Igor,Koj?inovi?, Jelena,Kukovecz, ákos,Markovi?, Berislav,Mileti?, Aleksandar,Nagy, Sándor Balázs,Sapi, Andras,Stenzel, David,Széchenyi, Aleksandar,Szenti, Imre,Tang, Yushu,Tatar, Dalibor,Varga, Gábor,Ziegenheim, Szilveszter
-
supporting information
(2021/10/20)
-
- Responsive Emulsions for Sequential Multienzyme Cascades
-
Multienzyme cascade biocatalysis is an efficient synthetic process, avoiding the isolation/purification of intermediates and shifting the reaction equilibrium to the product side. However, multienzyme systems are often limited by their incompatibility and cross-reactivity. Herein, we report a multi-responsive emulsion to proceed multienzyme reactions sequentially for high reactivity. The emulsion is achieved using a CO2, pH, and thermo-responsive block copolymer as a stabilizer, allowing the on-demand control of emulsion morphology and phase composition. Applying this system to a three-step cascade reaction enables the individual optimal condition for each enzyme, and a high overall conversion (ca. 97 % of the calculated limit) is thereby obtained. Moreover, the multi-responsiveness of the emulsion allows the facile and separate yielding/recycling of products, polymers and active enzymes. Besides, the system could be scaled up with a good yield.
- Sun, Zhiyong,Zhao, Qingcai,Haag, Rainer,Wu, Changzhu
-
p. 8410 - 8414
(2021/03/09)
-
- Synthesis of hydroxy benzoin/benzil analogs and investigation of their antioxidant, antimicrobial, enzyme inhibition, and cytotoxic activities
-
In this study, hydroxy benzoin (1-7), benzil (8-14), and benzoin/benzil-O-β-D-glucosides (15-25) were synthesized to investigate their biological activities. An efficient method for synthesizing hydroxy benzoin compounds (1-7) was prepared from four diffe
- Yayli, Nurettin,Kili?, G?zde,Celik, Gonca,Kahriman, Nuran,Kanbolat, Seyda,Bozdeveci, Arif,Karaoglu, Sengül Alpay,Aliyazicioglu, Rezzan,Sellitepe, Hasan Erdin?,Dogan, Inci Selin,Aydin, Ali
-
p. 788 - 804
(2021/07/26)
-
- Ultrasound-assisted aqueous phase synthesis of benzoin and derivatives thereof
-
The invention relates to a rapid and simple preparation method of benzoin and derivatives thereof. Benzoin and derivatives thereof can be synthesized under the assistance of ultrasonic waves at room temperature under a water phase condition. Taking benzoin as an example, in the operation, benzaldehyde, alkali and a catalyst are subjected to a room-temperature water phase reaction for about 15 minutes, and the product benzoin is separated out; and after filtering is conducted, a raw material benzaldehyde is added, and circular reaction is conducted. The alkali and the catalyst can be recycled. The synthesis route of the benzoin and the derivative is green and environment-friendly, and has a good application prospect in the fields of chemical engineering and medicines.
- -
-
Paragraph 0017-0019
(2021/10/27)
-
- Oxidative carbon-carbon bond cleavage of 1,2-diols to carboxylic acids/ketones by an inorganic-ligand supported iron catalyst
-
The carbon-carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon-carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented.
- Chen, Weiming,Xie, Xin,Zhang, Jian,Qu, Jian,Luo, Can,Lai, Yaozhu,Jiang, Feng,Yu, Han,Wei, Yongge
-
supporting information
p. 9140 - 9146
(2021/11/23)
-
- Iron-catalysed regioselective thienyl C–H/C–H coupling
-
Regioselective thienyl–thienyl coupling is arguably one of the most important transformations for organic electronic materials. A prototype of ideal organic synthesis to couple two thienyl groups by cutting two C–H bonds requires formal removal of two hydrogen atoms with an oxidant, which often limits the synthetic efficiency and versatility for oxidation-sensitive substrates (for example, donor and hole-transporting materials). Here, we found that diethyl oxalate, used together with AlMe3, acts as a two-electron acceptor in an iron-catalysed C–H activation. We describe the regioselective thienyl C–H/C–H coupling with an iron(III) catalyst, a trisphosphine ligand, AlMe3 and diethyl oxalate under mild conditions. The efficient catalytic system accelerated by ligand optimization polymerizes thiophene-containing monomers into homo- and copolymers bearing a variety of electron-donative π motifs. The findings suggest the versatility of iron catalysis for the synthesis of functional polymers, for which the potential of this ubiquitous metal has so far not been fully appreciated. [Figure not available: see fulltext.].
