- Highly Selective Hydrogenative Conversion of Nitriles into Tertiary, Secondary, and Primary Amines under Flow Reaction Conditions
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Flow reaction methods have been developed to selectively synthesize tertiary, secondary, and primary amines depending on heterogeneous platinum-group metal species under catalytic hydrogenation conditions using nitriles as starting materials. A 10 % Pd/C-packed catalyst cartridge affords symmetrically substituted tertiary amines in good to excellent yields. A 10 % Rh/C-packed catalyst cartridge enables the divergent synthesis of secondary and primary amines, with either cyclohexane or acetic acid as a solvent, respectively. Reaction parameters, such as the metal catalyst, solvent, and reaction temperature, and continuous-flow conditions, such as flow direction and second support of the catalyst in a catalyst cartridge, are quite important for controlling the reaction between the hydrogenation of nitriles and nucleophilic attack of in situ-generated amines to imine intermediates. A wide variety of aliphatic and aromatic nitriles could be highly selectively transformed into the corresponding tertiary, secondary, and primary amines by simply changing the metal species of the catalyst or flow parameters. Furthermore, the selective continuous-flow methodologies are applied over at least 72 h to afford three different types of amines in 80–99 % yield without decrease in catalytic activities.
- Yamada, Tsuyoshi,Park, Kwihwan,Furugen, Chikara,Jiang, Jing,Shimizu, Eisho,Ito, Naoya,Sajiki, Hironao
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- Thiamine hydrochloride as a recyclable organocatalyst for the efficient and chemoselective N-tert-butyloxycarbonylation of amines
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Thiamin hydrochloride promoted highly efficient and ecofriendly approach has been described for the chemoselective N-tert-butyloxycarbonylation of amines under solvent-free conditions at ambient temperature. The demonstrated approach has been applicable for the N-Boc protection of variety of aliphatic, aryl, heteroaryl amines. The chemoselective protection of amino group occurs in chiral amines and amino alcohol without racemization in high yield. Thiamin hydrochloride is stable, economical, easy to handle and environmentally friendly.
- Ingale, Ajit P.,Garad, Dnyaneshwar N.,Ukale, Dattatraya,Thorat, Nitin M.,Shinde, Sandeep V.
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supporting information
p. 3791 - 3804
(2021/11/04)
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- Ultrasound promoted environmentally benign, highly efficient, and chemoselective N-tert-butyloxycarbonylation of amines by reusable sulfated polyborate
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The sulfated polyborate catalyzed an efficient and chemoselective N-tert-butyloxycarbonylation of amines under ultrasonic irradiation is developed. A broad substrate scope has been demonstrated for N-Boc protection of various primary/secondary amines. It allows converting several aliphatic/aryl/heteroaryl amines, amino alcohol, aminoester, and chiral amines to their N-Boc-protected derivatives under solvent-free conditions with excellent yields. The protocol has several advantages such as easy catalyst, and product isolation, short reaction time, excellent yields, outstanding chemoselectivity, and catalyst recyclability, among others. This makes the process practicable, economical, and environmentally benign.
- Pise, Ashok S.,Ingale, Ajit P.,Dalvi, Navnath R.
-
supporting information
p. 3768 - 3780
(2021/10/26)
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- Sulfated tungstate: A highly efficient, recyclable and ecofriendly catalyst for chemoselective N-tert butyloxycarbonylation of amines under the solvent-free conditions
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Sulfated tungstate catalyzed an efficient and ecofriendly protocol has been described for the chemoselective N-tert-butyloxycarbonylation of amines under the solvent-free conditions at room temperature. The variety of functionalized aliphatic, aromatic and heteroaromatic amines efficiently undergoes the N-tert-butyloxycarbonylation under the developed protocol. The aminoalcohol, aminophenol, aminoester as well as various chiral amines underwent the chemoselective N-Boc protection under the optimized reaction condition. The rapid reaction rate, mild conditions, very good functional group tolerance, excellent yield, solvent-free, easy recovery products and excellent catalyst recyclability are the advantages of this protocol. This makes the protocol feasible, economical and environmentally benign.
- Ingale, Ajit P.,Shinde, Sandeep V.,Thorat, Nitin M.
-
supporting information
p. 2528 - 2543
(2021/07/02)
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- Non-innocent Radical Ion Intermediates in Photoredox Catalysis: Parallel Reduction Modes Enable Coupling of Diverse Aryl Chlorides
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We describe a photocatalytic system that elicits potent photoreductant activity from conventional photocatalysts by leveraging radical anion intermediates generated in situ. The combination of an isophthalonitrile photocatalyst and sodium formate promotes diverse aryl radical coupling reactions from abundant but difficult to reduce aryl chloride substrates. Mechanistic studies reveal two parallel pathways for substrate reduction both enabled by a key terminal reductant byproduct, carbon dioxide radical anion.
