- Solvent-modulated chemoselective deprotections of trialkylsilyl esters and chemoselective esterifications
-
A series of trialkylsilyl esters were deprotected or transesterificated into their corresponding carboxylic acids or methyl esters under a catalytic amount of CBr4 in alcohol reaction system. This method enables to desilylate secondary sp3-carbon, sp2-carbon, sp-carbon and aryl tethered trialkylsilyl esters to carboxylic acids, whereas primary sp 3-carbon tethered trialkylsilyl esters were further converted into their methyl esters under CBr4/MeOH reaction conditions. The highly chemoselective deprotections can be modulated and achieved by the introduced protecting trialkylsilyl groups and the used alcohols such as MeOH and EtOH under this photochemically-induced reaction conditions.
- Lee, Adam Shih-Yuan,Su, Feng-Yih
-
-
Read Online
- Design and synthesis of sulfonated carbons with amphiphilic properties
-
A new type of sulfonated carbon material with amphiphilic properties was synthesized by the hydrothermal carbonization of a mixture of furfural-sodium dodecylbenzene sulfonate at 180 °C in an autoclave. The addition of SDBS is necessary for the production of materials with long carbon chains and is possibly used to improve the solubilization of long carbon-chain and steric compounds such as pivalic acid. The resulting material was characterized by N2 adsorption, XPS, 13C NMR, XRD and FTIR. The synthesized material was proven to be a highly efficient solid-acid catalyst in reactions such as the esterification of pivalic acid with alcohols, and catalytic performance much better than that of conventional solid acid catalysts, e.g. Amberlyst-15 and Nafion resin, was observed.
- Jia, Rong,Ren, Jiawen,Liu, Xiaohui,Lu, Guanzhong,Wang, Yanqin
-
-
Read Online
- Synthesis of Benzo[a]carbazoles and an Indolo[2,3-a]carbazole from 3-Aryltetramic Acids
-
A simple and flexible approach to 3-pyrrolin-2-one fused carbazoles is disclosed. The key step involves the BF3-mediated electrophilic substitution of indoles with N-alkyl-substituted 3-aryltetramic acids, which provides access to indole-substituted 3-pyrrolin-2-ones. Scholl-type oxidative cyclizations of these materials led to the formation of the corresponding 3-pyrrolin-2-one-fused benzo[a]carbazoles and indolo[2,3-a]carbazoles. This work represents the first synthesis of the benzo[a]pyrrolo[3,4-c]carbazol-3(8H)-one ring system, while the indolo[2,3-a]pyrrolo[3,4-c]carbazol-5-one ring system is found in a number of biologically active compounds including the protein kinase C (PKC) inhibitor, staurosporine.
- Truax, Nathanyal J.,Banales Mejia, Fernando,Kwansare, Deborah O.,Lafferty, Megan M.,Kean, Maeve H.,Pelkey, Erin T.
-
-
Read Online
- Secondary metabolites by chemical screening, 39: Acyl α-L- rhamnopyranosides, a novel family of secondary metabolites from streptomyces sp.: Isolation and biosynthesis
-
In the course of our chemical screening program, the novel acyl α-L- rhamnopyranosides (1-6) were detected as metabolites from five different strains of Streptomycetes. The structures of all these compounds were elucidated by chemical and spectroscopic methods. The biosynthesis of 1 and 3 was established by feeding 13C-labelled acetate, glycerol, and d-glucose to Streptomyces griseoviridis (strain Tu 3634), and resulted in a complete labelling pattern of the 2,4-dimethyl-3-furanylcarbonyl and benzoyl residues, as well as the rhamnose moiety. These results reveal biosynthetic pathways of general importance and give an insight into the generation of the hexose phosphates, from which deoxysugars are formed. The acyl rhamnosides are members of a novel family of microbial metabolites and are considered as rhamnoconjugates from Streptomycetes.
- Grond, Stephanie,Langer, Hans-Jo?rg,Henne, Petra,Sattler, Isabel,Thiericke, Ralf,Grabley, Susanne,Za?hner, Hans,Zeeck, Axel
-
-
Read Online
- Three-component coupling reaction of benzylic halides, carbon dioxide, and N,N-dimethylformamide by using paired electrolysis: Sacrificial anode-free efficient electrochemical carboxylation of benzylic halides
-
Sacrificial anode-free efficient electrochemical carboxylation of benzylic halides was successfully performed by using a paired electrolysis protocol. Constant-current electrolysis of a DMF solution of benzylic halides in the presence of carbon dioxide using a one-compartment cell equipped with a Pt plate cathode and a Pt wire anode (quasi-divided cell) resulted in efficient three-component coupling reaction of benzylic halides, carbon dioxide and DMF to yield N-methyl-N-(phenylacetoxy)methylformamides, as carboxylated coupling products, in good yields.
- Senboku, Hisanori,Nagakura, Kotaro,Fukuhara, Tsuyoshi,Hara, Shoji
-
-
Read Online
- Scandium triflate catalyzed transesterification of carboxylic esters
-
The direct transesterification of carboxylic esters is efficiently catalyzed with Sc(OTf)3 (10 mol%) in boiling alcoholic solvent. Methyl, ethyl, isopropyl, and allyl esters were prepared from a broad range of different substrates in high yields. The application of microwave irradiation led to significantly reduced reaction times. Georg Thieme Verlag Stuttgart.
- Remme, Nicole,Koschek, Katharina,Schneider, Christoph
-
-
Read Online
- Phenylsilane as an effective desulfinylation reagent
-
The reduction using phenylsilane in a KOH-catalyzed system was applied successfully to the conversion of sulfinyl-substituted cyclopropylcarboxylates into the corresponding alcohols. The presence of sulfinyl substituents in the α-position to the carboxylate group caused a desulfinylation product formation with full regio- and stereoselectivity, instead of a carbonyl group reduction. Investigations performed on different α-sulfinylcarbonyl compounds revealed that phenylsilane treatment constitutes a regiospecific method for the desulfinylation of a-sulfinylesters; for corresponding ketones the reaction course depends on the character of the carbonyl group.
- Midura, Wanda H.,Rzewnicka, Aneta,Krysiak, Jerzy A.
-
-
Read Online
- PAH-supported tin hydride: A new tin reagent easily removable from reaction mixtures
-
We demonstrate here that a new pyrene-supported tin hydride can be used in radical chemistry. Final products were easily purified by adsorption of the PAH-supported tin side product with activated carbon.
- Gastaldi, Stéphane,Stien, Didier
-
-
Read Online
- Simple transformation of nitrile into ester by the use of chlorotrimethylsilane
-
Treatment of nitriles with alcohol and chlorotrimethylsilane at 50°C for 4 h could give esters in fair to good yields. Under similar reaction conditions, intramolecular lactonization via the concomitant nitrile and hydroxy groups in good yield were also demonstrated.
- Luo, Fen-Tair,Jeevanandam, Arumugasamy
-
-
Read Online
- Chemistry of palladium phosphinite (PPh2(OR)) and phosphonite (P(OPh)2(OH)) complexes: Catalytic activity in methoxycarbonylation and Heck coupling reactions
-
The new phosphinite and phosphonite complexes (1-8) are very efficient catalysts for the methoxycarbonylation of iodobenzene and Heck cross-coupling of bromobenzene with butyl acrylate. High catalytic activity of these complexes can be explained by their in situ transformations during the reaction, stimulated by the presence of water, acid (HCl) or base (NEt3). Hydrolysis of phosphinite palladium complexes of the form trans-PdCl 2[PPh2(OR)]2 (R = C6F5 2, tBu 3, or O-menthyl 4) results in the formation of the dimeric complex [μ-ClPd(PPh2OH)(PPh2O)]2 5, which is deprotonated by NEt3, producing a polymeric complex of formula [Pd(P(O)PPh2)2]n 8. The reverse reaction, protonolysis of 8 with HCl, leads back to 5 and the monomeric complex 5a. The phosphinite complex PdCl2[PPh2(OBu)]2 1 with a more lipophilic ligand, PPh2(OBu), does not undergo hydrolysis under the same conditions. In the reaction of PdCl2(cod) with P(OPh) 2(OH), the new dimer [μ-ClPd(P(OPh)2OH)(P(OPh) 2O)]2 6 was obtained, whereas reaction of Pd(OAc) 2 with P(OPh)2(OH) leads to the polymeric complex [Pd[P(O)(OPh)2]2]n 7. Protonolysis of 7 with HCl results in the formation of 6. The Royal Society of Chemistry 2006.
- Pryjomska, Iweta,Bartosz-Bechowski, Hubert,Ciunik, Zbigniew,Trzeciak, Anna M.,Ziolkowski, Jozef J.
-
-
Read Online
- Fragmentation of chloroperoxides: Hypochlorite-mediated dehydration of hydroperoxyacetals to esters
-
Hypochlorites efficiently dehydrate hydroperoxyacetals to furnish the corresponding esters. The reaction, which can be accomplished with stoichometric Ca(OCl)2 or with catalytic amounts of t-BuOCl, appears to involve formation and heterolytic fragmentation of secondary chloroperoxides, species not previously described in solution chemistry.
- Fisher, Thomas J.,Dussault, Patrick H.
