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All total 221 Articles be found
All total 221 Articles be foundOrganocatalyzed and uncatalyzed C=C/C=C and C=C/C=N exchange processes between knoevenagel and imine compounds in dynamic covalent chemistry
Kulchat, Sirinan,Meguellati, Kamel,Lehn, Jean-Marie
, p. 1219 - 1236 (2014)
Molecular diversity generation through reversible component exchange has acquired great importance in the last decade with the development of dynamic covalent chemistry. We explore here the recombination of components linked by C=C and C=N bonds through reversible double-bond formation, and cleavage in C=C/C=C and C=C/C=N exchange processes. The reversibility of the Knoevenagel reaction has been explored, and C=C/C=C C/C exchanges have been achieved among different benzylidenes, under organocatalysis by secondary amines such as L-proline. The substituents of these benzylidenes were shown to play a very important role in the kinetics of the exchange reactions. L-Proline is also used to catalyze the reversible C=C/C=C exchange between Knoevenagel derivatives of barbituric acid and malononitrile. Finally, the interconversion between Knoevenagel derivatives of dimethylbarbituric acid and imines (C=C/C=N exchange) has been studied and was found to occur rapidly in the absence of catalyst. The results of this study pave the way for the extension of dynamic combinatorial chemistry based on C=C/C=C and C=C/C=N exchange systems.
Switching the Cleavage Sites in Palladium on Carbon-Catalyzed Carbon-Carbon Bond Disconnection
Hattori, Tomohiro,Takakura, Ryoya,Ichikawa, Tomohiro,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
, p. 2737 - 2743 (2016)
We have demonstrated a palladium on carbon-catalyzed approach to regioselectively alter the cleavage sites of the C-C bonds of cinnamaldehyde derivatives by a slight change in the reaction conditions in isopropanol under an O2 atmosphere. Styrene derivatives could be selectively formed by the addition of Na2CO3 in association with the dissociation of carbon monoxide, while benzaldehyde derivatives were generated by the addition of CuCl and morpholine instead of Na2CO3. (Chemical Equation Presented).
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Splitter,J.S.,Calvin,M.
, p. 1445 - 1448 (1968)
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Iodine-catalyzed oxidative system for cyclization of primary alcohols with o-aminobenzamides to quinazolinones using DMSO as the oxidant in dimethyl carbonate
Ge, Wenlei,Zhu, Xun,Wei, Yunyang
, p. 10817 - 10822 (2013)
The iodine catalyzed one-pot two-step oxidative system for cyclization of primary alcohols with o-aminobenzamides to quinazolinones using DMSO as the oxidant has been achieved, providing a convenient and efficient method for the synthesis of quinazolinones in good to excellent yields via in situ oxidation of primary alcohols to aldehydes. The reaction was carried out in the green solvent DMC, under atmospheric conditions. The procedure is suitable for aromatic or alkyl primary alcohols. The Royal Society of Chemistry 2013.
Cobalt-catalysed selective synthesis of aldehydes and alcohols from esters
Pattanaik, Sandip,Gunanathan, Chidambaram
, p. 7345 - 7348 (2020)
Efficient and selective reduction of esters to aldehydes and alcohols is reported in which a simple cobalt pincer catalyst catalyses both transformations using diethylsilane as a reductant. Remarkably, the reaction selectivity is controlled by the stoichiometry of diethylsilane. This journal is
Silica phenyl sulfonic acid as a solid acid heterogeneous catalyst for chemoselective thioacetalization of carbonyl compounds and dethioacetalization under mild conditions
Veisi, Hojat,Sedrpoushan, Alireza,Zolfigol, Mohammad Ali,Mohanazadeh, Farajollah,Hemmati, Saba
, p. E204-E206 (2013)
Silica phenyl sulfonic acid (SPSA) is an effective catalyst for chemoselective thioacetalization of aldehydes in the presence of ketones under neutral conditions. In addition, a simple and an efficient procedure for deprotection of 1,3-dithianes and 1,3-dithiolanes of aromatic, aliphatic, and α,β-unsaturated aldehydes and ketones in the solvent-free to the corresponding parent carbonyl compounds was successfully carried out with SPSA in excellent yields.
Selective conversion of C=N bonds to their corresponding carbonyl compounds by the tribromoisocyanuric acid/wet SiO2 system as a novel reagent
Habibi, Davood,Zolfigol, Mohammad Ali,Faraji, Ali Reza,Rahmani, Payam
, p. 809 - 814 (2012)
Tribromoisocyanuric acid/wet SiO2 was used for the conversion of C=N bonds to their corresponding carbonyl compounds in oximes, semicarbazones, azines, and Schiff bases. The interesting feature of this system is that in those oximes, semicarbazones, azines, and Schiff bases which have conjugated or unconjugated C=C bonds, the C=N bond will selectively change to the relevant C=O bond while the conjugated or unconjugated C=C bond will remain intact. Springer-Verlag 2011.