- Chernowsky, Colleen P.,Chmiel, Alyah F.,Wickens, Zachary K.,Williams, Oliver P.,Yeung, Charles S.
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supporting information
p. 10882 - 10889
(2021/07/31)
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- Radical Chain Reduction via Carbon Dioxide Radical Anion (CO2?-)
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We developed an effective method for reductive radical formation that utilizes the radical anion of carbon dioxide (CO2?-) as a powerful single electron reductant. Through a polarity matched hydrogen atom transfer (HAT) between an electrophilic radical and a formate salt, CO2?- formation occurs as a key element in a new radical chain reaction. Here, radical chain initiation can be performed through photochemical or thermal means, and we illustrate the ability of this approach to accomplish reductive activation of a range of substrate classes. Specifically, we employed this strategy in the intermolecular hydroarylation of unactivated alkenes with (hetero)aryl chlorides/bromides, radical deamination of arylammonium salts, aliphatic ketyl radical formation, and sulfonamide cleavage. We show that the reactivity of CO2?- with electron-poor olefins results in either single electron reduction or alkene hydrocarboxylation, where substrate reduction potentials can be utilized to predict reaction outcome.
- Hendy, Cecilia M.,Smith, Gavin C.,Xu, Zihao,Lian, Tianquan,Jui, Nathan T.
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supporting information
p. 8987 - 8992
(2021/07/01)
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- Metal-Free Deoxygenation of Chiral Nitroalkanes: An Easy Entry to α-Substituted Enantiomerically Enriched Nitriles
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A metal-free, mild and chemodivergent transformation involving nitroalkanes has been developed. Under optimized reaction conditions, in the presence of trichlorosilane and a tertiary amine, aliphatic nitroalkanes were selectively converted into amines or nitriles. Furthermore, when chiral β-substituted nitro compounds were reacted, the stereochemical integrity of the stereocenter was maintained and α-functionalized nitriles were obtained with no loss of enantiomeric excess. The methodology was successfully applied to the synthesis of chiral β-cyano esters, α-aryl alkylnitriles, and TBS-protected cyanohydrins, including direct precursors of four active pharmaceutical ingredients (ibuprofen, tembamide, aegeline and denopamine).
- Pirola, Margherita,Faverio, Chiara,Orlandi, Manuel,Benaglia, Maurizio
-
supporting information
p. 10247 - 10250
(2021/06/18)
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- Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
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Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
- K?nig, Burkhard,Wang, Hua,Wang, Shun
-
p. 1653 - 1665
(2021/06/17)
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- Electrochemical phenothiazination of naphthylamines and its application in photocatalysis
-
N-Phenylphenothiazine as an inexpensive, highly reductive and oxygen tolerant organophotocatalyst has exhibited potential in various challenging photochemical transformations. Here we report a general and straightforward method to access structurally diverse N-phenylphenothiazine derivatives by means of a novel electrochemical tool. The introduction of a 2-naphthylamine moiety with an extended π-system and an amine group led to the variation of spectral characterization. Photochemical verification experiments demonstrated that the formed N-arylation products with good efficacy and chemo/site-control displayed competitive catalytic activity in challenging transformations. This journal is
- Chen, Song,Li, Ya-Nan,Xiang, Shao-Hua,Li, Shaoyu,Tan, Bin
-
supporting information
p. 8512 - 8515
(2021/08/31)
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- Highly efficient chemoselective N-tert butoxycarbonylation of aliphatic/aromatic/heterocyclic amines using diphenylglycoluril as organocatalyst
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An efficient approach for the Chemoselective N-tert-butoxycarbonylation of a variety of amines using diphenylglycoluril as organocatalyst has been described. For the first time, a plausible mechanism for the N-tert-butoxycarbonylation has been proposed using density functional theory (DFT) calculations supported by NMR studies. The reusability of the organocatalyst and observation of the desired N-Boc protected amines being formed without the formation of side products like urea, oxazolidinone, isocyanate, and N, N-di-Boc derivatives makes the present protocol desirable.