-
-
Read Online
- Role of Arabidopsis INDOLE-3-ACETIC ACID CARBOXYL METHYLTRANSFERASE 1 in auxin metabolism
-
The phytohormone auxin regulates a wide range of developmental processes in plants. Indole-3-acetic acid (IAA) is the main auxin that moves in a polar manner and forms concentration gradients, whereas phenylacetic acid (PAA), another natural auxin, does not exhibit polar movement. Although these auxins occur widely in plants, the differences between IAA and PAA metabolism remain largely unknown. In this study, we investigated the role of Arabidopsis IAA CARBOXYL METHYLTRANSFERASE 1 (IAMT1) in IAA and PAA metabolism. IAMT1 proteins expressed in Escherichia coli could convert both IAA and PAA to their respective methyl esters. Overexpression of IAMT1 caused severe auxin-deficient phenotypes and reduced the levels of IAA, but not PAA, in the root tips of Arabidopsis, suggesting that IAMT1 exclusively metabolizes IAA in vivo. We generated iamt1 null mutants via CRISPR/Cas9-mediated genome editing and found that the single knockout mutants had normal auxin levels and did not exhibit visibly altered phenotypes. These results suggest that other proteins, namely the IAMT1 homologs in the SABATH family of carboxyl methyltransferases, may also regulate IAA levels in Arabidopsis.
- Takubo, Eiko,Kobayashi, Makoto,Hirai, Shoko,Aoi, Yuki,Ge, Chennan,Dai, Xinhua,Fukui, Kosuke,Hayashi, Ken-ichiro,Zhao, Yunde,Kasahara, Hiroyuki
-
-
Read Online
- Oxygen Transfer Involving Non-Heme Iron. The reaction of (EDTA)Fe(III) with m-Chloroperbenzoic Acid
-
Oxygen transfer from percarboxylic acids to (ethylenediaminotetraacetato)iron(III) ((EDTA)Fe(III)) has been investigated (solvent CH3OH; T 30 deg C), using 2,4,6-tri-tert-butylphenol (TBPH) as a trapping reagent for the reactive iron-oxo intermediate formed upon oxygen transfer.In the presence of TBPH the percarboxylic acid peroxo bond undergoes 100 percent heterolytic cleavage during oxygen transfer to (EDTA)Fe(III), as demonstrated with phenylperacetic acid.This requires the reaction to involve the transfer of an oxene or oxygen atom to the iron(III) moiety of the (EDTA)Fe(III) catalyst to form what may be formally written as (EDTA)Fe(V)O.Since the so-constituted oxidant oxidized PhCH2COH by 1e- transfer to provide (PhCH2)2 at a rate greater than the oxidation of carboxylate ligand, the electron deficiency of the oxidant must reside at the oxygen to a greater extent than on iron.The structure of the oxidant is, therefore, best represented as something between (EDTA)Fe(V)O and one in which the iron(III) species stabilizes the oxygen atom by d-orbital overlap ((EDTA)Fe(III)O) species.The kinetics of the reaction of a percarboxylic acid with (EDTA)Fe(III) were studied by using m-chloroperbenzoic acid (MCPBA).The reaction was monitored by following the appearance of 2,4,6-tri-tert-butylphenoxyl radical (TPB*).Oxygen transfer was shown to be rate limiting from the first-order dependence upon and zero-order dependence upon .At constant and , the pseudo-first-order rate constants, kobsd, for the appearance of TBP* increases linearly with increase in and reaches a limiting value at high (EDTA)Fe(III) concentrations.Oxidation of TBPH to TBP* is shown to compete with methanol solvent oxidation to formaldehyde and the oxidative coupling of MCPBA with TBPH to provide a peroxidic component, OXO.The percentage yields of TBP*, CH2O, and OXO are independent of the concentration of (EDTA)Fe(III), provided the concentrations of MCPBA and TBPH are kept constant.However, increasing the initial concentration of MCPBA increases the concentration of OXO, and, correspondingly, the yield of the other two products decreases.Similarly, the yield of phenoxyl radical increases with increase in .The initial addition of formaldehyde retards the rate of the oxidation reactions.A kinetically competent series of reactions which allow the calculation of experimental values of kobsd and the yields of products have been arrived at by computer simulation (Scheme III).Comparison of the second-order rate constants (in methanol) for oxygen transfer from MCPBA to (tetraphenylporphyrinato)iron(III) chloride ((TPP)Fe(III)Cl) and to (EDTA)Fe(III) establishes the former to be but 45-fold a better acceptor.
- Balasubramanian, P. N.,Bruice, Thomas C.
-
-
Read Online
- Esterification of carboxylic acids with boron trichloride
-
Treatment of carboxylic acids with boron trichloride followed by addition of alcohol provides the carboxylic ester. This esterification, following BCl3 ether or ester O-C cleavage reaction conditions, proceeds cleanly in good yields with most substrates. Cleavage of benzyl esters with boron trichloride then treating with methanol affords the methyl ester.
- Dyke, Christopher A.,Bryson, Thomas A.
-
-
Read Online
- Sodium bis(2-methoxyethoxy)aluminium hydride in petroleum ether; a reagent for the selective reduction of brominated fatty esters to bromo alcohols
-
The combination of NaH2Al(OCH2CH2OMe)2/petroleum ether was found to be highly effective for the selective reduction of long chain esters to alcohols in the presence of alkyl bromides.
- Wells, Andy
-
-
Read Online
- Nucleophilic catalysis with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) for the esterification of carboxylic acids with dimethyl carbonate
-
1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) is an effective nucleophilic catalyst for carboxylic acid esterification with dimethyl carbonate (DMC). The reaction pathway of this new class of nucleophilic catalysis has been studied. A plausible, multistep mech
- Shieh, Wen-Chung,Dell, Steven,Repic, Oljan
-
-
Read Online
- Synthesis of Methyl Esters by Titanate-catalyzed Transesterifications
-
The low solubility of tetramethyl titanate has so far prevented the laboratory use of titanate-catalyzed transesterifications with formation of methyl esters.Two procedures are described here, which allow the application of this exceedingly mild method to the synthesis of methyl esters: one uses methyl propionate/Ti(OEt)4, the other one uses methanol/Gly-Ti, a new type of catalyst, prepared from Ti(OEt)4/ethylene glycol 2:1.
- Schnurrenberger, Peter,Zueger, Max F.,Seebach, Dietrich
-
-
Read Online
- MICROBIAL HYDROLYSIS AS A POTENT METHOD FOR THE PREPARATION OF OPTICALLY ACTIVE NITRILES, AMIDES AND CARBOXYLIC ACIDS
-
Many kinds of aromatic nitriles have been hydrolyzed to afford the corresponding amides and carboxylic acids, by the aid of enzyme system of Rhodococcus butanica.This enzymatic hydrolysis can be successfully applied to the kinetic resolution of α-arylpropionitriles, resulting in the formation of (R)-amides and (S)-carboxylic acids.
- Kakeya, Hideaki,Sakai, Naoko,Sugai, Takeshi,Ohta, Hiromichi
-
-
Read Online
- The oxidation of aldehydes to methyl esters using trichloroisocyanuric acid
-
Aldehydes are readily oxidized to methyl esters by a solution of methanol, pyridine, and trichloroisocyanuric acid in acetonitrile, acetone, or methylene chloride.
- Hiegel, Gene A.,Bayne, Christopher D.,Donde, Yariv,Tamashiro, Gerald S.,Hilberath, Lisa A.
-
-
Read Online
- Design of polyaromatic hydrocarbon-supported tin reagents: A new family of tin reagents easily removable from reaction mixtures
-
We report in this paper the preparation and use of stannanes 11, 12a, and 12b, compounds whose 3-pyrenylpropyl side chain affinity for activated carbon simplifies tin removal and product isolation. Our pyrene-supported reagents can be used for radical reductions and cyclizations (11), radical and cationic allylations (12a), and Stille couplings (12b) in much the same way as tributyltin derivatives.
- Stien, Didier,Gastaldi, Stephane
-
-
Read Online
- ACYLCo(III) SALEN. A NEW UNSYMMETRICAL KETONE SYNTHESIS
-
New acyl complexes of N,N'-ethylenebis(salicylideneiminato)cobalt(III) 2 were prepared and their acyl transfer reactions with several nucleophiles were examined.The reaction with MeMgI at room temp gave unsymmetrical ketones of the type MeCOR in reasonably good yields.
- Tabushi, Iawo,Seto, Kiyotomo,Kobuke, Yoshiaki
-
-
Read Online
- Selective Actinide-Catalyzed Tandem Proton-Transfer Esterification of Aldehydes with Alcohols for the Production of Asymmetric Esters
-
Actinide-catalyzed tandem proton-transfer esterification between aldehydes and alcohols is presented herein for the first time. It represents a novel convenient and external-oxidant-free methodology in the preparation of asymmetric ester compounds. Various kinds of aldehydes and alcohols can be applied to this reaction, affording the corresponding ester product in moderate to high yields. A plausible mechanism was proposed on the basis of the kinetic, stoichiometric, and deuterium-labeling studies.
- Liu, Heng,Eisen, Moris S.
-
-
Read Online
- Selective mono-C-methylations of arylacetonitriles and arylacetates with dimethylcarbonate: A mechanistic investigation
-
The very high mono-C-methylation selectivity (>99%) of arylacetic acid derivatives (ArCH2X; X = CN, CO2Me) with dimethyl carbonate (DMC) is due to a mechanism that involves consecutive methoxycarbonylation, methylation, and demethoxycarbonylation steps. Important aspects of this mechanism are clarified herein by a kinetic investigation. In the case of arylacetonitriles, at 140°C, the comparison of the rate constants of model reactions involving 2-phenyl propionitrile, phenylacetonitrile, 2-methoxycarbonylphenylacetonitrile, and 2-methyl-2-methoxy carbonylphenyl acetonitrile (compounds 1a-4a, respectively) with DMC indicates that the methylation process is the fastest and the irreversible step, which drives the overall reaction to completion. The situation is reversed for arylacetic esters, where the methylation is more difficult than the demethoxycarbonylation reaction; therefore, a higher reaction temperature is required.
