- Microflow electroorganic synthesis without supporting electrolyte
-
Anodic methoxylation of several organic compounds has been successfully achieved in the absence of intentionally added supporting electrolyte using an electrochemical microflow system. The Royal Society of Chemistry 2005.
- Horcajada, Roberto,Okajima, Masayuki,Suga, Seiji,Yoshida, Jun-Ichi
-
-
Read Online
- Microstructured reactor for electroorganic synthesis
-
In the present work a brief overview of microstructured devices, the advantages and disadvantages as well as the principles of a multiscale design approach are presented. The advantages mainly comprise uniform current density distribution, local control of the process parameters, high single-pass conversion of the reactant and reduced concentration of the supporting electrolyte needed to perform the reaction. The main challenge with this type of cell is gas evolution, a typical reaction taking place at the counter-electrode. The phenomena discussed are documented using the example of anodic methoxylation of 4-methylanisole. An analysis was made of the two-phase flow hydrodynamics inside the microstructured cell. The range of operational conditions suitable for the desired reaction was identified. The results were used together with the information on the electrode reaction kinetics in the form of the Butler-Volmer-type equation for the design of a suitable bipolar microstructured cell. A bipolar cell optimized to perform the desired reaction is reported. The results are compared with the published data. An analysis was performed that proved that the performance of the existing technology is more demanding in terms of energy consumption for the separation of the final product from the reaction mixture. The process intensification was evaluated on the basis of the available data.
- Bouzek, Karel,Jiricny, Vladimir,Kodym, Roman,Kristal, Jiri,Bystron, Tomas
-
-
Read Online
- Selective synthesis of 4,6-O-alkenylidene and -benzylidene acetals from unprotected sucrose by lanthanide(III) resin-catalyzed transacetalization
-
Lanthanide cation exchanged resins were used as catalysts for the acetalization of sucrose. Ytterbium(III)- and erbium(III)-exchanged resins promote the transacetalization of dialkyl acetals of α,β-unsaturated aldehydes. A two-step one-pot procedure provides direct access from the unsaturated aldehyde to a series of sucrose 4,6-acetals in good yields from unprotected sucrose without concomitant glycosidic bond cleavage.
- Porwanski,Salanski,Descotes,Bouchu,Queneau
-
-
Read Online
- Electro-Oxidative Selective Esterification of Methylarenes and Benzaldehydes
-
A mild and green electro-oxidative protocol to construct aromatic esters from methylarenes and alcohols is herein reported. Importantly, the reaction is free of metals, chemical oxidants, bases, acids, and operates at room temperature. Moreover, the design of the electrolyte was found critical for the oxidation state and structure of the coupling products, a rarely documented effect. This electro-oxidative coupling process also displays exceptional tolerance of many fragile easily oxidized functional groups such as hydroxy, aldehyde, olefin, alkyne, as well as neighboring benzylic positions. The enantiomeric enrichment of some chiral alcohols is moreover preserved during this electro-oxidative coupling reaction, making it overall a promising synthetic tool.
- Yu, Congjun,?zkaya, Bünyamin,Patureau, Frederic W.
-
supporting information
p. 3682 - 3687
(2021/02/01)
-
- Thiol-initiated photocatalytic oxidative cleavage of the C=C bond in olefins and its extension to direct production of acetals from olefins
-
The oxidative cleavage of olefins to produce aldehydes/ketones is an important reaction in organic syntheses. In this manuscript, a mild and operationally simple protocol for the aerobic oxidation of olefins to produce carbonyl compounds was realized over ZnIn2S4under visible light, using air as the oxidant and a thiol as the initiator. It was proposed that the photogenerated holes over ZnIn2S4attack the thiol to produce thiyl radicals, which initiate the oxidative cleavage of the C=C bond in olefins to produce aldehydes/ketones. By further coupling with the condensation between the as-obtained aldehydes/ketones and alcohols, this strategy can also be applied to the production of different acetals directly from the olefins. This study demonstrates a new pathway to realize the oxidative cleavage of olefins to produce aldehydes/ketones, and also provides a new protocol for the production of acetals directly from the olefins.
- Wang, Xinglin,Li, Yuanyuan,Li, Zhaohui
-
p. 1000 - 1006
(2021/02/26)
-
- MOF-808 as a recyclable catalyst for the photothermal acetalization of aromatic aldehydes
-
Metal-organic frameworks (MOFs) show promise for catalysis applications due to their porosity, high internal surface area, and structural adaptability. Typical acetylation reactions of aldehydes require elevated temperatures and excess alcohol to drive the reactions to completion. In this current work, MOF-808 is used as a heterogeneous catalyst for acetylation of aldehydes in methanol using a mild photothermal process. Optimized conditions gave 72% yield of 2-(dimethoxymethyl)naphthalene in the presence of 10 mol% MOF-808 at 45 °C using only a fluorescent lamp. MOF-808 can be recycled up to 5 times with no loss in catalytic activity. A proof-of-principle substrate scope demonstrates the potential utility for aromatic and aliphatic substrates.
- Rabon, Allison M.,Doremus, Jared G.,Young, Michael C.