- Awasthi, Amardeep,Mukherjee, Anagh,Singh, Mandeep,Rathee, Garima,Vanka, Kumar,Chandra, Ramesh
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- A Greener Approach for the Chemoselective Boc Protection of Amines Using Sulfonated Reduced Graphene Oxide as a Catalyst in Metal- And Solvent-Free Conditions
-
Sulfonated reduced graphene oxide (SrGO) has displayed great potential as a solid acid catalyst due to its efficiency, cost-effectiveness, and reliability. In this study, SrGO was synthesized by the introduction of sulfonic acid-containing aryl radicals onto chemically reduced graphene oxide using ultrasonication. The SrGO catalyst was characterized by Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). Further, SrGO was effectively utilized as a metal-free and reusable solid acid catalyst for the chemoselective N - t -Boc protection of various aromatic and aliphatic amines under solvent-free conditions. The N - t -Boc protection of amines was easily achieved under ambient conditions affording high yields (84-95percent) in very short reaction times (5 min-2 h). The authenticity of the approach was confirmed by a crystal structure. The catalyst could be easily recovered and was reused up to seven consecutive catalytic cycles without any substantial loss in its activity.
- Awasthi, Satish K.,Mishra, Anupam,Mittal, Rupali
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p. 591 - 601
(2020/02/13)
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- Method for preparing amine compound by alkali-catalyzed decarboxylation (by machine translation)
-
The method is simple and convenient (reaction conditions ;), more stable,atom utilization rate, by-products are only carbon dioxide pollution, and the yield can reach. suitable for industrial production Curtis; and the method, Lossen is suitable for industrial production . The method disclosed by the invention is simple and convenient to operate under the action of a base as, rearrangement, rearrangement reaction of an alkyl, aryl or heterocyclic aromatic carboxylic acid or an ester and hydroxylamine compound, 90%. (by machine translation)
- -
-
Paragraph 0035
(2020/03/25)
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- Tert-Butyl(3-cyano-4,6-dimethylpyridin-2-yl)carbonate as a green and chemoselective N-tert-butoxycarbonylation reagent
-
The use of tert-butyl(3-cyano-4,6-dimethylpyridin-2-yl)carbonate as a chemoselective tert-butoxycarbonylation reagent for aromatic and aliphatic amines has been demonstrated. To gain insight into this reaction, in situ React IR technology was used to confirm the effectivity and chemoselectivity of this novel Boc reagent. The reaction was carried out chemoselectively in high yield under mild, environment-friendly conditions and was completed quickly within 1 hour. Simultaneously, the Boc carrier was easily recyclable, and has great application prospects for industrial production.
- Du, Fangyu,Zhou, Qifan,Fu, Yang,Zhao, Hanqi,Chen, Yuanguang,Chen, Guoliang
-
supporting information
p. 6549 - 6554
(2019/05/04)
-
- Deacetylative Amination of Acetyl Arenes and Alkanes with C-C Bond Cleavage
-
The Br?nsted acid-catalyzed synthesis of primary amines from acetyl arenes and alkanes with C-C bond cleavage is described. Although the conversion from an acetyl group to amine has traditionally required multiple steps, the method described herein, which uses an oxime reagent as an amino group source, achieves the transformation directly via domino transoximation/Beckmann rearrangement/Pinner reaction. The method was also applied to the synthesis of γ-aminobutyric acids, such as baclophen and rolipram.
- Hyodo, Kengo,Hasegawa, Genna,Maki, Hiroya,Uchida, Kingo
-
p. 2818 - 2822
(2019/04/25)
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- Hydrosilane-Promoted Facile Deprotection of tert-Butyl Groups in Esters, Ethers, Carbonates, and Carbamates
-
Combination of PdCl2 with 1,1,3,3-tetramethyldisiloxane in the presence of activated carbon was found to be an effective catalyst system for the cleavage reaction of C?O bond of O?t-Bu moieties. The present catalytic reaction offers a practical method for the deprotection of tert-butyl esters, tert-butyl ethers, O-Boc, and N-Boc derivatives under mild conditions. The addition of activated carbon in the reaction mixture was proved to be crucial for not only sustaining the catalytic activity but also trapping the palladium species after the reaction. (Figure presented.).
- Ikeda, Takuya,Zhang, Zhenzhong,Motoyama, Yukihiro
-
supporting information
p. 673 - 677
(2019/01/04)
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- Catalytic Strategy for Regioselective Arylethylamine Synthesis
-
A mild, modular, and practical catalytic system for the synthesis of the highly privileged phenethylamine pharmacophore is reported. Using a unique combination of organic catalysts to promote the transfer of electrons and hydrogen atoms, this system performs direct hydroarylation of vinyl amine derivatives with a wide range of aryl halides (including aryl chlorides). This general and highly chemoselective protocol delivers a broad range of arylethylamine products with complete regiocontrol. The utility of this process is highlighted by its scalability and the modular synthesis of an array of bioactive small molecules.