- Tundo, Pietro,Selva, Maurizio,Perosa, Alvise,Memoli, Sofia
-
-
Read Online
- Discovery of multicomponent heterogeneous catalysts via admixture screening: PdBiTe catalysts for aerobic oxidative esterification of primary alcohols
-
In the present study, we demonstrate the utility of "admixture screening" for the discovery of new multicomponent heterogeneous Pd catalyst compositions that are highly effective for aerobic oxidative methyl esterification of primary alcohols. The identification of possible catalysts for this reaction was initiated by the screening of simple binary and ternary admixtures of Pd/charcoal in combination with one or two metal and/or metalloid components as the catalyst. This approach permitted rapid evaluation of over 400 admixture combinations for the oxidative methyl esterification of 1-octanol at 60°C in methanol. Product yields from these reactions varied widely, ranging from 2% to 88%. The highest yields were observed with Bi-, Te-, and Pb-based additives, and particularly from those containing both Bi and Te. Validation of the results was achieved by preparing specific PdBiTe catalyst formulations via a wet-impregnation method, followed by application of response surface methodology to identify the optimal Pd-Bi-Te catalyst stoichiometry. This approach revealed two very effective catalyst compositions: PdBi0.47Te0.09/C (PBT-1) and PdBi0.35Te0.23/C (PBT-2). The former catalyst was used in batch aerobic oxidation reactions with different primary alcohols and shown to be compatible with substrates bearing heterocycle and halide substituents. The methyl ester products were obtained in >90% yield in nearly all cases. Implementation of the PBT-2 catalyst in a continuous-flow packed-bed reactor achieved nearly 60 000 turnovers with no apparent loss of catalytic activity.
- Mannel, David S.,Ahmed, Maaz S.,Root, Thatcher W.,Stahl, Shannon S.
-
-
Read Online
- Design, synthesis, and in vitro evaluation of novel 1,3,4-oxadiazolecarbamothioate derivatives of Rivastigmine as selective inhibitors of BuChE
-
Rivastigmine has been prescribed for the therapy of Alzheimer’s disease (AD) symptoms. This drug is classified in the carbamate derivative group that has dual activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). According to the structure of Rivastigmine and its performance, a new series of 5-aryl-1,3,4-oxadiazole-2-carbamothioate compounds I–XI was synthesized using structure-based drug discovery approaches. For this purpose a set of these compounds were designed with computational docking method and their interactions with amino acid residues in the active sites of AChE and BuChE checked out. The structures of synthesized compounds were established by physicochemical and spectroscopic methods. The carbamoyl moiety of Rivastigmine structure was modified to carbamothioate and the effects of 1,3,4-oxadiazole heterocycle as a pharmacophoric nucleus were investigated. The potential of the synthesized compounds I–XI was evaluated against two most known agents of AD (AChE and BuChE) to determine their IC50 values. The results of the docking showed the range of binding affinity for the best poses of ten individual conformers for any compounds (I–XI) was between ?7.81 (VI) and ?6.75 (II) kcal/mol. The results of biological experiments displayed that most synthetic compounds (I–VIII) showed moderate to excellent selective activity range against BuChE (0.51–69.44 μM). In vitro cytotoxicity evaluation of these compounds (I–XI) by MTT assay on human dermal fibroblast (HDF) cell line exhibited no activity against HDF. The compound VI [S-(5-(p-tolyl)-1,3,4-oxadiazol-2-yl) ethyl(methyl)carbamothioate] showed the most stable binding affinity (?7.81 kcal/mol) and the lowest IC50 value (0.51 μM) in comparison with Rivastigmine with 7.72 μM and Donepezil with 5.20 μM against BuChE.
- Fallah, Akram,Mohanazadeh, Farajollah,Safavi, Maliheh
-
-
Read Online
- One-Carbon Homologation of Primary Alcohols to Carboxylic Acids, Esters, and Amides via Mitsunobu Reactions with MAC Reagents
-
A method is reported for the one-carbon homologation of an alcohol to the extended carboxylic acid, ester, or amide. The process involves the Mitsunobu reaction with an alkoxymalononitrile, followed by unmasking in the presence of a suitable nucleophile. The homologation and unmasking can even be performed in a one-pot process in high yield.
- Kagawa, Natsuko,Nibbs, Antoinette E.,Rawal, Viresh H.
-
-
Read Online
- Conversion of phenylacetonitrile in supercritical alcohols within a system containing small volume of water
-
The reaction of phenylacetonitrile in supercritical methanol and ethanol in a system containing a small volume of water was studied. The effects of various operating conditions, such as reaction temperature, reaction time, the mole ratio of phenylacetonitrile/water/methanol or ethanol on the product yield were systematically investigated. The optimal yield of methyl phenylacetate for phenylacetonitrile in supercritical methanol in a system containing a small volume of water was 70 % at 583 K and 2.5 h. The optimal yield of ethyl phenylacetate for phenylacetonitrile in supercritical ethanol with a small volume of water was 80 % at 583 K and 1.0 h. At the same time, a feasible mechanism was proposed for phenylacetonitrile in supercritical methanol and ethanol in a system containing a small volume of water.
- Hou, Zhi-Qiang,Zhang, Rui-Zhe,Luo, Li-Gang,Yang, Jing,Liu, Chun-Ze,Wang, Yuan-Yuan,Dai, Li-Yi
-
-
Read Online
- Catalytic Uses of Fe(CO)5: Formation of Carboxylic Acid Derivatives
-
Carboxylic acid derivatives were prepared by carbonylating an alkyl or aralkyl halide in the presence of a catalytic amount of iron carbonyl, a base, and an alcohol or water.
- Tustin, Gerald C.,Hembre, Robert T.
-
-
Read Online
- Resolution of secondary alcohols using 2-acyl-3-phenyl-l-menthopyrazoles as enantioselective acylating agents
-
The chelation of AlCl3 with N-acylpyrazoles leads to structural fixation of the acyl moiety and an acceleration in the rate of acylation of secondary alcohols. The chiral environment of the fixed acyl moiety of 2-acyl-3-phenyl-l-menthopyrazole 2 causes diastereofacial selectivity in the reaction with secondary alcohols, and thus 2 behaves as an enantioselective acylating agent. By the use of 2.4 molar equivalents of racemic 1-phenylethanol 3a, 2-acetyl-3-phenyl-l-menthopyrazole 2a afforded (S)-1-phenylethyl acetate (S)-4aa enantioselectively and unreacted 3a was recovered with (R)-configuration. Furthermore, the inverse configurational preferences were observed to give (R)-4aa and (S)-3a by the addition of strongly basic amines, which sometimes behaved as catalysts for enolate formation from 2 and AlCl3. These dramatic changes in stereoselective preference should be useful properties of 2-acyl-3-phenyl-l-menthopyrazole 2 as an enantioselective acylating agent.
- Kashima, Choji,Mizuhara, Saori,Miwa, Yohei,Yokoyama, Yukihiro
-
-
Read Online
- Methanolysis of ethyl esters of N-acetyl amino acids catalyzed by cyclosophoraoses isolated from Rhizobium meliloti
-
Methanolysis of four ethyl esters, N-acetyl-l-phenylalanine ethyl ester, N-acetyl-l-tyrosine ethyl ester, N-acetyl-l-tryptophan ethyl ester, and ethyl phenylacetate was catalyzed by a mixture of microbial cyclooligosaccharides termed cyclosophoraoses isolated from Rhizobium meliloti. Cyclosophoraoses [cyclic-(1→2)-β-d-glucans, collectively 'Cys'] are a mixture of large-ring molecules consisting of various numbers of glucose residues (17-27) linked by β-(1→2)-glycosidic bonds. Cys as a catalytic carbohydrate enhanced the methanolysis about 233-fold for N-acetyl-l-tyrosine ethyl ester in comparison with a control. The effect of dry organic solvents on the methanolysis of N-acetyl-l-tyrosine ethyl ester was investigated by high-performance liquid chromatography (HPLC), and it was found that the rate enhancement correlated closely with the hydrophobicity of the solvent.
- Park, Heylin,Jung, Seunho
-
-
Read Online
- Novel ether-functional spiro-tetronic acid derivatives: Molecule design, convenient synthesis and biological evaluation
-
A novel series of ether functionalization of spiro-tetronic acid derivatives have been designed and conveniently synthesized via three steps, including esterification, one-pot heterocyclization, and etherification reactions. The target molecules have been identified on the basis of analytical spectra data. All newly synthesized compounds have been screened for their potential insecticidal activity against Heliothis armigera and Plutella xylostella compared with spirodiclofen by standard method. Springer Science+Business Media B.V. 2012.
- Ke, Shaoyong,Zhang, Zhigang,Zhang, Ya-Ni,Shi, Liqiao,Zhou, Ronghua,Jiang, Aibing,Liang, Ying,Yang, Ziwen
-
-
Read Online
- Dimethyl malonate/LHMDS system as a new protocol for generating methyl formate anion (-COOMe) in the condensed-phase Dedicated to Professor Charles H. DePuy (1927-2013)
-
The treatment of dimethyl malonate with LHMDS in anhydrous THF (condensed-phase) generates, in addition to the expected corresponding lithium enolate, methyl formate anion (or methoxycarbonyl anion, -COOMe) which can react with several electrophiles to give corresponding methoxycarbonyl derivatives by nucleophilic substitution reaction.
