- The different, but interesting behaviors of benzyl systems in the Willgerodt-Kindler reaction under solvent-free conditions
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On the benzyl system, bearing various functional groups, have been carried out the Willgerodt-Kindler reaction to obtain thiobenzmorpholide (1). The reactions, under solvent-free conditions, were performed in both classical (reflux, room temperature) and
- Aghapoor, Kioumars,Darabi, Hossein Reza,Tabar-Heydar, Kourosh
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- Heterogeneous Ni catalysts for N-alkylation of amines with alcohols
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Nickel nanoparticles loaded onto various supports (Ni/MOx) have been prepared and studied for the N-alkylation of amines with alcohols. Among the catalysts, Ni/θ-Al2O3 prepared by in situ H 2-reduction of NiO/θ-Al2O3 shows the highest activity, and it acts as reusable heterogeneous catalyst for the alkylation of anilines and aliphatic amines with various alcohols (benzyl and aliphatic alcohols) under additive free conditions. Primary amines are converted into secondary amines and secondary amines into tertiary amines. For the reaction of aniline with an aliphatic alcohol the catalyst shows higher turnover number (TON) than precious metal-based state-of-the-art catalysts. Mechanistic studies suggest that the reaction proceeds through a hydrogen-borrowing mechanism. The activity of Ni catalysts depends on the nature of support materials; acid-base bifunctional supports give higher activity than basic or acidic supports, indicating that acid-base sites on supports are necessary. The presence of basic (pyridine) or acidic (acetic acid) additive in the solution decreased the activity of Ni/θ-Al2O3, which suggests the cooperation of the acid-base site of θ-Al2O3. For a series of Ni/θ-Al2O3 catalysts with different particle size, the turnover frequency (TOF) per surface Ni increases with decreasing Ni mean particle size, indicating that low-coordinated Ni species and/or metal-support interface are active sites. From these results, we propose that the active site for this reaction is metal-support interface, where low-coordinated Ni0 atoms are adjacent to the acid-base sites of alumina.
- Shimizu, Ken-Ichi,Imaiida, Naomichi,Kon, Kenichi,Hakim Siddiki,Satsuma, Atsushi
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- On the non-classical course of Polonowski reactions of N-benzylmorpholine- N-oxide (NBnMO)
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The Polonowski reaction of NBnMO (4) afforded tropone (10) and the novel isoindole 11 besides the expected products benzaldehyde and acetmorpholide, in a temperature-dependent ratio. The reaction proceeded via two primary carbenium-iminium ion intermediates, an exo-centered species 5 which underwent a benzylium-tropylium type rearrangement, and a ring-centered species 6, which reacted further to isoindole 11 by intramolecular electrophilic substitution. The experimental findings were in good agreement with DFT computational data.
- Rosenau, Thomas,Schmid, Peter,Kosma, Paul
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- Bis(alkyl) scandium and yttrium complexes coordinated by an amidopyridinate ligand: Synthesis, characterization and catalytic performance in isoprene polymerization, hydroelementation and carbon dioxide hydrosilylation
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New neutral bis(alkyl) Sc and Y complexes [N,Npy,N-]Ln(CH2SiMe3)2(THF)n [n = 0, Ln = Sc (1Sc), Y (1Y); n = 1, Ln = Y (1YTHF)] stabilized by a tridentate monoanionic amidopyridinate ligand were straightforwardly prepared by alkane elimination, upon mixing ligand [N,Npy,N-]H and metal precursor Ln(CH2SiMe3)3(THF)2 in toluene at 0 °C. Depending on the work-up conditions, yttrium bis(alkyl)s were isolated as either a pentacoordinate Lewis base free complex [N,Npy,N-]Y(CH2SiMe3)2 (1Y) or as a hexacoordinate THF adduct [N,Npy,N-]Y(CH2SiMe3)2THF (1YTHF). For the smaller Sc ion the only solvent-free complex [N,Npy,N-]Y(CH2SiMe3)2 (1Sc) was isolated as a pentacoordinate species irrespective of the reaction/work-up/crystallization conditions applied. Complexes 1Ln (Ln = Y, Sc) and 1YTHF were scrutinized as pre-catalysts in ternary catalytic systems Ln/borate/AliBu3 (borate = [HNMe2Ph][B(C6F5)4] or [Ph3C][B(C6F5)4]), applied to isoprene (IP) polymerization, providing moderate activity albeit high selectivity with predominant formation of 1,4-cis polyisoprene (up to 99%). The same complexes proved to be effcient catalysts also for the intermolecular hydrolelementation of styrene with various EH sustrates (pyrrolidine, morpholine, Ph2PH, PhPH2, PhSH) affording linear anti-Markovnikov addition products exclusively. After a preliminary activation by B(C6F5)3, selected bis(alkyl) complexes from this series have been finally used as valuable pre-catalysts for the CO2 hydrosylilation to CH4 in the presence of organosilanes as reducing agents (PhMe2SiH, PhSiH3, Et2MeSiH).
- Gurina,Kissel,Lyubov,Luconi,Rossin,Tuci,Cherkasov,Lyssenko,Shavyrin,Ob'Edkov,Giambastiani,Trifonov
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- Cesium carbonate-catalyzed reduction of amides with hydrosilanes
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Cesium carbonate has been found to be an effective catalyst for the reduction of tertiary carboxamides with the simple, commercially available PhSiH3 under solvent-free conditions. The catalytic system can effectively reduce a range of amides under relatively mild conditions (from room temperature to 80 C) to yield the corresponding amines in good to excellent yields (71-100%) and thus has the potential for practical applications.
- Xie, Weilong,Zhao, Mengdi,Cui, Chunming
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- Fast continuous alcohol amination employing a hydrogen borrowing protocol
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A continuous flow method for the direct conversion of alcohols to amines via a hydrogen borrowing approach is reported. The method utilises a low loading (0.5%) of a commercial catalyst system ([Ru(p-cymene)Cl2]2 and DPEPhos), reagent grade solvent and is selective for primary alcohols. Successful methylation of amines using methanol and the direct dimethylamination of alcohols using commercial dimethylamine solution are reported. The synthesis of two pharmaceutical agents Piribedil (5) and Buspirone (25) were accomplished in good yields employing these new methods.
- Labes, Ricardo,Mateos, Carlos,Battilocchio, Claudio,Chen, Yiding,Dingwall, Paul,Cumming, Graham R.,Rincón, Juan A.,Nieves-Remacha, Maria José,Ley, Steven V.
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- Reductive amination of carbonyl compounds over silica supported palladium exchanged molybdophosphoric acid catalysts
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Palladium exchanged molybdophosphoric acid supported on silica is reported as a highly effective catalyst for direct reductive amination of carbonyl compounds. The catalysts are characterized by X-ray diffraction and FT-infrared spectroscopy. The characterization results support the existence of Keggin ion of heteropoly molybdate on silica. The catalyst is facile, water tolerable and environmentally benign for reductive amination. A variety of secondary and tertiary amines can be synthesized over this catalyst in excellent yields under mild reaction conditions. A plausible reaction mechanism is proposed for the reductive amination of carbonyl compounds over this catalyst.
- Srivani,Prasad, P. S. Sai,Lingaiah
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- Palladium on activated carbon catalyzed reductive amination of aldehydes and ketones by triethylsilane
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Various aldehydes and ketones were efficiently transformed into the corresponding amines using amine derivatives in the presence of triethylsilane and a catalytic amount of palladium on activated carbon in ethanol. The proposed method provides a one-pot synthesis of various amines in excellent yields after short reaction times.
- Mirza-Aghayan, Maryam,Tavana, Mahdieh Molaee,Rahimifard, Mahshid,Boukherroub, Rabah
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- One-pot reductive amination of aldehydes and ketones using N-methyl-piperidine zinc borohydride (ZBNMPP) as a new reducing agent
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A one-pot reductive amination of aldehydes and ketones using N-methyl piperidine zinc borohydride as a new and stable reducing agent is described. The reaction has been carried out in methanol at room temperature under neutral conditions. Georg Thieme Verlag Stuttgart.