- Doba, Takahiro,Ilies, Laurean,Nakamura, Eiichi,Sato, Wataru,Shang, Rui
-
p. 631 - 638
(2021/07/25)
-
- Method for preparing benzoin in micro-reaction device
-
The invention relates to a method for preparing benzoin in a microreactor. According to the invention, benzaldehyde and sodium cyanide are used as raw materials, and benzoin is prepared through benzoin condensation. According to the preparation method for
- -
-
Paragraph 0018-0035
(2020/05/01)
-
- Synthesis of pentafluorobenzene-based NHC adducts and their catalytic activity in the microwave-assisted reactions of aldehydes
-
N-Heterocyclic carbenes (NHCs) have been widely used in organometallic chemistry as ligands, as well as standalone organocatalysts in various reactions, mostly using aromatic aldehydes as substrates. We have previously demonstrated the efficiency of azolium-2-carboxylate zwitterions in the hydroxymethylation of aldehydes, especially aliphatic aldehydes, under microwave irradiation. In the present work, we report a series of pentafluorobenzene-based NHC adducts and their efficiency in the hydroxymethylation and self-condensation of aliphatic and aromatic aldehydes using microwave irradiation. The free carbenes are released under the reaction conditions and 1,3-dimesityl-2-(perfluorophenyl)imidazolidine and 1,3-bis(2,6-dimethylphenyl)-2-(perfluorophenyl)imidazolidine proved to be the most potent precatalysts.
- Papadaki, Evanthia,Magrioti, Victoria
-
supporting information
(2019/12/24)
-
- N-Heterocyclic Carbene Acyl Anion Organocatalysis by Ball-Milling
-
The ability to conduct N-heterocyclic carbene-catalysed acyl anion chemistry under ball-milling conditions is reported for the first time. This process has been exemplified through applications to intermolecular-benzoin, intramolecular-benzoin, intermolecular-Stetter and intramolecular-Stetter reactions including asymmetric examples and demonstrates that this mode of mechanistically complex organocatalytic reaction can operate under solvent-minimised conditions.
- Nicholson, William I.,Seastram, Alex C.,Iqbal, Saqib A.,Reed-Berendt, Benjamin G.,Morrill, Louis C.,Browne, Duncan L.
-
p. 131 - 135
(2019/12/11)
-
- Bio-inspired NHC-organocatalyzed Stetter reaction in aqueous conditions
-
The first bio-inspired N-Heterocyclic Carbene (NHC)-catalyzed Stetter reaction in aqueous medium is reported with benzaldehyde and chalcone as model substrates. A screening of azolium salts as precatalysts revealed the remarkable efficiency of synthetic thiazolium salt 8 (up to 90% conversion in pure water at 75 °C). The reaction was successfully extended to various simple aldehyde substrates. The effect of temperature was also investigated in order to extend the reaction to lower temperature allowing a potential application to sensitive biomolecules. This study highlighted the influence of both solvent and temperature on the 1,4-diketone 3/benzoin 4 ratio. New precatalysts 26 and 27 were designed and synthesized to explore a possible compartmentalization of the reaction in aqueous conditions. Owing to the use of inexpensive metal-free N-Heterocyclic Carbene (NHC) as a bioinspired catalyst, we anticipate that this green strategy in aqueous conditions will be attractive for bioconjugation of many biomolecule-type aldehydes and enone derivatives. This journal is
- Barthélémy, Philippe,Debiais, Mégane,Desvergnes, Valérie,Drain, Reihana,Hamoud, Aladin
-
p. 40709 - 40718
(2020/11/23)
-
- Scalable Aerobic Oxidation of Alcohols Using Catalytic DDQ/HNO3
-
A selective, practical, and scalable aerobic oxidation of alcohols is described that uses catalytic amounts of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and HNO3, with molecular oxygen serving as the terminal oxidant. The method was successfully applied to the oxidation of a wide range of benzylic, propargylic, and allylic alcohols, including two natural products, namely, carveol and podophyllotoxin. The conditions are also applicable to the selective oxidative deprotection of p-methoxybenzyl ethers.