- Di Bussolo, Valeria,Princiotto, Salvatore,Martinelli, Elisa,Bordoni, Vittorio,Crotti, Paolo
-
-
Read Online
- Silica Chloride: A Versatile Heterogeneous Catalyst for Esterification and Transesterification
-
Silica chloride has been found to be an efficient catalyst for esterification of carboxylic acids (aliphatic, aromatic and conjugated) with alcohols (primary, secondary and tertiary) as well as for transesterification of esters (by both alcoholysis and acidolysis).
- Srinivas,Mahender,Das, Biswanath
-
-
Read Online
- Ni-catalyzed direct alcoholysis of N-acylpyrrole-type tertiary amides under mild conditions
-
N-Acylpyrrole-type amides are a class of versatile building blocks in asymmetric synthesis. We report that by employing Ni(COD)2/2,2′-bipyridine (5 mol%) catalytic system, the direct, catalytic alcoholysis of N-acylpyrrole-type aromatic and aliphatic amides with both primary and secondary alcohols can be achieved efficiently under very mild conditions (rt, 1 h) even at gram scale. By increasing the catalyst loading to 10 mol%, prolonging reaction time (18 h), and/or elevating reaction temperature to 50 °C/80 °C, the reaction could be extended to both complex and hindered N-acylpyrroles as well as to N-acylpyrazoles, Nacylindoles, and to other (functionalized) primary and secondary alcohols. In all cases, only 1.5 equiv. of alcohol were used. The value of the method has been demonstrated by the racemization-free, catalytic alcoholysis of chiral amides yielded from other asymmetric methodologies.
- Chen, Hang,Chen, Dong-Huang,Huang, Pei-Qiang
-
-
Read Online
- W(CO)6 Mediated C-S Bond Cleavage Reactions
-
W(CO)6-mediated reactions of thioethers in refluxing chlorobenzene yielded mainly the corresponding dimers.Optically active thioethers give the respective racemic products.Mercaptans, on the other hand, predominantly afford the corresponding reduced products.A deuterium labeling experiments suggest that the SH group is the hydrogen source in the latter reduction reactions.A free-radical mechanism is suggested.
- Ng, Chi Tat,Wang, Xiaojun,Luh, Tien-Yau
-
-
Read Online
- Chemoselective nucleophilic arylation and single-step oxidative esterification of aldehydes using siloxanes and a palladium-phosphinous acid as a reaction switch
-
Aldehydes and siloxanes form methyl esters in a single step through mild oxidative esterification in the presence of a palladium catalyst or, alternatively, afford secondary alcohols via TBAF-promoted arylation in the absence of a catalyst at increased temperatures under otherwise identical reaction conditions. Copyright
- Lerebours, Rachel,Wolf, Christian
-
-
Read Online
- Conversion of primary alcohols and aldehydes into methyl esters by ruthenium-catalysed hydrogen transfer reactions
-
Alcohols and aldehydes are oxidised to the corresponding methyl esters by reaction with methanol in the presence of crotononitrile as a hydrogen acceptor using a catalyst combination of Ru(PPh3)3(CO)H2 with xantphos. Georg Thieme Verlag Stuttgart.
- Owston, Nathan A.,Nixon, Tracy D.,Parker, Alexandra J.,Whittlesey, Michael K.,Williams, Jonathan M. J.
-
-
Read Online
- A Simple, efficient, green, cost effective and chemoselective process for the esterification of carboxylic acids
-
Carboxylic acids have been esterified under mild and solvent-free conditions in high yield and purity using the green reagents, dimethyl carbonate and diethyl carbonate, under acid catalysis. The present methodology is free of the disadvantages of base catalysis described earlier, such as high temperatures, use of autoclaves, use of the expensive DBU as base in stoichiometric amounts and the carbonate as solvent. High chemoselectivity is observed in the case of hydroxybenzoic acids.
- Rekha,Ramani, Modukuri V.,Ratnamala,Rupakalpana, Vempati,Subbaraju, Gottumukkala V.,Satyanarayana, Chava,Rao, C. Someswara
-
-
Read Online
- A solvent-reagent selection guide for Steglich-type esterification of carboxylic acids
-
The Steglich esterification is a widely employed method for the formation of esters under mild conditions. A number of issues regarding the sustainability of this transformation have been identified, chiefly the use of hazardous carbodiimide coupling reagents in conjunction with solvents with considerable issues such as dichloromethane (DCM) and N,N-dimethylformamide (DMF). To overcome these issues, we have developed a solvent-reagent selection guide for the formation of esters via Steglich-type reactions with the aim of providing safer, more sustainable conditions. Optimum reaction conditions have been identified after high-throughput screening of solvent-reagent combinations, namely the use of Mukaiyama's reagent (Muk) in conjunction with solvent dimethyl carbonate (DMC). The new reaction conditions were also exemplified through the synthesis of a small selection of building-block like molecules and includes the formation of t-butyl esters.
- Jordan, Andrew,Sneddon, Helen F.,Sydenham, Jack,Whymark, Kyran D.
-
supporting information
p. 6405 - 6413
(2021/09/10)
-
- Green Esterification of Carboxylic Acids Promoted by tert-Butyl Nitrite
-
In this work, the green esterification of carboxylic acids promoted by tert-butyl nitrite has been well developed. This transformation is compatible with a broad range of substrates and exhibits excellent functional group tolerance. Various drugs and substituted amino acids are applicable to this reaction under near neutral conditions, with good to excellent yields.
- Cheng, Xionglve,Jiang, Gangzhong,Li, Xingxing,Tao, Suyan,Wan, Xiaobing,Zhao, Yanwei,Zheng, Yonggao
-
supporting information
p. 2713 - 2718
(2021/06/25)
-
- Design, modification of phyllanthone derivatives as anti-diabetic and cytotoxic agents
-
Twelve benzylidene derivatives, one Baeyer-Villiger oxidative, six imine derivatives were successfully designed and synthesised from phyllanthone. In the search for potential new anti-diabetic agents, phyllanthone along with its benzylidene and oxidation analogues were evaluated for enzyme inhibition against α-glucosidase. In the benzylidene series, most analogues displayed stronger activity than the mother compound. Compound 1c revealed the strongest activity, outperforming the acarbose positive control with an IC50 value of 19.59 μM. Phyllanthone and its derivatives were then tested for cytotoxic activity against the K562 cell line. The imine analogues displayed the most powerful cytotoxic activity with 3cand 3d having IC50 values of 57.55 and 68.02 μM, respectively.
- Nguyen, Ngoc-Hong,Vo, Van-Giau,Phan, Hoang-Vinh-Truong,Ngo, Thanh-The,Sichaem, Jirapast,Nguyen, Thi-Phuong,Nguyen, Huu-Hung,Pham, Duc-Dung,Nguyen, Tien-Cong,Nguyen, Van-Kieu,Duong, Thuc-Huy
-
supporting information
p. 371 - 378
(2020/07/13)
-
- GPR52 Antagonist Reduces Huntingtin Levels and Ameliorates Huntington's Disease-Related Phenotypes
-
GPR52 is an orphan G protein-coupled receptor (GPCR) that has been recently implicated as a potential drug target of Huntington's disease (HD), an incurable monogenic neurodegenerative disorder. In this research, we found that striatal knockdown of GPR52 reduces mHTT levels in adult HdhQ140 mice, validating GPR52 as an HD target. In addition, we discovered a highly potent and specific GPR52 antagonist Comp-43 with an IC50 value of 0.63 μM by a structure-activity relationship (SAR) study. Further studies showed that Comp-43 reduces mHTT levels by targeting GPR52 and promotes survival of mouse primary striatal neurons. Moreover, in vivo study showed that Comp-43 not only reduces mHTT levels but also rescues HD-related phenotypes in HdhQ140 mice. Taken together, our study confirms that inhibition of GPR52 is a promising strategy for HD therapy, and the GPR52 antagonist Comp-43 might serve as a lead compound for further investigation.
- Wang, Congcong,Zhang, Yu-Fang,Guo, Shimeng,Zhao, Quan,Zeng, Yanping,Xie, Zhicheng,Xie, Xin,Lu, Boxun,Hu, Youhong
-
p. 941 - 957
(2020/11/30)
-
- Magnesium chloride (MgCl2) catalyzed highly regioselective C-3 ring opening of 2,3 epoxy alcohols by N-nucleophile
-
We herein report Magnesium chloride (MgCl2) catalyzed first highly C3-selective ring-opening reaction of various 2,3-epoxy alcohols with assorted N-Nucleophiles and sodium azide to furnish 3-amino-1,2 diols and 3-azido-1,2 diols respectively in high yields under mild reaction conditions. This protocol attributes the use of catalytic amount of Magnesium chloride (MgCl2), simple reaction conditions, practical operation and broad functional group tolerance.
- Kumar, Amit,Panda, Gautam
-
supporting information
(2021/04/09)
-
- B(C6F5)3-catalyzed O-H insertion reactions of diazoalkanes with phosphinic acids
-
A highly efficient base-, metal-, and oxidant-free catalytic O-H insertion reaction of diazoalkanes and phosphinic acids in the presence of B(C6F5)3has been developed. This powerful methodology provides a green approach towards the synthesis of a broad spectrum of α-phosphoryloxy carbonyl compounds with good to excellent yields (up to 99% yield). The protocol features the advantages of operational simplicity, high atom economy, practicality, easy scalability and environmental friendliness.