-
supporting information
(2021/04/02)
-
- Chemoenzymatic Synthesis of 5-Hydroxymethylfurfural (HMF)-Derived Plasticizers by Coupling HMF Reduction with Enzymatic Esterification
-
Biobased plasticizers, as substitutes for phthalates, have been synthesized from 5-hydroxymethylfurfural (HMF) and carboxylic acids (or esters) through a chemoenzymatic cascade process that involves as its first step the reduction of 5-hydroxymethylfurfural into 2,5-bis(hydroxymethyl)furan (BHMF), followed by the esterification of BHMF with carboxylic acids (or esters) by using a supported lipase (Novozym 435). The reduction of HMF into BHMF is performed by using monodisperse metallic Co nanoparticles with a thin carbon shell (Co@C) with high activity and selectivity. After optimization of reaction conditions (temperature, hydrogen pressure, and solvent), it is possible to achieve 97 % conversion of HMF with 99 % selectivity to BHMF after 2 h reaction time. The reduction of HMF and esterification of BHMF using carboxylic acids or vinyl esters as acyl donors by lipase are optimized separately in batch and in fixed-bed continuous reactors. The coupling of two flow reactors (for reduction and subsequent esterification) working under optimized reaction conditions affords the diesters of BHMF in roughly 90 % yield with no loss of activity during 60 h of operation.
- Arias, Karen S.,Carceller, Jose M.,Climent, Maria J.,Corma, Avelino,Iborra, Sara
-
p. 1864 - 1875
(2020/03/11)
-
- Amino acid derivative, feed composition and application thereof
-
The invention provides an amino acid derivative, a feed composition and application thereof, and belongs to the technical field of animal feed additives. The amino acid derivative is a compound with astructure shown as a formula (I), and a stereoisomer, a tautomer, a solvate, a metabolite, a feed acceptable salt or a prodrug thereof. In formula (I) shown in the specification, Z is a C1-C3 alkylene group. X is an indole ring group with a structure shown as a formula (II). The formula (II) is shown in the specification, wherein Y is phenyl with the structure shown in the formula (III) shown inthe specification. The amino acid derivative is used as an animal feed additive, and can promote the growth of animals and improve the feed conversion.
- -
-
Paragraph 0121-0125
(2020/05/14)
-
- Synthesis, structural determination and catalytic study of a new 2-D chloro-substituted zinc phosphate, (C8N2H20)[ZnCl(PO3(OH))]2
-
A novel chloro-substituted zinc-phosphate, (C8N2H20)[ZnCl(PO3(OH))], has been synthesized by a slow evaporation method in the presence of 1,3-cyclohexanebis- (methylamine), which acts as a template. The structure consists of vertex linked ZnO3Cl and PO3(OH) tetrahedral, assembled into corrugated porous layers [ZnCl(PO3(OH))2]∞ with (4.82) topology. The optical properties were also investigated using Diffuse Reflecting Spectroscopy (DRS), showing that the title compound has semiconducting properties. In addition, the catalytic activity of (C8N2H20)[ZnCl(PO3(OH))]2 has been tested in the acetalisation reaction of aldehydes. The title compound displayed a high catalytic activity with practically total conversion in many examples using MeOD as solvent and as the sole source of acetalisation. More importantly, the reaction crudes are very clean and only the preferred products are found in the NMR spectra.
- Rayes, Ali,Herrera, Raquel P,Moncer, Manel,Ara, Irene,Calestani, Gianluca,Ayed, Brahim,Mezzadri, Francesco
-
-
- Nickel-catalyzed intelligent reductive transformation of the aldehyde group using hydrogen
-
The selective transformation of the aldehyde group (-CHO) in multifunctional oxygenates is a key challenge in the development of sustainable biomass feedstock. Herein, a smart Ni-MFC catalyst was developed from a 2D Ni-based metal-organic framework (MOF), which efficiently promoted the transformation of -CHO in the presence of H2 to a methyl group (-CH3) via the reductive etherification and hydrogenolysis of the C-O ether bond in methanol. Moreover, the catalytic process could be controlled to directionally produce methyl ether (-CH2OR) using the reductive etherification protocol. For the catalytic reduction of vanillin, the Ni-MFC-700 catalyst guaranteed the full conversion of vanillin and 96.5% yield of the desired 2-methoxy-4-methylphenol (MMP), while the Ni-MFC-500 catalyst afforded about 82.7% yield of 4-(methoxymethyl)-2-methoxyphenol in methanol solvent. This is a novel and promising approach for the valorization of multifunctional oxygenates and biomass-derived platform compounds.
- Tong, Xinli,Guo, Pengfei,Liao, Shengyun,Xue, Song,Zhang, Haigang
-
supporting information
p. 5828 - 5840
(2019/11/11)
-
- Remote ‘Imidazole’ Based Ruthenium(II) p-Cymene Precatalyst for Selective Oxidative Cleavage of C?C Multiple Bonds
-
The dual role of remote ‘imidazole’ attached with the precatalyst [(p-cymene)RuII(L)Y]+ (L=2-(4-substituted-phenyl)-1H-imidazo[4,5-f][1,10] phenanthroline, Y=chloride/solvent) was explored for the selective oxidative cleavage of C?C multiple bonds to acetals/aldehydes. The presence of ‘imidazole’ in the precatalysts was found to be useful for the activation of oxidant and release of p-cymene from the precatalysts, which in turn was not effective without the ‘imidazole’ moiety. The mechanistic aspects of the precatalyst were evaluated from spectroscopic, kinetic, and few other controlled experiments. The loss of p-cymene is the key step for the reaction and found to be faster in solvated precatalyst, [(p-cymene)RuII(L)(MeOH)]++ and thus showed 3–4-fold more effective as compared to [(p-cymene)RuII(L)Cl]+.