- Alinezhad, Heshmatollah,Tajbakhsh, Mahmoud,Zamani, Reza
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- Copper-catalyzed oxygen atom transfer of N-oxides leading to a facile deoxygenation procedure applicable to both heterocyclic and amine N-oxides
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Deoxygenation of various types of N-oxides including both heterocyclic and alkyl(aryl)amine derivatives has successfully been developed by the copper-catalyzed oxygen atom transfer using diazo compounds as the oxygen acceptor. The reaction proceeds smoothly over a broad range of substrates with excellent functional group tolerance under mild conditions. This journal is
- Jeong, Jisu,Lee, Donggun,Chang, Sukbok
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- One-pot Reductive Amination of Carbonyl Compounds with NaBH4-B(OSO3H)3/SiO2 in Acetonitrile and in Solvent-free Condition
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An efficient one-pot procedure for the direct reductive amination of aldehyde and ketones was achieved in the presence of sodium borohydride by using B(OSO3H)3/SiO2(SBSA) as the reusable solid catalyst in acetonitrile and solvent-free conditions. Both aromatic and aliphatic aldehyde reacted well to give the corresponding amines in excellent yields. All the products are known and well-characterized. The catalyst is recoverable and could be easily recycled by filtration and reused several times without any significant loss of its activity. SBSA acts as a dual Br?nsted/Lewis acid that is an air-stable and cost-effective solid acid. [Figure not available: see fulltext.]
- Hamadi, Hosein,Javadi, Samira
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- N-Alkylation and N,C-Dialkylation of Amines with Alcohols in the Presence of Ruthenium Catalysts with Chelating N-Heterocyclic Carbene Ligands
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A series of new benzimidazolium salts and ruthenium(II) complexes containing chelating N-heterocyclic carbenes (NHCs) functionalized with a benzylic group and an acetal group were prepared. All of the synthesized compounds were characterized by elemental analysis and NMR spectroscopy, and the molecular structures of 2c and 2d were determined by X-ray crystallography. All of the complexes were tested in the alkylation of cyclic amine derivatives with alcohols and showed excellent activity in this reaction. Cyclic amines were alkylated with primary and heteroaromatic alcohols. The Ru-NHC complexes also catalyzed N,C3-dialkylation of cyclic amines. (Chemical Equation Presented).
- ?ahin, Zeynel,Gürbüz, Nevin,?zdemir, Ismail,?ahin, Onur,Büyükgüng?r, Orhan,Achard, Mathieu,Bruneau, Christian
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- A highly reactive and magnetic recyclable catalyst based on silver nanoparticles supported on ferrite for N-monoalkylation of amines with alcohols
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Fe3O4@SiO2-Ag catalyst was found to be highly active and selective in the N-alkylation of amines with a variety of aromatic and linear alcohols. The heterogeneous nature of the Fe3O4@SiO2-Ag catalyst allows easy recovery and regeneration by applying an external magnet for six subsequent reaction cycles. The prepared catalyst was characterized using electron microscopy techniques, X-ray diffraction, vibrating sample magnetometry and atomic absorption spectroscopy.
- Bayat, Ahmad,Shakourian-Fard, Mehdi,Nouri, Peyman,Hashemi, Mohammad Mahmoodi
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- Ruthenium-catalysed synthesis of tertiary amines from alcohols
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Secondary amines have been converted into tertiary amines by reactions with primary alcohols. A catalytic system of [Ru(cymene)Cl2]2 with dppf has been shown to be effective for this transformation for a range of primary alcohols and secondary amines. The methodology has been applied to the one pot synthesis of Piribedil and other piperazine and morpholine-containing products.
- Hamid, M. Haniti S.A.,Williams, Jonathan M.J.
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- Reductive amination of aldehydes and ketones in a heterogeneous system in THF and under solvent-free conditions using sodium borohydride-silica phosphoric acid
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A chemoselective, fast, efficient, and high yielding method for the preparation of amines by reductive amination of aldehydes and ketones using sodium borohydride in the presence of silica phosphoric acid in THF and under solvent-free conditions at room temperature is described.
- Alinezhad, Heshmatollah,Tajbakhsh, Mahmoud,Ahangar, Roja Enayati
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- Reductive amination of aldehydes and ketones under heterogeneous and solvent-free conditions using sodium-borohydride and silica-gel-supported sulfuric acid
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A regioselective and convenient procedure for preparation of amines by reductive amination of aldehydes and ketones using sodium borohydride in the presence of sulfuric acid supported on silica gel as an active, inexpensive, and recoverable catalyst under heterogeneous and solvent-free conditions at room temperature is described.
- Alinezhad, Heshmatollah,Tajbakhsh, Mahmood,Zare, Mahboobeh
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- Use of acetate as a leaving group in palladium-catalyzed nucleophilic substitution of benzylic esters
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The palladium complex prepared in situ from [Pd(η3-C3H5)(cod)]BF4 and bidentate phosphine DPPF was a good catalyst for the nucleophilic substitution of benzyl acetate. Significant acceleration of the palladium-catalyzed substitution was observed when an alcohol was employed as a reaction solvent. The palladium catalyst was effective for the benzylation of various stabilized carbanions, amines, and benzenesulfinate with benzylic acetates.
- Yokogi, Masashi,Kuwano, Ryoichi
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- Synthesis of organophosphorus compounds based on the reaction of elemental phosphorus with proton-donor reagents
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Reaction of elemental (white) phosphorus with proton-donor reagents has been studied. The following organophosphorus compounds containing P-O and P-S bonds have been synthesized: metal hypophosphites and phosphites, and ammonium salts of O,O′-diesters of dithiophosphoric, S,S′-diphenyldithiophosphoric, S,S′-dialkyltetrathiophosphoric, O,O′-alkylidenedithiophosphoric acids, and octathiotetraphosphetane. The reaction products include highly efficient inhibitors of steel corrosion with carbonic acid and hydrogen sulfide as well as compounds showing fungicide, anticancer, and anti-inflammatory activity.
- Badeeva,Platova,Batyeva
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- Reductive amination of aldehydes and ketones using sodium borohydride in the presence of silica chloride under solvent-free conditions
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A simple and convenient procedure for the preparation of amines from aldehydes and ketones with sodium borohydride activated by silica chloride as a catalyst under solvent-free conditions is described. A variety of aliphatic and aromatic aldehydes, ketones and amines when mixed with NaBH4/silica chloride at room temperature, afforded excellent yield of the corresponding amines.
- Alinezhad, Heshmatollah,Tajbakhsh, Mahmood,Hamidi, Neda
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- Direct reductive amination of carbonyl compounds using bis(triphenylphosphine) copper(I) tetrahydroborate
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A direct reductive amination protocol for aldehydes/ketones using bis(triphenylphosphine) copper(I) tetrahydroborate as a novel reducing agent in the presence of sulfamic acid has been developed. The reagent chemoselectively reduces the imine moiety and does not affect other reducible functionalities such as chloro, nitro, cyano and methoxy.
- Bhanushali, Mayur J.,Nandurkar, Nitin S.,Bhor, Malhari D.,Bhanage, Bhalchandra M.
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- Reductive amination using a combination of CaH2 and noble metal
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Amines were prepared by a reductive amination reaction in the presence of calcium hydride and Pt/C. The in situ formation of water seems to be the key to activate CaH2 to reduce the intermediate imine.
- Guyon, Carole,Da Silva, Eric,Lafon, Romain,Mtay, Estelle,Lemaire, Marc
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- One-pot reductive amination of carbonyl compounds using sodium borohydride-cellulose sulfuric acid
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A fast, efficient, and high yielding method for the preparation of amines by reductive amination of aldehydes and ketones using sodium borohydride in the presence of cellulose sulfuric acid in EtOH and under solvent-free conditions at room temperature is described.
- Alinezhad, Heshmatollah,Tollabian, Zakieh
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- Copper-Catalyzed Electrophilic Amination of Diorganozinc Reagents
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The copper-catalyzed electrophilic amination of diorganozinc reagents employing O-acyl N,N-dialkyl hydroxylamine derivatives as aminating agents is described. This reaction offers a general method for the preparation of tertiary amines in high yields and is noteworthy for its convenience both in terms of reaction conditions employed (room temperature, ≤1 h) and ease of product isolation (acid/base extractive workup). Copyright
- Berman, Ashley M.,Johnson, Jeffrey S.
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- Direct reductive amination of carbonyl compounds using sodium borohydride-silica chloride
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A simple and convenient procedure for reductive amination of aldehydes and ketones using sodium borohydride in the presence of silica chloride as an active, inexpensive, recoverable, and recyclable catalyst is described. The reactions were carried out with equimolar amounts of amine and carbonyl compound using silica chloride-sodium borohydride in THF at room temperature TUeBITAK.
- Alinezhad, Heshmatollah,Tajbakhsh, Mahmood,Hamidi, Neda
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- Samarium Diiodide Mediated Alkylation of Saturated Heterocycles alpha to Nitrogen
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A method for α-alkylation of saturated 5-, 6-, 7- and 8-membered aza-heterocycles is described.The auxiliary is an o-iodobenzyl group attached at the nitrogen.A radical introduced in the o-position is transferred to the amine α-position which subsequently leads to an addition reaction with pentan-3-one.