- Jiang, Jun,Zhang, Xinzhi,Zhang, Yangyang,Zhao, Jincheng
-
supporting information
p. 5772 - 5776
(2021/07/12)
-
- Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
-
Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
- K?nig, Burkhard,Wang, Hua,Wang, Shun
-
supporting information
p. 1653 - 1665
(2021/06/17)
-
- Electrocatalytic carboxylation of halogenated compounds with mesoporous silver electrode materials
-
Mesoporous silver materials are used as electrocatalysts for halogenated compounds. The mesoporous silver materials have uniform mesoporous size (8 nm), large specific surface area (12 m2g?1), high pore volume (0.07 cm3g?1), and a good 3D network structure of the metallic silver skeleton. The results show that the prepared materials exhibit high performance in electrocatalytic carboxylation of halogenated compounds to acid (78%).
- Jiang, Cheng-Jie,Liu, Yu-Ting,Lu, Jia-Xing,Shan, Si-Li,Wang, Huan,Zhang, Jing-Jie
-
p. 21986 - 21990
(2021/07/02)
-
- Copper on charcoal: Cu0nanoparticle catalysed aerobic oxidation of α-diazo esters
-
By using a charcoal supported nano Cu0catalyst (Cu/C), a highly efficient oxidation of α-diazo esters to α-ketoesters with molecular oxygen as the sole oxidant has been developed. In the presence of the Cu/C catalyst, 2-aryl-α-diazo esters with both electron-donating and electron-withdrawing groups can be oxidized to the corresponding α-ketoesters efficiently. Furthermore, this Cu/C catalyst can catalyse the reaction of aryl α-diazo ester with water to form aryl ketoester, 2-aryl-2-hydroxyl acetate ester and 2-aryl acetate ester. In this case, water is split by α-diazo ester, and the diazo group is displaced by the oxygen or hydrogen atom in water. Mechanistic investigation showed that the reaction of α-diazo ester with oxygen proceeds through a radical pathway. In the presence of 2,2,6,6-tetramethyl piperidine nitrogen oxide, the reaction of α-diazo ester with oxygen is dramatically inhibited. Furthermore, the reaction of α-diazo ester with water is investigated by an isotopic tracer method, and GCMS detection showed that a disproportionation reaction occurred between α-diazo ester and water.
- Chu, Changhu,Dong, Wenwen,Lin, Jia,Teng, Jiangge,Wang, Zhiwei,Zhao, Rong
-
supporting information
p. 6120 - 6126
(2021/07/21)
-
- Method for catalyzing non-tension non-polar carbon-carbon single bond hydrogenolysis of dicarbonyl compound
-
The invention belongs to the technical field of chemical engineering, and particularly relates to a method for catalyzing non-tension non-polar carbon-carbon single bond hydrogenolysis of a dicarbonyl compound. According to the method, in a rare earth catalysis system, a secondary alcohol (amine) compound or hydrosilyane is used as a hydrogen source, and non-tension carbon-carbon single bonds of diketone and ketone ester are subjected to hydrogenolysis to form monoketone (ester). The method is a first carbon-carbon bond hydrogenolysis reaction of ketone, and the reaction has the advantages of good atom economy, high position selectivity and chemical selectivity, mild conditions, simplicity and convenience in operation, strong functional group tolerance and the like. Diketone and ketone ester are wide in source, and application is wide when diketone and ketone ester are converted into monoketone (ester).
- -
-
Paragraph 0058-0063
(2021/08/06)
-
- Discovery of [1,2,4]triazole derivatives as new metallo-β-lactamase inhibitors
-
The emergence and spread of metallo-β-lactamase (MBL)-mediated resistance to β-lactam antibacterials has already threatened the global public health. A clinically useful MBL inhibitor that can reverse β-lactam resistance has not been established yet. We here report a series of [1,2,4]triazole derivatives and analogs, which displayed inhibition to the clinically relevant subclass B1 (Verona integron-encoded MBL-2) VIM-2. 3-(4-Bromophenyl)-6,7-dihydro-5H-[1,2,4]triazolo [3,4-b][1,3]thiazine (5l) manifested the most potent inhibition with an IC50 (half-maximal inhibitory concentration) value of 38.36 μM. Investigations of 5l against other B1 MBLs and the serine β-lactamases (SBLs) revealed the selectivity to VIM-2. Molecular docking analyses suggested that 5l bound to the VIM-2 active site via the triazole involving zinc coordination and made hydrophobic interactions with the residues Phe61 and Tyr67 on the flexible L1 loop. This work provided new triazole-based MBL inhibitors and may aid efforts to develop new types of inhibitors combating MBL-mediated resistance.
- Yuan, Chen,Yan, Jie,Song, Chen,Yang, Fan,Li, Chao,Wang, Cheng,Su, Huiling,Chen, Wei,Wang, Lijiao,Wang, Zhouyu,Qian, Shan,Yang, Lingling
-
-
- Multi-substituted pyrrole derivative and preparation method thereof
-
The invention discloses a multi-substituted pyrrole derivative and a preparation method thereof, and relates to the field of organic synthesis. According to the preparation method, diazonium or phenylhydrazone reacts with amino substituted unsaturated car
- -
-
Paragraph 0031
(2020/02/27)
-
- 3,3′-Disubstituted Oxindoles Formation via Copper-Catalyzed Arylboration and Arylsilylation of Alkenes
-
Arylboration and arylsilylation reactions of N-(2-iodoaryl)acrylamides with bis(pinacolato)-diboron (B2pin2) or PhMe2Si-Bpin are developed by using simple CuOAc as the sole catalyst. A range of boron-or silane-bearing 3,3′-disubstituted oxindoles are obtained in moderate to excellent yields. The reaction is proposed to proceed via a domino sequence involving intermolecular olefin borylcupration or silylcupration followed by intramolecular coupling of an alkyl-Cu intermediate with aryl iodide.
- Liang, Ren-Xiao,Chen, Ru-Yi,Zhong, Chao,Zhu, Jia-Wen,Cao, Zhong-Yan,Jia, Yi-Xia
-
supporting information
p. 3215 - 3218
(2020/04/10)
-
- Palladium-catalyzed intermolecular C-H silylation initiated by aminopalladation
-
A Pd(ii)-catalyzed intermolecular C-H silylation reaction initiated by aminopalladation has been developed. The C-H bonds were activated by an alkyl Pd(ii) species generated through aminopalladation and then disilylated with hexamethyldisilane to form disilylated indolines as the final products. The reaction provides a new method for the introduction of silyl groups into complex organic molecules.
- Ji, Xiaoming,Wei, Feng,Wan, Bin,Cheng, Cang,Zhang, Yanghui
-
supporting information
p. 7801 - 7804
(2020/07/27)
-
- Pd-Catalyzed Decarboxylative Olefination: Stereoselective Synthesis of Polysubstituted Butadienes and Macrocyclic P-glycoprotein Inhibitors
-
The efficient and stereoselective synthesis of polysubstituted butadienes, especially the multifunctional butadienes, represents a great challenge in organic synthesis. Herein, we wish to report a distinctive Pd(0) carbene-initiated decarboxylative olefination approach that enables the direct coupling of diazo esters with vinylethylene carbonates (VECs), vinyl oxazolidinones, or vinyl benzoxazinones to afford alcohol-, amine-, or aniline-containing 1,3-dienes in moderate to high yields and with excellent stereoselectivity. This protocol features operational simplicity, mild reaction conditions, a broad substrate scope, and gram-scalability. Notably, a structurally unique allylic Pd(II) intermediate was isolated and characterized. DFT calculation and control experiments demonstrated that a rare Pd(0) carbene intermediate could be involved in this reaction. Moreover, the polysubstituted butadienes as novel building blocks were unprecedentedly assembled into macrocycles, which efficiently inhibited the P-glycoprotein and dramatically reversed multidrug resistance in cancer cells by 190-fold.
- Chen, Xiangyang,Hao, Jiping,Houk, K. N.,Li, Yingzi,Lou, Liguang,Quan, Haitian,Song, Bichao,Wang, Lu,Xia, Yuanzhi,Xie, Peipei,Xu, Zhongliang,Yang, Weibo
-
supporting information
p. 9982 - 9992
(2020/06/27)
-
- Synthesis, α-glucosidase inhibition, and molecular docking studies of novel N-substituted hydrazide derivatives of atranorin as antidiabetic agents
-
A series of novel N-substituted hydrazide derivatives were synthesized by reacting atranorin, a compound with a natural depside structure (1), with a range of hydrazines. The natural product and 12 new analogues (2–13) were investigated for inhibition of α-glucosidase. The N-substituted hydrazide derivatives showed more potent inhibition than the original. The experimental results were confirmed by docking analysis. This study suggests that these compounds are promising molecules for diabetes therapy. Molecular dynamics simulations were carried out with compound 2 demonstrating the best docking model using Gromac during simulation up to 20 ns to explore the stability of the complex ligand-protein. Furthermore, the activity of all synthetic compounds 2–13 against a normal cell line HEK293, used for assessing their cytotoxicity, was evaluated.