- Dutta, Manali,Bania, Kusum Kumar,Pratihar, Sanjay
-
p. 2683 - 2694
(2019/05/24)
-
- Synthesis of (E)-α,β-unsaturated carboxylic esters derivatives from cyanoacetic acid via promiscuous enzyme-promoted cascade esterification/Knoevenagel reaction
-
A new enzymatic protocol based on lipase-catalyzed cascade toward (E)-α,β-unsaturated carboxylic esters is presented. The proposed methodology consists of elementary organic processes starting from acetals and cyanoacetic acid leading to the formation of desired products in a cascade sequence. The combination of enzyme promiscuous abilities gives a new opportunity to synthesize complex molecules in the one-pot procedure. Results of studies on the influence of an enzyme type, solvent, and temperature on the cascade reaction course are reported. The presented methodology provides meaningful qualities such as significantly simplified process, excellent E-selectivity of obtained products and recycling of a biocatalyst.
- Wilk, Monika,Trzepizur, Damian,Koszelewski, Dominik,Brodzka, Anna,Ostaszewski, Ryszard
-
-
- Chemoselective Nucleophilic Functionalizations of Aromatic Aldehydes and Acetals via Pyridinium Salt Intermediates
-
The development of a novel chemoselective functionalization can diversify the strategy for synthesizing the target molecules. The perfect chemoselectivity between aromatic and aliphatic aldehydes is difficult to achieve by the previous methods. The aromatic aldehyde-selective nucleophilic addition in the presence of aliphatic aldehydes was newly accomplished. Namely, the aromatic aldehyde-selective nucleophilic addition using arenes and allyl silanes proceeded in the presence of trialkylsilyl triflate and 2,2′-bipyridyl, while the aliphatic aldehydes completely remained unchanged. The reactive pyridinium-type salt intermediate derived from an aromatic aldehyde chemoselectively underwent the nucleophilic substitution. Moreover, the aromatic acetals as the protected aldehydes could be directly transformed into similar pyridinium salt intermediates, which reacted with various nucleophiles coexisting with the aliphatic aldehydes.
- Kawajiri, Takahiro,Kato, Maho,Nakata, Hiroki,Goto, Ryota,Aibara, Shin-Yo,Ohta, Reiya,Fujioka, Hiromichi,Sajiki, Hironao,Sawama, Yoshinari
-
p. 3853 - 3870
(2019/03/07)
-
- Unique chemoselective Mukaiyama aldol reaction of silyl enol diazoacetate with aldehydes and acetals catalyzed by MgI2 etherate
-
Functionalized diazo acetoacetates are prepared by an efficient Mukaiyama aldol reaction between 3-TBSO-2-diazo-3-butenoate with aldehydes and acetals under mild reaction conditions. A variety of substituted aldehydes and the corresponding acetals are both accessible in good to excellent yields through this methodology. MgI2 etherate (MgI2·(OEt2)n) is the preferred catalyst and, the addition proceeds without decomposition of the diazo moiety. In addition, this MgI2·(OEt2)n-catalyzed Mukaiyama aldol reaction shows unique chemoselectivity towards aldehydes and acetals.
- Meng, Xiangwei,Pan, Haokun,Zhong, Tengjiang,Zhang, Xingxian
-
-
- Ce(III)-Based frameworks: From 1d chain to 3d porous metal-organic framework
-
The reaction of pyridine-2,4-dicarboxylic acid (2,4-H2 pydc) with Ce(NO3)36H2O, by applying only minor changes to the reaction conditions, generated a series of new one-, two-, and three-dimensional (1D, 2D, and 3D) coordination polymers, namely, [Ce(pydc)(Hpydc)(H2O)4]n (1), [Ce(pydc)(Hpydc)(H2O)2]n (2), and {[Ce3(pydc)4(H2O)2NO3]4H2O}n (3). The ancillary ligand interaction as well as the reaction conditions determine the specific coordination modes for the Hpydc- and pydc2- ligands and, in turn, discriminate between 1D, 2D, and 3D frameworks. Characterization of the prepared materials was performed using single-crystal and powder X-ray diffraction analysis, Fourier transform infrared spectroscopy, CHN elemental analysis, thermogravimetric analysis, and nitrogen adsorption/desorption techniques. Compound 1 consists of 1D chains, that compose of Ce3+ ions bridged by Hpydc- and pydc2- ligands, which further link via noncovalent interactions to form a 3D supramolecular architecture. Compound 2 assembles into 2D sheets with 1D channels. Similarly, via hydrogen-bonding interactions between two adjacent sheets, the 2D layers are further stacked into the final 3D supramolecular structure. Compound 3 is a 3D metal-organic framework (MOF), showing 1D helical channels. The progressive skeletal variation from the 1D chains (1) to 2D sheets (2) and 3D framework (3) is attributed to the flexibility of both the Ce(III) coordination sphere and coordination modes of the Hpydc- and pydc2- ligands under different reaction conditions. The three compounds illustrate how the tuning of the coordination geometry of Ce(III) translates into different dimensionality, which is readily influenced by reaction temperature and ancillary ligand presence. Moreover, the porosity of MOF 3 was confirmed by N2 and CO2 gas adsorption/desorption. Finally, the catalytic activity of MOF 3 was examined in acetalization reactions in a series of aromatic aldehydes with methanol.
- Derakhshandeh, Parviz Gohari,Abednatanzi, Sara,Leus, Karen,Janczak, Jan,Van Deun, Rik,Van Der Voort, Pascal,Van Hecke, Kristof
-
p. 7096 - 7105
(2019/11/19)
-
- Preparation of acetals from aldehydes and alcohols under basic conditions
-
A new, simple protocol for the synthesis of acetals under basic conditions from non-enolizable aldehydes and alcohols has been reported. Such reactivity is facilitated by a sodium alkoxide along with a corresponding trifluoroacetate ester, utilizing formation of sodium trifluoroacetate as a driving force for acetal formation. The usefulness of this protocol is demonstrated by its orthogonality with various acid-sensitive protecting groups and by good compatibility with functional groups, delivering synthetically useful acetals complementarily to the synthesis under acidic conditions from aldehydes and alcohols.