Highly active and selective synthesis of imines from alcohols and amines or nitroarenes catalyzed by Pd/DNA in water with dehydrogenation
Tang, Lin,Sun, Huayin,Li, Yunfeng,Zha, Zhenggen,Wang, Zhiyong
, p. 3423 - 3428 (2012)
A direct imination was developed from alcohols and amines under catalysis of Pd/DNA by dehydrogenation without additional oxidant, affording the corresponding imines in moderate to good yields with excellent chemoselectivity. By virtue of the liberated molecular hydrogen, the nitroarenes could also be deoxidized in situ into amines and a one-pot tandem synthesis of imines was achieved from nitroarenes. This heterogeneous catalyst can be recovered and reused at least five times by taking advantage of its water-soluble reversibility. All these conformations were performed smoothly in water under mild conditions, and an atom economical and environmentally benign synthesis was embodied in this imination.
Vilsmeier-Haack synthesis of aromatic aldehydes using bis-(trichloromethyl) carbonate and dimethylformamide
Shan,Shi,Su
, p. 337 - 340 (2004)
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Cooperative catalysis of palladium nanoparticles and cobalt oxide support for formylation of aryl iodides under syngas atmosphere
Hamasaki, Akiyuki,Yasutake, Yutaro,Norio, Takafumi,Ishida, Tamao,Akita, Tomoki,Ohashi, Hironori,Yokoyama, Takushi,Honma, Tetsuo,Tokunaga, Makoto
, p. 146 - 152 (2014)
Formylation of aryl iodides proceeded effectively in the presence of palladium nanoparticles on cobalt oxide under a syngas atmosphere to afford aldehydes up to 91% yield. A cooperative effect between palladium nanoparticles and cobalt species derived from the support was integral to efficient transformation. Both palladium and cobalt were revealed to exist as zero valent metals after H2 treatment from X-ray absorption near edge structure and X-ray diffraction spectra. The catalyst could be reused at least 7 times without significant loss of activity.
Kinetics of Hydrolysis of Some N'-(4-Substituted Benzylidene)salicylohydrazides
Temerk, Yassien M.,Kamal, Mostafa M.,Ahmed, Mohamed E.
, p. 337 - 340 (1984)
The rates of hydrolysis of a series of substituted benzylidenesalicylohydrazide derivatives 40percent (v/v) ethanol-buffer mixture have been investigated by differential pulse polarography.The hydrolysis is catalysed by H+ and its rate follows strictly first-order kinetics.The rate constant decreases with increasing pH up to around pH 3.9, beyond which no measurable reaction was observed; here the protonation of imine begins to be significantly incomplete.The attack of water on the protonated substrate is considered to be the rate-determining step.The effects of pH, molecular structure, and temperature on the reaction rate and the activation energy are reported.Thermodynamic parameters (ΔG(formula), ΔH(formula), and ΔS(fomula)) for the hydrolysis are discussed.
Two-step radiosynthesis of [18F]N-succinimidyl-4-fluorobenzoate ([18F]SFB)
Glaser, Matthias,Arstad, Erik,Luthra, Sajinder K.,Robins, Edward G.
, p. 327 - 330 (2009)
The acylation reagent [18F]N-succinimidyl-4-fluorobenzoate (18F-SFB) has been prepared using a new two-step approach. The starting material p-[18F]fluorobenzaldehyde (18F-FBA) was obtained by an improved radiosy
A convenient method for in situ generation of I2 using CuSO 4/NaI and its applications to the deprotection of acetals, etherifications and iodolactonizations
Bailey, Aaron D.,Cherney, Steven M.,Anzalone, Peter W.,Anderson, Erin D.,Ernat, Justin J.,Mohan, Ram S.
, p. 215 - 218 (2006)
A convenient method for the in situ generation of I2 using CuSO4/NaI has been developed. The applications of this method to the deprotection of acetals, etherifications and iodolactonizations have been demonstrated. The use of toxic and corrosive molecular iodine is avoided. Georg Thieme Verlag Stuttgart.
A general and efficient method for the formylation of aryl and heteroaryl bromides
Klaus, Stefan,Neumann, Helfried,Zapf, Alexander,Struebing, Dirk,Huebner, Sandra,Almena, Juan,Riermeier, Thomas,Gross, Peter,Sarich, Martin,Krahnert, Wolf-Ruediger,Rossen, Kai,Beller, Matthias
, p. 154 - 158 (2006)
(Chemical Equation Presented) The key to the general and efficient palladium-catalyzed formylation of aryl and heteroaryl bromides is the use of the di-1-adamantyl-n-butylphosphane (cataC-Xium A) as ligand. Low pressure of the synthesis gas and appropriate choice of the base are also important for high yields (up to 99%) of a broad range of (hetero)aromatic aldehydes at unprecedented low catalyst concentrations (see scheme; TMEDA= N,N,N′,N′-tetramethylethylenediamine).
Deprotection of oximes, imines, and azines to the corresponding carbonyls using Cu-nanoparticles on cellulose template as green reusable catalyst
Baruah, Diganta,Saikia, Ujwal Pratim,Pahari, Pallab,Dutta, Dipak Kumar,Konwar, Dilip
, p. 59338 - 59343 (2014)
The deprotection of wide varieties of oximes, imines, and azines to their corresponding carbonyls has been achieved using Cu-nanoparticles on a cellulose template as a reusable catalyst. The reactions were carried out at 80-100 °C using microwave irradiation in water under neutral condition. The catalyst can be reused for several cycles with good to excellent yield.