- Booth, Susan E.,Benneche, Tore,Undheim, Kjell
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- Base-promoted N-alkylation using formamides as the N-sources in neat water
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An efficient catalyst-free, alternative method for the C-N bond formation reaction of alkyl electrophiles using formamides as the N-sources was achieved under mild conditions. The reaction possesses the advantages of a broad range of substrates scope and wide functional group tolerance. It should also be noted that this process was performed using the environmentally benign water as the sole solvent, and high yield can also be achieved in ten-gram scale.
- Chen, Wen-Xin,Zhang, Cai-Yun,Shao, Li-Xiong
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- Design and synthesis of macrocyclic ligands for specific interaction with crystalline ettringite and demonstration of a viable mechanism for the setting of cement
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Cementitious materials are among those most widely used by mankind while being among the least well understood. The detailed physicochemical processes involved in the hydration and setting of cement slurries are very complex, and a clearly defined quantitative account is still lacking: indeed, even the composition of the cement powder itself is not known exactly. Still less has there been any understanding of the mechanism by which numerous known retarders of the cement setting process act. In this article, we detail the synthesis of novel macrocyclic organophosphonate retarders 1a and 2a which were developed by rational methods. Attempts to synthesise these compounds as phosphonate ester derivatives were universally unsuccessful, however direct modification of the parent hexaaza-(3) and trioxatriaza-18-crown-6 (5) derivatives was successful, to provide the phosphonic acids 1b and 2b respectively. Subsequent testing of these compounds showed their ability to inhibit the growth of crystalline ettringite and delay the setting of cement. These results support the hypothesis that the formation of crystalline ettringite is the rate determining step in the setting of cement.
- Griffin, Jonathan L. W.,Coveney, Peter V.,Whiting, Andrew,Davey, Roger
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- Overcoming solid handling issues in continuous flow substitution reactions through ionic liquid formation
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Substitutions such as acylations, arylations, and alkylations are some of the most commonly run reactions for building complex molecules. However, the requirement of a stoichiometric base to scavange acid by-products creates significant challenges when operating in continuous flow due to solid handling issues associated with precipitating base·HX salts. We present a general and simple strategy to overcome these solid handling issues through the use of acid scavenging organic bases that generate low- to moderate-melting ionic liquids upon protonation. The application of these bases towards the most commonly run substitutions are demonstrated, enabling reactions to be run in flow without requiring additional equipment, specific solvents, or dilute reaction conditions to prevent clogging.
- Kashani, Saeed,Sullivan, Ryan J.,Andersen, Mads,Newman, Stephen G.
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- Nickel?Copper bimetallic mesoporous nanoparticles: As an efficient heterogeneous catalyst for N-alkylation of amines with alcohols
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A bimetallic catalyst (Ni/Cu-MCM-41) is prepared via co-condensation method. The latter is characterized by Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), diffuse reflectance spectroscopy (DRS), and nitrogen adsorption–desorption analysis. Catalytic performance of Ni/Cu-MCM-41 is probed in N-alkylation of amines with alcohols through a hydrogen autotransfer process. Noteworthy, this catalytic system appears very efficient for synthesis of a range of secondary and tertiary amines in good to excellent isolated yields. Moreover, the catalyst is successfully recovered and reused four times without notable decrease in its activity.
- Nasresfahani, Zahra,Kassaee, Mohamad Z.
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- A practical catalytic reductive amination of carboxylic acids
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We report reductive alkylation reactions of amines using carboxylic acids as nominal electrophiles. The two-step reaction exploits the dual reactivity of phenylsilane and involves a silane-mediated amidation followed by a Zn(OAc)2-catalyzed amide reduction. The reaction is applicable to a wide range of amines and carboxylic acids and has been demonstrated on a large scale (305 mmol of amine). The rate differential between the reduction of tertiary and secondary amide intermediates is exemplified in a convergent synthesis of the antiretroviral medicine maraviroc. Mechanistic studies demonstrate that a residual 0.5 equivalents of carboxylic acid from the amidation step is responsible for the generation of silane reductants with augmented reactivity, which allow secondary amides, previously unreactive in zinc/phenylsilane systems, to be reduced.
- Andrews, Keith G.,Denton, Ross M.,Hirst, David J.,Stoll, Emma L.,Tongue, Thomas,Valette, Damien
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- Reductive amination of aldehydes and ketones to their corresponding amines with NaBH4 in micellar media
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A variety of aliphatic and aromatic aldehydes and ketones were efficiently reduced to their corresponding amines when treated with primary and secondary amines and NaBH4 in micellar media at room temperature under neutral conditions. Springer-Verlag 2005.
- Alinezhad, Heshmatollah,Tajbakhsh, Mahmood,Salehian, Fatemeh
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- Synthesis of substituted amines and isoindolinones: Catalytic reductive amination using abundantly available AlCl3/PMHS
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AlCl3 has been employed for highly chemoselective reductive amination of carbonyl compounds in ethanol using polymethylhydrosiloxane as an inexpensive, stable and safe reducing agent without an inert atmosphere. A large range of functional groups such as nitro, carboxylic acid, acetyl, nitrile, halogen, methoxy, alkene and heterocycles were well tolerated. AlCl3 also catalyzed tandem amination-amidation of 2-carboxybenzaldehyde with different amines to afford N-substituted isoindolinones. The catalyst can be recycled at least three times without any significant effect on activity and selectivity.
- Kumar, Vishal,Sharma, Sushila,Sharma, Upendra,Singh, Bikram,Kumar, Neeraj
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- Highly efficient amination in neat water of benzyl chlorides with dialkylformamides catalysed by N-heterocyclic carbene-palladium(II)-1- methylimidazole complex
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Dialkylformamides are excellent N-sources in the amination of benzyl chlorides when catalysed by a NHC-Pd(II)-Im complex. In the presence of NaOH and the catalyst, variously substituted benzyl chlorides and five different dialkylformamides reacted smoothly to afford the corresponding N,N-dialkyl-benzylamines in good to almost quantitative yields in eco-friendly solvent water at 50 °C within 3 h.
- Chen, Wen-Xin,Zhang, Cai-Yun,Lu, Jian-Mei
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- Synthesis and applications of Fe3O4- diisopropylaminoacetamide as a versatile and reusable magnetic nanoparticle supported N,N-diisopropylethylamine equivalent
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A magnetic nanoparticle supported N,N-diisopropylaminoacetamide (Fe 3O4-DIPA) was developed for application as a magnetic recoverable, and reusable N,N-diisopropylethylamine equivalent. The Fe 3O4 nanoparticles were coated with a silica layer using the sol-gel method, followed by surface modification with 3- aminopropyltriethoxysilane. Subsequent acylation with chloroacetyl chloride and chlorine displacement with diisopropylamine afforded Fe3O 4-DIPA in 90% yield with a loading of 0.96 mmol/g. The applicability of Fe3O4-DIPA was demonstrated in the synthesis of amine derivatives cv sulfonation, acylation, and N-alkylation reactions. The desired products were obtained in excellent yields and purities after scavenging the residual starting amines by treatment with silica-supported dichlorotriazine. Fe3O4-DIPA was readily recovered by separation using a magnet and could be reused several times without significant loss of reactivity.
- Rattanaburi, Parintip,Khumraksa, Bannarak,Pattarawarapan, Mookda
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- Reductive amination of carbonyl compounds using NaBH4 in a Br?nsted acidic ionic liquid
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Reductive amination of carbonyl compounds using sodium borohydride is conducted in the Br?nsted acidic ionic liquid, 1-methyl imidazolium tetrafluoroborate ([HMIm][BF4]). The ionic liquid plays the dual role of solvent as well as catalyst for efficient conversion of aldehydes and ketones to amines in excellent yields without the formation of side products.
- Reddy, P. Srinivasa,Kanjilal, Sanjit,Sunitha,Prasad, Rachapudi B.N.
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- Benzimidazolin-2-ylidene N-heterocyclic carbene complexes of ruthenium as a simple catalyst for the N-alkylation of amines using alcohols and diols
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Simple air and moisture stable ruthenium complexes 1-3 and 3a were synthesized from readily available benzannulated N-heterocyclic carbene ligands (bimy = benzimidazolin-2-ylidene). These complexes were found to be efficient catalysts for the alkylation of amines using alcohols as alkylating agents. Catalysts 1, 2 and 3a gave excellent yields of up to 99% for the alkylation of various amines using benzylic and aliphatic alcohols at 130 °C for 18 h under solventless conditions. Catalyst 3a bearing both phosphine and carbene ligands gave excellent yields of up to 98% for the synthesis of heterocyclic amines by double alkylation of primary amines using linear diols. The practical utility of these catalysts was demonstrated for the synthesis of pharmaceutically important amines in a more environmentally benign way under solventless conditions.
