- Sustainable Manganese-Catalyzed Solvent-Free Synthesis of Pyrroles from 1,4-Diols and Primary Amines
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A general and selective metal-catalyzed conversion of biomass-derived primary diols and amines to the highly valuable 2,5-unsubstituted pyrroles has been developed. The reaction is catalyzed by a stable nonprecious manganese complex (1 mol %) in the absence of organic solvents whereby water and molecular hydrogen are the only side products. The manganese catalyst shows unprecedented selectivity, avoiding the formation of pyrrolidines, cyclic imides, and lactones.
- Borghs, Jannik C.,Lebedev, Yury,Rueping, Magnus,El-Sepelgy, Osama
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- Reaction of Diisobutylaluminum Borohydride, a Binary Hydride, with Selected Organic Compounds Containing Representative Functional Groups
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The binary hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], synthesized from diisobutylaluminum hydride (DIBAL) and borane dimethyl sulfide (BMS) has shown great potential in reducing a variety of organic functional groups. This unique binary hydride, (iBu)2AlBH4, is readily synthesized, versatile, and simple to use. Aldehydes, ketones, esters, and epoxides are reduced very fast to the corresponding alcohols in essentially quantitative yields. This binary hydride can reduce tertiary amides rapidly to the corresponding amines at 25 °C in an efficient manner. Furthermore, nitriles are converted into the corresponding amines in essentially quantitative yields. These reactions occur under ambient conditions and are completed in an hour or less. The reduction products are isolated through a simple acid-base extraction and without the use of column chromatography. Further investigation showed that (iBu)2AlBH4 has the potential to be a selective hydride donor as shown through a series of competitive reactions. Similarities and differences between (iBu)2AlBH4, DIBAL, and BMS are discussed.
- Amberchan, Gabriella,Snelling, Rachel A.,Moya, Enrique,Landi, Madison,Lutz, Kyle,Gatihi, Roxanne,Singaram, Bakthan
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supporting information
p. 6207 - 6227
(2021/05/06)
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- Method for catalytically synthesizing 1-substituted pyrrolidine/piperidine derivative by using supported metal
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The invention provides a method for catalytically synthesizing a 1-substituted pyrrolidine/piperidine derivative by using a supported metal. The method comprises: carrying out a reaction with ammoniato form a pyrrolidine ring/piperidine ring by using a supported metal as a catalyst, using 1,4-butanediol/1, 5-pentanediol as a cyclization raw material and using alcohol as an N-alkylation raw material, wherein the high-selectivity synthesis of the 1-substituted pyrrolidine/piperidine derivative is achieved through the one-step reaction, the active components of the supported metal catalyst are Cu, Ni and Pd/Ru, the total loading capacity of the active components Cu and Ni is 3-15 wt% of the carrier, and the loading capacity of Pd/Ru is 0-1 wt% of the carrier. According to the invention, themethod is simple, low in cost and environmentally friendly, the conversion rate of 1,4-butanediol/1,5-pentanediol is high, the selectivity of the pyrrolidine/piperidine derivatives is high, and the method is a production route with practical application value.
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Paragraph 0019
(2020/02/20)
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- Half-sandwich ruthenium-carbene catalysts: Synthesis, characterization, and catalytic application in the N-alkylation of amines with alcohols
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In this study, the synthesis and characterization of new half-sandwich ruthenium complexes containing oxygen functionalised N-aryl and N-alkyl benzimidazol-2-ylidene ligands have been reported. All ruthenium complexes were tested as catalysts for a wide range of substrates in the N-alkylation of secondary cyclic amines such as pyrrolidine and piperidine, and 4-methylaniline which was a primary aromatic amine with alcohols by hydrogen-borrowing process. The catalytic reactions were performed with 1 mol% catalyst loading at 120 °C, 16 h under solvent-free conditions. All ruthenium complexes showed excellent catalytic activity, and N-alkylated products were obtained selectively.