Chemoselective and ligand-free aerobic oxidation of benzylic alcohols to carbonyl compounds using alumina-supported mesoporous nickel nanoparticle as an efficient recyclable heterogeneous catalyst
Das, Asit Kumar,Nandy, Sneha,Bhar, Sanjay
, (2021)
An economically efficient and operationally simple ligand-free protocol for the chemoselective oxidation of benzylic alcohols to carbonyl compounds has been developed using alumina-supported nickel nanoparticles as a stable recyclable heterogeneous catalyst along with potassium tert-butoxide in the presence of aerial oxygen as an eco-friendly oxidant. The aliphatic alcohols remained unaffected under the present condition. Excellent chemoselectivity has also been demonstrated through intermolecular and intramolecular competition experiments. This protocol accommodates a diverse range of substituents with the tolerance of various sensitive moieties during the reaction. The catalyst could be recovered by filtration and reused consecutively without any significant loss in the catalytic activity. Moreover, the heterogeneity of the catalyst has also been established by the “hot filtration method (Sheldon's test)”.
Gold nanoparticles supported on ionic liquid-modified cellulose as an efficient and recyclable catalyst for the oxidation of alcohols to aldehydes/ketones and reduction of nitroarenes
Pourjavadi, Ali,Habibi, Zahra
, (2017)
A novel catalyst of gold nanoparticles supported on cellulose fibres with the ionic liquid framework (Au NPs@CL-IL) has been shown to be a highly active and recyclable catalyst for the oxidation of primary and secondary alcohols and reduction of nitroaren
Competitive demethylation and substitution in N,N,N-trimethylanilinium fluorides
Sun, Haoran,DiMagno, Stephen G.
, p. 806 - 812 (2007)
Fluorination of aromatic compounds by nucleophilic displacement of trimethylanilinium salts by fluoride is a commonly used reaction for radiotracer synthesis. Though the liberated trimethylamine is thought to be an excellent leaving group for this type of SNAr reaction, scattered reports show that amine demethylation (reverse Menschutkin reaction) sometimes dominates over substitution, particularly when relatively electron rich fluoroarenes are the desired targets. Here we provide systematic experimental and theoretical studies of trimethylanilinium demethylation and substitution. Results from these studies highlight the limits of this leaving group in fluoroarene synthesis and have important ramifications for the design of nucleophilic fluorinating agents featuring ammonium cations.
Nanorods of FeVO4: An efficient heterogeneous catalyst for chemoselective oxidation of benzylic alcohols
Heydari, Akbar,Sheykhan, Mehdi,Sadeghi, Masoud,Radfar, Iman
, p. 248 - 255 (2017)
Controllable fabrication of iron vanadate (FeVO4) was achieved by the hydrothermal approach. The excellent catalytic activity of the prepared nanorods of iron vanadate for the oxidation of benzylic alcohols as well as its potential for oxidation of the benzylic sp3 C-Hs in the presence of urea hydrogen peroxide (UHP) as oxidant was reported. The prepared nanorods and nanospheres were fully characterized by FT-IR, XRD, EDAX, ICP-AES, SEM, and TEM. In the presence of the catalyst, alcohols chemoselectively (100%) convert to the corresponding aldehydes/ketones, giving a total turnover number about 380 for 10 consecutive runs.
Oxidation of Benzylic Alcohols to Aromatic Aldehydes by DMSO/Water/I2: A Chemoselective Oxidation
Adib, Mehdi,Karajabad, Morteza Akherati,Sheikhi, Ehsan
, (2020)
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-
Fleet,Little
, p. 3749 (1977)
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Facile synthesis of size-controlled Ag supported on WO3 nanorods and their application as novel and active catalyst in oxidant-free dehydrogenation of benzyl alcohols
Paul, Bappi,Sharma, Sachin,Purkayastha, Debraj D.,Dhar, Siddhartha S.,Bal, Rajaram
, (2019)
A new and simple strategy for the size-tunable synthesis of silver supported tungsten oxide nanoparticles (NPs) was reported. Polyethylene glycol (PEG) of molecular weights 400 and 4000 was used as surfactant to tune the size of nanoparticles. These as-sy
Cobalt tungsten oxide hydroxide hydrate (CTOHH) on DNA scaffold: An excellent bi-functional catalyst for oxygen evolution reaction (OER) and aromatic alcohol oxidation
Kumaravel, Sangeetha,Thiruvengetam, Prabaharan,Ede, Sivasankara Rao,Karthick,Anantharaj,Sam Sankar, Selvasundarasekar,Kundu, Subrata
, p. 17117 - 17131 (2019)
A material with interdisciplinary properties is of wide interest for use in environmental applications. Currently, hydrogen generation by electrolysis and formation of carbonyl derivatives from alcohols are two different fields that focus on energy and environmental applications. In this work, a new material, Cobalt Tungsten Oxide Hydroxide Hydrate (CTOHH) on deoxyribonucleic acid (DNA) scaffold having chain-like morphology has been prepared for the first time by a facile microwave heating method. The same CTOHH was also prepared without the DNA scaffold and resulted in irregular aggregated molecular structures. Further, both CTOHH-DNA and CTOHH were converted into CoWO4-DNA and CoWO4, respectively by annealing them at a temperature of 600 °C. All the four catalysts were used for electrocatalytic oxygen evolution reaction (OER) and for oxidation of aromatic alcohols. In OER, CTOHH-DNA delivered fruitful results compared to all other electrocatalysts. For attaining a current density of 10 mA cm-2, it just required an overpotential of 355 mV with a Tafel slope value of 47.5 mV dec-1. Similarly, all four catalysts were also analyzed for selective and controlled oxidation of aromatic alcohols to their respective aldehydes and ketones using molecular oxygen as a green oxidant where CTOHH-DNA showed better results. Chemo-selectivity has been observed for CTOHH-DNA in the co-presence of hydroxyl and cyano functional groups. The durability of CTOHH-DNA was analyzed and it showed excellent catalytic activity retention up to five cycles.