- Shan, Siah Pei,Xiaoke, Xie,Gnanaprakasam, Boopathy,Dang, Tuan Thanh,Ramalingam, Balamurugan,Huynh, Han Vinh,Seayad, Abdul Majeed
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- A Bis(silylene)-Substituted ortho-Carborane as a Superior Ligand in the Nickel-Catalyzed Amination of Arenes
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The synthesis and structure of the first 1,2-bis(NHSi)-substituted ortho-carborane [(LSi:)C]2B10H10(termed SiCCSi) is reported (NHSi=N-heterocyclic silylene; L=PhC(NtBu)2). Its suitability to serve as a reliable bis(silylene) chelating ligand for transition metals is demonstrated by the formation of [SiCCSi]NiBr2and [SiCCSi]Ni(CO)2complexes. The CO stretching vibration modes of the latter indicate that the SiIIatoms in the SiCCSi ligand are even stronger σ donors than the PIIIatoms in phosphines and CIIatoms in N-heterocyclic carbene (NHC) ligands. Moreover, the strong donor character of the [SiCCSi] ligand enables [SiCCSi]NiBr2to act as an outstanding precatalyst (0.5 mol % loading) in the catalytic aminations of arenes, surpassing the activity of previously known molecular Ni-based precatalysts (1–10 mol %).
- Zhou, Yu-Peng,Raoufmoghaddam, Saeed,Szilvási, Tibor,Driess, Matthias
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- SiO2-Cu2O: An efficient and recyclable heterogeneous catalyst for N-benzylation of primary and secondary amines
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A mild, effective, and selective procedure is reported for the mono N-benzylation and N,N-dibenzylation of primary amines as well as mono N-benzylation of secondary amines using silica-supported copper(I) oxide in water. The silica-supported Cu2O was generated in situ by the reaction of Fehling solution and glucose at 100 C onto activated silica. The catalyst was filtered, washed with water, and oven-dried, and was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and atomic absorption spectroscopy. The prepared Cu2O-SiO2 was found to be thermally stable up to 325 C. The copper was uniformly distributed onto the surface of the silica, and the mean particle diameter was 7 nm. The catalyst served as a selective heterogenous catalyst for the N-benzylation of primary and secondary amines. The catalyst is recyclable and was used effectively upto fifth run without a significant loss of catalytic activity. Various reaction solvents including water, acetonitrile, and toluene were screened for N-benzylation of amines, and the success of the aqueous system highlights the low environmental impact of the procedure.
- Gupta, Manjulla,Paul, Satya,Gupta, Rajive
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- Reductive amination of aldehydes and ketones to their corresponding amines with N-methylpyrrolidine zinc borohydride
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A simple and convenient procedure for reductive amination of aldehydes and ketones using N-methylpyrrolidine zinc borohydride (ZBHNMP) as a reducing agent is described. The reactions are carried out with 1 equiv of amine and 1 equiv of aldehyde or ketone using 1 equiv of ZBHNMP in methanol under neutral conditions at room temperature.
- Alinezhad, Heshmat,Tajbakhsh, Mahmood,Salehian, Fatemeh,Fazli, Kazem
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- Mechanochemical Nucleophilic Substitution of Alcohols via Isouronium Intermediates**
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An expansion of the solvent-free synthetic toolbox is essential for advances in the sustainable chemical industry. Mechanochemical reactions offer a superior safety profile and reduced amount of waste compared to conventional solvent-based synthesis. Here
- Dalidovich, Tatsiana,Nallaparaju, Jagadeesh Varma,Shalima, Tatsiana,Aav, Riina,Kananovich, Dzmitry G.
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- Deoxygenative hydroboration of primary, secondary, and tertiary amides: Catalyst-free synthesis of various substituted amines
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Transformation of relatively less reactive functional groups under catalyst-free conditions is an interesting aspect and requires a typical protocol. Herein, we report the synthesis of various primary, secondary, and tertiary amines through hydroboration of amides using pinacolborane under catalyst-free and solvent-free conditions. The deoxygenative hydroboration of primary and secondary amides proceeded with excellent conversions. The comparatively less reactive tertiary amides were also converted to the corresponding N,N-diamines in moderate yields under catalyst-free conditions, although alcohols were obtained as a minor product.
- An, Duk Keun,Jaladi, Ashok Kumar,Kim, Hyun Tae,Yi, Jaeeun
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- Two-Step Protocol for Iodotrimethylsilane-Mediated Deoxy-Functionalization of Alcohols
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We have developed a two-step protocol for iodotrimethylsilane-mediated deoxy-functionalization of primary and secondary alcohols to afford products containing a C?N, C?S, or C?O bond. In the first step the alcohol undergoes iodination with iodotrimethylsilane, and in the second, the iodine atom is replaced by a N, S, or O nucleophile. Compared with traditional Mitsunobu reaction, non-acidic pre-nucleophiles can be used, and the reaction proceeds with retention of configuration. This operationally simple, highly efficient protocol can be used for some natural products and small-molecule drugs containing hydroxy-group.
- Chen, Yuming,He, Ru,Song, Hongjian,Yu, Guoqing,Li, Chenglin,Liu, Yuxiu,Wang, Qingmin
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supporting information
p. 1179 - 1183
(2021/02/01)
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- Pd(II)-Mediated C?H Activation for Cysteine Bioconjugation
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Selective bioconjugation remains a significant challenge for the synthetic chemist due to the stringent reaction conditions required by biomolecules coupled with their high degree of functionality. The current trailblazer of transition-metal mediated bioconjugation chemistry involves the use of Pd(II) complexes prepared via an oxidative addition process. Herein, the preparation of Pd(II) complexes for cysteine bioconjugation via a facile C?H activation process is reported. These complexes show bioconjugation efficiency competitive with what is seen in the current literature, with a user-friendly synthesis, common Pd(II) sources, and a more cost-effective ligand. Furthermore, these complexes need not be isolated, and still achieve high conversion efficiency and selectivity of a model peptide. These complexes also demonstrate the ability to selectively arylate a single surface cysteine residue on a model protein substrate, further demonstrating their utility.
- Frost, Christopher G.,Kociok-K?hn, Gabriele,Lubben, Anneke T.,Reeksting, Shaun B.,Tilden, James A. R.
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supporting information
(2022/01/19)
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- N?N Bond Formation Using an Iodonitrene as an Umpolung of Ammonia: Straightforward and Chemoselective Synthesis of Hydrazinium Salts
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The formation of hydrazinium salts by N?N bond formation has typically involved the use of hazardous and difficult to handle reagents. Here, mild and operationally simple conditions for the synthesis of hydrazinium salts are reported. Electrophilic nitrogen transfer to the nitrogen atom of tertiary amines is achieved using iodosylbenzene as oxidant and ammonium carbamate as the N-source. The resulting process is highly chemoselective and tolerant to other functional groups. A wide scope is reported, including examples with bioactive molecules. Insights on the structure of hydrazinium salts were provided by X-ray analysis. (Figure presented.).
- Tota, Arianna,Colella, Marco,Carlucci, Claudia,Aramini, Andrea,Clarkson, Guy,Degennaro, Leonardo,Bull, James A.,Luisi, Renzo
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supporting information
p. 194 - 199
(2020/10/28)
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- Hydrosilylative reduction of primary amides to primary amines catalyzed by a terminal [Ni-OH] complex
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A terminal [Ni-OH] complex1, supported by triflamide-functionalized NHC ligands, catalyzes the hydrosilylative reduction of a range of primary amides into primary amines in good to excellent yields under base-free conditions with key functional group tolerance. Catalyst1is also effective for the reduction of a variety of tertiary and secondary amides. In contrast to literature reports, the reactivity of1towards amide reduction follows an inverse trend,i.e., 1° amide > 3° amide > 2° amide. The reaction does not follow a usual dehydration pathway.
- Bera, Jitendra K.,Pandey, Pragati
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supporting information
p. 9204 - 9207
(2021/09/20)
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- BF3·Et2O as a metal-free catalyst for direct reductive amination of aldehydes with amines using formic acid as a reductant
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A versatile metal- and base-free direct reductive amination of aldehydes with amines using formic acid as a reductant under the catalysis of inexpensive BF3·Et2O has been developed. A wide range of primary and secondary amines and diversely substituted aldehydes are compatible with this transformation, allowing facile access to various secondary and tertiary amines in high yields with wide functional group tolerance. Moreover, the method is convenient for the late-stage functionalization of bioactive compounds and preparation of commercialized drug molecules and biologically relevant N-heterocycles. The procedure has the advantages of simple operation and workup and easy scale-up, and does not require dry conditions, an inert atmosphere or a water scavenger. Mechanistic studies reveal the involvement of imine activation by BF3and hydride transfer from formic acid.