- Kalo?lu, Murat
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- Synthesis of β-Chiral Amines by Dynamic Kinetic Resolution of α-Branched Aldehydes Applying Imine Reductases
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Imine reductases (IREDs) allow the one-step preparation of optically active secondary and tertiary amines by reductive amination of ketones. Until now, mainly α-chiral amines have been prepared by this route. In this study, we explored the possibility of synthesizing β-chiral amines, a class of compounds which is also frequently found as structural motif in pharmaceuticals but much more challenging to prepare due to the following reasons: (i) The aldehyde substrate already contains the chiral center and needs to be racemized to enable full conversion. (ii) Because the intermediate imine bears the stereo center two carbon atoms remote to the imine nitrogen, it is more challenging to achieve high enantioselectivity compared to α-chiral amine synthesis. For investigating the proof of concept, we first confirmed that different IREDs are able to convert a variety of α-branched aldehydes when combined with five different amine substrates. The IRED from Streptomyces ipomoeae was a suitable enzyme facilitating the dynamic kinetic resolution of 2-phenylpropanal and a substituted 2-methyl-3-phenylpropanal: the corresponding N-methylated β-chiral amines were obtained with '95 % conversion and 78 and 95 %ee. Other amines were formed with low to moderate enantiomeric excess. This exemplifies the potential of IREDs for the one-step synthesis of secondary β-chiral amines, but also the challenge to identify highly selective enzymes for a desired amine product.
- Matzel, Philipp,Wenske, Sebastian,Merdivan, Simon,Günther, Sebastian,H?hne, Matthias
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p. 4281 - 4285
(2019/08/20)
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- Acceptorless Dehydrogenative Coupling Using Ammonia: Direct Synthesis of N-Heteroaromatics from Diols Catalyzed by Ruthenium
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The synthesis of N-heteroaromatic compounds via an acceptorless dehydrogenative coupling process involving direct use of ammonia as the nitrogen source was explored. We report the synthesis of pyrazine derivatives from 1,2-diols and the synthesis of N-substituted pyrroles by a multicomponent dehydrogenative coupling of 1,4-diols and primary alcohols with ammonia. The acridine-based Ru-pincer complex 1 is an effective catalyst for these transformations, in which the acridine backbone is converted to an anionic dearomatized PNP-pincer ligand framework.
- Daw, Prosenjit,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 11931 - 11934
(2018/09/27)
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- Photometric Characterization of the Reductive Amination Scope of the Imine Reductases from Streptomyces tsukubaensis and Streptomyces ipomoeae
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Imine reductases (IREDs) have emerged as promising enzymes for the asymmetric synthesis of secondary and tertiary amines starting from carbonyl substrates. Screening the substrate specificity of the reductive amination reaction is usually performed by time-consuming GC analytics. We found two highly active IREDs in our enzyme collection, IR-20 from Streptomyces tsukubaensis and IR-Sip from Streptomyces ipomoeae, that allowed a comprehensive substrate screening with a photometric NADPH assay. We screened 39 carbonyl substrates combined with 17 amines as nucleophiles. Activity data from 663 combinations provided a clear picture about substrate specificity and capabilities in the reductive amination of these enzymes. Besides aliphatic aldehydes, the IREDs accepted various cyclic (C4–C8) and acyclic ketones, preferentially with methylamine. IR-Sip also accepted a range of primary and secondary amines as nucleophiles. In biocatalytic reactions, IR-Sip converted (R)-3-methylcyclohexanone with dimethylamine or pyrrolidine with high diastereoselectivity (>94–96 % de). The nucleophile acceptor spectrum depended on the carbonyl substrate employed. The conversion of well-accepted substrates could also be detected if crude lysates were employed as the enzyme source.
- Matzel, Philipp,Krautschick, Lukas,H?hne, Matthias
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p. 2022 - 2027
(2017/10/07)
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- Diisobutylaluminum borohydride: An efficient reagent for the reduction of tertiary amides to the corresponding amines under ambient conditions
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A synthetically simple mixed metal hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], is easily generated from a 1:1 mixture of borane-dimethylsulfide (BMS) and diisobutylaluminum hydride (DIBAL). The reduction of tertiary amides using (iBu)2AlBH4 is complete within five minutes under ambient conditions and the product tertiary amines were isolated in 70–99% yields by a simple acid-base extraction. This new methodology, reported herein, works well for reduction of tertiary aliphatic and aromatic amides as well as lactams to the corresponding amines and product isolation and purification does not require column chromatography.