- Arseniyadis, Stellios,Clavier, Louis,Copin, Chloé,Fournier, Jean,Giffard, Jean-Fran?ois,Jean, Alexandre,Katsina, Tania,Macedo Portela Da Silva, Nayane,Tamion, Rodolphe
-
supporting information
p. 856 - 860
(2020/07/14)
-
- Green preparation method α - hydroxyketone
-
The invention relates to a green preparation method of alpha-hydroxyketone. The method comprises the following steps: adding ketone, iodine, 1,4-diazabicyclo[2.2.2]octane and methanol into a glass reaction bottle in sequence; then stirring and reacting for 14 to 30h at room temperature in an air atmosphere under the irradiation of a 23W compact type fluorescent lamp, so as to obtain a reaction mixture; carrying out silica gel column chromatographic separation to obtain the pure alpha-hydroxyketone. The green preparation method provided by the invention has the characteristics of greenness, high efficiency, simplicity in operation, moderate conditions, wide applicability and easiness for industrialization.
- -
-
Paragraph 0087-0090
(2020/08/27)
-
- 1-butyl-3-methylimidazolium bromide as a solvent and precatalyst for stetter reaction
-
Stetter reaction between aromatic aldehydes and acrylonitrile/ethyl acrylate performing in [Bmim]Br in the presence of NaOH is described. N-Heterocyclic carbene (NHC) generates in situ is shown to be an efficient catalyst. Benzoin condensation also occured as side reaction.
- Phungpis, Baramee,Hahnvajanawong, Viwat
-
p. 2028 - 2032
(2020/09/02)
-
- A Bifunctional Iron Nanocomposite Catalyst for Efficient Oxidation of Alkenes to Ketones and 1,2-Diketones
-
We herein report the fabrication of a bifunctional iron nanocomposite catalyst, in which two catalytically active sites of Fe-Nx and Fe phosphate, as oxidation and Lewis acid sites, were simultaneously integrated into a hierarchical N,P-dual doped porous carbon. As a bifunctional catalyst, it exhibited high efficiency for direct oxidative cleavage of alkenes into ketones or their oxidation into 1,2-diketones with a broad substrate scope and high functional group tolerance using TBHP as the oxidant in water under mild reaction conditions. Furthermore, it could be easily recovered for successive recycling without appreciable loss of activity. Mechanistic studies disclose that the direct oxidation of alkenes proceeds via the formation of an epoxide as intermediate followed by either acid-catalyzed Meinwald rearrangement to give ketones with one carbon shorter or nucleophilic ring-opening to generate 1,2-diketones in a cascade manner. This study not only opens up a fancy pathway in the rational design of Fe-N-C catalysts but also offers a simple and efficient method for accessing industrially important ketones and 1,2-diketones from alkenes in a cost-effective and environmentally benign fashion.