- Boyington, Allyson J.,Seath, Ciaran P.,Zearfoss, Avery M.,Xu, Zihao,Jui, Nathan T.
-
supporting information
p. 4147 - 4153
(2019/03/07)
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- Decarboxylative Elimination of N-Acyl Amino Acids via Photoredox/Cobalt Dual Catalysis
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A dual-catalytic strategy for the synthesis of enamides and enecarbamates directly from easily accessible and inexpensive amino acids has been realized. This mild and efficient protocol makes use of an organic photoredox catalyst and a cobaloxime catalyst to achieve decarboxylative elimination using hydrogen evolution to drive the oxidation. Thus, the reaction occurs without a stoichiometric oxidant or the forcing conditions previously employed in attempts to achieve similar eliminations.
- Cartwright, Kaitie C.,Tunge, Jon A.
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p. 11801 - 11806
(2018/12/11)
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- Base-Mediated Intramolecular Decarboxylative Synthesis of Alkylamines from Alkanoyloxycarbamates
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A general and effective method for the synthesis of alkylamine via intramolecular decarboxylation of alkanoyloxycarbamates is described. The alkanoyloxycarbamates are readily prepared with alkyl carboxylic acids and hydroxylamine. The reaction shows a broad range of substrates (primary and secondary alkyl) with functional tolerance, and the corresponding products were obtained in good yields under mild conditions.
- Li, Peihe,Ma, Nuannuan,Wang, Zheng,Dai, Qipu,Hu, Changwen
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p. 8233 - 8240
(2018/05/31)
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- Catalytic Reductions and Tandem Reactions of Nitro Compounds Using in Situ Prepared Nickel Boride Catalyst in Nanocellulose Solution
-
A mild and efficient method for the in situ reduction of a wide range of nitroarenes and aliphatic nitrocompounds to amines in excellent yields using nickel chloride/sodium borohydride in a solution of TEMPO-oxidized nanocellulose in water (0.01 wt %) is described. The nanocellulose has a stabilizing effect on the catalyst, which increases the turnover number and enables low loading of nickel catalyst (0.1-0.25 mol % NiCl2). In addition, two tandem protocols were developed in which the in situ formed amines were either Boc-protected to carbamates or further reacted with an epoxide to yield β-amino alcohols in excellent yields.
- Prathap, Kaniraj Jeya,Wu, Qiong,Olsson, Richard T.,Dinér, Peter
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supporting information
p. 4746 - 4749
(2017/09/23)
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- One-pot synthesis of primary amines from carboxylic acids through rearrangement of in situ generated hydroxamic acid derivatives
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A one-pot synthesis of primary amines from carboxylic acids through a Lossen rearrangement of hydroxamic acid derivatives, which were in situ generated by the reaction of carboxylic acids with O-trimethylsilylhydroxylamine (NH2OTMS) and carbonyl diimidazole (CDI, 1.5 equiv) in dimethyl sulfoxide at room temperature, has been achieved. This one-pot method could be applied to various carboxylic acids such as aromatic, heteroaromatic, aliphatic, and optically active substrates.
- Hoshino, Yujiro,Ohtsuka, Naoya,Okada, Takuya,Honda, Kiyoshi
-
supporting information
p. 5304 - 5307
(2016/11/16)
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- A strategy for generating alkyl radicals from aliphatic esters and lactones via sequential hydrolysis and photoinduced decarboxylation
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Sequential hydrolysis and photoinduced decarboxylation of methyl aliphatic esters lead to efficient generation of alkyl radicals under mild conditions. The generated alkyl radicals react with a variety of reagents to produce addition, reduction, and substitution products. In addition, the new tin and halogen free process for alkyl radical generation is applicable to a variety of aliphatic esters including those of dipeptides, steroids, saccharides, and lactones.