Catalytic Conversions in Water. Part 23: Steric Effects and Increased Substrate Scope in the Palladium-Neocuproine Catalyzed Aerobic Oxidation of Alcohols in Aqueous Solvents
Ten Brink, Gerd-Jan,Arends, Isabel W. C. E.,Hoogenraad, Marcel,Verspui, Goeran,Sheldon, Roger A.
, p. 1341 - 1352 (2003)
The steric influence of substituents on the 2-and 9-positions of phenanthroline in the (2,9-R2-1,10-phenanthroline)palladium(II)- catalyzed aerobic oxidation of 2-hexanol was investigated by means of high throughput experimentation. (Neocuproine)Pd-(OAc)2 (R=CH 3) was found to be a highly active catalyst for alcohol oxidation in 1:1 water/DMSO mixtures. The catalyst is unique in that it tolerates water, polar co-solvents and a wide variety of functional groups in the alcohol. Turn-over frequencies of > 1500 h-1 were achieved and a series of alcohols was oxidised with 0.1 to 0.5 mol % of catalyst.
Catalytic oxidation of primary aromatic alcohols using half sandwich Ir(III), Rh(III) and Ru(II) complexes: A practical and theoretical study
Thangavel, Saravanan,Boopathi, Subramaniam,Mahadevaiah,Kolandaivel, Ponmalai,Pansuriya, Pramod B.,Friedrich, Holger B.
, p. 160 - 171 (2016)
The complexes [Cp*IrCl(N-(pyridin-2-ylmethylene)aniline)]PF6 (1), [Cp*RhCl(N-(pyridin-2-ylmethylene)aniline)]PF6 (2), (where Cp*?=?1,2,3,4,5-pentamethylcyclopentadiene) and [η6-areneRuCl(N-(pyridin-2-ylmethylene)aniline)]PF6 (3) have been synthesized and the structure and purity of these were confirmed by single crystal XRD and elemental analyses. Iridium and rhodium complexes exhibit the P21/n space group, the ruthenium complex the P21/c space group and all three complexes show the expected pseudo octahedral “piano-stool” geometry. The catalytic performance of these complexes for the dehydrogenation of primary alcohols to their respective aldehydes with different bases and solvents was investigated. The complexes of iridium and ruthenium give good conversions in different alkaline solutions. Density functional theory was applied to determine the respective MO energy levels, bond lengths, bond angles and binding energies of all the metal complexes. It was also used to study the activity, stability and intermediates of the complexes. A Gibbs free energy (ΔG) DFT calculation was carried out to help understand the reaction mechanism/catalytic cycle of the Rh complex (2). The energy barrier for oxidation of aromatic alcohols by the rhodium hydride complex is much lower (10.32?kcal/mol) than the barrier for hydride transfer of the corresponding Rh benzyloxo species (15.19?kcal/mol), in agreement with mechanisms proposed for related systems.
Synergistic catalysis of Cu+/Cu0 for efficient and selective N-methylation of nitroarenes with para-formaldehyde
Dong, Xiaosu,Wang, Zhaozhan,Yuan, Youzhu,Yang, Yong
, p. 304 - 313 (2019)
In this paper, an inexpensive heterogeneous copper nanoparticles catalyst derived from CuAl-layered double hydroxide via an in situ topotactic transformation process was developed. Cu nanoparticles with uniform size were homogeneously dispersed on amorphous Al2O3 with strong metal-support interaction. Characterization results reveals that the Cu0 and Cu+ were simultaneously formed with Cu+ species as the dominant sites on the surface during the reduction process. The resultant catalyst Cu/Al2O3 demonstrates high catalytic activity, selectivity and durability for the reductive N-methylation of easily available nitroarenes in a cost-efficient, environmentally friendly and cascade manner. A broad spectrum of nitroarenes could be efficiently N-methylated to their corresponding N,N-dimethyl amines with good compatibility of various functional groups. The protocol is also applicable for the late-stage functionalization of biologically and pharmaceutically active nitro molecules. A structure-function relationship discloses that Cu0 and Cu+ sites on the surface pronouncedly boosts the reaction efficiency in a synergistic manner, in which Cu0 could facilitate H2 production and N-methylation of anilines, while Cu+ is considerably more active and participates in the overall process of the selective N-methylation of nitroarenes. Moreover, the catalyst also showed a strong stability and could be easily separated for successive reuses without an appreciable loss in activity and selectivity.