- Grabowski, Jakub,Granda, Jaros?aw M.,Jurczak, Janusz
-
p. 3114 - 3120
(2018/05/17)
-
- Access to Wieland-Miescher Diketone-Derived Building Blocks by Stereoselective Construction of the C-9 Quaternary Carbon Center Using the Mukaiyama Aldol Reaction
-
The Mukaiyama aldol reaction has been used to efficiently install a lateral chain at the C-9 position of the Wieland-Miescher ketone derivative 3 within two steps, representing a shortcut compared to that of the classical sequences. The treatment of the silylated enol ether 8 with a wide range of acetals in the presence of tin tetrachloride led to a the diastereoselective construction of the C-9 quaternary center of 33 new building blocks derived from the Wieland-Miescher ketone derivative 3.
- Schiavo, Lucie,Lebedel, Ludivine,Massé, Paul,Choppin, Sabine,Hanquet, Gilles
-
p. 6247 - 6258
(2018/06/22)
-
- Silver-Catalyzed Olefination of Acetals and Ketals with Diazoesters to β-Alkoxyacrylates
-
The first silver-catalyzed reaction of acetals or ketals with diazoesters leading to trisubstituted or tetrasubstituted β-alkoxyacrylates is now reported. A broad range of acetals and ketals bearing different substituents is compatible with this protocol and thus provides an attractive approach for the synthesis of complex β-alkoxyacrylates. The power of this method was further demonstrated by the successful synthesis of picoxystrobin, which is one of the most popular agricultural fungicides commercialized by Dupont.
- Li, Jiawen,Qian, Bo,Huang, Hanmin
-
supporting information
p. 7090 - 7094
(2018/11/23)
-
- Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions
-
We report here on the use of ethyl nitroacetate as a glycine template to produce α-amino esters. This started with a study of its condensation with various arylacetals to give ethyl 3-aryl-2-nitroacrylates followed by a reduction (NaBH4 and then zinc/HCl) into α-amino esters. The scope of this method was explored as well as an alternative with arylacylals instead. We also focused on various [2 + 3] cycloadditions, one leading to a spiroacetal, which led to the undesired ethyl 5-(benzamidomethyl)isoxazole-3-carboxylate. The addition of ethyl nitroacetate on a 5-methylene-4,5-dihydrooxazole using cerium(IV) ammonium nitrate was also explored and the synthesis of other oxazole-bearing α-amino esters was achieved using gold(I) chemistry.
- Gagnot, Glwadys,Hervin, Vincent,Coutant, Eloi P.,Desmons, Sarah,Baatallah, Racha,Monnot, Victor,Janin, Yves L.
-
supporting information
p. 2846 - 2852
(2018/11/27)
-
- House bulb light-induced photochemical acetalization of carbonyl compounds catalyzed by Eosin Y
-
We have systematically studied the reactions of acetalization and found that high reaction efficiency can be achieved using cheap and readily available organic Eosin Y as catalyst. The reaction proceeds smoothly under house bulbs and shows excellent functional group tolerance. The substrates of the reaction system are compatible with aromatic aldehydes, aliphatic aldehydes, aromatic ketones, and cyclic ketones with high yields.
- Zhou, Quan,Jia, Tao,Li, Xiao-Xuan,Zhou, Lin,Li, Chang-Jiang,Feng, Yi-Si
-
supporting information
p. 1068 - 1075
(2018/05/23)
-
- Hierarchical porous organic polymer as an efficient metal-free catalyst for acetalization of carbonyl compounds with alcohols
-
An efficient melamine-porous organic polymer (M-POP) as N-functionalized organic polymer catalyst was synthesized with melamine and terephthalaldehyde by a facile microwave-assisted method. The synthesized M-POP exhibited a high specific surface area with hierarchical pore structure of both mesoporosity and microporosity. The rich N-moieties namely, C[dbnd]N and N–H from the melamine precursor were found to show hydrogen-bonding ability with various organic molecules such as carbonyl compounds. This was illustrated in the acetalization of aldehydes and ketones with methanol or ethylene glycol under mild conditions as a metal-free H-bonding catalyst with high product selectivity. The superior catalytic performance of M-POP was attributed to the availability of a large number of H-bonding sites both as H-donor and H-acceptor between the reactants and the catalyst.
- Kim, Joong-Jo,Lim, Cheang-Rae,Reddy, Benjaram M.,Park, Sang-Eon
-
-
- Acid-catalyzed highly diastereoselective and effective synthesis of 1,3-disubstituted tetrahydropyrano[3,4-b]indoles
-
We successfully explored for the first time that trifluoroacetic acid (TFA) can effectively catalyze the oxa-Pictet-Spengler reaction of secondary tryptophols and acetals to synthesize 1,3-disubstituted 1,3,4,9-tetrahydropyrano[3,4-b]indoles in high yield (up to >99%) and diastereoselectivity (>20:1). The secondary tryptophols were synthesized from indole-3-acetic acid. The one-pot synthesis of tetrahydropyrano[3,4-b]indoles was successfully developed from secondary tryptophols and in situ prepared acetals from aldehydes and trimethylorthoformate and thus the cost-efficiency of the protocol was effectively enhanced. Finally, the catalytic asymmetric synthesis of the 1,3-disubstituted tetrahydropyrano[3,4-b]indole was also demonstrated after enantioselective achievement of highly enantiopure secondary tryptophols.