- Alam, Mahboob,Chavasiri, Warinthorn,Duong, Thuc-Huy,Huynh, Ngoc-Vinh,Nguyen, Huu-Hung,Nguyen, Thi-Phuong,Nguyen, Tien-Cong,Paramita Devi, Asshaima,Phan, Hoang-Vinh-Truong,Sichaem, Jirapast,Tran, Hoai-Duc,Tran, Nguyen-Minh-An
-
-
- Modulation of estrogen-related receptors subtype selectivity: Conversion of an ERRβ/γ selective agonist to ERRα/β/γ pan agonists
-
Estrogen Related Receptors (ERRs) are key regulators of energy homeostasis and play important role in the etiology of metabolic disorders, skeletal muscle related disorders, and neurodegenerative diseases. Among the three ERR isoforms, ERRα emerged as a potential drug target for metabolic and neurodegenerative diseases. Although ERRβ/γ selective agonist chemical tools have been identified, there are no chemical tools that effectively target ERRα agonism. We successfully engineered high affinity ERRα agonism into a chemical scaffold that displays selective ERRβ/γ agonist activity (GSK4716), providing novel ERRα/β/γ pan agonists that can be used as tools to probe the physiological roles of these nuclear receptors. We identified the structural requirements to enhance selectivity toward ERRα. Molecular modeling shows that our novel modulators have favorable binding modes in the LBP of ERRα and can induce conformational changes where Phe328 that originally occupies the pocket is dislocated to accommodate the ligands in a rather small cavity. The best agonists up-regulated the expression of target genes PGC-1α and PGC-1β, which are necessary to achieve maximal mitochondrial biogenesis. Moreover, they increased the mRNA levels of PDK4, which play an important role in energy homeostasis.
- Avdagic, Amer,Billon, Cyrielle,Burris, Sheryl L.,Burris, Thomas P.,Elagawany, Mohamed,Elgendy, Bahaa,Goher, Shaimaa S.,Hegazy, Lamees,Sanders, Ryan,Shahien, Mohamed,Sitaula, Sadichha
-
-
- Iron-catalysed 1,2-aryl migration of tertiary azides
-
1,2-Aryl migration of α,α-diaryl tertiary azides was achieved by using the catalytic system of FeCl2/N-heterocyclic carbene (NHC) SIPr·HCl. The reaction generated aniline products in good yields after one-pot reduction of the migration-resultant imines.
- Wei, Kaijie,Yang, Tonghao,Chen, Qing,Liang, Siyu,Yu, Wei
-
supporting information
p. 11685 - 11688
(2020/10/19)
-
- Cu(I)/chiral bisoxazoline-catalyzed enantioselective sommelet-hauser rearrangement of sulfonium ylides
-
Catalytic asymmetric thia-Sommelet-Hauser rearrangement of sulfonium ylides remains a great challenge due to its multistep reaction mechanism involving metal carbene formation, proton transfer, and [2,3]-sigmatropic rearrangement. In particular, the key problem of such reactions is the differentiation of the enantiotopic lone pair electrons of sulfur, which generates the sulfonium ylide intermediate bearing chirality on the sulfur atom. With a modified chiral bisoxazoline ligand, we developed a Cu(I)- catalyzed asymmetric thia-Sommelet-Hauser rearrangement with good to excellent enantioselectivities. Mechanistic studies provide insights into the details of the reaction mechanism.
- Wang, Jianbo,Li, Shu-Sen
-
supporting information
p. 12343 - 12358
(2020/11/10)
-
- CuII-Catalyzed Oxidative Formation of 5-Alkynyltriazoles
-
In an alcoholic solvent under the catalysis of Cu(OAc)2?H2O, organic azide and terminal alkyne could oxidatively couple to afford 5-alkynyl-1,2,3-triazole (alkynyltriazole) at room temperature under an atmosphere of O2 in a few hours. The involvement of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) is essential, without which the redox neutral coupling instead proceeds to produce 5-H-1,2,3-triazole (protiotriazole) as the major product. Therefore, DBN switches the redox neutral coupling between terminal alkyne and organic azide, the copper-catalyzed “click” reaction to afford protiotriazole, to an oxidation reaction that results in alkynyltriazole. The organic base DBN is effective in accelerating the copper(II)-catalyzed oxidation of terminal alkyne or copper(I) acetylide, which is intercepted by an organic azide to produce alkynyltriazole. The proposed mechanistic model suggests that the selectivity between alkynyl- and protiotriazole, and other acetylide or triazolide oxidation products is determined by the competition between copper(I)-catalyzed redox neutral cycloaddition and copper(II)/O2-mediated acetylide oxidation after the formation of copper(I) acetylide.
- Liu, Peiye,Brassard, Christopher J.,Lee, Justin P.,Zhu, Lei
-
p. 380 - 390
(2020/01/24)
-
- A visible-light-photocatalytic water-splitting strategy for sustainable hydrogenation/deuteration of aryl chlorides
-
Hydrogenation/deuteration of carbon chloride (C?Cl) bonds is of high significance but remains a remarkable challenge in synthetic chemistry, especially using safe and inexpensive hydrogen donors. In this article, a visible-light-photocatalytic watersplitting hydrogenation technology (WSHT) is proposed to in-situ generate active H-species (i.e., Had) for controllable hydrogenation of aryl chlorides instead of using flammable H2. When applying heavy water-splitting systems, we could selectively install deuterium at the C?Cl position of aryl chlorides under mild conditions for the sustainable synthesis of high-valued added deuterated chemicals. Sub-micrometer Pd nanosheets (Pd NSs) decorated crystallined polymeric carbon nitrides (CPCN) is developed as the bifunctional photocatalyst, whereas Pd NSs not only serve as a cocatalyst of CPCN to generate and stabilize H (D)-species but also play a significant role in the sequential activation and hydrogenation/deuteration of C?Cl bonds. This article highlights a photocatalytic-WSHT for controllable hydrogenation/deuteration of low-cost aryl chlorides, providing a promising way for the photosynthesis of high-valued added chemicals instead of the hydrogen evolution.
- Ling, Xiang,Xu, Yangsen,Wu, Shaoping,Liu, Mofan,Yang, Peng,Qiu, Chuntian,Zhang, Guoqiang,Zhou, Hongwei,Su, Chenliang
-
p. 386 - 392
(2020/02/25)
-
- Dehydrogenative cross-coupling of primary alcohols to form cross-esters catalyzed by a manganese pincer complex
-
Base-metal-catalyzed dehydrogenative cross-coupling of primary alcohols to form cross-esters as major products, liberating hydrogen gas, is reported. The reaction is catalyzed by a pincer complex of earth-abundant manganese in the presence of catalytic base, without any hydrogen acceptor or oxidant. Mechanistic insight indicates that a dearomatized complex is the actual catalyst, and indeed this independently prepared dearomatized complex catalyzes the reaction under neutral conditions.
- Das, Uttam Kumar,Ben-David, Yehoshoa,Leitus, Gregory,Diskin-Posner, Yael,Milstein, David
-
p. 479 - 484
(2019/01/11)
-
- Aldehyde effect and ligand discovery in Ru-catalyzed dehydrogenative cross-coupling of alcohols to esters
-
The presence of different aldehydes is found to have a significant influence on the catalytic performance when using PN(H)P type ligands for dehydrogenation of alcohols. Accordingly, hybrid multi-dentate ligands were discovered based on an oxygen-transfer alkylation of PNP ligands by aldehydes. The relevant Ru-PNN(PO) system provided the desired unsymmetrical esters in good yields via acceptorless dehydrogenation of alcohols. Hydrogen bonding interactions between the phosphine oxide moieties and alcohol substrates likely assisted the observed high chemoselectivity.
- Jiang, Xiaolin,Zhang, Jiahui,Zhao, Dongmei,Li, Yuehui
-
supporting information
p. 2797 - 2800
(2019/03/27)
-
- Enantioselective rhodium-catalysed insertion of trifluorodiazoethanes into tin hydrides
-
Aryl substituted 2,2,2-trifluorodiazoethanes undergo rhodium(II)-catalysed insertion reactions with tin hydrides affording the corresponding α-(trifluoromethyl)benzyl stannanes. This reactivity contrasts with that of diazo esters which predominantly afford CH2 reduction products in the presence of tin hydrides. The first example of asymmetric insertion into tin hydrides using diazo compounds is also described. In addition, this system extends to asymmetric germanium hydride and silane insertion.
- Hyde, Stephen,Veliks, Janis,Ascough, David M.H.,Szpera, Robert,Paton, Robert S.,Gouverneur, Véronique
-
-
- ARYL-SUBSTITUTED ACETAMIDE AND PYRROLIDIN-2-ONE DERIVATIVES AND THEIR USE FOR THE TREATMENT OF SEIZURES
-
Aryl-substituted acetamide and pyrrolidin-2-one (γ-butyrolactam) derivatives have useful activity in the inhibition, prevention, or treatment of seizures. The derivatives may be useful in the treatment of epilepsy, including medically refractory epilepsy, and nerve agent poisoning.
- -
-
Paragraph 0055; 0056
(2019/06/09)
-
- Development of novel liver?X?receptor modulators based on a 1,2,4-triazole scaffold
-
Liver X Receptor (LXR) agonists have been reported as a potential treatment for atherosclerosis, Alzheimer's disease and hepatitis C virus (HCV) infection. We have designed and synthesized a series of potent compounds based on a 1,2,4-triazole scaffold as novel LXR modulators. In cell-based cotransfection assays these compounds generally functioned as LXR agonists and we observed compounds with selectivity towards LXRα (7-fold) and LXRβ (7-fold) in terms of potency. Assessment of the effects of selected compounds on LXR target gene expression in HepG2 cells revealed that compounds 6a-b and 8a-b behaved as inverse agonists on FASN expression even though they were agonists in the LXRα and LXRβ cotransfection assays. Interestingly, these compounds had no effect on the expression of SREBP-1c confirming a unique LXR modulator pharmacology. Molecular docking studies and evaluation of ADME properties in-silico show that active compounds possess favorable binding modes and ADME profiles. Thus, these compounds may be useful for in vivo characterization of LXR modulators with unique profiles and determination of their potential clinical utility.