- Fan, Qing-Hua,Liu, Xintong,Luo, Zhenli,Pan, Yixiao,Xu, Lijin,Yang, Ji,Yao, Zhen,Zhang, Xin
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supporting information
p. 5205 - 5211
(2021/07/29)
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- A convenient way for alkylation of amines using xanthate esters
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N-alkylation of amines by the reaction with xanthate esters in the presence of acetic acid catalyst in ethanol is reported. Short reaction time, high yield, general applicability and environmentally benign nature are the noteworthy features of our protocol. The probable mechanism for the formation N-alkylation of amines is proposed.
- Sukrutha, Kodipura P.,Swaroop, Toreshettahally R.,Preetham, Ramesh,Lokanath, Neratur K.,Rangappa, Kanchugarakoppal S.,Sadashiva, Maralinganadoddi P.
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p. 2316 - 2323
(2021/06/14)
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- Transition-Metal-Free, General Construction of Thioamides from Chlorohydrocarbon, Amide and Elemental Sulfur
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A general method for one-pot synthesis of thioamides is developed through a three-component reaction involving chlorohydrocarbon, amide and elemental sulfur. Such a strategy does not only avoid residual transition metal in the product but also prevent the generation of C?N coupling by-product. The latter is prone to be generated when alkane halide and amine are present. With the protocol proposed in this work, both alkyl and aryl thioamides can be obtained in moderate to excellent yields with a high tolerance of various functional groups. External oxidants are not required in the reaction. In addition, the reaction mechanisms are addressed using a combination of controlling experiments and quantum chemical calculations.
- Chen, Xinzhi,Ge, Xin,Jin, Hao,Qian, Chao,Zhou, Shaodong
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supporting information
p. 3403 - 3406
(2021/06/25)
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- Sulfated polyborate: A dual catalyst for the reductive amination of aldehydes and ketones by NaBH4
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An efficient, quick, and environment-friendly one-pot reductive amination of aldehydes or ketones was developed. In ethanol at 70 °C, a imination catalyzed by sulfated polyborate and further reduced by sodium borohydride yields various amines. The present method has many significant benefits, including a shorter reaction time, excellent yields, and a hassle-free, straightforward experimental process. The reaction has a wide range of applications due to its flexibility, including secondary amine for reductive amination.
- Ganwir, Prerna,Chaturbhuj, Ganesh
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supporting information
(2021/05/19)
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- Direct: N -alkylation of sulfur-containing amines
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An efficient ruthenium-catalyzed method has been developed for the direct N-alkylation of sulfur-containing amines with alcohols, for the first time, by a step-economical and environmentally friendly hydrogen borrowing strategy. The present methodology features base-free conditions and broad substrate scope, with water being the only by-product. Moreover, this protocol has been applied to the synthesis of the pharmaceutical drug Quetiapine.
- Li, Chen,Ge, Min-Tong,Bai, Liang,Xia, Ai-Bao,Xu, Dan-Qian,Xu, Zhen-Yuan
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supporting information
p. 4478 - 4482
(2021/05/31)
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- Homoleptic Bis(trimethylsilyl)amides of Yttrium Complexes Catalyzed Hydroboration Reduction of Amides to Amines
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Homoleptic lanthanide complex Y[N(TMS)2]3 is an efficient homogeneous catalyst for the hydroboration reduction of secondary amides and tertiary amides to corresponding amines. A series of amides containing different functional groups such as cyano, nitro, and vinyl groups were found to be well-tolerated. This transformation has also been nicely applied to the synthesis of indoles and piribedil. Detailed isotopic labeling experiments, control experiments, and kinetic studies provided cumulative evidence to elucidate the reaction mechanism.
- Ye, Pengqing,Shao, Yinlin,Ye, Xuanzeng,Zhang, Fangjun,Li, Renhao,Sun, Jiani,Xu, Beihang,Chen, Jiuxi
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supporting information
p. 1306 - 1310
(2020/02/22)
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- Method for synthesizing tertiary amine derivative by catalyzing hydroboration reaction of tertiary amide by rare earth
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The invention discloses a method for synthesizing a tertiary amine derivative by catalyzing a hydroboration reaction of tertiary amide by rare earth. Under the protection of nitrogen, in a rare earthcatalysis system, the tertiary amine derivative is prepared through a hydrogen transfer reduction reaction catalyzed by rare earth with tertiary amide and pinacol borane as raw materials. The method has the advantages and effects that a novel synthesis process is utilized, and the tertiary amine derivative prepared by using the method disclosed by the invention is high in quality and stable in process; the raw materials are widely sourced or easy to prepare and store, and the reaction yield is high; and in addition, a catalyst can be directly commercially purchased or is easily, directly and simply synthesized, and can be used in actual production.
- -
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Paragraph 0020
(2020/02/27)
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- Diethylsilane as a Powerful Reagent in Au Nanoparticle-Catalyzed Reductive Transformations
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Diethylsilane (Et2SiH2), a simple and readily available dihydrosilane, that exhibits superior reactivity, as compared to monohydrosilanes, in a series of reductive transformations catalyzed by recyclable and reusable Au nanoparticles (1 mol-%) supported on TiO2. It reduces aldehydes or ketones almost instantaneously at ambient conditions. It can be used in a one pot rapid reductive amination procedure, in which premixing of aldehyde and amine is required prior to the addition of the reducing agent and the catalyst, even in a protic solvent. An unprecedented method for the synthesis of N-arylisoindolines is also shown in the reductive amination between o-phthalaldehyde and anilines. In this transformation, it is proposed that the intermediate N,2-diphenylisoindolin-1-imines are reduced stepwise to the isoindolines. Finally, Et2SiH2 readily reduces amides into amines in excellent yields and shorter reaction times relative to previously known analogous nano Au(0)-catalyzed protocols.
- Louka, Anastasia,Kidonakis, Marios,Saridakis, Iakovos,Zantioti-Chatzouda, Elisavet-Maria,Stratakis, Manolis
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p. 3508 - 3514
(2020/06/02)
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- Chemoselective Reductive Aminations in Aqueous Nanoreactors Using Parts per Million Level Pd/C Catalysis
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Condensation in recyclable water between aldehydes or ketones and amines occurs smoothly within the hydrophobic cores of nanomicelles, resulting in imine formation that is subject to subsequent reduction leading, overall, to reductive amination. This micellar technology enables the synthesis of several types of pharmaceuticals, a new procedure that relies on only 2000 ppm (0.20 mol %) palladium from commercially available Pd/C. A broad range of substrates can be used under mild conditions, leading to high chemical yields of the desired secondary and tertiary amines.
- Casotti, Gianluca,Gao, Eugene S.,Jin, Henry S.,Lipshutz, Bruce H.,Takale, Balaram S.,Thakore, Ruchita R.
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supporting information
(2020/09/09)
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- Thioglycerol-Stabilized Rhodium Nanoparticles in Biphasic Medium as Catalysts in Multistep Reactions
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Small rhodium nanoparticles (ca. 3.5 nm) were prepared by the decomposition of an organometallic precursor under hydrogen pressure in glycerol using 1-thioglycerol as stabilizer. Full characterization in the solid state [HR-TEM, EDX, XPS] showed a fcc structure for the Rh0/RhI nanoparticles capped with thiolate ligand. Reduction of different functionalities, including nitro groups and imines, was applied to tandem reductive amination of aldehydes with primary and secondary amines, and to the synthesis of N-substituted anilines from nitrobenzene. In addition, thiolate-capped RhNPs could be recovered and reused up to 5 runs without loss of activity nor selectivity.
- Guerrero-Ríos, Itzel,Portales-Martínez, Benjamín,Reina, Antonio,Serrano-Maldonado, Alejandro
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supporting information
(2020/07/04)
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- A hydrogen borrowing annulation strategy for the stereocontrolled synthesis of saturated aza-heterocycles
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An iridium catalyzed method for the synthesis of saturated aza-heterocycles from amines and diols is reported. A wide range of substituted heterocycles can be obtained using this approach including products bearing substituents at the C2, C3 and C4 positions. Employing water as the solvent, enantiopure diols could undergo annulation with minimal racemization, enabling the synthesis of valuable enantioenriched C3 and C4-substituted saturated aza-heterocycles.
