- Isochroman-3-ones ones via site-selective ring opening of benzocyclobutenones promoted by lithium tetramethylpiperidide and reaction with aromatic aldehydes
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In the presence of Li-TMP and an aromatic aldehyde, benzocyclobutenone undergoes an unusual heterolytic C(1)-C(4) bond fission, and subsequent reaction with the aldehyde gives, after acidic workup, isochroman-3-one in high yield.
- Matsumoto, Takashi,Hamura, Toshiyuki,Kuriyama, Yokusu,Suzuki, Keisuke
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- CSJ acting as a versatile highly efficient greener resource for organic transformations
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Simple, new, greener and efficient alternatives to the existing protocols have been developed for the reduction of aromatic aldehydes to their corresponding alcohols, decarboxylation of substituted benzoic acids (C6-C1) and substituted cinnamic acids (C6-C3) with a hydroxyl group at the para position with respect to the acid group to corresponding phenolic compounds and vinyl phenols respectively by using a natural feedstock, cucumber juice (CSJ), which acts as a greener solvent system, performing a substrate-selective reaction. Additionally, the hydrolysis of the acetyl as well as the benzoyl group of aromatic compounds has been carried out to afford excellent yield by CSJ.
- Maity, Himadri Sekhar,Misra, Kaushik,Mahata, Tanushree,Nag, Ahindra
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- Comparative study on reducing aromatic aldehydes by using ammonia borane and lithium amidoborane as reducing reagents
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Lithium amidoborane (LiNH2BH3) and ammonia borane (NH3BH3) reduce aromatic aldehydes in tetrahydrofuran (THF) through two different pathways. LiNH2BH3 only transfers hydridic hydrogen on boron to aldehydes through a hydroboration process to achieve lithium aminoborate; ammonia borane, on the other hand, transfers both protic and hydridic hydrogens on N and B, respectively, to aldehydes to directly achieve corresponding alcohols. Mechanistic investigations confirm that protic H(N) and hydridic H(B) of ammonia borane participate in the reduction, in which the dissociation of both B-H and N-H bonds is likely to be involved in the rate-determining step. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012.
- Xu, Weiliang,Fan, Hongjun,Wu, Guotao,Chen, Ping
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- Water as a green solvent for fast and efficient reduction of carbonyl compounds with NaBH4 under microwave irradiation
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Reduction of varieties of carbonyl compounds such as aldehydes, ketones, α,β-unsaturated aldehydes and ketones, α-diketones and acyloins was carried out very fast and efficiently by sodium borohydride in water under microwave irradiation. The corresponding product alcohols were obtained in high to excellent yields.
- Zeynizadeh, Behzad,Setamdideh, Davood
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- Homoleptic Zinc-Catalyzed Hydroboration of Aldehydes and Ketones in the Presence of HBpin
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Here, we report the reaction between N-phenyl-o-phenylenediamine and pyrrole-2-carboxaldehyde to afford the N-phenyl-o-phenyl-enediiminopyrrole ligand {L-H2} in quantitative yield. A one-pot reaction between {L-H2} and diethylzinc (ZnEt2) in a 2:1 ratio afforded the homoleptic zinc metal complex [{L-H}2Zn] (1). The solid-state structures of ligand {L-H2} and zinc complex 1 were confirmed using X-ray crystallography. Further, complex 1 was used for chemoselective hydroboration of aldehydes and ketones in the presence of pinacolborane (HBpin) at ambient temperature to produce the corresponding boronate esters in high yield.
- Kumar, Gobbilla Sai,Harinath, Adimulam,Narvariya, Rajrani,Panda, Tarun K.
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- Potassium formate as a small molecule switch: Controlling oxidation-reduction behaviour in a two-step sequence
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A one-pot reaction sequence is described in which the addition of one compound allowed switching between simultaneously occurring oxidation and reduction reactions.
- Willemsen, Jorgen S.,Van Hest, Jan C. M.,Rutjes, Floris P. J. T.
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- Arylboronic acid-facilitated selective reduction of aldehydes by tributyltin hydride
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Aldehydes were selectively reduced in the presence of a ketone with tributyltin hydride (n-Bu3SnH) and arylboronic acids. The double bond of an α-β-unsaturated system was not affected under the reaction conditions.
- Yu,Wang
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- Modified hydroborate agent: (2,2′-bipyridyl)(tetrahydroborato)zinc complex, [Zn(BH4)2(bpy)], as a new, stable, efficient ligand-metal hydroborate and chemoselective reducing agent
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(2,2′-Bipyridyl)(tetrahydroborato)zinc complex, [Zn(BH4)2(bpy)], is a new white stable compound which has been used for efficient reduction of variety of carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and α, β-unsaturated carbonyl compounds (1,2-reduction) to their corresponding alcohols in acetonitrile at room temperature. Excellent chemoselectivity was also observed for the reduction of aldehydes over ketones with this reducing agent.
- Zeynizadeh, Behzad
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- High loading polymer reagents based on polycationic Ultraresins. Polymer-supported reductions and oxidations with increased efficiency
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Ultraresin 1 was prepared from highly branched polyethylene imine (M n=10,000) via reductive cross-linking with terephthaldialdehyde. Following quaternization with methyl iodide, the polycationic Ultraresin 2, with iodide as a counterion, was obtained. These novel resins combine low swelling with high mechanical stability. By anion exchange polycationic Ultraresins carrying borohydride (3) and periodate (22) were generated and were investigated as very high loading polymer reagents. Ultra-borohydride resin 3 had a reducing activity of up to 12 mmol/g depending on the substrate. It proved successful in diverse reductions including those of aldehydes, ketones, and nitroolefines. The resin was employed in the reductive amination of aldehydes with an excess of amines, which were removed by the use of a scavenger resin. Periodate resin 22 was obtained with an active loading of up to 5.4 mmol/g and was employed in oxidations of sulfides, diols, hydroquinones, and hydrazines.
- Barth, Michael,Shah, Syed Tasadaque Ali,Rademann, J?rg
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- Highly efficient conversion of benzoates to alcohols with sodium borohydride in DME-MeOH
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Methoxybenzoates were quantitatively reduced to the corresponding alcohols with sodium borohydride in a mixed solvent (DME-MeOH). The described method was applicable to a large scale synthesis.
- Zanka, Atsuhiko,Ohmori, Hiroki,Okamoto, Takumi
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- A convenient nickel-catalysed hydrosilylation of carbonyl derivatives
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Hydrosilylation of aldehydes and ketones catalysed by nickel acetate and tricyclohexylphosphine as the catalytic system was demonstrated using polymethylhydrosiloxane as a cheap reducing reagent. The Royal Society of Chemistry 2013.
- Zheng, Jianxia,Darcel, Christophe,Sortais, Jean-Baptiste
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- CuCl2.2H2O MeOH. A new reagent system for the deprotection of tetrahydropyranyl ethers
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Cupric chloride dihydrate in methanol cleave the tetrahydropyranyl ethers to the corresponding alcohols in excellent yields under mild conditions.
- Davis, K. Joju,Bhalerao,Vittal Rao
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- An Efficient, Stable and Reusable Palladium Nanocatalyst: Chemoselective Reduction of Aldehydes with Molecular Hydrogen in Water
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Palladium nanoparticles (Pd-BNP) stabilized by a binaphthyl-backbone can be efficiently used for the chemoselective reduction of aldehydes in the presence of hydrogen at room temperature in water. The Pd-BNP catalyst is easily recovered and reused for five catalytic cycles. (Figure presented.).
- Kotha, Surya Srinivas,Sharma, Nidhi,Sekar, Govindasamy
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- In pursuit of fluorinated sigma receptor ligand candidates related to [18F]-FPS
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This paper describes the synthesis of N-arylmethyl(1-benzyl) and N-aroyl(1-benzoyl) 4-(4-fluoromethylphenoxymethyl)piperidines as potential sigma receptor ligands analogous to the potent and highly selective sigma-1 ligand [18F]-FPS, but with enhanced or alternative binding and transport profiles. The synthesis involves N-aroylation of 4-hydroxmethylpiperidine or ethyl nipecotate, functional group manipulation of the ester group or simple activation of the hydroxyl group to introduce the phenoxy component, and subsequent functional group manipulation to reduce the amide group and introduce the fluorine into the fluoromethyl substituent. In its development, the synthesis was found to require early N-aroylation of the piperidine precursor to avoid complications due to anchimeric assistance by its nitrogen in subsequent displacement reactions. New evidence is presented on the pathway followed in a literature report of direct displacement of a benzylic hydroxyl group by fluoride ion under Appel-like conditions. Relevant to the literature report, the halide ion in the fluoromethylphenoxy 1-benzylpiperidine derivatives was surprisingly labile to hydrolytic displacement on chromatography and this aspect is worthy of further study. Moreover, the NMR spectra of the amides were complicated by geometric isomerism about the amide C(O)-N bond, but detailed analysis of spectra from 2-anisoyl derivatives allowed the assignment of diastereomeric contributors to consistent, secondary atropisomerism about the aryl-C(O) bond.
- Jwad, Rasha S.,Pang, Alan H. C.,Hunter, Luke,Read, Roger W.
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- Synthesis and rearrangement of N-organyloxy β-lactams derived from a (4+2)/(3+2) sequential cycloaddition reaction involving enol ethers and nitro alkenes
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The synthesis of N-organyloxy β-lactams 2 by treatment of nitroso acetals 1 with a base is discussed. Based on the formation of a by-product, a mechanism for the rearrangement to N-organyloxy β-lactams is proposed. This mechanism is supported by trapping of the intermediate acyl nitro compound 8 with dimethylamine. Furthermore, it was discovered that upon more forcing basic conditions these N-organyloxy β-lactams can rearrange further to 3-organyloxy β-lactams. By using a series of structurally diverse N-organyloxy β-lactams the generality of this novel rearrangement is demonstrated. A mechanism for the conversion of N-organyloxy β-lactams to 3-organyloxy β-lactams is proposed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Van Berkom, Leon W. A.,Kuster, George J. T.,De Gelder, Rene,Scheeren, Hans W.