- Goher, Shaimaa S.,Griffett, Kristine,Hegazy, Lamees,Elagawany, Mohamed,Arief, Mohamed M.H.,Avdagic, Amer,Banerjee, Subhashis,Burris, Thomas P.,Elgendy, Bahaa
-
supporting information
p. 449 - 453
(2019/01/04)
-
- Enantioselective Construction of Quaternary All-Carbon Centers via Copper-Catalyzed Arylation of Tertiary Carbon-Centered Radicals
-
An enantioselective copper-catalyzed arylation of tertiary carbon-centered radicals, leading to quaternary all-carbon stereocenters, has been developed herein. The tertiary carbon-centered radicals, including both benzylic and nonbenzylic radicals, were produced by the addition of trifluoromethyl radical to α-substituted acrylamides, and subsequently captured by chiral aryl copper(II) species to give C-Ar bonds with excellent enantioselectivity. Importantly, an acylamidyl (CONHAr) group adjacent to the tertiary carbon radical is essential for the asymmetric radical coupling. The reaction itself features broad substrate scope, excellent functional group compatibility and mild conditions.
- Wu, Lianqian,Wang, Fei,Chen, Pinhong,Liu, Guosheng
-
supporting information
p. 1887 - 1892
(2019/02/05)
-
- Synthesis, Antimicrobial, and Antioxidant Screening of Aryl Acetic Acid Incorporated 1,2,4-Triazolo-1,3,4-Thiadiazole Derivatives
-
Some novel [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives were synthesized from aryl acetic acids. All the synthesized derivatives were selected for the screening of antibacterial potential against Gram-positive bacteria [Staphylococcus aureus (MTCC 3160) and Micrococcus luteus (MTCC 1538)] and Gram-negative bacteria [Escherichia coli (MTCC 1652) and Pseudomonas aeruginosa (MTCC 424)] and antifungal potential against Aspergillus niger (MTCC 8652) and Candida albicans (MTCC 227), and free radical scavenging activity through 2,2-diphenyl-2-picrylhydrazyl hydrate method. The compounds TH-4, TH-13, and TH-19 were found to be more potent antimicrobial agents compared to standard drugs. The compounds TH-3, TH-9, and TH-18 also showed significant antimicrobial activity. The compound TH-13 showed antioxidant activity with IC50 value better than the standard compound. The structures of all the synthesized compounds were confirmed by Fourier transform infrared, 1H-NMR, liquid chromatography–mass spectrometry, and CHN analyzer.
- Kamboj, Vipan Kumar,Kapoor, Archana,Jain, Sandeep
-
p. 1376 - 1382
(2019/02/20)
-
- Synthesis and bio-evaluation of natural butenolides-acrylate conjugates
-
A series of novel 3-aryl-4-hydroxy-2(5H) furanone-acrylate hybrids were designed and synthesized based on the natural butenolides and acrylates scaffolds. The structures of the prepared compounds were characterized by 1H-NMR, 13C-NMR and electrospray ionization mass spectrometry (ESI-MS), and the bioactivity of the target compounds against twelve phytopathogenic fungi was investigated. The preliminary in vitro antifungal activity screening showed that most of the target compounds had moderate inhibition on various pathogenic fungi at the concentration of 100 mg·L?1, and presented broad-spectrum antifungal activities. Further studies also indicated that compounds 7e and 7k still showed some inhibitory activity against Pestallozzia theae, Sclerotinia sclerotiorum and Gibberella zeae on rape plants at lower concentrations, which could be optimized as a secondary lead for further research.
- Bao, Longzhu,Wang, Shuangshuang,Song, Di,Wang, Jingjing,Cao, Xiufang,Ke, Shaoyong
-
-
- Substituted phenyl[(5-benzyl-1,3,4-oxadiazol-2-yl)sulfanyl]acetates/acetamides as alkaline phosphatase inhibitors: Synthesis, computational studies, enzyme inhibitory kinetics and DNA binding studies
-
Substituted phenyl[(5-benzyl-1,3,4-oxadiazol-2-yl)sulfanyl]acetates/acetamides 9a-j were synthesized as alkaline phosphatase inhibitors. Phenyl acetic acid 1 through a series of reactions was converted into 5-benzyl-1,3,4-oxadiazole-2-thione 4. The intermediate oxadiazole 4 was then reacted with chloroacetyl derivatives of phenols 6a-f and anilines derivatives 8a-d to afford the title oxadiazole derivatives 9a-j. All of the title compounds 9a-j were evaluated for their inhibitory activity against human alkaline phosphatise (ALP). It was found that compounds 9a-j exhibited good to excellent alkaline phosphatase inhibitory activity especially 9h displayed potent activity with IC50 value 0.420 ± 0.012 μM while IC50 value of standard (KH2PO4) was 2.80 μM. The enzyme inhibitory kinetics of most potent inhibitor 9h was determined by Line-weaever Burk plots showing non-competitive mode of binding with enzyme. Molecular docking studies were performed against alkaline phosphatase enzyme (1EW2) to check the binding affinity of the synthesized compounds 9a-j against target protein. The compound 9h exhibited excellent binding affinity having binding energy value (?7.90 kcal/mol) compared to other derivatives. The brine shrimp viability assay results proved that derivative 9h was non-toxic at concentration used for enzyme assay. The lead compound 9h showed LD50 106.71 μM while the standard potassium dichromate showed LD50 0.891 μM. The DNA binding interactions of the synthesized compound 9h was also determined experimentally by spectrophotometric and electrochemical methods. The compound 9h was found to bind with grooves of DNA as depicted by both UV–Vis spectroscopy and cyclic voltammetry with binding constant values 7.83 × 103 and 7.95 × 103 M?1 respectively revealing significant strength of 9h-DNA complex. As dry lab and wet lab results concise each other it was concluded that synthesized compounds, especially compound 9h may serve as lead compound to design most potent inhibitors of human ALP.
- Iqbal,Ashraf,Hassan, Mubashir,Abbas,Jabeen, Erum
-
-
- Efficient Synthesis of Spirooxindole Pyrrolones by a Rhodium(III)-Catalyzed C?H Activation/Carbene Insertion/Lossen Rearrangement Sequence
-
A rhodium(III)-catalyzed domino annulation of simple olefins with diazo oxindoles to give spirooxindole pyrrolone products is described. This reaction can be formally viewed as the result of an anomalous tandem C?H activation, carbene insertion, Lossen rearrangement, and a nucleophilic addition process. The potential utility of this reaction was further demonstrated by the late-stage diversification of drug molecules.
- Ma, Biao,Wu, Peng,Wang, Xing,Wang, Zhengyu,Lin, Hai-Xia,Dai, Hui-Xiong
-
supporting information
p. 13335 - 13339
(2019/08/20)
-
- Directed Iridium-Catalyzed Hydrogen Isotope Exchange Reactions of Phenylacetic Acid Esters and Amides
-
For the first time, a catalytic protocol for a highly selective hydrogen isotope exchange (HIE) of phenylacetic acid esters and amides under very mild reaction conditions is reported. Using a homogeneous iridium catalyst supported by a bidentate phosphine-imidazolin-2-imine P,N ligand, the HIE reaction on a series of phenylacetic acid derivatives proceeds with high yields, high selectivity, and with deuterium incorporation up to 99 %. The method is fully adaptable to the specific requirements of tritium chemistry, and its effectiveness was demonstrated by direct tritium labeling of the fungicide benalaxyl and the drug camylofine. Further insights into the mechanism of the HIE reaction with catalyst 1 have been provided utilizing DFT calculations, NMR studies, and X-ray diffraction analysis.
- Valero, Mégane,Becker, Daniel,Jess, Kristof,Weck, Remo,Atzrodt, Jens,Bannenberg, Thomas,Derdau, Volker,Tamm, Matthias
-
supporting information
p. 6517 - 6522
(2019/05/01)
-
- Palladium-Catalyzed C?H Silylation through Palladacycles Generated from Aryl Halides
-
A highly efficient palladium-catalyzed disilylation reaction of aryl halides through C?H activation has been developed for the first time. The reaction has broad substrate scope. A variety of aryl halides can be disilylated by three types of C?H activation, including C(sp2)?H, C(sp3)?H, and remote C?H activation. In particular, the reactions are also unusually efficient. The yields are essentially quantitative in many cases, even in the presence of less than 1 mol % catalyst and 1 equivalent of the silylating reagent under relatively mild conditions. The disilylated biphenyls can be converted into disiloxane-bridged biphenyls.
- Lu, Ailan,Ji, Xiaoming,Zhou, Bo,Wu, Zhuo,Zhang, Yanghui
-
supporting information
p. 3233 - 3237
(2018/02/23)
-
- Selective conversion of primary amides to esters promoted by KHSO4
-
Primary amides, either aliphatic or aromatic, are easily converted to the corresponding esters via reflux in lower primary alcohols in the presence of KHSO4. Secondary amides lead to complicated mixtures under analogous conditions, whereastertiary amides were inert. Use of isopropyl alcohol resulted inthe formation of product atslower rate and lower yieldalong withside products, whereas, use of tertiary alcoholsdid not give successful conversion andallyl and benzyl alcohol provided complex mixtures.