- Ma, Zhiming,Ren, Peng,Song, Tao,Xiao, Jianliang,Yang, Yong,Yuan, Youzhu
-
p. 4617 - 4629
(2020/05/19)
-
- AIR OXIDATION METHOD OF BENZYLIC POSITION OF ORGANIC COMPOUND AND AIR OXIDATION CATALYST
-
PROBLEM TO BE SOLVED: To provide an air oxidation method by which a hydroxy group or oxo group can be introduced by efficient air oxidation of a benzylic position under relatively mild reaction conditions by using a metal complex as a catalyst without a joint use of an additive agent. SOLUTION: An air oxidation method is a method for carrying out air oxidation of a benzylic position of an organic compound having the benzylic position includes bringing the organic compound into contact with molecular oxygen in the presence of a catalyst that is a polynuclear metal complex including two or more kinds of metals. SELECTED DRAWING: None COPYRIGHT: (C)2020,JPO&INPIT
- -
-
Paragraph 0066-0072
(2020/12/01)
-
- Electron Donor-Acceptor Complex-Initiated Photochemical Cyanation for the Preparation of α-Amino Nitriles
-
An electron donor-acceptor complex-initiated α-cyanation of tertiary amines has been described. The reaction protocol provides a novel method to synthesize various α-amino nitriles under mild conditions. The reaction can proceed smoothly without the presence of photocatalysts and transition metal catalysts, and either oxidants are unnecessary or O2 is the only oxidant. The practicality of this method is showcased not only by the late-stage functionalization of natural alkaloid derivatives and pharmaceutical intermediate, but also by the applicability of a stop-flow microtubing reactor.
- Xia, Qing,Li, Yufei,Cheng, Lan,Liang, Xin,Cao, Chenlin,Dai, Peng,Deng, Hongping,Zhang, Weihua,Wang, Qingmin
-
supporting information
p. 9638 - 9643
(2020/12/21)
-
- Fast-Synthesis of α-Phosphonyloxy Ketones as Drug Scaffolds in a Capillary Microreactor
-
A simple, room temperature approach for the fast single-step synthesis of α-phosphonyloxy ketone, a drug scaffold, has been developed which involves highly reactive species i.e., 1,2-dicarbonyls that readily react with trialkyl phosphites and formic acids in batch as well as in continuous-flow with the flow rate of 3 ml/min (tR = ～4 s). The present approach reduced the synthesis time from hours to minutes in batch, which was further lowered to a few seconds precisely controlled by single capillary microfluidics. A wide range of 1,2-dicarbonyl derivatives were smoothly transformed to their corresponding α-phosphonyloxy ketones in moderate to good yields (50–82 %) under optimized flow-reaction conditions. Further, the α-phosphonyloxy ketones produced can be utilized in batch process to form benzoin, oxazole core, and α,α′-diarylated carbonyl compounds in 82 %, 50 %, and 54 % yields, respectively, which are alternative key precursors/scaffolds of natural products and active pharmaceutical ingredients (APIs).
- Ramanjaneyulu, Bandaru T.,Vidyacharan, Shinde,Yim, Se Jun,Kim, Dong-Pyo
-
p. 7730 - 7734
(2019/12/24)
-
- A novel bi-functional surfactant-based paramagnetic deep-eutectic catalyst for improved benzoin condensation and multi-component synthesis of pyrrole derivatives
-
A new professional magnetic surfactant-based deep-eutectic (DE) and viscose liquefy catalyst (GS2+·2FeCl4, MGSFe) was synthesized by an optimized reaction of the as-prepared cationic gemini-surfactant (GS) with two moles of FeCl3·6H2O. The structure of the GS and MGSFe were characterized by NMR, FT-IR, UV–visible, CHN, pH, surface tension (?), and vibrating sample magnetometry (VSM) analyses. The MGSFe, that is a high viscose brownish liquid at >50 °C, was successfully tested as a highly active paramagnetic catalyst for improved benzoin condensation and three-component synthesis of substituted pyrroles with the highest turnover number (TON) and turnover frequency (TOF) that ever reported for this purpose. The superior activity of MGSFe is due to its amphiphile properties, the synergistic effects between GS2+ and 2FeCl4 ? as hydrogen-bond-donor and magnetic hydrogen-bond-acceptor components of this novel magneto-responsive DE, and reusability without loss of activity even in four consequence cycles run for synthesis of pyrroles. This magnetic GS-based DE can be used as oil miscible additive, pollutant adsorbent, and carrier of biomaterials to targeted poisons.