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- Solvolytic Reactions in Fluorinated Alcohols. Role of Nucleophilic and Other Solvation Effects
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Rate constants and products for solvolyses of chlorodiphenylmethane (Ph2CHCl) and p-methoxybenzyl chloride in 2,2,2-trifluoroethanol (TFE)/water and TFE/ethanol are reported, along with additional kinetic data for solvolyses of tert-butyl and other alkyl halides (RX) in 97% w/w TFE/water and in 97% w/w hexafluoropropan-2-ol/water (HFIP). Results are discussed in terms of the solvent ionizing power (Y) and the solvent nucleophilicity (N), and contributions from other solvation effects are considered. Comparisons with other SN1 solvolyses show that solvolyses of Ph2CHCl in TFE mixtures are unexpectedly fast, but product ratios are unexceptional. An additional solvation effect influences solvolyses leading to delocalized cations, and a delocalized cationic transition state for concerted elimination may explain the recent results of Takeuchi et al., (J. Org. Chem. 1997, 62, 4904) without the need to postulate additional specific solvation effects for adamantyl systems, such as Bronsted-base solvation of α- and β-hydrogen atoms; concerted elimination may occur because simple tertiary alkyl cations are too unstable to form in predominantly aqueous media. Iodide/bromide and bromide/chloride rate ratios are very similar for 1-adamantyl halides and corresponding solvolyses of tert-butyl halides; these ratios decrease in the order aq EtOH > TFE > HFIP, as expected for an electrophilic solvation effect (this effect can readily be incorporated into Y values). From kinetic data for a series of tertiary alkyl chlorides in 97% TFE/water, it is shown that the susceptibility of rates of solvolyses of RCl to N decreases with an increase in steric hindrance or with an increase in charge stabilization. Also, the small kinetic solvent isotope effects for typical solvolyses (e.g., methyl tosylate) indicate that nucleophilic attack lags behind heterolysis of the C-X bond.
- Bentley, T. William,Llewellyn, Gareth,Ryu, Zoon Ha
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- Microwave induced an efficient synthesis of alcohols via cross-Cannizzaro reaction
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Aromatic aldehydes 1 are converted to alcohols 2 by cross-Cannizzaro reactions under microwave irradiations in dry media within 20-25 sec. in excellent yields.
- Thakuria, Julfikar Ali,Baruah, Mukulesh,Sandhu, Jagir Singh
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- Hydrosilylation of aldehydes and ketones catalyzed by [Ph3P(CuH)]6
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Exposure of an aldehyde or ketone to ≤ 5 mol% (in copper) of Stryker's reagent [Ph3P(CuH)]6 in the presence of one of several silanes affords the corresponding protected alcohol in high yields. Aldehydes can be cleanly reduced in the presence of ketones.
- Lipshutz, Bruce H.,Chrisman, Will,Noson, Kevin
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- Easy and partial hydrogenation of aromatic carbonyls to benzyl alcohols using Pd/C(en)-catalyst
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Although 10% Pd/C catalyzed hydrogenolysis of aromatic ketones and aldehydes readily affords methylene compounds via intermediary benzyl alcohols, the employment of 10% Pd/C-ethylenediamine complex [Pd/C(en)] as a catalyst eased the formation of benzyl alcohols.
- Sajiki, Hironao,Hattori, Kazuyuki,Hirota, Kosaku
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- Silica triflate as a new, efficient, and reusable reagent for the chemoselective silylation of alcohols and phenols and deprotection of silyl ethers
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Silica triflate was easily prepared via reaction of silica gel and trifluoromethane sulfonyl chloride at room temperature. This compound can be employed as an efficient and reusable reagent for the chemoselective silylation of alcohols and phenols in solution and under solvent-free conditions. This reagent also effectively catalyzed the deprotection of silyl ethers in refluxing methanol.
- Shirini,Marjani,Nahzomi, H. Taherpour,Zolfigol
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- Wet THF as a suitable solvent for a mild and convenient reduction of carbonyl compounds with NaBH4
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NaBH4 in wet THF can readily reduce varieties of carbonyl compounds such as aldehydes, ketones, conjugated enones, acyloins, and α-diketones to their corresponding alcohols in good to excellent yields. Reduction reactions were performed at room temperature or under reflux condition. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing system.
- Zeynizadeh, Behzad,Behyar, Tarifeh
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- Oxidation of Benzyltrialkylstannanes by Iodosylbenzene Catalyzed by Iron Tetrakis(pentafluorophenyl)porphyrin Chloride. Possible Role of Benzyloxy Radicals
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The oxidations of some benzyltrialkylstannanes by iodosylbenzene induced by tetrakis(pentafluorophenyl)porphyrin chloride (TPFP)FeCl have been investigated.Benzaldehydes and benzyl alcohols are the main reaction products, accompanied by minor amounts of 1,2-diarylethanes and benzyl chlorides.A mechanism seems likely involving the formation of a benzyltrialkylstannane cation radical, which undergoes C-Sn bond cleavage to afford a benzyl radical.The formation of 1,2-diarylethane from this radical is straightforward, whereas it is suggested that benzyl alcohol and benzaldehyde result from the disproportionation of a benzyloxy radical, formed in a oxygen transfer reaction from iodosylbenzene to the benzyl radical.In CH2Cl2, benzyl alcohol can also be the result of hydrogen atom abstraction from the solvent by the benzyloxy radical.
- Baciocchi, Enrico,Ioele, Marcella
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- Functionalized cyclobutenes via multicomponent thermal [2 + 2] cycloaddition reactions
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(Chemical Equation Presented) Enamine [2 + 2] cycloadditions can be achieved in useful yields simply by stirring a mixture of an aldehyde, diethylamine, a dialkyl fumarate, and potassium carbonate in acetonitrile at 25°C, conditions that are compatible with the presence of a potential leaving group on the β-position of the intermediate enamine. Methylation and elimination of the product cyclobutanes completes a mild nonphotochemical route to functionalized cyclobutenes.
- Sheldrake, Helen M.,Wallace, Timothy W.,Wilson, Craig P.
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- Late-Stage Solubilization of Poorly Soluble Peptides Using Hydrazide Chemistry
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A novel late-stage solubilization of peptides using hydrazides is described. A solubilizing tag was attached through a selective N-alkylation at a hydrazide moiety with the aid of a 2-picoline-borane complex in 50% acetic acid-hexafluoro-2-propanol. The tag, which tolerates ligation and desulfurization conditions, can be detached by a Cu-mediated selective oxidative hydrolysis of the N-alkyl hydrazide. This new method was validated through the synthesis of HIV-1 protease.
- Sato, Kohei,Tanaka, Shoko,Wang, Junzhen,Ishikawa, Kenya,Tsuda, Shugo,Narumi, Tetsuo,Yoshiya, Taku,Mase, Nobuyuki
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- Efficient method for tetrahydropyranylation of alcohols and phenols and deprotection of THP ethers using H14[NaP5W 30O110] as a Green Catalyst
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A simple and effective method for tetrahydropyranylation of alcohols and phenols and the regeneration of THP ethers using a catalytic amount of H 14[NaP5W30O110] is reported. Copyright Taylor & Francis Group, LLC.
- Heravi, Majid M.,Haghighi, Masoumeh,Derikvand, Fatemeh,Bamoharram, Fatemeh F.
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- (PhCH2PPh3)+Br3-: A versatile reagent for the preparation, deprotection, and oxidation of trimethylsilyl ethers
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Benzyltriphenylphosphonium tribromide (BTPTB), as a stable solid reagent, is easily prepared by the reaction of benzyltriphenylphosphonium bromide with Br2. This reagent can be used as an efficient catalyst for the conversion of alcohols to their corresponding trimethylsilyl ethers (TMS ethers) with hexamethyldisilazane (HMDS). Desilylation of TMS ethers is also catalyzed by BTPTB in MeOH at room temperature in high yields. BTPTB is also able to oxidize the TMS ethers to their corresponding carbonyl compounds in a mixture of MeOH/H2O in good to high yields. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.
- Shirini,Imanzadeh,Mousazadeh,Mohammadpoor-Baltork,Aliakbar,Abedini
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- A new alternative to Stryker's reagent in hydrosilylation: Synthesis, structure, and reactivity of a well-defined carbene-copper(II) acetate complex
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A new, air stable and well-defined carbene-copper(II) complex has been prepared, which is an efficient precatalyst for the 1,2- and 1,4-reduction of carbonyl compounds under hydrosilylation conditions. The Royal Society of Chemistry 2005.
- Yun, Jaesook,Kim, Daesung,Yun, Hoseop
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- THIOETHER PROTECTION VIA SELECTIVELY CLEAVABLE SULFONIUM SALTS
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There are few protecting groups available for the thioether functionality.The selective cleavage of 4-phthalimidobutyl- and p-methoxybenzylsulfonium salts make these derivatives ideal for thioether protection.
- Doi, Joyce Takahashi,Luehr, Gary W.
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- A novel Cu(II)-Mg-system for allylation and reduction of carbonyl compounds
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Allylation of a variety of carbonyl compounds with allylic halides could be induced by Cu(II)-Mg to give corresponding homoallylic alcohols with high chemoselectivity. Cu(II)-Mg/THF-H2O was found to be an efficient reduction system of aldehyde to alcohol.