- Saito, Hikaru,Kanetake, Takayuki,Osaka, Kazuyuki,Maeda, Kousuke,Morita, Toshio,Yoshimi, Yasuharu
-
supporting information
p. 1645 - 1648
(2015/03/14)
-
- An Aminopyridinato Titanium Catalyst for the Intramolecular Hydroaminoalkylation of Secondary Aminoalkenes
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The easily accessible 2-(methylamino)pyridinato titanium complex initially synthesized by Kempe is used as catalyst for efficient intramolecular hydroaminoalkylation reactions of secondary aminoalkenes. The corresponding reactions of N-aryl-substituted 1-aminohept-6-enes and 1-aminohex-5-enes directly give access to 2-methylcyclohexyl- or 2-methylcyclopentylamines in good yields. In addition, intramolecular hydroaminoalkylations of an N-alkyl-substituted secondary aminoalkene and a geminally β-disubstituted substrate are described for the first time. While all products are formed as mixtures of two diastereoisomers, better trans/cis ratios are observed during the formation of 2-methylcylopentylamines.
- D?rfler, Jaika,Bytyqi, Besnik,Hüller, Sascha,Mann, Nicola M.,Brahms, Christian,Schmidtmann, Marc,Doye, Sven
-
supporting information
p. 2265 - 2276
(2015/07/27)
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- Self-propagated Lossen rearrangement induced by a catalytic amount of activating agents under mild conditions
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A mild self-propagated Lossen rearrangement induced by a catalytic amount of activating agents in medium to high polar organic solvents has been developed. The rearrangement of aromatic and aliphatic hydroxamic acids in the presence of a catalytic amount (0.01 equiv) of acetic anhydride and an equimolar amount of base such as well-dried potassium carbonate afforded the corresponding amines in high yields. This alternative to traditional Lossen rearrangement provides a simple and mild method for the synthesis of amines from free hydroxamic acids.
- Hoshino, Yujiro,Shimbo, Yuki,Ohtsuka, Naoya,Honda, Kiyoshi
-
supporting information
p. 710 - 712
(2015/01/30)
-
- N-Protection of amines using pyridinium 2,2,2-trifluoroacetate ionic liquid as an efficient and reusable catalyst
-
A simple, green, and efficient method for the N-tert-butoxycarbonylation of amines by pyridinium 2,2,2-trifluoroacetate ([Py][OTf]) as an efficient and reusable catalyst is reported. In general, electron donating groups on aryl group give rise to the higher yields than electron withdrawing groups. Clean reaction, short reaction times, high yields, reusability of catalyst, and easy preparation of it are some advantages of this work.
- Karimian, Somaye,Tajik, Hassan
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p. 218 - 220
(2014/02/14)
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- Photocatalytic decarboxylative reduction of carboxylic acids and its application in asymmetric synthesis
-
The decarboxylative reduction of naturally abundant carboxylic acids such as α-amino acids and α-hydroxy acids has been achieved via visible-light photoredox catalysis. By using an organocatalytic photoredox system, this method offers a mild and rapid entry to a variety of high-value compounds including medicinally relevant scaffolds. Regioselective decarboxylation is achieved when differently substituted dicarboxylic acids are employed. The application of this method to the synthesis of enantioenriched 1-aryl-2,2,2-trifluoroethyl chiral amines starting from natural α-amino acids further testifies to the utility of the developed photocatalytic decarboxylative reduction protocol.
- Cassani, Carlo,Bergonzini, Giulia,Wallentin, Carl-Johan
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supporting information
p. 4228 - 4231
(2014/09/30)
-
- A synthetic dolastatin 10 analogue suppresses microtubule dynamics, inhibits cell proliferation, and induces apoptotic cell death
-
We have synthesized eight analogues (D1-D8) of dolastatin 10 containing several unique amino acid subunits. Of these agents, D5 was found to be most effective in inhibiting both HeLa cell proliferation and microtubule assembly in vitro. At low nanomolar concentrations, D5 inhibited the proliferation of several types of cancer cells in culture. D5 bound to tubulin with a dissociation constant of 29.4 ± 6 μM. D5 depolymerized microtubules in cultured cells and produced mulitpolar spindles. At its half-maximal inhibitory concentration (15 nM), D5 strongly suppressed the dynamics of individual microtubules in live MCF-7 cells. D5 increased the accumulation of checkpoint proteins BubR1 and Mad2 at the kinetochoric region and caused G2/M block in these cells. The blocked cells underwent apoptosis with the activation of Jun N-terminal kinase. The results suggested that D5 exerts its antiproliferative action by dampening microtubule dynamics.
- Gajula, Praveen Kumar,Asthana, Jayant,Panda, Dulal,Chakraborty, Tushar Kanti
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p. 2235 - 2245
(2013/05/22)
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- INHIBITION OF BACTERIAL BIOFILMS WITH ARYL CARBAMATES
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Disclosure is provided for carbamate compounds that prevent, remove and/or inhibit the formation of biofilms, compositions including these compounds, devices including these compounds, and methods of using the same.