- Tamaddon, Fatemeh,Tadayonfar, SeydEhsan
-
-
- Halogenated 1,2,3-triazole carbene, and preparation method and application thereof
-
The invention provides a halogenated 1,2,3-triazole carbene, and a preparation method and an application thereof. The halogenated 1,2,3-triazole carbene has a structure represented by formula [1]; andin the formula [1], R1 and R2 are independently selecte
- -
-
Paragraph 0162-0166
(2019/10/01)
-
- Benzoin compound preparing method
-
The invention provides a benzoin compound preparing method. Specifically, the benzoin compound preparing method takes mesoporous material immobilized imidazolium salt ion liquid as catalysts to catalyze aromatic aldehydes into various benzoin compounds. T
- -
-
Paragraph 0060; 0061
(2019/05/02)
-
- Redetermination of the Structure of a Water-Soluble Hypervalent Iodine(V) Reagent AIBX and Its Synthetic Utility in the Oxidation of Alcohols and Synthesis of Isoxazoline N-Oxides
-
The structure of a water-soluble hypervalent iodine(V) reagent AIBX is re-examined through its single-crystal X-ray analysis and theoretical calculations including Mayer bond order and localized orbital locator (LOL) and AIBX is believed to be a pseudocyclic iodylarene because of the strong electron-withdrawing nature of the trimethylammonium cation on its phenyl ring, which would decrease the electron density of carboxylic anion and make the ortho-carboxyl oxygen anion incapable to form hypervalent bond with iodine atom. However, the cyclic benziodoxole structure of AIBX could be obtained by adding a Br?nsted acid, which was supported by the calculation result including the increase of Mayer bond order and the shortening of the I-O bond length. Moreover, the fact that the system of AIBX and TFA could oxidize various alcohols to their corresponding carbonyl compounds would indicate that AIBX constitutes a cyclic benziodoxole structure under acidic conditions. In addition, an efficient method has been developed for the synthesis of isoxazoline N-oxides via AIBX-induced dehydrogenative cyclization using β-keto esters as substrates and methyl nitroacetate as a nucleophile.
- Shen, Hui-Jie,Duan, Ya-Nan,Zheng, Ke,Zhang, Chi
-
p. 14381 - 14393
(2019/11/13)
-
- Efficient Oxidation of Benzylic and Aliphatic Alcohols Using a Bioinspired Cross-Bridged Cyclam Manganese Complex with H2O2
-
The cross-bridged cyclam manganese complex Mn(Me2EBC)Cl2 efficiently catalyzes the oxidation of benzylic and aliphatic alcohols at pH 3 in a mixture of acetonitrile and water at room temperature. The environmentally benign and high oxygen content oxidant H2O2 was adopted. Conversions of the alcohols to the corresponding carbonyl compounds reached 98 % with good to excellent selectivity. In addition, several lignin model compounds were also catalytically oxidized under these conditions, with excellent conversion (up to 96 %) and selectivity (up to 99 %).
- Zhang, Zhan,Khrouz, Lhoussain,Yin, Guochuan,Andrioletti, Bruno
-
supporting information
p. 323 - 327
(2018/11/27)
-
- N-Heterocyclic Carbene-Catalyzed Decarboxylative Alkylation of Aldehydes
-
We found that N-heterocyclic carbene catalysis promoted the unprecedented decarboxylative coupling of aryl aldehydes and tertiary or secondary alkyl carboxylic acid-derived redox-active esters to produce aryl alkyl ketones. The mild and transition-metal-free reaction conditions are attractive features of this method. The power of this protocol was demonstrated by the functionalization of pharmaceutical drugs and natural product. A reaction pathway involving single electron transfer from an enolate form of Breslow intermediate to a redox ester followed by recombination of the resultant radical pair to form a carbon-carbon bond is proposed.
- Ishii, Takuya,Kakeno, Yuki,Nagao, Kazunori,Ohmiya, Hirohisa
-
supporting information
p. 3854 - 3858
(2019/04/25)
-
- Development of an imidazole salt catalytic system for the preparation of bis(indolyl) methanes and bis(naphthyl)methane
-
Imidazolium salts are shown to catalyze the rapid room temperature reaction of indoles or naphthol with aldehydes to provide bis(indolyl)methanes or bis(naphthol)methane in excellent yields and the reaction proceeds optimally in dichloromethane with no base additives. The reaction exhibits a broad substrate tolerance and occurs through nucleophilic activation of the indoles and naphthols through a cation–π interaction.