- Sarangi,Sarangi, Chintamani,Nayak,Nayak, Amalendu,Nanda,Nanda, Bhagabat,Das,Das, Nalin B.,Sharma,Sharma, Ram P.
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- Oxidative decarboxylation of 4-methoxyphenylacetic acid induced by potassium 12-tungstocobalt(III)ate. The role of intramolecular electron transfer
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A kinetic study of the oxidation of 4-methoxyphenylacetic acid (AnCH2CO2H: An = 4-MeOC6H4) with potassium 12-tungstocobalt(III)ate (K5[CoIIIW12O40] ≡ CoIIIW) has been carried out in aqueous solution at different pH values (between 2.15 and 4.98). The reaction proceeds via a rate determining electron transfer, followed by a fast decarboxylation step leading to a 4-methoxybenzyl radical. From the analysis of the kinetic data the rate constants for reaction of CoIIIW with AnCH2CO2H and AnCH2CO2- respectively, k1 and k2, have been derived as k1 = 0.109 M-1 s-1 and k2 = 2.948 M-1 s-1, indicating that in the oxidation of 4-methoxyphenylacetic acid by CoIIIW, ionization of the carboxylic group results in an almost 30-fold acceleration of the decarboxylation rate. In order to explain this behavior, it is proposed that no aromatic radical cation is formed as a reaction intermediate, electron removal from the aromatic ring being instead concerted with an intramolecular side-chain to nucleus electron transfer, directly leading to a carboxyl radical which then undergoes rapid decarboxylation to give the 4-methoxybenzyl radical.
- Baciocchi, Enrico,Bietti, Massimo
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- Zn(BH4)2/Al2O3: A new synthetic method for the efficient and convenient reduction of organic carbonyl compounds to their corresponding alcohols
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Zn(BH4)2 (0.5-2 mmol) in the presence of Al 2O3 (1 mmol) reduces a variety of organic carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and α,β-unsaturated carbonyl compounds to their corresponding alcohols. The reduction reactions were realized in THF at room temperature affording high to excellent yields of the products. The chemoselective reduction of aldehydes over ketones was successfully accomplished with this reducing system. In addition, regioselectivity and exclusive 1,2-reduction of conjugated carbonyl compounds to their corresponding allylic alcohols in high to excellent yields was successfully accomplished.
- Setamdideh, Davood,Khezri, Behrooz,Rahmatollahzadeh, Mehdi
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- An efficient and highly selective deprotecting method for β-(trimethylsilyl)ethoxymethyl ethers
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A series of β-(trimethylsilyl)ethoxymethyl ethers were hydrolyzed to their corresponding alcohols in high yields by using a catalytic amount of CBr4 (15%) in MeOH under refluxing reaction conditions. The chemoselective deprotection between trialkylsilyl and β-(trimethylsilyl)-ethoxymethyl-protected alcohols can be achieved by using an alcohol with steric hindrance such as iPrOH. The selectivity also can be achieved in the CBr4/MeOH reaction mixture under ultrasonic reaction conditions.
- Chen, Ming-Yi,Lee, Adam Shih-Yuan
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- An iron-catalysed hydrosilylation of ketones
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The combination of Fe(OAc)2 and multi-nitrogen-based ligands such as N,N,N′,N′-tetramethyethylenediamine, bis-tert-butyl- bipyridine, or bis(oxazolinyl)pyridine can efficiently catalyse hydrosilylation of ketones to give the corresponding alcohols in high yields including asymmetric catalysis. The Royal Society of Chemistry.
- Nishiyama, Hisao,Furuta, Akihiro
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- NaBH4/NaHSO4·H2O a heterogeneous acidic system for a mild and convenient reduction of carbonyl compounds under protic condition
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NaBH4 in the presence of sodium bisulfate (NaHSO 4·H2O), a weakly acidic reagent, efficiently reduces a variety of carbonyl compounds such as aldehydes, ketones, α, β-unsaturated aldehydes and ketones, α-diketones and acyloins to their corresponding alcohols in acetonitrile under heterogeneous condition. Reduction reactions were accomplished at room temperature or under reflux condition.
- Zeynizadeh, Behzad,Behyar, Tarifen
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- CHEMOSELECTIVE REDUCTION OF ALDEHYDES WITH TETRA-n-BUTYLAMMONIUM TRIACETOXYBOROHYDRIDE
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Aldehydes, but not ketones, are smoothly reduced to alcohols by tetra-n-butylammonium triacetoxyborohydride in refluxing benzene.
- Nutaitis, Charles F.,Gribble, Gordon W.
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- Effect of the niobium state on the properties of NbSiBEA as bifunctional catalysts for gas- and liquid-phase tandem processes
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NbSiBEA zeolites contained isolated framework mononuclear Nb(V) (Nb0.7SiBEA) and a mixture of framework mononuclear and extra-framework polynuclear Nb(V) (Nb2.0SiBEA) were prepared by two-step postsynthesis method as evidenced by XRD, NMR, DR UV–vis and FTIR. DR UV–vis showed that two types of framework mononuclear Nb(V) are present in Nb0.7SiBEA, while Nb2.0SiBEA mainly contained isolated mononuclear Nb(V) in the framework of zeolite and polynuclear Nb(V) in the extra-framework position. FTIR with pyridine and 2,6-di-tert-butylpyridine as probe molecules showed that major amount Lewis and weak Br?nsted acidic sites are formed by incorporation of niobium in the framework of zeolites as mononuclear Nb(V). The catalytic properties of Nb-containing zeolites were investigated in tandem processes of ethanol conversion into 1,3-butadiene (gas-phase) and synthesis of unsymmetrical ethers from aromatic aldehyde and aliphatic alcohol (liquid-phase). It has been found that Nb0.7SiBEA catalyst, containing only isolated framework mononuclear Nb(V) is more active than Nb2.0SiBEA in the conversion of ethanol and ethanol/acetaldehyde mixture into 1,3-butadiene, MPV reduction of crotonaldehyde with ethanol and etherification of 4-methoxybenzyl alcohol with 2-butanol. The higher specific activity (turnover number/frequency) of Nb0.7SiBEA than Nb2.0SiBEA catalyst has been revealed for gas- and liquid-phase tandem processes.
- Kyriienko, Pavlo I.,Larina, Olga V.,Popovych, Nataliia O.,Soloviev, Sergiy O.,Millot, Yannick,Dzwigaj, Stanislaw
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- Hydrogen bonding and catalysis of solvolysis of 4-methoxybenzyl fluoride
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Values of ko = 8.0 × 10-3 s-1 and kH = 2.5 × 10-2 M-1 s-1, respectively, were determined for the spontaneous and the acid-catalyzed cleavage of 4-methoxybenzyl fluoride (1-F) to form the 4-methoxybenzyl carbocation (1+). Values of kF = 1.8 × 107 M-1 s-1 and kHF = 7.2 × 104 M-1 s-1 were determined for addition of F- and HF to 1+ for reaction in the microscopic reverse direction. Evidence is presented that the reversible addition of HF to 1+ to give 1-F + H+ proceeds by a concerted reaction mechanism. The relatively small 250-fold difference between the reactivities of fluoride ion and neutral HF toward 1+ is attributed to the tendency of the strong aqueous solvation of F- to decrease its nucleophilic reactivity and to the advantage for the concerted compared with the usual stepwise pathway for addition of HF. There is no significant stabilization of the transition state for cleavage of 1-F from general acid catalysis by 0.80 M cyanoacetate buffer at pH 1.7. The estimated 3 kcal/mol larger Marcus intrinsic barrier for heterolytic cleavage of 1-F than for cleavage of 1-Cl is attributed to a lag in the development at the transition state of the ca. 30 kcal/mol greater stabilizing solvation of the product ion F- compared with Cl-. The decrease in the electronegativity of X along the series X = F, OH, Cl is accompanied by a ca. 1010-fold increase in the carbon basicity compared with the proton basicity of X-.
- Toteva, Maria M.,Richard, John P.
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- Practical reduction of carbonyl compounds with NaBH4 and silica gel in an aprotic solvent
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Selective and high-yielding synthesis of alcohols can be easily achieved by the reduction of a variety of ketones and aldehydes with a combination of inexpensive and readily available laboratory reagents, NaBH4 and silica gel, in hexane under mild and neutral conditions.
- Yakabe, Shigetaka,Hirano, Masao,Morimoto, Takashi
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- ATP regeneration by a single polyphosphate kinase powers multigram-scale aldehyde synthesisin vitro
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ATP recycling systems are required to avoid the addition of stoichiometric quantities of cofactor and facilitate industrial implementation of ATP-dependent enzymes. One factor that limits the biocatalytic application of these enzymes is the lack of a scalable AMP to ATP regeneration system. Whole-cells or a combination of purified enzymes are often exploited for ATP regeneration from AMP, whereas cell free systems comprising a single crude enzyme preparation would be preferred. To establish such a system, we focussed on polyphosphate kinases (PPKs) to find a single enzyme that could be used to power ATP-consuming reactions. Screening of some previously reported PPKs revealed limitations of these biocatalysts for scale-up purposes. As such, a panel of novel putative PPK2-III enzymes was constructed and compared to characterised enzymes belonging to the same class. Multidimensional small-scale screening revealed that PPK12 (from an unclassifiedErysipelotrichaceaebacterium) displays enhanced expression levels, ATP formation rates, polyphosphate tolerance and stability under a variety of harsh conditions. The carboxylic acid reductase (CAR) catalysed reduction of carboxylates to aldehydes was chosen as a model reaction to test the applicability of PPK12 as a bifunctional biocatalyst for ATP regeneration from AMP. The implementation of the identified ATP-recycling enzyme provided the first example of cell free multigram-scale aldehyde synthesis employing enzymes and a single PPK2-III, paving the way for affordable scalable ATP regeneration technologies.