- -
-
Page/Page column 33
(2012/02/01)
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- Direct stereospecific amination of alkyl and aryl pinacol boronates
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The direct amination of alkyl and aryl pinacol boronates is accomplished with lithiated methoxyamine. This reaction directly provides aliphatic and aromatic amines, stereospecifically, and without preactivation of the boronate substrate.
- Mlynarski, Scott N.,Karns, Alexander S.,Morken, James P.
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supporting information
p. 16449 - 16451,3
(2020/09/15)
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- Nucleophilic substitution reaction at the nitrogen of arylsulfonamides with phosphide anion
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A novel nucleophilic substitution reaction at the nitrogen of arylsulfonamides by means of phosphide anions has been described. This reaction allows for the efficient transformation of arylsulfonamides into synthetically valuable phosphamides, amines, and a variety of protected amines.
- Yoshida, Suguru,Igawa, Kazunobu,Tomooka, Katsuhiko
-
supporting information
p. 19358 - 19361
(2013/02/22)
-
- Design-driven LO: The discovery of new ultra long acting dibasic β2-adrenoceptor agonists
-
Starting with the molecular scaffold of the DA2/β 2 dual agonist sibenadet (Viozan), a number of molecular changes were incorporated, which were designed to increase the potency and selectivity of the target molecule, and improve its
- Connolly, Stephen,Alcaraz, Lilian,Bailey, Andrew,Cadogan, Elaine,Christie, Jadeen,Cook, Anthony R.,Fisher, Adrian J.,Hill, Stephen,Humphries, Alexander,Ingall, Anthony H.,Kane, Zoe,Paine, Stuart,Pairaudeau, Garry,Stocks, Michael J.,Young, Alan
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scheme or table
p. 4612 - 4616
(2011/09/12)
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- Saccharin sulfonic acid catalyzed N-Boc protection of amines and formation of tertbutyl ethers from alcohols
-
Saccharin sulfonic acid (SaSA), as a stable reagent is easily prepared by the reaction of saccharin with neat chlorosulfonic acid at room temperature. This compound is able to catalyze conversion of amines to their corresponding N-Boc protected amines with (Boc)2O. Alcohols were also converted to their corresponding tert-butyl ethers. All reactions took place under mild conditions giving the desired products in good to high yields.
- Shirini,Zolfigol,AbediniM.
-
experimental part
p. 603 - 607
(2010/10/21)
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- Synthesis of carbamates from amines and dialkyl carbonates: Influence of leaving and entering groups
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A number of carbamates were synthesised through a halogen-free process by reacting amines with symmetrical and unsymmetrical carbonates. The results obtained showed a specific trend of preferred leaving groups (in the dialkyl carbonates) depending on whether a catalyst or a base was used. On the other hand, investigations conducted on the preferred entering groups (amines) for the synthesis of carbamates showed the same trend regardless of whether a catalyst or a base was used. Finally, in accordance with the results obtained, it was possible to synthesise sterically hindered carbamates in high yield by transesterification of methyl carbamate with a sterically hindered alcohol. Georg Thieme Verlag Stuttgart New York.
- Tundo, Pietro,McElroy, C. Robert,Aricò, Fabio
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experimental part
p. 1567 - 1571
(2010/09/05)
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- Microwave-assisted N-Boc deprotection under mild basic conditions using K3PO4·H2O in MeOH
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A simple and efficient method for the deprotection of secondary Boc-protected amino compounds under mild basic conditions using K3PO4·H2O in MeOH assisted by microwave irradiation has been presented.
- Dandepally, Srinivasa Reddy,Williams, Alfred L.
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scheme or table
p. 1071 - 1074
(2009/05/11)
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- Microwave-assisted carbamoylation of amines
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The influence of microwave irradiation on the reaction of various amines with benzyl chloroformate and di-tert-butyl dicarbonate was investigated. Microwave irradiation was successfully applied to the carbamoylation of several nonfunctionalized and functionalized amines, including amino acids and nucleobases, leading to satisfactory to high product conversion within very short reaction times. Copyright Taylor & Francis Group, LLC.
- Azzena, Ugo,Dettori, Giovanna,Pisano, Luisa,Pittalis, Mario
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p. 3623 - 3634
(2008/03/13)
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- Decarboxylative reduction of free aliphatic carboxylic acids by photogenerated cation radical
-
The decarboxylation of free carboxylic acids was effected by a photogenerated cation radical of phenanthrene to yield the reduction product in the presence of a thiol, which provides an alternative method to the Barton decarboxylation procedure for aliphatic acids such as N-Boc amino acids. The Royal Society of Chemistry.