- Wang, Pei,Zhao, Jia-Zhen,Li, Hong-Feng,Liang, Xiang-Ming,Zhang, Ya-Lun,Da, Chao-Shan
-
supporting information
p. 129 - 133
(2016/12/23)
-
- Phosphorylated Polyacrylonitrile Fibers as an Efficient and Greener Acetalization Catalyst
-
A novel solid acid catalyst (PANEAPF) is developed by immobilization of phosphoric acid on polyacrylonitrile fiber through covalent bonding. Various characterization techniques such as elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), etc. are utilized to confirm the successful grafting and the stability of the fiber catalysts during application. PANEAPF shows high catalytic activity in the acetalization of aldehydes owing to the high utilization efficiency of its functionalized acid sites. In addition, the strong polarity micro-environment in the surface layers of PANEAPF make it highly suitable for catalytic application in both water and alcohol. Furthermore, the fiber catalyst can be applied to the acetalization of aldehydes in a continuous-flow process at room temperature, and shows excellent reactivity and superior recyclability (over 20 times). The many advantages of PANEAPF such as simple preparation, convenient regulation of acid amount, high durability, and eco-friendly process make it very attractive for fixed-bed reactors in the chemical industry.
- Xu, Gang,Cao, Jian,Zhao, Yali,Zheng, Lishuo,Tao, Minli,Zhang, Wenqin
-
supporting information
p. 2565 - 2575
(2017/09/25)
-
- A bifunctional cerium phosphate catalyst for chemoselective acetalization
-
Acid-base solid catalysts synthesized with structurally controlled uniform active sites can lead to unique catalysis. In this study, a CePO4 catalyst was synthesized using a hydrothermal method and found to exhibit high catalytic performance for the chemoselective acetalization of 5-hydroxymethylfurfural with alcohols, in sharp contrast to other homogeneous and heterogeneous acid and/or base catalysts. In the presence of CePO4, various combinations of carbonyl compounds and alcohols are efficiently converted into the corresponding acetal derivatives in good to excellent yields. Mechanistic studies show that CePO4 most likely acts as a bifunctional catalyst through the interaction of uniform Lewis acid and weak base sites with 5-hydroxymethylfurfural and alcohol molecules, respectively, which results in high catalytic performance.
- Kanai, Shunsuke,Nagahara, Ippei,Kita, Yusuke,Kamata, Keigo,Hara, Michikazu
-
p. 3146 - 3153
(2017/04/04)
-
- Graphitic carbon nitride catalysed photoacetalization of aldehydes/ketones under ambient conditions
-
Graphitic-C3N4 is shown for the first time to catalyse photoacetalization of aldehydes/ketones with alcohols to acetals in high yields using visible light under ambient conditions; transient charge separation over the material is effective to catalyse the reaction in the absence of Lewis or Br?nsted acids, giving a new green alternative catalyst.
- Abdullah Khan,Teixeira, Ivo F.,Li, Molly M. J.,Koito, Yusuke,Tsang, Shik Chi Edman
-
supporting information
p. 2772 - 2775
(2016/02/18)
-
- NOVEL SUGAR-DERIVED GELATOR
-
There is provided a novel gelator containing a sugar derivative. A gelator including a compound of Formula (1) or Formula (2): wherein each of R1 and R3 is independently a linear or branched alkyl group having a carbon atom number of 1 to 20, a cyclic C3-20 alkyl group, or a linear or branched alkenyl group having a carbon atom number of 2 to 20, n is 0 or an integer of 1 to 4, R2 is a hydrogen atom, a linear or branched alkyl group having a carbon atom number of 1 to 10, or an aryl group optionally having a substituent, and R4 and R5 are each a hydroxy group.
- -
-
Paragraph 0144; 0145; 0146; 0147
(2015/02/18)
-
- Highly efficient acetalization of carbonyl compounds catalyzed by anilin-aldehyde resin salts
-
A mild procedures for the syntheses of ethylene acetals and dimethyl acetals from the corresponding aldehydes and ketones catalyzed by 1mol% of anilinealdehyde resin salts are described. This method is also useful for the synthesis of dimethyl acetals of diaryl ketones.
- Tanemura, Kiyoshi,Suzuki, Tsuneo
-
supporting information
p. 797 - 799
(2015/06/22)
-
- Structural optimization of super-gelators derived from naturally-occurring mannose and their morphological diversity
-
Mannose derivatives were synthesized as low molecular-weight gelators with various alkoxy substituents on the aromatic ring of methyl-4,6-O-benzilidene- α-d-mannopyranoside. Most of these mannose derivatives could gel in various solvents, such as octane, cyclohexane, toluene, ethylene glycol and ethanol solutions, at concentrations lower than 2.0 wt%. In particular, the critical gelation concentration (CGC) of methyl-4,6-O-(4-butoxybenzylidene)- α-d-mannopyranoside (2) for squalane was only 0.025 wt%, one of the lowest CGCs we have ever experienced. The observations of xerogels by FE-SEM, TEM and AFM revealed that the length of the alkoxy chains of the mannose derivatives influences the gel morphologies. Moreover, the toluene gels formed from the mannose derivatives 1-6 functionalized by a linear alkoxy group exhibited thixotropic properties. Interestingly, the gels of various solvents formed from methyl-4,6-O-(4-dodecyloxybenzylidene)-α-d-mannopyranoside (6) (with the longest alkoxy chain on the aromatic ring in this paper) exhibited thixotropic properties. Thus, we confirmed that alkoxy groups on the aromatic ring exert noticeable effects on the gelation properties of these mannose derivatives. the Partner Organisations 2014.