- Tavanti, Michele,Hosford, Joseph,Lloyd, Richard C.,Brown, Murray J. B.
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- Synthesis and catalytic activity of water-soluble ruthenium(II) complexes bearing a naphthyridine-carboxylate ligand
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The synthesis of water-soluble (η6-arene)ruthenium(II) complexes based on pyrazolyl-naphthyridine ligands modified with a carboxylate group is reported. The complexes are easily accessible in good yields via complexation of [(arene)RuCl2]2 with 7-pyrazolyl-1,8- naphthyridine-2-carboxylic acid (1). All complexes have been characterized by spectroscopic and elemental analyses. The complexes {[Ru(η6- arene)(N,N′-1)Cl]Cl} (arene = benzene (5), p-cymene (6)) were further confirmed by X-ray diffraction studies. These complexes are soluble in water (ca. 10 mg/mL) and are catalytically active in hydrogen-transfer reduction of carbonyl compounds in aqueous medium with the use of HCOOH/HCOONa as the hydrogen source.
- Huang, Chang-Yao,Kuan, Kai-Yuan,Liu, Yi-Hong,Peng, Shie-Ming,Liu, Shiuh-Tzung
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- A mild and efficient tetrahydropyranylation and detetrahydropyranylation of alcohols and phenols by VCl3
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Vanadium chloride is found to be an efficient catalyst for the tetrahydropyranylation and detetrahydropyranylation of various alcohols and phenols, giving good yields at room temperature and short reaction times. 2005 Springer Science+Business Media, Inc.
- Narsimha Reddy,Sunil Kumar,Kumar,Srinivasulu,Thirupathi Reddy,Rajitha
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- Chemoselective tetrahydropyranylation of alcohols and their detetrahydropyranylation using silicasulphuric acid as a reusable catalyst
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A simple, mild, and efficient protocol for chemoselective protection of alcohols over phenols as tetrahydropyranyl ethers and their deprotection using silicasulphuric acid as a reusable solid acid catalyst is described.
- Pore,Desai, Uday V.,Mane,Wadgaonkar
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- Titanyl Acetylacetonate as an Efficient Catalyst for a Mild and Convenient Reduction of Carbonyl Compounds with NaBH4 under Aprotic Condition
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Titanyl acetylacetonate, TiO(acac)2, is used as an efficient catalyst for the reduction of carbonyl compounds with sodium borohydride under aprotic condition. Reduction reactions are performed in CH3CN and THF. The corresponding alcohols are obtained in high to excellent yields and the chemoselective reduction of aldehydes over ketones is achieved successfully.
- Zeynizadeh, Behzad
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- A Mild Heteroatom (O -, N -, and S -) Methylation Protocol Using Trimethyl Phosphate (TMP)-Ca(OH) 2Combination
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A mild heteroatom methylation protocol using trimethyl phosphate (TMP)-Ca(OH)2combination has been developed, which proceeds in DMF, or water, or under neat conditions, at 80 °C or at room temperature. A series of O-, N-, and S-nucleophiles, including phenols, sulfonamides, N-heterocycles, such as 9H-carbazole, indole derivatives, and 1,8-naphthalimide, and aryl/alkyl thiols, are suitable substrates for this protocol. The high efficiency, operational simplicity, scalability, cost-efficiency, and environmentally friendly nature of this protocol make it an attractive alternative to the conventional base-promoted heteroatom methylation procedures.
- Tang, Yu,Yu, Biao
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- A Bifunctional Copper Catalyst Enables Ester Reduction with H2: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
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Employing a bifunctional catalyst based on a copper(I)/NHC complex and a guanidine organocatalyst, catalytic ester reductions to alcohols with H2 as terminal reducing agent are facilitated. The approach taken here enables the simultaneous activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered "soft"copper(I) hydrides to previously unreactive "hard"ester electrophiles and paves the way for a replacement of stoichiometric reducing agents by a catalyst and H2.
- Kaicharla, Trinadh,Ngoc, Trung Tran,Teichert, Johannes F.,Tzaras, Dimitrios-Ioannis,Zimmermann, Birte M.
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supporting information
p. 16865 - 16873
(2021/10/20)
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- Iron-catalyzed chemoselective hydride transfer reactions
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A Diaminocyclopentadienone iron tricarbonyl complex has been applied in chemoselective hydrogen transfer reductions. This bifunctional iron complex demonstrated a broad applicability in mild conditions in various reactions, such as reduction of aldehydes over ketones, reductive alkylation of various functionalized amines with functionalized aldehydes and reduction of α,β-unsaturated ketones into the corresponding saturated ketones. A broad range of functionalized substrates has been isolated in excellent yields with this practical procedure.
- Coufourier, Sébastien,Ndiaye, Daouda,Gaillard, Quentin Gaignard,Bettoni, Léo,Joly, Nicolas,Mbaye, Mbaye Diagne,Poater, Albert,Gaillard, Sylvain,Renaud, Jean-Luc
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supporting information
(2021/06/07)
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- Visible Light Induced Reduction and Pinacol Coupling of Aldehydes and Ketones Catalyzed by Core/Shell Quantum Dots
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We present an efficient and versatile visible light-driven methodology to transform aryl aldehydes and ketones chemoselectively either to alcohols or to pinacol products with CdSe/CdS core/shell quantum dots as photocatalysts. Thiophenols were used as proton and hydrogen atom donors and as hole traps for the excited quantum dots (QDs) in these reactions. The two products can be switched from one to the other simply by changing the amount of thiophenol in the reaction system. The core/shell QD catalysts are highly efficient with a turn over number (TON) larger than 4 × 104 and 4 × 105 for the reduction to alcohol and pinacol formation, respectively, and are very stable so that they can be recycled for at least 10 times in the reactions without significant loss of catalytic activity. The additional advantages of this method include good functional group tolerance, mild reaction conditions, the allowance of selectively reducing aldehydes in the presence of ketones, and easiness for large scale reactions. Reaction mechanisms were studied by quenching experiments and a radical capture experiment, and the reasons for the switchover of the reaction pathways upon the change of reaction conditions are provided.
- Xi, Zi-Wei,Yang, Lei,Wang, Dan-Yan,Feng, Chuan-Wei,Qin, Yufeng,Shen, Yong-Miao,Pu, Chaodan,Peng, Xiaogang
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p. 2474 - 2488
(2021/02/05)
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- Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
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The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
- Mukherjee, Aparajita,Bhattacharya, Samaresh
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p. 15617 - 15631
(2021/05/19)
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- Ambient-pressure highly active hydrogenation of ketones and aldehydes catalyzed by a metal-ligand bifunctional iridium catalyst under base-free conditions in water
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A green, efficient, and high active catalytic system for the hydrogenation of ketones and aldehydes to produce corresponding alcohols under atmospheric-pressure H2 gas and ambient temperature conditions was developed by a water-soluble metal–ligand bifunctional catalyst [Cp*Ir(2,2′-bpyO)(OH)][Na] in water without addition of a base. The catalyst exhibited high activity for the hydrogenation of ketones and aldehydes. Furthermore, it was worth noting that many readily reducible or labile functional groups in the same molecule, such as cyan, nitro, and ester groups, remained unchanged. Interestingly, the unsaturated aldehydes can be also selectively hydrogenated to give corresponding unsaturated alcohols with remaining C=C bond in good yields. In addition, this reaction could be extended to gram levels and has a large potential of wide application in future industrial.
- Wang, Rongzhou,Yue, Yuancheng,Qi, Jipeng,Liu, Shiyuan,Song, Ao,Zhuo, Shuping,Xing, Ling-Bao
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- Efficient and chemoselective hydrogenation of aldehydes catalyzed by well-defined PN3-pincer manganese(ii) catalyst precursors: An application in furfural conversion
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Well-defined and air-stable PN3-pincer manganese(ii) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the CC double bond/CC triple bond intact. Our methodology was demonstrated for the conversion of biomass derived feedstocks such as furfural and 5-formylfurfural to furfuryl alcohol and 5-(hydroxymethyl)furfuryl alcohol respectively.
- Gholap, Sandeep Suryabhan,Dakhil, Abdullah Al,Chakraborty, Priyanka,Li, Huaifeng,Dutta, Indranil,Das, Pradip K.,Huang, Kuo-Wei
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supporting information
p. 11815 - 11818
(2021/11/30)
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- Redox-active ligand based Mn(i)-catalyst for hydrosilylative ester reduction
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Herein a Mn(i) catalyst bearing a redox-active phenalenyl (PLY) based ligand is reported for the efficient hydrosilylation of esters to alcohols using the inexpensive silane source polymethylhydrosiloxane (PMHS) under mild conditions. Mechanistic investigations suggest a strong ligand-metal cooperation where a ligand-based single electron transfer (SET) process initiates the reaction through Si-H bond activation.
- Chakraborty, Soumi,Das, Arpan,Mandal, Swadhin K.
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supporting information
p. 12671 - 12674
(2021/12/04)
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- A mild and selective Cu(II) salts-catalyzed reduction of nitro, azo, azoxy, N-aryl hydroxylamine, nitroso, acid halide, ester, and azide compounds using hydrogen surrogacy of sodium borohydride
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The first mild, in situ, single-pot, high-yielding well-screened copper (II) salt-based catalyst system utilizing the hydrogen surrogacy of sodium borohydride for selective hydrogenation of a broad range of nitro substrates into the corresponding amine under habitancy of water or methanol like green solvents have been described. Moreover, this catalytic system can also activate various functional groups for hydride reduction within prompted time, with low catalyst-loading, without any requirement of high pressure or molecular hydrogen supply. Notably, this system explores a great potential to substitute expensive traditional hydrogenation methodologies and thus offers a greener and simple hydrogenative strategy in the field of organic synthesis.