A Magnetically Recyclable Palladium-Catalyzed Formylation of Aryl Iodides with Formic Acid as CO Source: A Practical Access to Aromatic Aldehydes
You, Shengyong,Zhang, Rongli,Cai, Mingzhong
, p. 1962 - 1970 (2021)
A magnetically recyclable palladium-catalyzed formylation of aryl iodides under CO gas-free conditions has been developed by using a bidentate phosphine ligand-modified magnetic nanoparticles-anchored- palladium(II) complex [2P-Fe 3O 4@SiO 2-Pd(OAc) 2] as catalyst, yielding a wide variety of aromatic aldehydes in moderate to excellent yields. Here, formic acid was employed as both the CO source and the hydrogen donor with iodine and PPh 3as the activators. This immobilized palladium catalyst can be obtained via a simple preparative procedure and can be facilely recovered simply by using an external magnetic field, and reused at least 9 times without any apparent loss of catalytic activity.
NMO·TPB: A selectivity variation on the Ley-Griffith TPAP oxidation
Moore, Peter W.,Mirzayans, Paul M.,Williams, Craig M.
, p. 3567 - 3571 (2015)
A non-hygroscopic tetraphenylborate salt of N-methylmorpholine-N-oxide (NMO) is reported (NMO·TPB), which modulates the standard Ley-Griffith oxidation such that benzylic and allylic alcohols are oxidised selectively. An attractive feature of this new protocol is that anhydrous conditions are not required for this selective tetra-n-propylammonium perruthenate (TPAP) oxidation, superseding the requirement of molecular sieves.
Organocatalysis of c?￡/c?￡N and C?￡C/ C?￡N exchange in dynamic covalent chemistry
Wilhelms, Nadine,Kulchat, Sirinan,Lehn, Jean-Marie
, p. 2635 - 2651 (2012)
The reversibly formed C?￡N bond plays a very important role in dynamic covalent chemistry and the C?￡N/C?￡N exchange of components between different imine constituents to create dynamic covalent libraries has been extensively used. To facilitate diversity generation, we have investigated an organocatalyzed approach, using L-proline as catalyst, to accelerate the formation of dynamic libraries of [n×n] imine components. The organocatalysis methodology has also been extended, under somewhat modified conditions, to reversible C?￡C/C?￡N exchange processes between Knoevenagel derivatives of barbituric acid and imines, allowing for the generation of increased diversity. Copyright
Chemoselective hydrogen peroxide oxidation of primary alcohols to aldehydes by a water-soluble and reusable iron(iii) catalyst in pure water at room temperature
Yan, Qi,Fang, Ye Chen,Jia, Yun Xue,Duan, Xin Hong
, p. 2372 - 2377 (2017)
Hydrogen peroxide oxidation of primary alcohols to aldehydes is described, which is catalyzed by a novel, reusable and water-soluble FeCl3 complex in situ-formed with quaternary ammonium salt-functionalized 8-aminoquinoline. This reaction exhibits unique chemoselectivity and broad functional-group tolerance, and it can operate efficiently in pure water at room temperature.
A transition metal free expedient approach for the C[dbnd]C bond cleavage of arylidene Meldrum's acid and malononitrile derivatives
Suresh, Muthiah,Kumari, Anusueya,Singh, Raj Bahadur
, (2019)
A transition metal free expedient approach for the C[dbnd]C bond cleavage of electron deficient alkenes such as arylidene Meldrum's acid and malononitrile derivatives are discussed. The C[dbnd]C bond of these compound were cleaved to benzoic acid in good yield at high temperature. Most importantly, with oxone in CH3CN/H2O at 45 °C or m-CPBA in DCM or NaClO2 in THF/H2O or PIDA in THF at room temperature furnished benzaldehyde derivatives selectively in excellent yields.
Copper/imidazolium/TEMPO-catalyzed aerobic oxidation of benzylic alcohols in water
Chen, Congyan,Liu, Bo,Chen, Wanzhi
, p. 3387 - 3391 (2013)
Various imidazolium salts bearing hydrophilic groups were prepared that reacted with copper powder to afford water-soluble? copper complexes of N-heterocyclic carbenes. These copper complexes can catalyze the selective oxidation of benzyl alcohols to the corresponding aldehydes in water at room temperature without the need for a base. Georg Thieme Verlag Stuttgart . New York.
Monolithic and flexible polyimide film microreactors for organic microchemical applications fabricated by laser ablation
Min, Kyoung-Ik,Lee, Tae-Ho,Park, Chan Pil,Wu, Zhi-Yong,Girault, Hubert H.,Ryu, Ilhyong,Fukuyama, Takahide,Mukai, Yu,Kim, Dong-Pyo
, p. 7063 - 7067 (2010)
Keeping limber: A monolithic and flexible polyimide film microreactor is introduced for organic reactions and syntheses. Unlike glass microreactors, it is easy to fabricate, yet it is inert to solvents and acids under harsh conditions, unlike other polymer microreactors.
Palladium nanoparticles supported on core-shell and yolk-shell Fe3O4@nitrogen doped carbon cubes as a highly efficient, magnetically separable catalyst for the reduction of nitroarenes and the oxidation of alcohols
Movahed, Siyavash Kazemi,Lehi, Noushin Farajinia,Dabiri, Minoo
, p. 69 - 79 (2018)
The preparation of palladium nanoparticles (Pd NPs) supported on Fe3O4@nitrogen doped carbon (N-C) core-shell (C-S) and yolk–shell (Y-S) nanostructures is reported. The Fe3O4@N-C@Pd C-S nanostructures were synth
Controlled Aerobic Oxidation of Primary Benzylic Alcohols to Aldehydes Catalyzed by Polymer-Supported Triazine-Based Dendrimer-Copper Composites
Pan, Shiguang,Yan, Shuo,Osako, Takao,Uozumi, Yasuhiro
, p. 1152 - 1156 (2018)
A controlled aerobic oxidation of primary benzylic alcohols to the corresponding benzaldehydes by using polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported triazine-based polyethyleneamine dendrimer-copper complexes [PS-PEG-TD2-Cu(II)] was developed. In particular, PS-PEG-TD2-Cu(OAc) 2 efficiently catalyzed the aerobic oxidation of benzylic alcohols in the presence of a catalytic amount of TEMPO under atmospheric conditions to give the corresponding aldehydes in up to quantitative yield. The catalyst was readily recovered by simple filtration and reused four times without significant loss of its catalytic activity.