- Ono, Fumiyasu,Watanabe, Hisayuki,Shinkai, Seiji
-
p. 25940 - 25947
(2014/07/07)
-
- Diterpenoid alkaloid lappaconine derivative catalyzed asymmetric α-hydroxylation of β-dicarbonyl compounds with hydrogen peroxide
-
A new framework derived from the commercially available diterpenoid alkaloid lappaconitine was evaluated as a Bronsted base catalyst for the enantioselective α-hydroxylation of β-dicarbonyl compounds by using 30% hydrogen peroxide as a green and highly practical source of oxygen. This protocol allows convenient access to the corresponding α-hydroxy-β- oxo esters, α-hydroxy-β-oxo amides and (-)-kjellmanianone with up to 98% yield and 92% ee. Copyright
- Li, Zhi,Lian, Mingming,Yang, Fan,Meng, Qingwei,Gao, Zhanxian
-
supporting information
p. 3491 - 3495
(2014/06/09)
-
- Stepwise construction of discrete heterometallic coordination cages based on self-sorting strategy
-
A chelation-directed self-sorting synthesis of a series of cationic heterometallic coordination cages (HCCs) with tunable sizes is described. Two complexation modes were found in the cage-forming process. Metal-anchoring host-guest behavior and size-selective in-cage catalytic activities were found for the HCCs.
- Li, Hao,Han, Ying-Feng,Lin, Yue-Jian,Guo, Zi-Wei,Jin, Guo-Xin
-
supporting information
p. 2982 - 2985
(2014/03/21)
-
- A new generation of aprotic yet Bronsted acidic imidazolium salts: Low toxicity, high recyclability and greatly improved activity
-
Catalysts which have low antimicrobial toxicity and are aprotic, yet which can act as Bronsted acidic catalysts in the presence of protic additives have been developed. The catalysts are recyclable, considerably more active (i.e. can be used at 10-50 times lower loadings) and of broader scope than their antecedent generation.
- Myles, Lauren,Gore, Rohitkumar G.,Gathergood, Nicholas,Connon, Stephen J.
-
supporting information
p. 2740 - 2746
(2013/10/08)
-
- The catalytic versatility of low toxicity dialkyltriazolium salts: In situ modification facilitates diametrically opposed catalysis modes in one pot
-
The ability of triazolium salts to serve as a precatalyst for both an acid and a powerful base/nucleophile (controlled by additives) has been exploited in a process characterised by a unique in situ catalyst modification strategy. The Royal Society of Chemistry 2013.
- Myles, Lauren,Gathergood, Nicholas,Connon, Stephen J.
-
supporting information
p. 5316 - 5318
(2013/06/27)
-
- Method for the selective formation of dimethyl acetals in the presence of hydroxylamine
-
An inexpensive and mild method for the formation of dimethyl acetals from the corresponding aldehydes is achieved using hydroxylamine and methanol under neutral conditions at room temperature. Notably, the reaction is selective for aldehydes in the presence of ketones, rendering this an example of a chemoselective acetalization. For saturated, sterically accessible aldehydes, catalytic amounts of hydroxylamine may be employed to attain the corresponding dimethyl acetal as the sole product in good to excellent yield. Unsaturated and hindered aldehydes required stoichiometric amounts of hydroxylamine but provided dimethyl acetals as the major product in typically excellent yield. In some cases, the corresponding oxime was also observed but may be separated from the acetal by flash column chromatography or distillation. The involvement of an intermediate oxime compound is postulated. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file. Taylor & Francis Group, LLC.
- Mickelsen, Ky J.,Tajc, Chelsea M.,Greenwood, Kevin R.,Browder, Cindy C.
-
experimental part
p. 186 - 194
(2011/10/31)
-
- Bis(perfluorooctanesulfonyl)imide supported on fluorous silica gel: Application to protection of carbonyls
-
The immobilization of bis(perfluorooctanesulfonyl)imide (HNPf2) on fluorous silica gel (FSG) and its utilization in protection of carbonyls have been investigated. This system is reasonably general and can be applied to converting several carbonyls to the corresponding acetals and ketals in good to excellent yields. There is no need for the use of anhydrous solvents or inert atmosphere. Recycling studies have shown that the FSG-supported HNPf2 catalyst can be readily recovered and reused several times without significant loss of activity.
- Hong, Mei,Xiao, Guomin
-
experimental part
p. 121 - 126
(2012/08/28)
-
- Indium(III) triflate catalysed transacetalisation reactions of diols and triols under solvent-free conditions
-
Acyclic acetals and ketals undergo transacetalisation in the presence of catalytic quantities of indium(III) triflate (In(OTf)3) and diols or triols under solvent-free conditions to generate the corresponding cyclic acetals and ketals in excellent yield. The methodology has been further developed to encompass a tandem acetalisation-acetal exchange protocol, which provides a facile and high yielding route to cyclic ketals from unreactive ketones under very mild reaction conditions.
- Smith, Brendan M.,Kubczyk, Tomasz M.,Graham, Andrew E.
-
supporting information; experimental part
p. 7775 - 7781
(2012/09/21)
-
- Conjugation chemistry through acetals toward a dextran-based delivery system for controlled release of siRNA
-
New conjugation chemistry for polysaccharides, exemplified by dextran, was developed to enable the attachment of therapeutic or other functional moieties to the polysaccharide through cleavable acetal linkages. The acid-lability of the acetal groups allows the release of therapeutics under acidic conditions, such as that of the endocytic compartments of cells, regenerating the original free polysaccharide in the end. The physical and chemical behavior of these acetal groups can be adjusted by modifying their stereoelectronic and steric properties, thereby providing materials with tunable degradation and release rates. We have applied this conjugation chemistry in the development of water-soluble siRNA carriers, namely acetal-linked amino-dextrans, with various amine structures attached through either slow- or fast-degrading acetal linker. The carriers with the best combination of amine moieties and structural composition of acetals showed high in vitro transfection efficiency and low cytotoxicity in the delivery of siRNA.