- Kalola, Anirudhdha G.,Prasad, Pratibha,Mokariya, Jaydeep A.,Patel, Manish P.
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supporting information
p. 3565 - 3589
(2021/10/12)
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- Reaction of Diisobutylaluminum Borohydride, a Binary Hydride, with Selected Organic Compounds Containing Representative Functional Groups
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The binary hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], synthesized from diisobutylaluminum hydride (DIBAL) and borane dimethyl sulfide (BMS) has shown great potential in reducing a variety of organic functional groups. This unique binary hydride, (iBu)2AlBH4, is readily synthesized, versatile, and simple to use. Aldehydes, ketones, esters, and epoxides are reduced very fast to the corresponding alcohols in essentially quantitative yields. This binary hydride can reduce tertiary amides rapidly to the corresponding amines at 25 °C in an efficient manner. Furthermore, nitriles are converted into the corresponding amines in essentially quantitative yields. These reactions occur under ambient conditions and are completed in an hour or less. The reduction products are isolated through a simple acid-base extraction and without the use of column chromatography. Further investigation showed that (iBu)2AlBH4 has the potential to be a selective hydride donor as shown through a series of competitive reactions. Similarities and differences between (iBu)2AlBH4, DIBAL, and BMS are discussed.
- Amberchan, Gabriella,Snelling, Rachel A.,Moya, Enrique,Landi, Madison,Lutz, Kyle,Gatihi, Roxanne,Singaram, Bakthan
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supporting information
p. 6207 - 6227
(2021/05/06)
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- Hydroboration Reaction and Mechanism of Carboxylic Acids using NaNH2(BH3)2, a Hydroboration Reagent with Reducing Capability between NaBH4and LiAlH4
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Hydroboration reactions of carboxylic acids using sodium aminodiboranate (NaNH2[BH3]2, NaADBH) to form primary alcohols were systematically investigated, and the reduction mechanism was elucidated experimentally and computationally. The transfer of hydride ions from B atoms to C atoms, the key step in the mechanism, was theoretically illustrated and supported by experimental results. The intermediates of NH2B2H5, PhCH= CHCOOBH2NH2BH3-, PhCH= CHCH2OBO, and the byproducts of BH4-, NH2BH2, and NH2BH3- were identified and characterized by 11B and 1H NMR. The reducing capacity of NaADBH was found between that of NaBH4 and LiAlH4. We have thus found that NaADBH is a promising reducing agent for hydroboration because of its stability and easy handling. These reactions exhibit excellent yields and good selectivity, therefore providing alternative synthetic approaches for the conversion of carboxylic acids to primary alcohols with a wide range of functional group tolerance.
- Wang, Jin,Ju, Ming-Yue,Wang, Xinghua,Ma, Yan-Na,Wei, Donghui,Chen, Xuenian
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p. 5305 - 5316
(2021/04/12)
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- Deoxygenative hydroboration of primary, secondary, and tertiary amides: Catalyst-free synthesis of various substituted amines
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Transformation of relatively less reactive functional groups under catalyst-free conditions is an interesting aspect and requires a typical protocol. Herein, we report the synthesis of various primary, secondary, and tertiary amines through hydroboration of amides using pinacolborane under catalyst-free and solvent-free conditions. The deoxygenative hydroboration of primary and secondary amides proceeded with excellent conversions. The comparatively less reactive tertiary amides were also converted to the corresponding N,N-diamines in moderate yields under catalyst-free conditions, although alcohols were obtained as a minor product.
- An, Duk Keun,Jaladi, Ashok Kumar,Kim, Hyun Tae,Yi, Jaeeun
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- Synthesis and catalytic activity of N-heterocyclic silylene (NHSi) iron (II) hydride for hydrosilylation of aldehydes and ketones
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A novel silylene supported iron hydride [Si, C]FeH (PMe3)3 (1) was synthesized by C (sp3)-H bond activation with zero-valent iron complex Fe (PMe3)4. Complex 1 was fully characterized by spectroscopic methods and single crystal X-ray diffraction analysis. To the best of our knowledge, 1 is the first example of silylene-based hydrido chelate iron complex produced through activation of the C (sp3)?H bond. It was found that complex 1 exhibited excellent catalytic activity for hydrosilylation of aldehydes and ketones. The catalytic system showed good tolerance and catalytic activity for the substrates with different functional groups on the benzene ring. It is worth mentioning that, the experimental results showed that both ketones and aldehydes could be reduced in good to excellent yields under the same catalytic conditions. Based on the experiments and literature reports, a possible catalytic mechanism was proposed.
- Du, Xinyu,Qi, Xinghao,Li, Kai,Li, Xiaoyan,Sun, Hongjian,Fuhr, Olaf,Fenske, Dieter
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- Experimental and density functional theory studies on hydroxymethylation of phenylboronic acids with paraformaldehyde over a Rh-PPh3 catalyst
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The synthesis of benzyl alcohols (BAs) is highly vital for their wide applications in organic synthesis and pharmaceuticals. Herein, BAs was efficiently synthesized via hydroxymethylation of phenylboronic acids (PBAs) and paraformaldehyde over a simple Rh-PPh3 catalyst combined with an inorganic base (NaOH). A variety of BAs with the groups of CH3?, CH3O?, Cl?, Br?, and so on were obtained with moderate to good yields, indicating that the protocol had a good universality. Density functional theory (DFT) calculations proposed the Hayashi-type arylation mechanism involved the arylation step of PBA and Rh(OH)(PPh3)2 catalyst to form Rh(I)-bound aryl intermediates and the hydrolysis step of Rh(I)-bound aryl intermediates and HCHO to generate BA product (the rate-determining step). The present route provides a valuable and direct method for the synthesis of BAs and expands the application range of paraformaldehyde.
- Wang, Kuan,Lan, Jie,He, Zhen-Hong,Cao, Zhe,Wang, Weitao,Yang, Yang,Liu, Zhao-Tie
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- Hydrosilylation of Carbonyl Compounds Catalyzed by a Nickel Complex Bearing a PBP Ligand
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The efficient catalytic hydrosilylation of ketones and aldehydes has been investigated using a nickel pincer hydride complex supported by a diphosphino-boryl ligand (PBP). It was found that the presence of the boryl group within the skeleton of the ligand has a beneficial effect on the catalytic activities observed for ketones compared to related pincer systems. The analysis of the reaction mechanism allows for the synthesis and characterization of a nickel alkoxide derivative by insertion of the carbonyl moiety into the Ni?H bond. Combined experimental and theoretical analysis (DFT) support a reaction mechanism that involves the initial formation of an alkoxide complex followed by reaction with the silane to release the corresponding silyl ether and regenerate the catalyst.
- Antonio Fernández, José,Manuel García, Juan,Ríos, Pablo,Rodríguez, Amor
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supporting information
p. 2993 - 2998
(2021/07/10)
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- Silver-Catalyzed Hydroboration of C-X (X = C, O, N) Multiple Bonds
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AgSbF6 was developed as an effective catalyst for the hydroboration of various unsaturated functionalities (nitriles, alkenes, and aldehydes). This atom-economic chemoselective protocol works effectively under low catalyst loading, base- A nd solvent-free moderate conditions. Importantly, this process shows excellent functional group tolerance and compatibility with structurally and electronically diverse substrates (>50 examples). Mechanistic investigations revealed that the reaction proceeds via a radical pathway. Further, the obtained N,N-diborylamines were showcased to be useful precursors for amide synthesis.
- Pandey, Vipin K.,Tiwari, Chandra Shekhar,Rit, Arnab
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supporting information
p. 1681 - 1686
(2021/03/03)
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- CeO2-nanocubes as efficient and selective catalysts for the hydroboration of carbonyl groups
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The CeO2-nanoparticle catalysed hydroboration of carbonyl compounds with HBpin (pin = OCMe2CMe2O) is reported to afford the corresponding borate esters in excellent yield. A series of aromatic and aliphatic aldehydes and ketones having synthetically important functional groups were well-Tolerated under mild reaction conditions. Further, chemoselective hydroboration of aldehydes over other reducible functional groups such as ketone, nitrile, hydroxide, alkene, alkyne, amide, ester, nitro, and halides was achieved. Importantly the catalyst can be recycled up to ten runs with slight loss in activity. This journal is
- Bhawar, Ramesh,Bose, Shubhankar Kumar,Patil, Kiran S.
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supporting information
p. 15028 - 15034
(2021/09/04)
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- Efficient Solvent-Free Hydrosilylation of Aldehydes and Ketones Catalyzed by Fe2(CO)9/C6H4-o-(NCH2PPh2)2BH
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An efficient solvent-free catalyst system for hydrosilylation of aldehydes and ketones was developed based on iron pre-catalyst Fe2(CO)9/C6H4-o-(NCH2PPh2)2BH. The reactions were tolerant of many functional groups and the corresponding alcohols were isolated in good to excellent yields following basic hydrolysis of the reaction products. The reaction is likely catalyzed by an in situ generated pincer ligated iron hydride complex. Graphic Abstract: [Figure not available: see fulltext.]