- Wang, Xu,Aldrich, Courtney C.
-
-
- Bioinspired models for an unusual 3-histidine motif of diketone dioxygenase enzyme
-
Bioinspired models for contrasting the electronic nature of neutral tris-histidine with the anionic 2-histidine-1-carboxylate facial motif and their subsequent impact on catalysis are reported. Herewith, iron(ii) complexes [Fe(L)(CH3CN)3](SO3CF3)21-3 of tris(2-pyridyl)-based ligands (L) have been synthesized and characterized as accurate structural models for the neutral 3-histidine triad of the enzyme diketone dioxygenase (DKDO). The molecular structure of one of the complexes exhibits octahedral coordination geometry and Fe-N11py bond lengths [1.952(4) to 1.959(4) ?] close to the Fe-NHis bond distances (1.98 ?) of the 3-His triad in the resting state of the enzyme, as obtained by EXAFS studies. The diketonate substrate-adduct complexes [Fe(L)(acacR)](SO3CF3) (R = Me, Ph) of 1-3 have been obtained using Na(acacR) in acetonitrile. The Fe2+/3+ redox potentials of the complexes (1.05 to 1.2 V vs. Fc/Fc+) and their substrate adducts (1.02 to 1.19 V vs. Fc/Fc+) appeared at almost the same redox barrier. All diketonate adducts exhibit two Fe(ii) → acac MLCT bands around 338 to 348 and 430 to 490 nm. Exposure of these adducts to O2 results in the decay of both MLCT bands with a rate of (kO2) 5.37 to 9.41 × 10-3 M-1 s-1. The kO2 values were concomitantly accelerated 20 to 50 fold by the addition of H+ (acetic acid), which nicely models the rate enhancement in the enzyme kinetics by the glutamate residue (Glu98). The oxygenation of the phenyl-substituted adducts yielded benzoin and benzoic acid (40% to 71%) as cleavage products in the presence of H+ ions. Isotope-labeling experiments using 18O2 showed 47% incorporation of 18O in benzoic acid, which reveals that the oxygen originates from dioxygen. Thus, the present model complexes exhibit very similar chemical surroundings to the active site of DKDO and mimic its functions elegantly. On the basis of these results, the C-C bond cleavage reaction mechanism is discussed.
- Ramasubramanian, Ramamoorthy,Anandababu, Karunanithi,M?sch-Zanetti, Nadia C.,Belaj, Ferdinand,Mayilmurugan, Ramasamy
-
supporting information
p. 14326 - 14336
(2019/10/11)
-
- Coupling of Sulfoxonium Ylides with Arynes: A Direct Synthesis of Pro-Chiral Aryl Ketosulfoxonium Ylides and Its Application in the Preparation of α-Aryl Ketones
-
A general, mild, and versatile synthesis of the challenging α-aryl-β-ketosulfoxonium ylides has been developed for the first time, substituting traditional methods starting from diazo compounds. The arylation of easily accessible β-ketosulfoxonium ylides using aryne chemistry allowed the preparation of a large scope of the pro-chiral ylides in very good yields (40 examples; up to 85%). As applications, these ylides were smoothly converted into α-aryl ketones after desulfurization in good yields (up to 98%) as well as in other important derivatives.
- Talero, Alexánder Garay,Martins, Bruna Sim?es,Burtoloso, Antonio C. B.
-
p. 7206 - 7211
(2018/11/23)
-
- Method of reducing carbonyl compound into alcohol in air atmosphere at room temperature
-
The invention belongs to the field of organic synthesis and relates to a method of reducing carbonyl compound into alcohol in air atmosphere at room temperature. The method includes: firstly, adding methanol, a catalyst and the carbonyl compound into a reaction bottle and slowly adding silane into the reaction bottle, magnetically stirring the components and carrying out a reaction for 10 min to 8hours in air atmosphere at room temperature to obtain a mixture containing a benzyl compound after the reaction is finished; secondly, extracting the mixture containing the benzyl compound with an extraction agent dichloromethane, mixing organic phases, and washing the organic phases with a washing agent deionized water, drying the organic phases with anhydrous sodium sulfate, and evaporating theorganic phases to remove a solvent and obtain a crude product of a benzyl alcohol compound; finally, separating and purifying the crude product through column chromatography to prepare a pure productof the benzyl alcohol compound. In the method, a reducing agent is low in toxicity and is clean and environment-friendly. The method is free of a noble metal catalyst and is low in cost, is gentle inreaction conditions, and can reach high selectivity and yield.