- Yoshimi, Yasuharu,Itou, Tatsuya,Hatanaka, Minoru
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p. 5244 - 5246
(2008/09/19)
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- Scope of the Suzuki-Miyaura aminoethylation reaction using organotrifluoroborates
-
(Chemical Equation Presented) Potassium β-aminoethyltrifluoroborates were prepared in good yields via hydroboration of the corresponding enecarbamates using the Snieckus hydroborating reagent. A wide variety of phenethylamines containing a potentially fre
- Molander, Gary A.,Jean-Gerard, Ludivine
-
p. 8422 - 8426
(2008/03/11)
-
- HClO4-SiO2 as a new, highly efficient, inexpensive and reusable catalyst for N-tert-butoxycarbonylation of amines
-
Perchloric acid adsorbed on silica-gel (HClO4-SiO2) was found to be a new, highly efficient, inexpensive and reusable catalyst for chemoselective N-tert-butoxycarbonylation of amines at room temperature and under solvent-free conditions. The Royal Society of Chemistry 2006.
- Chakraborti, Asit K.,Chankeshwara, Sunay V.
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p. 2769 - 2771
(2008/03/28)
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- N-boc protection of amines with di-tert-butyldicarbonate in water under neutral conditions in the presence of β-cyclodextrin
-
A new protocol for protection of aryl and aliphatic amines was developed with (Boc)2O in the presence of β-cyclodextrin in water. A catalytic amount of β-cyclodextrin is specific for activation of amines. This procedure works well on a wide variety of both electron-rich and electron-deficient amines. Georg Thieme Verlag Stuttgart.
- Somi Reddy,Narender,Nageswar,Rama Rao
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p. 1110 - 1112
(2007/10/03)
-
- Ruthenium-induced allylcarbamate cleavage in living cells
-
(Chemical Equation Presented) Easy going: A ruthenium-catalyzed release of amines from their respective allylcarbamates is disclosed and is a step towards the design of catalysts as tools for cellular biology. The reaction tolerates the combination of water, air, and thiols and can be performed inside living mammalian cells. Cp* = pentamethylcyclopentadienyl, cod = 1,5-cyclooctadiene.
- Streu, Craig,Meggers, Eric
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p. 5645 - 5648
(2008/02/07)
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- Useful reagents for introduction of Boc and Fmoc protective groups to amines: Boc-DMT and Fmoc-DMT
-
New amino-protecting reagents, Boc-DMT and Fmoc-DMT, were prepared, and found to be useful for the introduction of Boc and Fmoc groups into amines. Both the reagents can protect various amines including amino acids in good yield in aqueous media. Since the reagents are neither unstable nor irritating, they are practically useful. Georg Thieme Verlag Stuttgart.
- Hioki, Kazuhito,Kinugasa, Mizuho,Kishimoto, Michiko,Fujiwara, Miho,Tani, Shohei,Kunishima, Munetaka
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p. 1931 - 1933
(2007/10/03)
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- Single-step conversion of N-benzyl, N-trityl and N-diphenylmethyl amines to t-butyl carbamates using polymethylhydrosiloxane
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t-Butyl carbamates were obtained efficiently in high yields from the corresponding N-benzyl, N-trityl and N-diphenylmethyl precursors in a single-step reductive transformation employing polymethylhydrosiloxane and di-t-butyl dicarbonate under Pd(OH)2/C catalysis.
- Chandrasekhar,Babu, B. Nagendra,Reddy, Ch. Raji
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p. 2057 - 2059
(2007/10/03)
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- A generic approach for the catalytic reduction of nitriles
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The scope of nickel boride mediated reduction of nitriles has been extended further to allow the preparation of Boc protected amines via a mild catalytic process. It is noteworthy that the toxicity of this procedure is greatly reduced due to its catalytic
- Caddick, Stephen,Judd, Duncan B.,Lewis, Alexandra K. De K.,Reich, Melanie T.,Williams, Meredith R. V.
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p. 5417 - 5423
(2007/10/03)
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- Chemoselective conversion of azides to t-butyl carbamates and amines
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Azides were converted to the corresponding carbamates using a system of 20 mol% of decaborane (B10H14) and 20 weight% of 10% Pd/C in methanol in the presence of di-tert-butyl dicarbonate at rt in high yields and to the corresponding amines using a system of 10 mol% of decaborane and 20 weight% of 10% Pd/C in methanol in the absence of di-tert-butyl dicarbonate at rt in high yields.