- Armstrong, Roly J.,Chamberlain, Anna E. R.,Donohoe, Timothy J.,Paterson, Kieran J.,Twin, Heather C.
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supporting information
p. 3563 - 3566
(2020/04/03)
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- Hydrazone complexes of ruthenium(II): Synthesis, crystal structures and catalytic applications in N-alkylation reactions
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A series of new Ru(II) complexes of 8-hydroxy quinoline-2-carboxyaldehyde hydrazone of the general formula [RuH(CO)(EPh3)2L] (1–6) (E = P or As, L = N’-((8-hydroxyquinolin-2-yl)methylene)thiophene-2-carbohydrazide (HQ-THy), N’-((8-hydroxyquinolin-2-yl)methylene)isonicotinohydrazide (HQ-IHy), N’-((8-hydroxyquinolin-2-yl)methylene) benzohydrazide (HQ-BHy)) have been synthesized. They have been characterized by elemental analysis, IR, NMR (1H, 13C & 31P) and ESI-MS spectral methods. Further, structures of two of the complexes have been determined by single crystal X-ray diffraction technique which revealed a pseudo octahedral geometry with the coordination of the quinoline nitrogen and quinoline oxygen atoms of the ligand. All the new complexes have been employed as efficient catalysts in N-alkylation reactions for the synthesis of tertiary amines by the coupling of secondary amines with aromatic primary alcohols at low catalyst loading with maximum yields. In addition, the effects of substituents on the ligands, different solvents as well as bases and amounts of catalyst loading on the catalytic activity of the complexes have been thoroughly investigated. Complex 1 was found to be efficient catalyst towards N-alkylation of alcohols with the amine. Further, a variety of secondary amines and aromatic (hetero) primary alcohols with various functional groups have also been successfully used in the N-alkylation reactions and it has been found that only one equivalent of the alcohol was consumed in the process.
- Murugan, Kaliyappan,Natarajan, Karuppannan,Nirmala, Muthukumaran,Vijayapritha, Subbarayan,Viswanathamurthi, Periasamy
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- Efficient One-Pot Reductive Aminations of Carbonyl Compounds with Aquivion-Fe as a Recyclable Catalyst and Sodium Borohydride
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A one-pot reductive amination of aldehydes and ketones with NaBH4 was developed with a view to providing efficient, economical and greener synthetic conditions. A recyclable iron-based Lewis catalyst, Aquivion-Fe, was used to promote imine formation in cyclopentyl methyl ether, followed by the addition of a small amount of methanol to the reaction mixture to enable C=N reduction by NaBH4. The protocol, applied to a wide number of amines and carbonyl compounds, resulted in ever complete conversion of these latter with excellent chemoselectivity towards the expected amination products in the most cases. Isolated yields, determined for a selection of the screened substrates, were found consistent with the previously obtained conversion and selectivity data. Cinacalcet, an important active pharmaceutical ingredient, was efficiently prepared by the title procedure.
- Airoldi, Veronica,Piccolo, Oreste,Roda, Gabriella,Appiani, Rebecca,Bavo, Francesco,Tassini, Riccardo,Paganelli, Stefano,Arnoldi, Sebastiano,Pallavicini, Marco,Bolchi, Cristiano
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supporting information
p. 162 - 168
(2019/12/11)
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- Direct benzylation of amines with benzylic alcohols catalyzed by palladium/phosphine-borane catalyst system
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Direct catalytic benzylation of amines with benzylic alcohols to give benzylamines has been newly developed by using palladium/phosphine-borane catalyst system. In this catalytic reaction, the linking between both phosphine and borane moieties in the ligand is very important. Hydroxy group of benzylic alcohols is activated by Lewis acidic borane to form a benzylpalladium intermediate which is attacked by amines to give benzylamine products.
- Onodera, Gen,Kumagae, Hidenobu,Nakamura, Daiki,Hayasaki, Takuto,Fukuda, Tsutomu,Kimura, Masanari
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supporting information
(2020/11/04)
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- Catalytic Transfer Hydrodebenzylation with Low Palladium Loading
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A highly-efficient catalytic system for hydrodebenzylation reaction is described. The cleavage of O-benzyl and N-benzyl protecting groups was performed using an uncommonly low palladium loading (0.02–0.3 mol%; TON up to 5000) in a relatively short reaction time. The approach was used for a variety of substrates including pharmaceutically important precursors, and gram-scale deprotection reaction was shown. Transfer conditions together with easy-to-make Pd/C catalyst are the key features of this debenzylation scheme. (Figure presented.).
- Yakukhnov, Sergey A.,Ananikov, Valentine P.
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supporting information
p. 4781 - 4789
(2019/09/16)
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- Photochemical benzylic bromination in continuous flow using BrCCl3 and its application to telescoped p-methoxybenzyl protection
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BrCCl3 represents a rarely used benzylic brominating reagent with complementary reactivity to other reagents. Its reactivity has been revisited in continuous flow, revealing compatibility with electron-rich aromatic substrates. This has brought about the development of a p-methoxybenzyl bromide generator for PMB protection, which was successfully demonstrated on a pharmaceutically relevant intermediate on 11 g scale, giving 91% yield and a PMB-Br space-time-yield of 1.27 kg L?1 h?1
- Otake, Yuma,Williams, Jason D.,Rincón, Juan A.,De Frutos, Oscar,Mateos, Carlos,Kappe, C. Oliver
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supporting information
p. 1384 - 1388
(2019/02/14)
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- B(C6F5)3-Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane
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The first B(C6F5)3-catalyzed deoxygenative reduction of amides into the corresponding amines with readily accessible and stable ammonia borane (AB) as a reducing agent under mild reaction conditions is reported. This metal-free protocol provides facile access to a wide range of structurally diverse amine products in good to excellent yields, and various functional groups including those that are reduction-sensitive were well tolerated. This new method is also applicable to chiral amide substrates without erosion of the enantiomeric purity. The role of BF3 ? OEt2 co-catalyst in this reaction is to activate the amide carbonyl group via the in situ formation of an amide-boron adduct. (Figure presented.).
- Pan, Yixiao,Luo, Zhenli,Han, Jiahong,Xu, Xin,Chen, Changjun,Zhao, Haoqiang,Xu, Lijin,Fan, Qinghua,Xiao, Jianliang
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supporting information
p. 2301 - 2308
(2019/01/30)
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- Heterogeneous Catalytic Reduction of Tertiary Amides with Hydrosilanes Using Unsupported Nanoporous Gold Catalyst
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We have demonstrated that the unsupported nanoporous gold (AuNPore) was a green and highly efficient heterogeneous catalyst for the reduction of amides to amines using hydrosilanes as reductants. A variety of tertiary amides with a broad functional groups were reduced to the corresponding tertiary amines in the presence of 2 mol% of AuNPore and PheMe2SiH or (Me2SiH)2O under mild conditions. AuNPore catalyst was recovered by simple filtration and used for twelve times without any loss of catalytic activity. The AuNPore/hydrosilane system was also successfully applied to the hydrosilative reduction of sulfoxides and N-oxides. (Figure presented.).
- Zhao, Yuhui,Zhang, Sheng,Yamamoto, Yoshinori,Bao, Ming,Jin, Tienan,Terada, Masahiro
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supporting information
p. 4817 - 4824
(2019/10/28)
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- Hydrosilylative Reduction of Tertiary Amides to Amines Catalyzed by N-(Phosphinoaryl)anilido Complexes of Iron and Cobalt
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The synthesis and structural characterization of low-coordinate Fe(II) and Co(II) complexes supported by the monoanionic P,N-ligand N-(2-dicyclohexylphosphinophenyl)-2,6-diisopropylanilide are described. A three-coordinate (P,N)Fe-hexamethyldisilazide complex (2), and four-coordinate (P,N)Fe- (3-Fe) and (P,N)Co-alkyl (3-Co) complexes were evaluated as pre-catalysts for the hydrosilylative reduction of amides with PhSiH3 (5 mol % pre-catalyst, 1 equiv. PhSiH3, 80 °C, 1–24 h). The Fe complex 2 proved to be more broadly effective for the reduction of a variety of tertiary amide substrates, and was shown to mediate the reduction of N,N-dibenzylbenzamide at a loading of 1 mol %, to achieve near quantitative formation of tribenzylamine in 1 h (80 °C). Complex 2 also proved effective for the hydrosilylation of tertiary amides under ambient conditions (5 mol % Fe, 24 h), which is a unique example of room temperature amide hydrosilylation mediated by an Fe catalyst without the need for photochemical activation. Given the widespread use of amide reduction protocols in synthesis, the development of efficient Fe-based catalysts that operate under mild conditions is an important target.