- -
-
Paragraph 0070; 0071
(2019/01/08)
-
- “Inverse” Frustrated Lewis Pairs: An Inverse FLP Approach to the Catalytic Metal Free Hydrogenation of Ketones
-
For the first time have boron-containing weak Lewis acids been demonstrated to be active components of Frustrated Lewis Pair (FLP) catalysts in the hydrogenation of ketones to alcohols. Combining the organosuperbase (pyrr)3P=NtBu with the Lewis acid 9-(4-CF3-C6H4)-BBN generated an “inverse” FLP catalyst capable of hydrogenating a range of aliphatic and aromatic ketones including N-, O- and S-functionalized substrates and bio-mass derived ethyl levulinate. Initial computational and experimental studies indicate the mechanism of catalytic hydrogenation with “inverse” FLPs to be different from conventional FLP catalysts that contain strong Lewis acids such as B(C6F5)3.
- Mummadi, Suresh,Brar, Amandeep,Wang, Guoqiang,Kenefake, Dustin,Diaz, Rony,Unruh, Daniel K.,Li, Shuhua,Krempner, Clemens
-
supporting information
p. 16526 - 16531
(2018/10/20)
-
- Oxazolium Salts as Organocatalysts for the Umpolung of Aldehydes
-
Oxazolium salts were successfully employed for the first time as organocatalysts for benzoin, Stetter, and redox esterification reactions. An N-mesityl oxazolium salt catalyzed homobenzoin reaction of aromatic, heteroaromatic, and aliphatic aldehydes delivered α-hydroxy ketones in high yields. This new type of catalyst proved remarkably effective for the Stetter reaction of challenging substrates such as β-alkyl-α,β-unsaturated ketones and electron-rich aromatic aldehydes in comparison to common thiazolium and triazolium salts.
- Garapati, Venkata Krishna Rao,Gravel, Michel
-
supporting information
p. 6372 - 6375
(2018/10/15)
-
- Highly chemoselective intermolecular cross-benzoin reactions using an: Ad hoc designed novel N-heterocyclic carbene catalyst
-
The design of a novel N-heterocyclic carbene catalyst incorporating a bulky yet highly electron-deficient N-aryl substituent has allowed the development of an efficient protocol for the first highly chemoselective intermolecular benzoin condensations between two non-identical aromatic aldehydes.
- Delany, Eoghan G.,Connon, Stephen J.
-
supporting information
p. 780 - 786
(2018/02/09)
-
- Lewis acid-mediated defluorinative [3+2] cycloaddition/aromatization cascade of 2,2-difluoroethanol systems with nitriles
-
The properties of C?F bonds, including high thermal and chemical stability, make derivatization of organic fluorine-containing compounds by the activation of the C?F bond and subsequent functionalization quite challenging. We herein report a Lewis acid-mediated defluorinative cycloaddition/aromatization cascade of 2,2-difluoroethanols with nitriles as a novel synthetic method for the preparation of 2,4,5-trisubstituted oxazoles. This reaction, which involves cleavage of two C?F bonds and the consecutive formation of C?O and C?N bonds in a one-pot fashion, features a broad substrate scope and moderate to high reaction yields. Mechanistic studies revealed that the reaction is initiated by the Lewis acid-mediated ring closure of the 2,2-difluoroethanol to produce the fluoroepoxide intermediate. (Figure presented.).
- Hsieh, Min-Tsang,Lee, Kuo-Hsiung,Kuo, Sheng-Chu,Lin, Hui-Chang
-
p. 1605 - 1610
(2018/03/05)
-
- Metal-free catalytic enantioselective silylation of aromatic aldehydes in water
-
An environmentally friendly and transition metal-free method for the preparation of chiral α-hydroxysilanes was developed. Enantioselective addition of a silicon nucleophile to aromatic aldehydes in water was achieved by using a new hydroxyl-functionalized chiral carbene as catalyst, affording the corresponding products in good yields and moderate enantioselectivities.