- Cui, Lina,Cohen, Jessica L.,Chu, Crystal K.,Wich, Peter R.,Kierstead, Paul H.,Frechet, Jean M. J.
-
p. 15840 - 15848,9
(2020/08/24)
-
- PROCESS FOR THE PREPARATION OF TEMSIROLIMUS AND ITS INTERMEDIATES
-
Novel intermediates, process for their preparation and their use in the preparation of therapeutically effective antineoplastic agents, in particular Temsirolimus of formula (I).
- -
-
Page/Page column 10
(2011/08/06)
-
- AN IMPROVED PROCESS FOR THE PREPARATION OF TEMSIROLIMUS AND ITS INTERMEDIATES
-
Novel intermediates, process for their preparation and their use in the preparation of therapeutically effective antineoplastic agents, in particular Temsirolimus of formula (I).
- -
-
Page/Page column 17-18
(2011/08/21)
-
- Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
-
A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.
- Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Yamaguchi, Hitoshi,Kubota, Yoshihiro,Asami, Masatoshi
-
supporting information; experimental part
p. 2081 - 2089
(2011/04/19)
-
- Aerobic oxidation of benzylic halides to carbonyl compounds with molecular oxygen catalyzed by tempo/kno2 in aqueous media
-
Benzylic halides were successfully oxidized to the corresponding aldehydes and ketones in good to excellent yields in aqueous media with molecular oxygen as oxidant in the presence of catalytic amounts of TEMPO (2,2,6,6- tetramethylpiperidyl-1-oxy) and potassium nitrite (KNO2).
- Liu, Qifa,Lu, Ming,Yang, Fei,Wei, Wei,Sun, Feng,Yang, Zhenbang,Huang, Sufeng
-
scheme or table
p. 1106 - 1114
(2010/04/29)
-
- Visible light flavin photo-oxidation of methylbenzenes, styrenes and phenylacetic acids
-
We report the photocatalytic oxidation of benzylic carbon atoms under mild conditions using riboflavin tetraacetate as photocatalyst and blue-emitting LEDs (440 nm) as light source. Oxygen is the terminal oxidant and hydrogen peroxide appears as the only byproduct in most cases. The process oxidizes toluene derivatives, stilbenes, styrenes and phenylacetic acids to their corresponding benzaldehydes. A benzyl methyl ether and acylated benzyl amines are oxidized directly to the corresponding methyl ester or benzylimides. The mechanism of the reactions has been investigated and the results indicate that oxygen addition to benzyl radicals is a key step of the oxidation process in the case of phenylacetic acids.
- Lechner, Robert,Kuemmel, Susanne,Koenig, Burkhard
-
experimental part
p. 1367 - 1377
(2011/12/01)
-
- The use of anhydrous CeCl3 as a recyclable and selective catalyst for the acetalization of aldehydes and ketones
-
An efficient, clean, chemoselective and solvent-free method for the synthesis of ketone and aldehyde dimethyl acetals was developed using trimethyl orthoformate and commercially available anhydrous CeCl3 as a recyclable catalyst. The method is general and affords the protected carbonyl compounds in good yields and under mild conditions, including aryl and alkyl ketones and activated aldehydes. The catalyst could be utilised directly for 3 cycles, without significant loss of activity.
- Silveira, Claudio C.,Mendes, Samuel R.,Ziembowicz, Francieli I.,Lenarda?o, Eder J.,Perin, Gelson
-
scheme or table
p. 371 - 374
(2010/09/07)
-
- Cobalt(II) schiff base functionalized mesoporous silica as an efficient and recyclable chemoselective acetalization catalyst
-
Cobalt(II) Schiff base functionalized mesoporous silica was synthesized from covalent attachment via the introduction of Co(OAc)2 to salicylaldimine functionalized mesoporous silica. The catalyst proved to be chemoselective one for the acetalization of aldehydes to the corresponding acetals in alcohol. The immobilized catalyst can be easily recovered and reused for at least ten reaction cycles without significant loss of its catalytic activity.
- Rajabi
-
scheme or table
p. 695 - 701
(2010/11/16)
-
- Highly recyclable, imidazolium derived ionic liquids of low antimicrobial and antifungal toxicity: A new strategy for acid catalysis
-
Imidazolium derived ionic liquid catalysts have been developed which are aprotic and of low antimicrobial and antifungal toxicity, yet which can act as efficient Bronsted acidic catalysts in the presence of protic additives. The catalysts can be utilised at low loadings and can be recycled 15 times without any discernible loss of activity. The Royal Society of Chemistry 2010.
- Myles, Lauren,Gore, Rohitkumar,Pulak, Marcel,Gathergood, Nicholas,Connon, Stephen J.