- Fang, Fei,Chang, Jiarui,Zhang, Jie,Chen, Xuenian
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p. 3509 - 3515
(2021/03/16)
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- Dynamic Kinetic Cross-Electrophile Arylation of Benzyl Alcohols by Nickel Catalysis
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Catalytic transformation of alcohols via metal-catalyzed cross-coupling reactions is very important, but it typically relies on a multistep procedure. We here report a dynamic kinetic cross-coupling approach for the direct functionalization of alcohols. The feasibility of this strategy is demonstrated by a nickel-catalyzed cross-electrophile arylation reaction of benzyl alcohols with (hetero)aryl electrophiles. The reaction proceeds with a broad substrate scope of both coupling partners. The electron-rich, electron-poor, and ortho-/meta-/para-substituted (hetero)aryl electrophiles (e.g., Ar-OTf, Ar-I, Ar-Br, and inert Ar-Cl) all coupled well. Most of the functionalities, including aldehyde, ketone, amide, ester, nitrile, sulfone, furan, thiophene, benzothiophene, pyridine, quinolone, Ar-SiMe3, Ar-Bpin, and Ar-SnBu3, were tolerated. The dynamic nature of this method enables the direct arylation of benzylic alcohol in the presence of various nucleophilic groups, including nonactivated primary/secondary/tertiary alcohols, phenols, and free indoles. It thus offers a robust alternative to existing methods for the precise construction of diarylmethanes. The synthetic utility of the method was demonstrated by a concise synthesis of biologically active molecules and by its application to peptide modification and conjugation. Preliminary mechanistic studies revealed that the reaction of in situ formed benzyl oxalates with nickel, possibly via a radical process, is an initial step in the reaction with aryl electrophiles.
- Guo, Peng,Wang, Ke,Jin, Wen-Jie,Xie, Hao,Qi, Liangliang,Liu, Xue-Yuan,Shu, Xing-Zhong
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supporting information
p. 513 - 523
(2021/01/12)
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- Zirconium and hafnium polyhedral oligosilsesquioxane complexes-green homogeneous catalysts in the formation of bio-derived ethers: Via a MPV/etherification reaction cascade
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The polyhedral oligosilsesquioxane complexes, {[(isobutyl)7Si7O12]ZrOPri·(HOPri)}2 (I), {[(cyclohexyl)7Si7O12]ZrOPri·(HOPri)}2 (II), {[(isobutyl)7Si7O12]HfOPri·(HOPri)}2 (III) and {[(cyclohexyl)7Si7O12]HfOPri·(HOPri)}2 (IV), were synthesized in good yields from the reactions of M(OPri)4 (M = Zr, Hf) with R-POSS(OH)3 (R = isobutyl, cyclohexyl), resp. I-IV were characterized by 1H, 13C and 29Si NMR spectroscopy and their dimeric solid-state structures were confirmed by X-ray analysis. I-IV catalyze the reductive etherification of 2-hydroxy- and 4-hydroxy and 2-methoxy and 4-methoxybenzaldehyde and vanillin to their respective isopropyl ethers in isopropanol as a "green"solvent and reagent. I-IV are durable and robust homogeneous catalysts operating at temperatures of 100-160 °C for days without significant loss of catalytic activity. Likewise, I-IV selectively catalyze the conversion of 5-hydroxymethylfurfural (HMF) into 2,5-bis(isopropoxymethyl)furane (BPMF), a potentially high-performance fuel additive. Similar results were achieved by using a combination of M(OPri)4 and ligand R-POSS(OH)3 as a catalyst system demonstrating the potential of this "in situ"approach for applications in biomass transformations. A tentative reaction mechanism for the reductive etherification of aldehydes catalysed by I-IV is proposed. This journal is
- Garg, Shipra,Unruh, Daniel K.,Krempner, Clemens
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p. 211 - 218
(2021/01/28)
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- Uranyl(VI) Triflate as Catalyst for the Meerwein-Ponndorf-Verley Reaction
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Catalytic transformation of oxygenated compounds is challenging in f-element chemistry due to the high oxophilicity of the f-block metals. We report here the first Meerwein-Ponndorf-Verley (MPV) reduction of carbonyl substrates with uranium-based catalysts, in particular from a series of uranyl(VI) compounds where [UO2(OTf)2] (1) displays the greatest efficiency (OTf = trifluoromethanesulfonate). [UO2(OTf)2] reduces a series of aromatic and aliphatic aldehydes and ketones into their corresponding alcohols with moderate to excellent yields, using iPrOH as a solvent and a reductant. The reaction proceeds under mild conditions (80 °C) with an optimized catalytic charge of 2.3 mol % and KOiPr as a cocatalyst. The reduction of aldehydes (1-10 h) is faster than that of ketones (>15 h). NMR investigations clearly evidence the formation of hemiacetal intermediates with aldehydes, while they are not formed with ketones.
- Kobylarski, Marie,Monsigny, Louis,Thuéry, Pierre,Berthet, Jean-Claude,Cantat, Thibault
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supporting information
p. 16140 - 16148
(2021/11/01)
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- Sodium Aminodiboranate, a New Reagent for Chemoselective Reduction of Aldehydes and Ketones to Alcohols
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Sodium aminodiboranate (NaNH 2(BH 3) 2, NaADBH) is a new member of the old borane family, which exhibits superior performance in chemoselective reduction. Experimental results show that NaADBH can rapidly reduce aldehydes and ketones to the corresponding alcohols in high efficiency and selectivity under mild conditions. There are little steric and electronic effects on this reduction.
- Wang, Jin,Guo, Yu,Li, Shouhu,Chen, Xuenian
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supporting information
p. 1104 - 1108
(2021/05/25)
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- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
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Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
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p. 803 - 808
(2021/07/20)
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- A [3+2] cycloaddition-1,2-acyl migration-hydrolysis cascade for regioselective synthesis of 1,2,3-triazoles in water
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A cascade sequence involving [3+2] cycloaddition, 1,2-acyl migration and hydrolysis produces 2H-1,2,3-triazolesviathe regioselective formation ofN2-carboxyalkylated triazoles. The reaction proceeds in aqueous media through intriguing reaction kinetics using a CuI-prolinamide catalyst system. Prolinamide promotes the novel organocatalytic 1,2-acyl migration as well as hydrolysis of the resultingN2-carboxyalkylated triazoles.
- Chakraborti, Gargi,Dash, Jyotirmayee,Mandal, Tirtha,Roy, Charles Patriot
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supporting information
p. 7970 - 7973
(2021/08/17)
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- Hydrosilylation of Aldehydes and Ketones Catalyzed by a 2-Iminopyrrolyl Alkyl-Manganese(II) Complex
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A well-defined and very active single-component manganese(II) catalyst system for the hydrosilylation of aldehydes and ketones is presented. First, the reaction of 5-(2,4,6-iPr3C6H2)-2-[N-(2,6-iPr2C6H3)formimino]pyrrolyl potassium (KL) and [MnCl2(Py)2] afforded the binuclear 2-iminopyrrolyl manganese(II) pyridine chloride complex [Mn2{κ2N,N′-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H)═N(2,6-iPr2C6H3)}2(Py)2(μ-Cl)2] 1. Subsequently, the alkylation reaction of complex 1 with LiCH2SiMe3 afforded the respective (trimethylsilyl)methyl-Mn(II) complex [Mn{κ2N,N′-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H)═N(2,6-iPr2C6H3)}(Py)CH2SiMe3] 2 in a good yield. Complexes 1 and 2 were characterized by elemental analysis, 1H NMR spectroscopy, Evans' method, FTIR spectroscopy, and single-crystal X-ray diffraction. While the crystal structure of complex 1 has been identified as a binuclear entity, in which the Mn(II) centers present pentacoordinate coordination spheres, that of complex 2 corresponds to a monomer with a distorted tetrahedral coordination geometry. Complex 2 proved to be a very active precatalyst for the atom-economic hydrosilylation of several aldehydes and ketones under very mild conditions, with a maximum turnover frequency of 95 min-1, via a silyl-Mn(II) mechanistic route, as asserted by a combination of experimental and theoretical efforts, the respective silanes were cleanly converted to the respective alcoholic products in high yields.
- Cruz, Tiago F. C.,Gomes, Pedro T.,Veiros, Luís F.
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- Biomimetic Hydrogenation Catalyzed by a Manganese Model of [Fe]-Hydrogenase
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[Fe]-hydrogenase is an efficient biological hydrogenation catalyst. Despite intense research, Fe complexes mimicking the active site of [Fe]-hydrogenase have not achieved turnovers in hydrogenation reactions. Herein, we describe the design and development of a manganese(I) mimic of [Fe]-hydrogenase. This complex exhibits the highest activity and broadest scope in catalytic hydrogenation among known mimics. Thanks to its biomimetic nature, the complex exhibits unique activity in the hydrogenation of compounds analogous to methenyl-H4MPT+, the natural substrate of [Fe]-hydrogenase. This activity enables asymmetric relay hydrogenation of benzoxazinones and benzoxazines, involving the hydrogenation of a chiral hydride transfer agent using our catalyst coupled to Lewis acid-catalyzed hydride transfer from this agent to the substrates.
- Hu, Xile,Pan, Hui-Jie
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supporting information
p. 4942 - 4946
(2020/02/11)
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- Cyclopentadienone iron tricarbonyl complexes-catalyzed hydrogen transfer in water
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The development of efficient and low-cost catalytic systems is important for the replacement of robust noble metal complexes. The synthesis and application of a stable, phosphine-free, water-soluble cyclopentadienone iron tricarbonyl complex in the reduction of polarized double bonds in pure water is reported. In the presence of cationic bifunctional iron complexes, a variety of alcohols and amines were prepared in good yields under mild reaction conditions.
- Coufourier, Sébastien,Gaillard, Sylvain,Mbaye, Mbaye Diagne,Ndiaye, Daouda,Renaud, Jean-Luc
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supporting information
(2020/01/28)
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- Production of γ-Valerolactone from One-Pot Transformation of Biomass-Derived Carbohydrates Over Chitosan-Supported Ruthenium Catalyst Combined with Zeolite ZSM-5
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It remains as a challenge to directly transform the biomass-derived C5 carbohydrates, such as furfural (FF) and its upstream product xylose and hemicellulose, to γ-valerolactone (GVL), a versatile renewable chemical platform, due to various restrictions in the current synthetic strategies. Using formic acid as green hydrogen source, we synthesized the recyclable chitosan-Ru/PPh3 catalyst system, effective for both the hydrogenation of FF to furfuryl alcohol (FAL) and the reduction of levulinic acid (LA) or ethyl levulinate (EL) to GVL, affording up to 99 % product yields. The combination of chitosan-Ru/PPh3 with ZSM-5 could successfully achieve up to 79 % yield of GVL from one-pot conversion of FF under mild condition. Preliminary studies indicated that this method could also be applied to the direct conversion of biomass-derived C5 carbohydrates such as xylose and hemicellulose to GVL in 37 % or 30 % yield, respectively.