A Facile and Efficient Catalytic System for the Oxidation of Alcohols with Gold(III) and Ionic Liquid Immobilized TEMPO under Solvent-Free Conditions
Wang, Zhao-Gang,Xu, Kui,Shen, Meng-Nan,Lu, Ming
, p. 2459 - 2462 (2014)
A facile and efficient protocol for the oxidation of alcohols with gold(III) and ionic liquid immobilized TEMPO is described. This catalytic system is highly selective for the oxidation of primary and secondary benzylic alcohols, heterocyclic alcohols, and allylic alcohols affording the respective carbonyl compounds in good to excellent yields.
A new fluorous/organic amphiphilic ether solvent, F-626: Execution of fluorous and high temperature classical reactions with convenient biphase workup to separate product from high boiling solvent
Matsubara, Hiroshi,Yasuda, Shinji,Sugiyama, Hiroyuki,Ryu, Ilhyong,Fujii, Yasuyuki,Kita, Katsumi
, p. 4071 - 4076 (2002)
A new fluorous/organic amphiphilic ether solvent, 1H,1H,2H,2H-perfluorooctyl 1,3-dimethylbutyl ether (F-626), is introduced. The basic properties of F-626, especially the partition coefficients with organic solvents/FC-72 (perfluorohexane), were investigated. F-626 was easy to remove by fluorous biphase treatment. Using F-626 as a solvent, LAH reduction, catalytic hydrogenation, and fluorous reductive radical reactions were successful. Classical high temperature reactions up to 200°C, such as the Vilsmeier formylation, the Wolff-Kishner reduction, and the Diels-Alder reaction, were also examined in F-626. The yields of the products in F-626 were almost comparable with those conducted in common organic solvents, which prove that F-626 has the potential to be an easily recyclable high boiling solvent.
Surfactant/I2/water: An efficient system for deprotection of oximes and imines to carbonyls under neutral conditions in water
Gogoi, Pranjal,Hazarika, Parasa,Konwar, Dilip
, p. 1934 - 1936 (2005)
(Chemical Equation Presented) I2/surfactant/water system deprotecting oximes and imines to the corresponding carbonyl compounds under neutral conditions in water at 25-40°C with very high to excellent yields.
Hypophosphorous acid-iodine: A novel reducing system. Part 2: Reduction of benzhydrols to diarylmethylene derivatives
Gordon, Paul E.,Fry, Albert J.
, p. 831 - 833 (2001)
A mixture of hypophosphorous acid (H3PO2) and iodine in acetic acid reduces a variety of substituted benzhydrols to the corresponding methylene derivatives in very high yields. The active reducing agent is hydrogen iodide generated by reaction between iodine and hypophosphorous acid.
Colorimetric detection of fluoride ion by 5-arylidenebarbituric acids: Dual interaction mode for fluoride ion with single receptor
Saravanan, Chinnusamy,Easwaramoorthi, Shanmugam,Wang, Leeyih
, p. 5151 - 5157 (2014)
Two 5-arylidenebarbituric acid derivatives (IH and IM) have been synthesized by the Knoevenagel condensation of barbituric acid with 4-N,N-dimethylamino benzaldehyde and studied for anion sensing activities. Both receptors sense fluoride ion with high selectivity and sensitivity and the sensing action has been demonstrated by naked eye detection, UV-visible absorption, and fluorescence spectral changes in the presence of F-. Indeed, the F- sensing mechanism for receptor IH depends on F - ion concentration. While at higher concentrations F- forms strong hydrogen bonding interaction with the N-H proton of the receptor, at lower concentrations sensing is influenced by the deprotonation of the methylene proton, followed by the chemical reaction, which is also confirmed by the 1H-NMR technique. On the other hand, when replacing the N-H proton with a methyl group, IM does not show any concentration dependent behaviour with F-. The F- concentration dependent sensing is attributed to the changes in the receptor-anion interaction equilibrium, where at higher F- concentrations, F- interacts with the receptor through hydrogen bonding and at lower concentrations it induces a chemical reaction.
Environmentally friendly organic synthesis using bismuth compounds: bismuth(III) iodide catalyzed deprotection of acetals in water
Bailey, Aaron D.,Baru, Ashvin R.,Tasche, Kendall K.,Mohan, Ram S.
, p. 691 - 694 (2008)
The chemoselective deprotection of a wide range of acetals and ketals in water is catalyzed by bismuth(III) iodide. Bismuth(III) compounds are remarkably nontoxic and hence are attractive as environmentally friendly catalysts.