- Hale, Dylan J.,Murphy, Luke J.,McDonald, Robert,Ferguson, Michael J.,Turculet, Laura
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p. 3818 - 3827
(2019/06/17)
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- Bench-Stable Cobalt Pre-Catalysts for Mild Hydrosilative Reduction of Tertiary Amides to Amines and Beyond
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The readily synthesized and bench-stable cobalt dichloride complex (dpephos)CoCl2 is employed as a pre-catalyst for a diversity of silane additions to unsaturated organic molecules, including the normally challenging reduction of amides to amines. With regard to hydrosilative reduction of amides even more effective and activator free catalytic systems can be generated from the bench-stable, commercially available Co(acac)2 and Co(OAc)2 with dpephos and PPh3 ligands. These systems operate under mild conditions (100 °C), with many examples of room temperature transformations, presenting a first example of mild cobalt-catalyzed hydrosilylation of amides.
- Nurseiit, Alibek,Janabel, Jaysan,Gudun, Kristina A.,Kassymbek, Aishabibi,Segizbayev, Medet,Seilkhanov, Tulegen M.,Khalimon, Andrey Y.
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p. 790 - 798
(2019/01/09)
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- Selective Synthesis of Secondary Amines from Nitriles by a User-Friendly Cobalt Catalyst
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Selective hydrogenation/reductive amination of nitriles to secondary amines catalyzed by an inexpensive and user-friendly cobalt complex, (Xantphos)CoCl2, is reported. The use of (Xantphos)CoCl2 and ammonia borane (NH3?BH3) combination affords the selective reduction of nitriles to symmetrical secondary amines, whereas the employment of (Xantphos)CoCl2 and dimethylamine borane (Me2NH?BH3) along with external amines produce unsymmetrical secondary amines and tertiary amines. The general applicability of this methodology is demonstrated by the synthesis of 43 symmetrical and unsymmetrical secondary and tertiary amines bearing diverse functionalities. (Figure presented.).
- Sharma, Dipesh M.,Punji, Benudhar
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supporting information
p. 3930 - 3936
(2019/07/12)
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- Manganese(III) Porphyrin-Catalyzed Dehydrogenation of Alcohols to form Imines, Tertiary Amines and Quinolines
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Manganese(III) porphyrin chloride complexes have been developed for the first time as catalysts for the acceptorless dehydrogenative coupling of alcohols and amines. The reaction has been applied to the direct synthesis of imines, tertiary amines and quinolines where only hydrogen gas and/or water are formed as the by-product(s). The mechanism is believed to involve the formation of a manganese(III) alkoxide complex which degrades into the aldehyde and a manganese(III) hydride species. The latter reacts with the alcohol to form hydrogen gas and thereby regenerates the alkoxide complex.
- Azizi, Kobra,Akrami, Sedigheh,Madsen, Robert
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p. 6439 - 6446
(2019/04/26)
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- Selective, Catalytic, and Dual C(sp3)-H Oxidation of Piperazines and Morpholines under Transition-Metal-Free Conditions
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By using cheap and innocuous reagents, such as NaClO2, NaOCl, and catalytic amounts of TEMPO, a new environmentally friendly protocol for the selective and catalytic TEMPO C(sp3)-H oxidation of piperazines and morpholines to 2,3-diketopiperazines (2,3-DKP) and 3-morpholinones (3-MPs), respectively, has been developed. This novel direct access to 2,3-DKP from piperazines provides significant advantages over the traditional N-monoacylation/intramolecular C-N cyclization procedure. Additionally, by modulating the amounts of TEMPO, 2-alkoxyamino-3-morpholinone can be prepared from morpholine derivatives, which would enable further functionalization at the C2 position of the morpholine skeleton.
- Chamorro-Arenas, Delfino,Osorio-Nieto, Urbano,Quintero, Leticia,Hernández-García, Luís,Sartillo-Piscil, Fernando
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p. 15333 - 15346
(2019/01/03)
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- Cobalt complex, preparation method thereof, and application thereof in selective catalysis of transfer hydrogenation reaction of cyano group
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The invention discloses a cobalt complex, a preparation method thereof, and an application thereof in the selective catalysis of a transfer hydrogenation reaction of a cyano group. The structural formula of the cobalt complex is represented by formula I. The cobalt complex is prepared through a reaction of a cobalt salt and an NNP ligand or a PNP ligand under the protection of an inert atmosphere;and the chemical formula of the cobalt salt is CoX12, wherein X1 represents halogen, a sulfate radical, a perchlorate radical, a hexafluorophosphate radical, a hexafluoroantimonate radical, a tetrafluoroborate radical, a trifluoromethanesulfonate radical or a tetra(pentafluorophenyl)borate radical. The cobalt complex can be used in the selective catalysis of the transfer hydrogenation reaction ofthe cyano group to obtain a primary amine compound, a secondary amine compound and a tertiary amine compound, the primary amine compound, the secondary amine compound and the tertiary amine compoundare important intermediates in a series of subsequent functionalizing reactions, and the cobalt complex has a very high catalysis activity, and has great research values and a great application prospect.
- -
-
Paragraph 0173-0175; 0177
(2018/05/07)
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- Direct Reductive Amination of Carbonyl Compounds with H2 Using Heterogeneous Catalysts in Continuous Flow as an Alternative to N-Alkylation with Alkyl Halides
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A general continuous-flow procedure for direct reductive amination of secondary and primary amines with aromatic and aliphatic aldehydes as well as ketones is reported. The use of hydrogen gas and commercially available Pt/C as a heterogeneous catalyst is a key. In addition to exhibiting an excellent functional group tolerance, this method allows the fast formation of C?N bonds without production of any hazardous chemical waste. Applications to the synthesis of key intermediates toward active pharmaceutical ingredients (Donepezil and Arformoterol/Tamsulosin) are also described. (Figure presented.).
- Laroche, Benjamin,Ishitani, Haruro,Kobayashi, Shū
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supporting information
p. 4699 - 4704
(2018/12/04)
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- Alkylation of cyclic amines with alcohols catalyzed by Ru(II) complexes bearing N-Heterocyclic carbenes
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This paper includes the synthesis of 2-(1,3-dioxane-2-yl)ethyl substituted benzimidazole substituted N-heterocyclic carbenes precursors and their ruthenium complexes. Synthesized compounds were characterized by elemental analysis and NMR spectroscopy. All complexes have been tested in the alkylation of pyrrolidine and morpholine with alcohols, showing an excellent activity in this reaction.
- Ulu, ?znur Do?an,Gürbüz, Nevin,?zdemir, ?smail
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p. 645 - 651
(2018/01/04)
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- Unmodified Fe3O4 nanostructure promoted with external magnetic field: safe, magnetically recoverable, and efficient nanocatalyst for N- and C-alkylation reactions in green conditions
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Transition metal compounds have emerged as suitable catalysts for organic reactions. Magnetic compounds as soft Lewis acids can be used as catalysts for organic reactions. In this report, the Fe3O4 nanostructures were obtained from Fe2+ and Fe3+-salts, under an external magnetic field (EMF) without any protective agent. The X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy tools were used to characterize these magnetic compounds. The two-dimensional (2-D, it showed nanometric size in the two dimensions, nanorod structure) Fe3O4 compound showed high catalytic activity and stability in N- and C-alkylation reactions. A diverse range of N- and C-alkylation products were obtained in moderate to high yield under green and mild conditions in air. Also the N- and C-alkylation products can be obtained with different selectivity and yield by exposure reactions with EMF. Results of alkylation reactions showed that the presence of Fe(II) and Fe(III) species on the surface of magnetic catalysts (phase structure of magnetic compounds) are essential as very cheap active sites. Also, morphology of magnetic catalysts had influence on their catalytic performances. After the reaction, the catalyst/product(s) separation could be easily achieved with an external magnet and more than 95% of catalyst could be recovered. The catalyst was reused at least four times without any loss of its high catalytic activity for N- and C-alkylation reactions.
- Rafiee, Ezzat,Joshaghani, Mohammad,Abadi, Parvaneh Ghaderi-Shekhi
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p. 2503 - 2522
(2018/01/04)
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- Derisking the Cu-Mediated 18F-Fluorination of Heterocyclic Positron Emission Tomography Radioligands
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Molecules labeled with fluorine-18 (18F) are used in positron emission tomography to visualize, characterize and measure biological processes in the body. Despite recent advances in the incorporation of 18F onto arenes, the development of general and efficient approaches to label radioligands necessary for drug discovery programs remains a significant task. This full account describes a derisking approach toward the radiosynthesis of heterocyclic positron emission tomography (PET) radioligands using the copper-mediated 18F-fluorination of aryl boron reagents with 18F-fluoride as a model reaction. This approach is based on a study examining how the presence of heterocycles commonly used in drug development affects the efficiency of 18F-fluorination for a representative aryl boron reagent, and on the labeling of more than 50 (hetero)aryl boronic esters. This set of data allows for the application of this derisking strategy to the successful radiosynthesis of seven structurally complex pharmaceutically relevant heterocycle-containing molecules.