- Huo, Yuwen,Shen, Panpan,Duan, Wenzeng,Chen, Zhen,Song, Chun,Ma, Yudao
-
p. 1359 - 1362
(2018/01/02)
-
- An efficient synthesis of triazolium ion based NHC precursors using diaryliodonium salts and their photophysical properties
-
Copper-catalysed N-arylation of fused triazoles using diaryliodonium salts as an aryl source is described. This scalable protocol displayed good compatibility towards diverse sensitive functional groups like ester, alkyl and nitro groups and halogens (F, Cl, Br). The synthetic usefulness of the prepared triazolium salts was proved by preparing α-hydroxyketone through benzoin condensation. Photophysical studies of these compounds showed promising Stokes-shifted fluorescence emission in aqueous medium, so this molecular framework could be a proficient probe for biological applications.
- Pilania, Meenakshi,Rohman, Mostofa Ataur,Arun,Mehra, Manish Kumar,Mitra, Sivaprasad,Kumar, Dalip
-
supporting information
p. 7340 - 7345
(2018/10/24)
-
- Catalytic enantioselective radical coupling of activated ketones with: N -aryl glycines
-
Asymmetric H-bonding catalysis as a viable strategy for enantioselective radical coupling of ketones is demonstrated. With a visible-light-mediated dual catalytic system involving a dicyanopyrazine-derived chromophore (DPZ) photosensitizer and a chiral phosphoric acid (CPA), N-aryl glycines with a variety of 1,2-diketones and isatins underwent a redox-neutral radical coupling process and furnished two series of valuable chiral 1,2-amino tertiary alcohols in high yields with good to excellent enantioselectivities (up to 97% ee). In this catalysis platform, the formation of neutral radical intermediates between ketyl and H-bonding catalyst CPA is responsible for presenting stereocontrolling factors. Its success in this work should provide inspiration for expansion to other readily accessible ketones to react with various radical species, thus leading to a productive approach to access chiral tertiary alcohol derivatives.
- Liu, Yang,Liu, Xiangyuan,Li, Jiangtao,Zhao, Xiaowei,Qiao, Baokun,Jiang, Zhiyong
-
p. 8094 - 8098
(2018/11/20)
-
- An iodine/DMSO-catalyzed sequential one-pot approach to 2,4,5-trisubstituted-1H-imidazoles from α-methylene ketones
-
A sequential one-pot approach to 2,4,5-trisubstituted imidazoles has been developed from α-methylene ketones and aldehydes. This methodology employs air-moisture stable reaction conditions and an inexpensive iodine/DMSO system affording a diverse range of known and novel (substrate scope) 2,4,5-trisubstituted imidazoles in moderate to excellent yields. The iodine/DMSO system was extended to the domino convergent synthesis of two functionalized intermediates, benzil and benzaldehyde, to produce the final product.
- Jayram, Janeeka,Jeena, Vineet
-
p. 37557 - 37563
(2018/11/26)
-
- NaBrO3/bmim[HSO4]: a versatile system for the selective oxidation of 1,2-diols, α-hydroxyketones, and alcohols
-
Abstract: Sodium bromate with bmim[HSO4] has been found to be an excellent oxidizing agent in aqueous medium. NaBrO3:bmim[HSO4] oxidized 1,2-diols, α-hydroxyketones, and alcohols to the corresponding carbonyl compounds in excellent yields. This method offers advantages such as low cost reagents, aqueous reaction conditions, moderate temperatures and short reaction times and hence environmentally benign reaction. Moreover, the ionic liquid bmim[HSO4] could be recycled for at least three times without loss of significant activity. Graphical abstract: [Figure not available: see fulltext.]
- Khurana, Jitender M.,Lumb, Anshika,Chaudhary, Ankita
-
p. 381 - 386
(2017/02/10)
-