-
supporting information; experimental part
p. 1157 - 1162
(2010/10/04)
-
- A facile procedure for acetalization of aldehydes and ketones catalyzed by cerium(III) trifluoromethanesulfonate
-
Aldehydes and ketones are readily protected in the presence of trialkyl orthoformate and a catalytic amount of cerium(III) trifluoromethanesulfonate under mild conditions to give the corresponding acetals in good to excellent yields. Due to the mild reaction conditions, this method is compatible with acid-sensitive substrates. Copyright
- Ono, Fumiaki,Inatomi, Yoshiko,Tada, Yuusuke,Mori, Masaki,Sato, Tsuneo
-
experimental part
p. 96 - 97
(2009/11/30)
-
- Zinc chloride as an efficient catalyst for chemoselective dimethyl acetalization
-
Commercially available anhydrous zinc chloride has been found to be a highly efficient catalyst for dimethyl acetalization in high yields by treatment of aldehydes and ketones with trimethyl orthoformate in methanol-cyclohexane at reflux temperature. Copyright Taylor & Francis Group, LLC.
- Roy, Anupam,Rahman, Matiur,Das, Sudarshan,Kundu, Dhiman,Kundu, Shrishnu Kumar,Majee, Adinath,Hajra, Alakananda
-
experimental part
p. 590 - 595
(2009/07/04)
-
- A novel approach to the practical synthesis of sulfides: An InBr 3-Et3SiH catalytic system promoted the direct reductive sulfidation of acetais with disulfides
-
We have demonstrated a facile and direct synthesis of sulfide derivatives using acetais and ketals, derived, from aromatic/ conjugated, aldehydes and aromatic ketones, with disulfides and the InBr3-Et3SiH reducing system., We also succeeded in developing an unprecedented one-pot preparation of an aliphatic sulfide from a disulfide and an aliphatic acetal. (Wiley-VCH Verlag GmbH & Co. KGaA.
- Sakai, Norio,Moritaka, Kohei,Konakahara, Takeo
-
supporting information; experimental part
p. 4123 - 4127
(2009/12/09)
-
- Pyridinium ion catalysis of carbonyl protection reactions
-
Aprotic pyridinium ions incorporating electron-withdrawing substituents on the aromatic ring are powerful catalysts for the acetalization of aldehydes and the formation of dithianes, dithiolanes, dioxanes, and dioxolanes. Under optimum conditions the best catalyst can be used at a loading as low as 0.1 mol% and can outperform a Bronsted acid catalyst with a pka of 2.2. Georg Thieme Verlag Stuttgart.
- Procuranti, Barbara,Myles, Lauren,Gathergood, Nicholas,Connon, Stephen J.
-
experimental part
p. 4082 - 4086
(2010/03/05)
-
- Carbon tetrabromide/sodium triphenylphosphine-m-sulfonate (TPPMS) as an efficient and easily recoverable catalyst for acetalization and tetrahydropyranylation reactions
-
A solid complex, conveniently prepared from carbon tetrabromide and sodium triphenylphos-phine-m-sulfonate (TPPMS), can be used as an easily recoverable catalyst for the selective acetalization of aldehydes and tetrahydropyranylation of alcohols. The catalyst can be recovered by simple pre-cipitation with ether and can be reused at least 7 times without loss of catalytic activity.
- Huo, Congde,Chan, Tak Hang
-
experimental part
p. 1933 - 1938
(2011/02/28)
-
- Reductive openings of acetals: Explanation of regioselectivity in borane reductions by mechanistic studies
-
(Graph Presented) The mechanisms of regioselective reductive openings of acetals were investigated in several model systems by a combination of Hammett plots, kinetic experiments, density functional calculations, and 11B NMR. The regioselectivity of borane reductions of cyclic acetals can be controlled by the choice of borane. Lewis acid activation of BH3·NMe 3 increases the reaction rate and renders the borane the most electrophilic species, which associates to the more electron-rich oxygen of the acetal. In contrary, without activation, the regioselectivity is instead directed by the Lewis acid, as exemplified by the reaction with BH 3·THF.
- Johnsson, Richard,Olsson, Dan,Ellervik, Ulf
-
p. 5226 - 5232
(2008/12/21)
-
- Tetrafluoroboric acid adsorbed on silica gel as a reusable heterogeneous dual-purpose catalyst for conversion of aldehydes/ketones into acetals/ketals and back again
-
Aldehydes and ketones can be protected as acetals and ketals by treatment with trimethyl orthoformate (TMOF) or triethyl orthoformate (TEOF) under the catalytic influence of tetrafluoroboric acid adsorbed on silica gel (HBF 4-SiO2). In the case of aldehydes or ketones with highly electrophilic carbonyl group, the reactions are carried out under solvent-free conditions. Aryl alkyl ketones, aryl styryl ketones, aldehydes with weakly electrophilic carbonyl groups, and aldehydes with substituents that can coordinate with the catalyst require the presence of the corresponding alcohol as solvent. For substrates that can be converted into acetals under neat conditions, the acetal formation takes place at a faster rate when the alcohol is used as the solvent. The catalyst can be recovered and reused/recycled four times (after reactivation after each use) without any significant decrease in its catalytic efficiency. The parent aldehydes/ketones are regenerated from the corresponding acetals/ketals in high yields by the treatment with water-alcohol in the presence of HBF4-SiO2 at room temperature for short times. Excellent selectivity was observed during inter- and intramolecular competition studies involving carbonyl substrates with varying electronic and steric environments. Selective acetal formation of benzaldehyde takes place in the presence of 4-(dimethylamino)benzaldehyde, thiophene-2-carboxaldehyde, 1-naphthaldehyde, 9-anthraldehyde, or acetophenone, but 3-nitrobenzaldehyde undergoes selective acetal formation in preference to benzaldehyde. In the case of 4-acetylbenzaldehyde, exclusive acetal formation of the aldehyde carbonyl group occurs. Georg Thieme Verlag Stuttgart.
- Kumar, Dinesh,Kumar, Raj,Chakraborti, Asit K.
-
p. 1249 - 1256
(2008/12/22)
-