- Wang, Tianlong,He, Jianghua,Zhang, Yuetao
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p. 1611 - 1619
(2020/03/04)
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- Synthesis, antiinflammatory activity, and molecular docking studies of bisphosphonic esters as potential MMP-8 and MMP-9 inhibitors
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Bisphosphonic acids (or bisphosphonates) have been successfully used in the clinic treatment of bone diseases for over decades. Additionally, the antiinflammatory activity of these compounds has been gaining attention. In our previous work, we synthesized and in vivo evaluated the bisphosphonic esters 1 and 2, finding a moderate edema inhibition upon oral and topical administration on BALB/c mice. Thus, in this work, the bioisosteric replacement of an amide functional group for an ester afforded the new bisphosphonates 3–6, which had a moderate oral edema inhibition (25 mg/kg dose) and a significant topical antiinflammatory activity (2 mg/ear) on BALB/c mice, with 6 being the most active hit (55.9% edema inhibition), comparable to the positive control (55.5% edema inhibition) on a TPA topical model. Next, to assess the acute toxicity of the synthesized derivatives, test animals were administered with 50–100 mg/kg of 3–6, respectively, by an oral route, and after 14 days, neither lethality nor a significative weight loss were observed. Finally, a structure–activity relationship (SAR) and a molecular docking analysis of 3–6 helped us to explain the trend observed in biological tests. Considering all these aspects, we propose the inhibition of MMP-8 and MMP-9 as a possible action mechanism of the synthesized derivatives.
- Cortes-Pacheco, Abimelek,Jiménez-Arellanes, María Adelina,Juárez-Vázquez, María del Carmen,López-Torres, Adolfo,Palacios-Can, Francisco José,Ramírez-Marroquín, Oscar Abelardo,Razo-Hernández, Rodrigo Said,Valcarcel-Gami?o, José Antonio
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p. 1277 - 1287
(2020/07/10)
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- Bimetallic Bis-NHC-Ir(III) Complex Bearing 2-Arylbenzo[d]oxazolyl Ligand: Synthesis, Catalysis, and Bimetallic Effects
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Herein, an unprecedented bimetallic bis-NHC Cp*Ir complex 1 bearing 2-arylbenzo[d]oxazolyl and NHC ligands is reported. A significant increase in activity was observed for N-methylation of amines and reduction of aldehydes with MeOH catalyzed by 1 compared to the monometallic analogues (2-11). Under the optimal conditions, it showed to be highly effective in N-methylation of nitroarenes with MeOH as both C1 and H2 source. Substrates, including aromatic amines, ketones, and nitro compounds with various functional groups, can be well-tolerated. Mechanistic studies and DFT calculation highlight the significance of bimetallic centers cooperativity.
- Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhan, Bing,Li, Zhi-Ming,Hou, Xiu-Feng
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p. 3514 - 3523
(2020/10/09)
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- Diethylsilane as a Powerful Reagent in Au Nanoparticle-Catalyzed Reductive Transformations
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Diethylsilane (Et2SiH2), a simple and readily available dihydrosilane, that exhibits superior reactivity, as compared to monohydrosilanes, in a series of reductive transformations catalyzed by recyclable and reusable Au nanoparticles (1 mol-%) supported on TiO2. It reduces aldehydes or ketones almost instantaneously at ambient conditions. It can be used in a one pot rapid reductive amination procedure, in which premixing of aldehyde and amine is required prior to the addition of the reducing agent and the catalyst, even in a protic solvent. An unprecedented method for the synthesis of N-arylisoindolines is also shown in the reductive amination between o-phthalaldehyde and anilines. In this transformation, it is proposed that the intermediate N,2-diphenylisoindolin-1-imines are reduced stepwise to the isoindolines. Finally, Et2SiH2 readily reduces amides into amines in excellent yields and shorter reaction times relative to previously known analogous nano Au(0)-catalyzed protocols.
- Louka, Anastasia,Kidonakis, Marios,Saridakis, Iakovos,Zantioti-Chatzouda, Elisavet-Maria,Stratakis, Manolis
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p. 3508 - 3514
(2020/06/02)
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- Continuous-Flow Amide and Ester Reductions Using Neat Borane Dimethylsulfide Complex
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Reductions of amides and esters are of critical importance in synthetic chemistry, and there are numerous protocols for executing these transformations employing traditional batch conditions. Notably, strategies based on flow chemistry, especially for amide reductions, are much less explored. Herein, a simple process was developed in which neat borane dimethylsulfide complex (BH3?DMS) was used to reduce various esters and amides under continuous-flow conditions. Taking advantage of the solvent-free nature of the commercially available borane reagent, high substrate concentrations were realized, allowing outstanding productivity and a significant reduction in E-factors. In addition, with carefully optimized short residence times, the corresponding alcohols and amines were obtained in high selectivity and high yields. The synthetic utility of the inexpensive and easily implemented flow protocol was further corroborated by multigram-scale syntheses of pharmaceutically relevant products. Owing to its beneficial features, including low solvent and reducing agent consumption, high selectivity, simplicity, and inherent scalability, the present process demonstrates fewer environmental concerns than most typical batch reductions using metal hydrides as reducing agents.
- ?tv?s, Sándor B.,Kappe, C. Oliver
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p. 1800 - 1807
(2020/02/27)
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- Cobalt-catalysed selective synthesis of aldehydes and alcohols from esters
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Efficient and selective reduction of esters to aldehydes and alcohols is reported in which a simple cobalt pincer catalyst catalyses both transformations using diethylsilane as a reductant. Remarkably, the reaction selectivity is controlled by the stoichiometry of diethylsilane. This journal is
- Pattanaik, Sandip,Gunanathan, Chidambaram
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supporting information
p. 7345 - 7348
(2020/07/14)
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- Hydrosilylation of Esters Catalyzed by Bisphosphine Manganese(I) Complex: Selective Transformation of Esters to Alcohols
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Selective and efficient hydrosilylations of esters to alcohols by a well-defined manganese(I) complex with a commercially available bisphosphine ligand are described. These reactions are easy alternatives for stoichiometric hydride reduction or hydrogenation, and employing cheap, abundant, and nonprecious metal is attractive. The hydrosilylations were performed at 100 °C under solvent-free conditions with low catalyst loading. A large variety of aromatic, aliphatic, and cyclic esters bearing different functional groups were selectively converted into the corresponding alcohols in good yields.
- Bagh, Bidraha,Behera, Rakesh R.,Ghosh, Rahul,Khamari, Subrat,Panda, Surajit
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supporting information
p. 3642 - 3648
(2020/04/20)
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- Bench-Stable Manganese NHC Complexes for the Selective Reduction of Esters to Alcohols with Silanes
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Selective reduction of esters to alcohols was accomplished through Mn(I)-mediated hydrosilylation reaction. The manganese tricarbonyl complex [Mn(bis-NHC)(CO)3Br] resulted an active pre-catalyst for the reduction of a variety of esters using phenylsilane and the cheap and readily available polymethylhydrosiloxane. An in situ examination of the catalytic reaction using 55Mn NMR spectroscopy allowed us to detect the formation of Mn(I) intermediate active species. (Figure presented.).
- Sousa, Sara C. A.,Realista, Sara,Royo, Beatriz
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p. 2437 - 2443
(2020/04/30)
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- Synthesis and structure activity relationships of cyanopyridone based anti-tuberculosis agents
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Mycobacterium tuberculosis, the causative agent of tuberculosis, relies on thymidylate kinase (MtbTMPK) for the synthesis of thymidine triphosphates and thus also DNA synthesis. Therefore, this enzyme constitutes a potential Achilles heel of the pathogen. Based on a previously reported MtbTMPK 6-aryl-substituted pyridone inhibitor and guided by two co-crystal structures of MtbTMPK with pyridone- and thymine-based inhibitors, we report the synthesis of a series of aryl-shifted cyanopyridone analogues. These compounds generally lacked significant MtbTMPK inhibitory potency, but some analogues did exhibit promising antitubercular activity. Analogue 11i demonstrated a 10-fold increased antitubercular activity (MIC H37Rv, 1.2 μM) compared to literature compound 5. Many analogues with whole-cell antimycobacterial activity were devoid of significant cytotoxicity.