- Taylor, Nicholas J.,Emer, Enrico,Preshlock, Sean,Schedler, Michael,Tredwell, Matthew,Verhoog, Stefan,Mercier, Joel,Genicot, Christophe,Gouverneur, Véronique
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supporting information
p. 8267 - 8276
(2017/06/27)
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- Oxidation-Reduction Condensation of Diazaphosphites for Carbon-Heteroatom Bond Formation Based on Mitsunobu Mechanism
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An efficient oxidation-reduction condensation reaction of diazaphosphites with various nonacidic pronucleophiles in the presence of DIAD as a weak oxidant has been developed for carbon-heteroatom bond formation. This mild process affords structurally diverse tertiary amines, secondary amines, esters, ethers, and thioethers in moderate to excellent yields. The selective synthesis of secondary amines from primary amines has been achieved. Importantly, a practical application to the synthesis of antiparkinsonian agent piribedil has been demonstrated.
- Huang, Hai,Kang, Jun Yong
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p. 544 - 547
(2017/02/10)
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- Efficient and Selective Hydrosilylation of Secondary and Tertiary Amides Catalyzed by an Iridium(III) Metallacycle: Development and Mechanistic Investigation
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Readily accessible cationic IrIII metallacycles catalyze efficiently the chemoselective hydrosilylation of tertiary and secondary amides to amines. The catalyst described herein operates at low loadings using inexpensive 1,1,3,3-tetramethyldisiloxane and allows fast reactions with high yields, selectivities, and turnover numbers. A transient iminium intermediate has been observed for the first time by using mass spectrometry, and the activation of the catalyst and the silane reagent have been studied by using DFT calculations. These fundamental insights support the present and future improvements of IrIII metallacycles through proper ligand modifications and enable further broad applications of catalysts based on metallacycles.
- Corre, Yann,Trivelli, Xavier,Capet, Frédéric,Djukic, Jean-Pierre,Agbossou-Niedercorn, Francine,Michon, Christophe
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p. 2009 - 2017
(2017/06/13)
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- A Manganese Pre-Catalyst: Mild Reduction of Amides, Ketones, Aldehydes, and Esters
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A new (N-phosphinoamidinate)manganese complex is shown to be a useful pre-catalyst for the hydrosilative reduction of carbonyl compounds, and in most cases at room temperature. The Mn-catalyzed reduction of tertiary amides to tertiary amines, with a useful scope, is demonstrated for the first time by use of this catalyst, and is competitive with the most effective transition-metal catalysts known for such transformations. Ketones, aldehydes, and esters were also successfully reduced under mild conditions by using this new Mn catalyst.
- Kelly, Colin M.,McDonald, Robert,Sydora, Orson L.,Stradiotto, Mark,Turculet, Laura
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supporting information
p. 15901 - 15904
(2017/12/13)
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- General Reductive Amination of Aldehydes and Ketones with Amines and Nitroaromatics under H2 by Recyclable Iridium Catalysts
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Heterogeneous iridium catalysts were prepared and applied for the reductive amination of aldehydes and ketones with nitroaromatics and amines using H2. The iridium catalysts were prepared by pyrolysis of ionic liquid 1-methyl-3-cyanomethylimidazoulium chloride ([MCNI]Cl) with iridium chloride (IrCl3) in activated carbons. Iridium particles were well dispersed and stable in the N-doped carbon materials from [MCNI]Cl with activated carbon. The Ir@NC(600-2h) catalyst was found to be highly active and selective for the reductive amination of aldehydes and ketones using H2 and a variety of nitrobenzenes and amines were selectively converted into the corresponding secondary and tertiary amines. The Ir@NC(600-2h) catalyst can be reusable several times without evident deactivation.
- Sui, Dejun,Mao, Fei,Fan, Haipeng,Qi, Zhengliang,Huang, Jun
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supporting information
p. 1371 - 137
(2017/10/05)
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- Preparation method of acrylamide-based compounds
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The present invention relates to the field of fine chemical materials, particularly to a new mild, efficient and economical preparation process technology of a class of acrylamide-type compounds, wherein a beta-amine substituted propionamide precursor is subjected to an in-situ amine elimination reaction under the action of a suitable electrophilic reagent so as to prepare the target product.
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Paragraph 0016
(2018/01/11)
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- Mitsunobu Reaction Using Basic Amines as Pronucleophiles
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A novel protocol for extending the scope of the Mitsunobu reaction to include amine nucleophiles to form C-N bonds through the utilization of N-heterocyclic phosphine-butane (NHP-butane) has been developed. Both aliphatic alcohols and benzyl alcohols are suitable substrates for C-N bond construction. Various acidic nucleophiles such as benzoic acids, phenols, thiophenol, and secondary sulfonamide also provide the desired products of esters, ethers, thioether, and tertiary sulfonamide with 43-93% yields. Importantly, C-N bond-containing pharmaceuticals, Piribedil and Cinnarizine, have been synthesized in one step from the commercial amines under this Mitsunobu reaction system.
- Huang, Hai,Kang, Jun Yong
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p. 6604 - 6614
(2017/07/15)
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- Colloid and Nanosized Catalysts in Organic Synthesis: XVIII.1 Disproportionation and Cross-Coupling of Amines During Catalysis with Immobilized Nickel Nanoparticles
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It has been stated that immobilized nickel nanoparticles catalyze disproportionation and cross-coupling of amines. The influence of the support on the catalysis of these properties in the in plug-flow reactor has been studied. The use of active carbon as the support has been found advantageous for the cross-coupling of amines, whereas alumina was a better support for the disproportionation reaction.
- Popov, Yu. V.,Mokhov,Latyshova,Nebykov,Panov,Davydova
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p. 2757 - 2761
(2018/02/21)
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- Cyclometalated palladium pre-catalyst for N-alkylation of amines using alcohols and regioselective alkylation of sulfanilamide using aryl alcohols
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Simple pyrazole based palladacycle-phosphine with a high turnover has been developed and applied for the N-alkylation of amines and sulfanilamide using alcohols as substrates by hydrogen borrowing strategy. N-alkylation of primary and secondary amines resulted in high isolated yields at 100–130 °C, under solvent free conditions. More challenging secondary aliphatic as well as aromatic alcohols were also successfully utilized as alkylating agents under similar reaction conditions. The turn over number reached up to 43000 for N-benzylation of aniline using benzyl alcohol. Notably, regioselective N-alkylation of 2-aminobenzothiazole and 4-aminobenzenesulfonamide to the corresponding 2-N-(alkylamino)azoles and 4-amino-(N-alkyl)benzenesulfonamides using alcohols as alkylating agents have been achieved using our new pre-catalyst-phosphine system.
- Mamidala, Ramesh,Mukundam, Vanga,Dhanunjayarao, Kunchala,Venkatasubbaiah, Krishnan
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supporting information
p. 2225 - 2233
(2017/03/24)
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- Continuous-Flow Multistep Synthesis of Cinnarizine, Cyclizine, and a Buclizine Derivative from Bulk Alcohols
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Cinnarizine, cyclizine, buclizine, and meclizine belong to a family of antihistamines that resemble each other in terms of a 1-diphenylmethylpiperazine moiety. We present the development of a four-step continuous process to generate the final antihistamines from bulk alcohols as the starting compounds. HCl is used to synthesize the intermediate chlorides in a short reaction time and excellent yields. This methodology offers an excellent way to synthesize intermediates to be used in drug synthesis. Inline separation allows the collection of pure products and their immediate consumption in the following steps. Overall isolated yields for cinnarizine, cyclizine, and a buclizine derivative are 82, 94, and 87 %, respectively. The total residence time for the four steps is 90 min with a productivity of 2 mmol h-1. The incredible bulk: Bulk alcohols are converted continuously into chlorides using HCl in a microflow. A reaction network that consists of four steps and two inline separations leads to the continuous preparation of cinnarizine, cyclizine, and a buclizine derivative with yields of 82, 94, and 87 %, respectively. The total residence time for the four steps is 90 min with a productivity of 2 mmol h-1.
- Borukhova, Svetlana,Nol, Timothy,Hessel, Volker
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