- Jung, Yeon Joo,Chang, Yu Mi,Lee, Ji Hee,Yoon, Cheol Min
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p. 8735 - 8739
(2007/10/03)
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- Convenient synthesis of protected primary amines form nitriles
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Investigations into the use of nickel chloride and sodium borohydride for the reduction of nitriles showed the secondary amine dimers to be the major products under normal conditions. The addition of a suitable trapping agent, such as di-tert-butyl dicarbonate, allowed the isolation of the protected primary amines. (C) 2000 Elsevier Science Ltd.
- Caddick, Stephen,De K. Haynes, Alexandra K.,Judd, Duncan B.,Williams, Meredith R.V.
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p. 3513 - 3516
(2007/10/03)
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- Efficient synthesis of protected β-phenylethylamines, enantiomerically pure protected β-phenyl-α-benzylethylamines and β-phenyl-α-isopropylethylamines using organozinc chemistry
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The β-aminoalkylzinc reagents 9a, 10 and 11 have been efficiently prepared using DMF as a solvent. Palladium-catalysed coupling of these reagents with substituted aryl iodides, under mild and convenient conditions, gives protected β-phenylethylamines 6 in
- Hunter, Christopher,Jackson, Richard F. W.,Rami, Harshad K.
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p. 219 - 223
(2007/10/03)
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- A convenient transformation of N-substituted ureas into N-(t-butoxycarbonyl)amines using a copper(II) salt-lithium t-butoxide system
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Treatment of N-substituted ureas with a copper(II) reagent prepared from lithium t-butoxide and copper(II) halide led to give the corresponding N-(t-butoxycarbonyl)amines under mild conditions. On the contrary, no reaction of N,N-disubstituted ureas proce
- Yamaguchi, Jun-ichi,Shusa, Yuji,Suyama, Takayuki
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p. 8251 - 8254
(2007/10/03)
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- N-carboalkoxy-2-nitrobenzenesulfonamides: A practical preparation of N- Boc-, N-Alloc-, and N-Cbz-protected primary amines
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N-Carboalkoxy-2-nitrobenzenesulfonamides, readily prepared by acylation of 2-nitrobenzenesulfonamide (o-NsNH2), can be alkylated by either conventional or Mitsunobu protocols. Since the o-nosyl group can be deprotected under mild conditions, a variety of N-carboalkoxy derivatives of primary amines may be prepared in excellent yields from the corresponding alcohols and/or halides. In addition, allyloxycarbonyl (Alloc), t- butoxycarbonyl (t-Boc), and benzyloxycarbonyl (Cbz) groups can be deprotected in the presence of the o-nosyl group, allowing the resultant N-alkylated 2- nitrobenzenesulfonamides to be used for further preparation of secondary amines.
- Fukuyama, Tohru,Cheung, Mui,Kan, Toshiyuki
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p. 1301 - 1303
(2007/10/03)
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- Antithrombotic azacycloalkylalkanoyl peptides and pseudopeptides
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The present invention relates to azacycloalkylalkanoyl peptides and pseudopeptides which inhibit platelet aggregation and thrombus formation thereby being useful in the prevention and treatment of thrombosis associated with disease states such as myocardial infarction, stroke, peripheral arterial disease, and disseminated intravascular coagulation, to methods for the prevention or treatment of thrombosis in a mammal in need of such therapy comprising the administration of a therapeutically effective amount of such compounds, and to pharmaceutical compositions comprising such compounds.
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- Chemoselective alkoxycarbonylation reagent having trifluoromethylsulfonyl-4-trifluoromethylanilide as a leaving group
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N-Benzyloxy- and N-tert-butoxycarbonyltrifluoromethylsulfonyl-4-trifluoromethylanilides were prepared and were found to be chemoselective and shelf-storable alkoxycarbonylation reagents.
- Yasuhara, Tomohisa,Nagaoka, Yasuo,Tomioka, Kiyoshi
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p. 2233 - 2234
(2007/10/03)
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- One-pot conversion of azides to Boc-protected amines with trimethylphosphine and Boc-ON
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Reaction of azides with trimethylphosphine followed by addition of 2- (tert-butoxycarbonyloxyimino)-2-phenyl-acetonitrile (Boc-ON) at -20°C and stirring at r.t. for 5 h affords the desired Boc-amines in 87-100% yields. Similar types are obtained by mixing
- Ariza, Xavier,Urpi, Felix,Viladomat, Carles,Vilarrasa, Jaume
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p. 9101 - 9102
(2007/10/03)
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