Solid phase oxidation of alcohols and benzyl halides to carbonyls using bromate exchange resin
Sikdar, Atul Pd.,Chetri, Ajoy B.,Baishya, Gakul,Das, Pranab J.
, p. 3147 - 3151 (2003)
Aromate exchange resin prepared by a simple elution technique and used for the biphasic oxidation of alcohols and benzyi halides to corresponding carbonyl compounds.
Oxidative deprotection of oximes using pyridinium fluorochromate and hydrogen peroxide
Ganguly,Sukai,De,De
, p. 1607 - 1612 (2001)
A simple convenient procedure of oxidative deoximation has been developed using pyridinium fluorochromate (PFC), in combination with 30% hydrogen peroxide. The method has been found to be effective for a wide range of aliphatic and aromatic oximes, and may be used for selective cleavage of aldoximes in the presence of ketoximes.
Bimetallic Cu-Pd Nanoparticles Supported on Bio-silica as an Efficient Catalyst for Selective Aerobic Oxidation of Benzylic Alcohols
Buxaderas, Eduardo,Graziano-Mayer, Marilyn,Volpe, María Alicia,Radivoy, Gabriel
, p. 1387 - 1393 (2017)
A new bimetallic heterogeneous catalyst consisting of copper and palladium nanoparticles supported on bio-silica is presented. The use of TEMPO as co-catalyst allowed the aerobic oxidation of primary benzylic alcohols into the corresponding aldehydes with excellent selectivity and good activity. The methodology could be applied to the oxidation of allylic and heterobenzylic alcohols. The catalyst is easy to prepare from commercial starting materials and can be recovered and reused without apparent loss of activity.
Supramolecular Catalysis of the oxa-Pictet–Spengler Reaction with an Endohedrally Functionalized Self-Assembled Cage Complex
Harman, W. Hill,Hooley, Richard J.,Ngai, Courtney,Sanchez-Marsetti, Colomba M.
, p. 23505 - 23509 (2020)
An endohedrally functionalized self-assembled Fe4L6 cage complex can catalyze oxa-Pictet—Spengler cyclizations of tryptophols and various aldehyde derivatives, showing strong rate accelerations and size-selectivity. Selective molecular recognition of substrates controls the reactivity, and the cage is capable of binding and activating multiple different species along the multistep reaction pathway. The combination of a functionalized active site, size-selective reactivity, and multistep activation, all from a single host molecule, illustrates the biomimetic nature of the catalysis.
Green and reusable homogeneous oxidative system with ceric ammonium nitrate/[Imim-PEG1000-TEMPO] for efficient aerobic oxidation of alcohols and one-pot synthesis of benzimidazoles from alcohols under ambient conditions
Wang, Zhao-Gang,Xia, Yong-Gen,Jin, Yong,Lu, Ming
, p. 109 - 112 (2015)
An efficient and reusable catalytic system for aerobic oxidation of alcohols and one-pot synthesis of benzimidazoles from alcohols with ceric ammonium nitrate and PEG1000-ionic liquid-immobilized 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) is described. This system shows excellent activity and selectivity, affording the target products with good yields. Moreover, the catalytic system can be recycled and reused without significant loss of catalytic activity after seven runs.
Discovery of indanone derivatives as multi-target-directed ligands against Alzheimer's disease
Huang, Ling,Miao, Hui,Sun, Yang,Meng, Fanchao,Li, Xingshu
, p. 429 - 439 (2014)
A series of indanone derivatives were designed, synthesized, and tested using a variety of assays to assess their potential as anti-Alzheimer's disease (AD) agents. The investigations assessed the activities of the agents for the inhibition of cholinesterases (AChE and BuChE), the inhibition of amyloid beta (Aβ) self-assembly, and the catalysis of the disassembly of preformed Aβ oligomers and measured their antioxidant activities. Our results demonstrate that most of the synthesized compounds demonstrated good inhibitory activity against AChE with IC50 values in the nanomolar range. In particular, compounds 9 (IC50 Combining double low line 14.8 nM) and 14 (IC50 Combining double low line 18.6 nM) exhibited markedly higher inhibitory activities than tacrine and similar activities to donepezil. In addition, 9 and 14 significantly inhibited Aβ aggregation (inhibition rates of 85.5% and 83.8%, respectively), catalysed the disaggregation of Aβ fibrils generated by self-induced Aβ aggregation, and exhibited antioxidant activity. Furthermore, these two compounds can cross the blood-brain barrier (BBB) in vitro. These properties highlight the potential of these new compounds to be developed as multi-functional drugs for the treatment of Alzheimer's disease.
Pyridinium fluorochromate supported on wet alumina: A mild convenient reagent for the facile deprotection of aldoximes
Ganguly, Nemai C.,De, Prithwiraj,Sukai, Arun K.,De, Sripada
, p. 1 - 7 (2002)
A simple mild method of oxidative deoximation based on pyridinium fluorochromate (PFC) on wet alumina support is described. This method is particularly effective for rapid deprotection of aldoximes and aliphatic ketoximes. Sterically hindered ketoximes are resistant to the reagent.