- Sattenapally, Narsimha,Sharma, Jhanvi,Hou, Yuqing
-
p. 174 - 183
(2018/09/10)
-
- Synthesis and characterization of stable ZnO nanoparticles using imidazolium-based ionic liquids and their applications in esterification reaction
-
ZnO nanoparticles have been synthesized from zinc acetate using 1-octyl-3-methylimidazolium hexafluorophosphate as capping agent under microwave irradiation condition in a very short period of time and characterized using UV-visible spectroscopy, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and NH3-TPD analysis. The ZnO NPs have been used as a solid reusable acid catalyst for esterification of carboxylic acids with alcohols.
- Kavya,Vijaya Kumar,Ramesh Kumar
-
p. 1112 - 1120
(2018/09/21)
-
- Macrolide Synthesis through Intramolecular Oxidative Cross-Coupling of Alkenes
-
A RhIII-catalyzed intramolecular oxidative cross-coupling between double bonds for the synthesis of macrolides is described. Under the optimized reaction conditions, macrocycles containing a diene moiety can be formed in reasonable yields and with excellent chemo- and stereoselectivity. This method provides an efficient approach to synthesize macrocyclic compounds containing a 1,3-conjugated diene structure.
- Jiang, Bing,Zhao, Meng,Li, Shu-Sen,Xu, Yun-He,Loh, Teck-Peng
-
supporting information
p. 555 - 559
(2018/02/21)
-
- Palladium-Catalyzed Tandem Reaction of Three Aryl Iodides Involving Triple C-H Activation
-
A novel palladium-catalyzed tandem reaction of N-(2-iodoaryl)acrylamides with two aryl iodides for the synthesis of spirooxindole has been achieved. The reaction underwent the process of triple C-H activation and four C-C bond formations based on the double trapping of transient spirocyclic palladacycles which are obtained through remote C-H activation.
- Luo, Xiai,Xu, Yankun,Xiao, Genhua,Liu, Wenjuan,Qian, Cheng,Deng, Guobo,Song, Jianxin,Liang, Yun,Yang, Chunming
-
supporting information
p. 2997 - 3000
(2018/05/28)
-
- Stereoselective synthesis of 3,4-di-substituted mercaptolactones via photoredox-catalyzed radical addition of thiophenols
-
A visible light mediated radical addition of thiophenols on 4-phenylbut-3-enoic acids to give diastereoselective synthesis of 3,4-disubstituted γ-lactones is reported. The reaction precludes the conventional prerequisite of conjugate addition. Furthermore, the lactones were successfully utilized in the synthesis of γ-ketoamides.
- Kouser, Farzana,Sharma, Vijay Kumar,Rizvi, Masood,Sultan, Shaista,Chalotra, Neha,Gupta, Vivek K.,Nandi, Utpal,Shah, Bhahwal Ali
-
supporting information
p. 2161 - 2166
(2018/05/05)
-
- Pd-Catalyzed Three-Component Domino Reaction of Vinyl Benzoxazinanones for Regioselective and Stereoselective Synthesis of Allylic Sulfone-Containing Amino Acid Derivatives
-
A Pd-catalyzed, highly regioselective and stereoselective three-component domino allylic substitution/N-H carbene insertion reaction under mild conditions is described. This reaction demonstrates a wide substrate scope and satisfactory functional group tolerance, providing a broad range of allylic sulfone-containing amino acid derivatives. Moreover, DBU mediates highly diastereoselective cross-dehydrogenative coupling annulation of allylic sulfones without using peroxides or any metal oxidants. This developed protocol affords 7-membered ring heterocyclic compounds incorporating both sulfone-containing amino acid esters and one quaternary carbon center. Mechanistic studies indicate that an unusual umpolung of glycine occurred in this annulation.
- Hao, Jiping,Xu, Yi,Xu, Zhongliang,Zhang, Zhiqiang,Yang, Weibo
-
supporting information
p. 7888 - 7892
(2019/01/04)
-
- 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.
-
supporting information
p. 7206 - 7211
(2018/11/23)
-
- One and Two-Carbon Homologation of Primary and Secondary Alcohols to Corresponding Carboxylic Esters Using β-Carbonyl BT Sulfones as a Common Intermediate
-
Herein we report the efficient one- and two-carbon homologation of 1° and 2° alcohols to their corresponding homologated esters via the Mitsunobu reaction using β-carbonyl benzothiazole (BT) sulfone intermediates. The one-carbon homologation approach uses standard Mitsunobu C-S bond formation, oxidation and subsequent alkylation, while the two-carbon homologation uses a less common C-C bond forming Mitsunobu reaction. In this latter case, the use of β-BT sulfone bearing esters lowers the pKa sufficiently enough for the substrate to be used as a carbon-based nucleophile and deliver the homologated β-BT sulfone ester, and this superfluous sulfone group can then be cleaved. In this paper we describe several methods for the effective desulfonylation of BT sulfones and have developed methodology for one-pot alkylation-desulfonylation sequences. As such, overall, a one-carbon homologation sequence can be achieved in a two-pot (four step) procedure and the two-carbon homologation in a two-pot (three step) procedure (three-pot; four step when C-acid synthesis is included). This methodology has been applied to a wide variety of functionality (esters, silyl ethers, benzyls, heteroaryls, ketones, olefins and alkynes) and are all tolerated well providing good to very good overall yields. The power of our method was demonstrated in site-selective ingenol C20 allylic alcohol two-carbon homologation.
- Bon, David J.-Y. D.,Ková?, Ond?ej,Ferugová, Vendula,Zále?ák, Franti?ek,Pospí?il, Ji?í
-
p. 4990 - 5001
(2018/05/17)
-
- Palladium-Catalyzed Decarboxylative Carbonylative Transformation of Benzyl Aryl Carbonates: Direct Synthesis of Aryl 2-Arylacetates
-
A procedure on palladium-catalyzed decarboxylative alkoxycarbonylation of carbonates for the synthesis of aryl 2-arylacetates has been developed. A broad range of aryl 2-arylacetates were obtained in good yields under mild conditions under a carbon monoxide atmosphere. Interestingly, other alcohols can be added as nucleophiles as well, and the corresponding esters were also obtained in good yields.
- Xu, Jian-Xing,Wu, Xiao-Feng
-
p. 5938 - 5941
(2018/09/21)
-
- Palladium-Catalyzed Carbonylative Direct Transformation of Benzyl Amines under Additive-Free Conditions
-
In this communication, we developed a new procedure for the direct carbonylative transformation of benzyl amines. Using dimethyl carbonate as the solvent, methyl 2-arylacetates can be produced in good to excellent yields from the corresponding primary, secondary, and tertiary benzyl amines with palladium as the catalyst. Notably, no base or any other additive is required here. In addition, our procedure can also be applied in the preparation of methylphenidate, which is a marketing drug and used in the treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy.
- Li, Yahui,Wang, Zechao,Wu, Xiao-Feng
-
p. 738 - 741
(2018/01/17)
-
- Ni-Catalyzed chemoselective alcoholysis of: N -acyloxazolidinones
-
Although N-acyloxazolidinone-based (catalytic) asymmetric synthetic methodologies occupy an important position in modern organic synthesis, the catalytic cleavage of a chiral auxiliary remains underdeveloped. We report the Ni(cod)2/bipyr.-catalyzed alcoholysis of N-acyloxazolidinones to deliver esters. The reaction is broad in scope for both N-acyloxazolidinone substrates and alcohol nucleophiles, and displays good functional group tolerance and excellent chemoselectivity. A gram-scale methanolysis allowed the enantioselective synthesis of the C22-C26 segment of a close analogue of the potent immunosuppressant agent FK506.
- Huang, Pei-Qiang,Geng, Hui
-
supporting information
p. 593 - 599
(2018/02/14)
-
- A sustainable procedure toward alkyl arylacetates: Palladium-catalysed direct carbonylation of benzyl alcohols in organic carbonates
-
A sustainable procedure for the synthesis of various alkyl arylacetates from benzyl alcohols has been developed. With palladium as the catalyst and organic carbonates as the green solvent and in situ activator, benzyl alcohols were carbonylated in an efficient manner without any halogen additives.
- Li, Yahui,Wang, Zechao,Wu, Xiao-Feng
-
supporting information
p. 969 - 972
(2018/03/13)
-
- Selective catalytic tailoring of the H unit in herbaceous lignin for methyl: P -hydroxycinnamate production over metal-based ionic liquids
-
Selective valorization of lignin to achieve high value and commodity chemicals is attracting increasing attention. In this work, an efficient and reusable metal-based ionic liquid (MBIL) was developed for the selective tailoring of p-coumaric acid ester (pCA), a typical p-hydroxyphenyl (H) unit, into methyl p-hydroxycinnamate (MPC). Under optimized conditions and in the presence of catalyst [Bmim][FeCl4], a volatile aromatic product of 10.5 wt% was obtained, of which, 70.5% separated as pure MPC with an isolated yield of 71.1 mg g-1. FT-IR, 13C NMR, ANO and 2D HSQC demonstrated that the H unit was preferentially tailored from lignin, of which, 86.0 wt% of the H structure unit is cut off from lignin, with 70.6% being selectively converted to MPC. Further investigation demonstrated that MBIL prefers to tailor ester bonds compared to ether bonds using model compounds, and the superior catalytic ester bond cleavage performance exhibited by [Bmim][FeCl4] can be ascribed to the relatively narrow energy gap between the lignin ester bond and [FeCl4]- anion and to the comparatively low absolute binding energy between the cation and anion through DFT calculations.
- Li, Zhangmin,Cai, Zhenping,Zeng, Qiang,Zhang, Tian,France, Liam John,Song, Changhua,Zhang, Yaqin,He, Hongyan,Jiang, Lilong,Long, Jinxing,Li, Xuehui
-
p. 3743 - 3752
(2018/08/21)
-