- Snelling, Rachel A.,Amberchan, Gabriella,Resendez, Angel,Murphy, Chris L.,Porter, Lauren,Singaram, Bakthan
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p. 4073 - 4077
(2017/09/28)
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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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- Ruthenium(II) and iridium(III) complexes featuring NHC-sulfonate chelate
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Three new complexes bearing a chelating (κ2C,O) NHC-SO3 ligand have been prepared. An original method for the synthesis of the imidazolium-sulfonate NHC precursor is described. The 5-membered ruthena- and irida-cycle containing complexes were fully characterized and evaluated in a series of catalytic transformations involving hydrogen auto-transfer processes.
- Rajaraman,Sahoo,Hild,Fischmeister,Achard,Bruneau
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supporting information
p. 17467 - 17472
(2015/10/19)
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- Rhodium complex encapsulated functionalized hexagonal mesoporous silica for heterogeneous hydroaminomethylation
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HRh(CO)(PPh3)3 complex was encapsulated into the pores of amino functionalized hexagonal mesoporous silica. The catalyst was characterized by physico-chemical techniques like P-XRD, 31P-CPMAS NMR, FT-IR, SEM, ICP and N2 adsorption analysis. The catalyst was active for hydroaminomethylation and a variety of alkenes and amines were used as reactants for hydroaminomethylation. The catalyst afforded to achieve 100% conversion with high (>95%) selectivity to corresponding amines. Parametric variations were performed by taking 1-hexene and morpholine as representative reactants for the study of catalyst amount, temperature, pressure and 1-hexene:morpholine ratio. Significant amounts of aldehydes and enamines were observed during the course of the reaction indicating that there could be two possible rate determining steps. The catalyst was effectively recycled up to five times without much loss in its activity and selectivity.
- Sudheesh,Shukla, Ram S.
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p. 159 - 166
(2013/03/28)
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- Catalytic hydrogenation of amides to amines under mild conditions
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Under (not so much) pressure: A general method for the hydrogenation of tertiary and secondary amides to amines with excellent selectivity using a bimetallic Pd-Re catalyst has been developed. The reaction proceeds under low pressure and comparatively low temperature. This method provides organic chemists with a simple and reliable tool for the synthesis of amines. Copyright
- Stein, Mario,Breit, Bernhard
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supporting information
p. 2231 - 2234
(2013/03/28)
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- Fluorine-containing ionic liquids from N-alkylpyrrolidine and N-methylpiperidine and fluorinated acetylacetones: Low melting points and low viscosities
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A family of new fluorine-containing ionic liquids (3-14) was synthesized in high yield by the reaction of N-alkylpyrrolidine, N-methylpiperidine and fluorinated 1,3-diketones: 1,1,1,5,5,5-hexafluoroacetylacetone, 1,1,1-trifluoro-2,4-pentanedione and 4,4,4-trifluoro-1-phenyl-1,3-butanedione. Their properties, such as the phase-transition temperature, density, and viscosity, were determined. Most of them show relatively low melting points and low viscosities. The influence of fluorinated 1,3-diketonate anions and the structural variation in cyclic amine cations on the above physicochemical properties was examined. X-ray single-crystal diffraction analysis of compound 7 confirms the proton transfer from 4,4,4-trifluoro-1-phenyl-1,3-butanedione to N-butylpyrrolidine. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Li, Xiaoju,Zeng, Zhuo,Garg, Sonali,Twamley, Brendan,Shreeve, Jean'ne M.
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experimental part
p. 3353 - 3358
(2009/02/07)
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- RUTHENIUM CATALYZED SYNTHESIS OF TERTIARY AMINES FROM AMINES AND ALCOHOLS
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Unsymmetrical secondary and tertiary amines are prepared by the ruthenium catalyzed reaction of alcohols with amines, which provides highly efficient method for synthesis of cyclic amines.
- Murahashi, Shun-Ichi,Kondo, Kaoru,Hakata, Toshiyuki
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p. 229 - 232
(2007/10/02)
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