A highly efficient heterogeneous aerobic alcohol oxidation catalyzed by immobilization of bipyridine copper(I) complex in MCM-41
Zhao, Hong,Chen, Qiurong,Wei, Li,Jiang, Yuanyuan,Cai, Mingzhong
, p. 8725 - 8731 (2015)
A heterogeneous copper(I)-catalyzed aerobic oxidation of primary benzylic and allylic alcohols to aldehydes was achieved under air in EtOH at 50°C in the presence of 5 mol % of MCM-41-immobilized bipyridine copper(I) complex [MCM-41-bpy-CuI] and 5 mol % of 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) using aqueous ammonia as base, yielding a variety of aromatic and α,β-unsaturated aldehydes in good to excellent yields. This heterogeneous copper catalyst can be easily recovered by a simple filtration of reaction solution and reused for at least 10 consecutive trials without any decreases in activity. The use of recyclable heterogeneous copper catalyst and green reagents, such as air as oxidant and ethanol as solvent, made the system attractive for environmentally sustainable processes.
Photofragmentation via Single-Electron Transfer: Selective Labilization of C-C Bonds in Amino Alcohols with Several Bonds between Heteroatom Substituents
Ci, Xiaohong,Whitten, David G.
, p. 3459 - 3461 (1989)
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A DFT and experimental study of the spectroscopic and hydrolytic degradation behaviour of some benzylideneanilines
Nelson, Peter N.,Robertson, Tahjna I.
, (2021/10/12)
The spectroscopic and hydrolytic degradation behaviour of some N-benzylideneanilines are investigated experimentally and theoretically via high quality density function theoretical (DFT) modelling techniques. Their absorption and vibrational spectra, accurately predicted by DFT calculations, are highly dependent on the nature of the substituents on the aromatic rings, hence, though some of their spectroscopic features are similar, energetic differences exist due to differences in their electronic structures. Whereas the o-hydroxy aniline derived adducts undergo hydrolysis via two pathways, the most energetically economical of which is initiated by a fast enthalpy driven hydration, over a conservative free energy (ΔG?) barrier of 53 kJ mol?1, prior to the rate limiting entropy controlled lysis step which occurs via a conservative barrier of ca.132 kJ mol?1, all other compounds hydrolyse via a slower two-step pathway, limited by the hydration step. Barriers heights for both pathways are controlled primarily by the structure and hence, stability of the transition states, all of which are cyclic for both pathways.
PhIO-Mediated oxidative dethioacetalization/dethioketalization under water-free conditions
Du, Yunfei,Ouyang, Yaxin,Wang, Xi,Wang, Xiaofan,Yu, Zhenyang,Zhao, Bingyue,Zhao, Kang
, p. 48 - 65 (2021/06/16)
Treatment of thioacetals and thioketals with iodosobenzene in anhydrous DCM conveniently afforded the corresponding carbonyl compounds in high yields under water-free conditions. The mechanistic studies indicate that this dethioacetalization/dethioketalization process does not need water and the oxygen of the carbonyl products comes from the hypervalent iodine reagent.
One-Pot Direct Oxidation of Primary Amines to Carboxylic Acids through Tandem ortho-Naphthoquinone-Catalyzed and TBHP-Promoted Oxidation Sequence
Kim, Hun Young,Oh, Kyungsoo,Si, Tengda
supporting information, p. 18150 - 18155 (2021/12/09)
Biomimetic oxidation of primary amines to carboxylic acids has been developed where the copper-containing amine oxidase (CuAO)-like o-NQ-catalyzed aerobic oxidation was combined with the aldehyde dehydrogenase (ALDH)-like TBHP-mediated imine oxidation protocol. Notably, the current tandem oxidation strategy provides a new mechanistic insight into the imine intermediate and the seemingly simple TBHP-mediated oxidation pathways of imines. The developed metal-free amine oxidation protocol allows the use of molecular oxygen and TBHP, safe forms of oxidant that may appeal to the industrial application.
Trialkylammonium salt degradation: Implications for methylation and cross-coupling
Assante, Michele,Baillie, Sharon E.,Juba, Vanessa,Leach, Andrew G.,McKinney, David,Reid, Marc,Washington, Jack B.,Yan, Chunhui
, p. 6949 - 6963 (2021/06/02)
Trialkylammonium (most notably N,N,N-trimethylanilinium) salts are known to display dual reactivity through both the aryl group and the N-methyl groups. These salts have thus been widely applied in cross-coupling, aryl etherification, fluorine radiolabelling, phase-transfer catalysis, supramolecular recognition, polymer design, and (more recently) methylation. However, their application as electrophilic methylating reagents remains somewhat underexplored, and an understanding of their arylation versus methylation reactivities is lacking. This study presents a mechanistic degradation analysis of N,N,N-trimethylanilinium salts and highlights the implications for synthetic applications of this important class of salts. Kinetic degradation studies, in both solid and solution phases, have delivered insights into the physical and chemical parameters affecting anilinium salt stability. 1H NMR kinetic analysis of salt degradation has evidenced thermal degradation to methyl iodide and the parent aniline, consistent with a closed-shell SN2-centred degradative pathway, and methyl iodide being the key reactive species in applied methylation procedures. Furthermore, the effect of halide and non-nucleophilic counterions on salt degradation has been investigated, along with deuterium isotope and solvent effects. New mechanistic insights have enabled the investigation of the use of trimethylanilinium salts in O-methylation and in improved cross-coupling strategies. Finally, detailed computational studies have helped highlight limitations in the current state-of-the-art of solvation modelling of reaction in which the bulk medium undergoes experimentally observable changes over the reaction timecourse. This journal is