- Boshoff, Helena I. M.,Caljon, Guy,Forbes, He Eun,Hulpia, Fabian,Jian, Yanlin,Munier-Lehmann, Héle?ne,Risseeuw, Martijn D. P.,Van Calenbergh, Serge
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- KMnO4-catalyzed chemoselective deprotection of acetate and controllable deacetylation-oxidation in one pot
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A novel and efficient protocol for chemoselective deacetylation under ambient conditions was developed using catalytic KMnO4. The stoichiometric use of KMnO4 highlighted the dual role of a heterogeneous oxidant enabling direct access to aromatic aldehydes in one-pot sequential deacetylation-oxidation. The reaction employed an alternative solvent system and allowed the clean transformation of benzyl acetate to sensitive aldehyde in a single step while preventing over-oxidation to acids. Use of inexpensive and readily accessible KMnO4 as an environmentally benign reagent and the ease of the reaction operation were particularly attractive, and enabled the controlled oxidation and facile cleavage of acetate in a preceding step. This journal is
- Gurawa, Aakanksha,Kumar, Manoj,Rao, Dodla S.,Kashyap, Sudhir
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supporting information
p. 16702 - 16707
(2020/10/27)
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- Cerium(IV) Carboxylate Photocatalyst for Catalytic Radical Formation from Carboxylic Acids: Decarboxylative Oxygenation of Aliphatic Carboxylic Acids and Lactonization of Aromatic Carboxylic Acids
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We found that in situ generated cerium(IV) carboxylate generated by mixing the precursor Ce(OtBu)4 with the corresponding carboxylic acids served as efficient photocatalysts for the direct formation of carboxyl radicals from carboxylic acids under blue light-emitting diodes (blue LEDs) irradiation and air, resulting in catalytic decarboxylative oxygenation of aliphatic carboxylic acids to give C-O bond-forming products such as aldehydes and ketones. Control experiments revealed that hexanuclear Ce(IV) carboxylate clusters initially formed in the reaction mixture and the ligand-to-metal charge transfer nature of the Ce(IV) carboxylate clusters was responsible for the high catalytic performance to transform the carboxylate ligands to the carboxyl radical. In addition, the Ce(IV) carboxylate cluster catalyzed direct lactonization of 2-isopropylbenzoic acid to produce the corresponding peroxy lactone and ?3-lactone via intramolecular 1,5-hydrogen atom transfer (1,5-HAT).
- Hirosawa, Keishi,Mashima, Kazushi,Satoh, Tetsuya,Shinohara, Koichi,Shirase, Satoru,Tamaki, Sota,Tsurugi, Hayato
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supporting information
(2020/03/25)
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- GaN nanowires as a reusable photoredox catalyst for radical coupling of carbonyl under blacklight irradiation
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Employing photo-energy to drive the desired chemical transformation has been a long pursued subject. The development of homogeneous photoredox catalysts in radical coupling reactions has been truly phenomenal, however, with apparent disadvantages such as the difficulty in separating the catalyst and the frequent requirement of scarce noble metals. We therefore envisioned the use of a hyper-stable III-V photosensitizing semiconductor with a tunable Fermi level and energy band as a readily isolable and recyclable heterogeneous photoredox catalyst for radical coupling reactions. Using the carbonyl coupling reaction as a proof-of-concept, herein, we report a photo-pinacol coupling reaction catalyzed by GaN nanowires under ambient light at room temperature with methanol as a solvent and sacrificial reagent. By simply tuning the dopant, the GaN nanowire shows significantly enhanced electronic properties. The catalyst showed excellent stability, reusability and functional tolerance. All reactions could be accomplished with a single piece of nanowire on Si-wafer. This journal is
- Botton, Gianluigi,Cen, Yunen,Cheng, Shaobo,Li, Chao-Jun,Liu, Mingxin,Mi, Zetian,Rashid, Roksana T.,Tan, Lida
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p. 7864 - 7870
(2020/08/19)
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- Selective hydrogenation of primary amides and cyclic di-peptides under Ru-catalysis
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A ruthenium(II)-catalyzed selective hydrogenation of challenging primary amides and cyclic di-peptides to their corresponding primary alcohols and amino alcohols, respectively, is reported. The hydrogenation reaction operates under mild and eco-benign conditions and can be scaled-up.
- Subaramanian, Murugan,Sivakumar, Ganesan,Babu, Jessin K.,Balaraman, Ekambaram
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supporting information
p. 12411 - 12414
(2020/10/30)
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- Efficient One-Pot Reductive Aminations of Carbonyl Compounds with Aquivion-Fe as a Recyclable Catalyst and Sodium Borohydride
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A one-pot reductive amination of aldehydes and ketones with NaBH4 was developed with a view to providing efficient, economical and greener synthetic conditions. A recyclable iron-based Lewis catalyst, Aquivion-Fe, was used to promote imine formation in cyclopentyl methyl ether, followed by the addition of a small amount of methanol to the reaction mixture to enable C=N reduction by NaBH4. The protocol, applied to a wide number of amines and carbonyl compounds, resulted in ever complete conversion of these latter with excellent chemoselectivity towards the expected amination products in the most cases. Isolated yields, determined for a selection of the screened substrates, were found consistent with the previously obtained conversion and selectivity data. Cinacalcet, an important active pharmaceutical ingredient, was efficiently prepared by the title procedure.
- Airoldi, Veronica,Piccolo, Oreste,Roda, Gabriella,Appiani, Rebecca,Bavo, Francesco,Tassini, Riccardo,Paganelli, Stefano,Arnoldi, Sebastiano,Pallavicini, Marco,Bolchi, Cristiano
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supporting information
p. 162 - 168
(2019/12/11)
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- Bulky N-Heterocyclic-Carbene-Coordinated Palladium Catalysts for 1,2-Addition of Arylboron Compounds to Carbonyl Compounds
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The synthesis of primary, secondary, and tertiary alcohols by the 1,2-addition of arylboronic acids or boronates to carbonyl compounds, including unactivated ketones, using novel bulky yet flexible N-heterocyclic carbene (NHC)-coordinated 2,6-di(pentan-3-yl)aniline (IPent)-based cyclometallated palladium complexes (CYPs) as catalysts is reported. The PhS-IPent-CYP-catalyzed reactions are efficient at low catalyst loadings (0.02–0.3 mol% Pd), and the exceptional catalytic activity for 1,2-addition is attributed to the steric bulk of the NHC ligand. These reactions can yield a wide range of functionalized benzylic alcohols that are difficult to synthesize by classical protocols using highly active organomagnesium or lithium reagents.
- Okuda, Yuta,Nagaoka, Masahiro,Yamamoto, Tetsuya
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p. 6291 - 6300
(2020/11/30)
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- Potassium Fluoride-Catalyzed Hydroboration of Aldehydes and Ketones: Facile Reduction to Primary and Secondary Alcohols
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A catalytic hydroboration of various ketones and aldehydes can be achieved in the presence of inexpensive and commercially available inorganic salts containing fluoride anion. As a result, the reduction of carbonyl moieties to the corresponding primary and secondary alcohols can be achieved at room temperature under mild conditions.
- Kuciński, Krzysztof,Hreczycho, Grzegorz
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supporting information
p. 552 - 555
(2020/02/04)
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- 1-D manganese(ii)-terpyridine coordination polymers as precatalysts for hydrofunctionalisation of carbonyl compounds
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Reductive catalysis with earth-abundant metals is currently of increasing importance and shows potential in replacing precious metal catalysis. In this work, we revealed catalytic hydroboration and hydrosilylation of ketones and aldehydes achieved by a structurally defined manganese(ii) coordination polymer (CP) as a precatalyst under mild conditions. The manganese-catalysed methodology can be applied to a range of functionalized aldehydes and ketones with turnover numbers (TON) of up to 990. Preliminary results on the regioselective catalytic hydrofunctionalization of styrenes by the Mn-CP catalyst are also presented.
- Johnson, Jahvon,Li, Sihan,Mo, Zixuan,Neary, Michelle C.,Zeng, Haisu,Zhang, Guoqi,Zheng, Shengping
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supporting information
p. 2610 - 2615
(2020/03/05)
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- Palladium-Catalyzed Selective Reduction of Carbonyl Compounds
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Two new examples of structurally characterized β-diketiminate analogues i.e., conjugated bis-guanidinate (CBG) supported palladium(II) complexes, [LPdX]2; [L= {(ArHN)(ArN)–C=N–C=(NAr)(NHAr)}; Ar = 2,6-Et2-C6H3], X = Cl (1), Br (2) have been reported. The synthesis of complexes 1–2 was achieved by two methods. Method A involves deprotonation of LH by nBuLi followed by the treatment of LLi (insitu formed) with PdCl2 in THF, which afforded compound 1 in good yield (75 %). In Method B, the reaction between free LH and PdX2 (X = Cl or Br) in THF allowed the formation of complexes 1 (Yield 73 %) and 2 (Yield 52 %), respectively. Moreover, these complexes were characterized thoroughly by several spectroscopic techniques (1H, 13C NMR, UV/Vis, FT-IR, and HRMS), including single-crystal X-ray structural and elemental analyses. In addition, we tested the catalytic activity of these complexes 1–2 for the hydroboration of carbonyl compounds with pinacolborane (HBpin). We observed that compound 1 exhibits superior catalytic activity when compared to 2. Compound 1 efficiently catalyzes various aldehydes and ketones under solvent-free conditions. Furthermore, both inter- and intramolecular chemoselectivity hydroboration of aldehydes over other functionalities have been established.
- Sarkar, Nabin,Mahato, Mamata,Nembenna, Sharanappa
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p. 2295 - 2301
(2020/05/18)
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- Synthesis and Reactivity of Fluorinated Triaryl Aluminum Complexes
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The addition of the Grignard 3,4,5-ArFMgBr to aluminum(III) chloride in ether generates the novel triarylalane Al(3,4,5-ArF)3·OEt2. Attempts to synthesize this alane via transmetalation from the parent borane with trimethylaluminum gave a dimeric structure with bridging methyl groups, a product of partial transmetalation. On the other hand, the novel alane Al(2,3,4-ArF)3 was synthesized from the parent borane and trimethylaluminum. Interestingly, the solid-state structure of Al(2,3,4-ArF)3 shows an extended chain structure resulting from neighboring Al···F contacts. Al(3,4,5-ArF)3·OEt2 was then found to be an effective catalyst for the hydroboration of carbonyls, imines, and alkynes with pinacolborane.
- Ould, Darren M. C.,Carden, Jamie L.,Page, Rowan,Melen, Rebecca L.
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supporting information
p. 14891 - 14898
(2020/10/02)
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