- Nickel Boride Catalyzed Reductions of Nitro Compounds and Azides: Nanocellulose-Supported Catalysts in Tandem Reactions
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Nickel boride catalyst prepared in situ from NiCl2 and sodium borohydride allowed, in the presence of an aqueous solution of TEMPO-oxidized nanocellulose (0.01 wt%), the reduction of a wide range of nitroarenes and aliphatic nitro compounds. Here we describe how the modified nanocellulose has a stabilizing effect on the catalyst that enables low loading of the nickel salt pre-catalyst. Ni-B prepared in situ from a methanolic solution was also used to develop a greener and facile reduction of organic azides, offering a substantially lowered catalyst loading with respect to reported methods in the literature. Both aromatic and aliphatic azides were reduced, and the protocol is compatible with a one-pot Boc-protection of the obtained amine yielding the corresponding carbamates. Finally, bacterial crystalline nanocellulose was chosen as a support for the Ni-B catalyst to allow an easy recovery step of the catalyst and its recyclability for new reduction cycles.
- Proietti, Giampiero,Prathap, Kaniraj Jeya,Ye, Xinchen,Olsson, Richard T.,Dinér, Peter
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supporting information
p. 133 - 146
(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.
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supporting information
p. 3768 - 3780
(2021/10/26)
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- Nanoceria as an efficient and green catalyst for the chemoselective N-tert-butyloxycarbonylation of amines under the solvent-free conditions
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Nanocerium oxide mediated an efficient and green protocol has been described for the chemoselective N-tert-butyloxycarbonylation of amines under the solvent-free conditions at ambient temperature. Various aliphatic, aromatic and heteroaromatic amines were protected using developed protocol and several functional groups such as alcohol, phenol and ester were well tolerated under these conditions. 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.
- Garad, Dnyaneshwar N.,Ingale, Ajit P.,Shinde, Sandeep V.,Ukale, Dattatraya
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supporting information
p. 1656 - 1668
(2021/04/05)
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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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- 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.
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supporting information
p. 2528 - 2543
(2021/07/02)
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- Solvent-freeN-Boc deprotection byex situgeneration of hydrogen chloride gas
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An efficient, scalable and sustainable method for the quantitative deprotection of thetert-butyl carbamate (N-Boc) protecting group is described, using down to near-stoichiometric amounts of hydrogen chloride gas in solvent-free conditions. We demonstrate theex situgeneration of hydrogen chloride gas from sodium chloride and sulfuric acid in a two-chamber reactor, introducing a straightforward method for controlled and stoichiometric release of HCl gas. The solvent-free conditions allow deprotection of a wide variety ofN-Boc derivatives to obtain the hydrochloride salts in quantitative yields. The procedure obviates the need for any work-up or purification steps providing an uncomplicated green alternative to standard methods. Due to the solvent-free, anhydrous conditions, this method shows high tolerance towards acid sensitive functional groups and furnishes expanded functional group orthogonality.
- De Borggraeve, Wim M.,Gilles, Philippe,Van Mileghem, Seger,Verschueren, Rik H.
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supporting information
p. 5782 - 5787
(2021/07/12)
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- Integrating Hydrogen Production and Transfer Hydrogenation with Selenite Promoted Electrooxidation of α-Nitrotoluenes to E-Nitroethenes
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Developing an electrochemical carbon-added reaction with accelerated kinetics to replace the low-value and sluggish oxygen evolution reaction (OER) is markedly significant to pure hydrogen production. Regulating the critical steps to precisely design electrode materials to selectively synthesize targeted compounds is highly desirable. Here, inspired by the surfaced adsorbed SeOx2? promoting OER, NiSe is demonstrated to be an efficient anode enabling α-nitrotoluene electrooxidation to E-nitroethene with up to 99 % E selectivity, 89 % Faradaic efficiency, and the reaction rate of 0.25 mmol cm?2 h?1 via inhibiting side reactions for energy-saving hydrogen generation. The high performance can be associated with its in situ formed NiOOH surface layer and absorbed SeOx2? via Se leaching-oxidation during electrooxidation, and the preferential adsorption of two -NO2 groups of intermediate on NiOOH. A self-coupling of α-carbon radicals and subsequent elimination of a nitrite molecule pathway is proposed. Wide substrate scope, scale-up synthesis of E-nitroethene, and paired productions of E-nitroethene and hydrogen or N-protected aminoarenes over a bifunctional NiSe electrode highlight the promising potential. Gold also displays a similar promoting effect for α-nitrotoluene transformation like SeOx2?, rationalizing the strategy of designing materials to suppress side reactions.
- Chong, Xiaodan,Liu, Cuibo,Wang, Changhong,Yang, Rong,Zhang, Bin
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p. 22010 - 22016
(2021/09/02)
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- Application of allylic amine formation from aziridine-2-ol under Appel reaction condition: Synthesis of N-(tert-butoxycarbonyl)-D-vinyl glycine methyl ester
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PPh3/I2/imidazolde mediated allyl amine formation from aziridine-2-alcohol was explored for the synthesis of N-(tert-butoxycarbonyl)-D-vinyl glycine methyl ester.
- Chavan, Subhash P.,Kawale, Sanket A.,Patil, Niteen B.,Kalbhor, Dinesh B.
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supporting information
(2021/05/18)
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- A One-Pot Iodo-Cyclization/Transition Metal-Catalyzed Cross-Coupling Sequence: Synthesis of Substituted Oxazolidin-2-ones from N-Boc-allylamines
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A one-pot iodo-cyclization/transition metal-catalyzed cross-coupling sequence is reported to access various C5-functionalized oxazolidin-2-ones from unsaturated N-Boc-allylamines. Depending on the Grignard reagents used for the cross-coupling, e.g., aryl- or cyclopropylmagnesium bromide, a cobalt or copper catalyst has to be used to obtain the functionalized oxazolidin-2-ones in good yields.
- Chaumont-Olive, Pauline,Cossy, Janine
-
supporting information
(2020/05/14)
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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
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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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- Amidate compound, catalyst for polyurethane production, and method for producing polyurethane resin
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Provided is an amidate compound represented by the formula (1): wherein A is a substituted or unsubstituted hydrocarbon group, n is an integer of 1 or more, and D is a nitrogen-containing organic group represented by the formula (2): wherein R1, R2, and R3 are the same or different, and are each a hydrocarbon group that may contain a heteroatom; some or all of R1, R2, and R3 may be bonded together to form a ring structure; X is a nitrogen atom, an oxygen atom, or a sulfur atom; and a is 0 or 1, wherein a is 1 when X is a nitrogen atom, and a is 0 when X is an oxygen atom or a sulfur atom.
- -
-
Page/Page column 126; 127
(2020/07/09)
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- PRODUCTION METHOD FOR AMIDATE COMPOUND
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A method for producing an amidate compound represented by Formula (3), comprising reacting a urethane compound represented by Formula (1) with a carboxylate compound represented by Formula (2): (in the formulas, A, n, R1, R2, R3, R4, R5, R6, X, and a are as described in the Description).
- -
-
Paragraph 0147-0149
(2020/02/13)
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- O-Alkyl S-(Pyridin-2-yl)carbonothiolates: Operationally Simple and Highly Nitrogen-Selective Reagents for Alkoxy Carbonylation of Amino Groups
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Amino groups are selectively protected in good yields by reaction with O-Alkyl S-(pyridin-2-yl)carbonothiolates in an appropriate solvent at room temperature in air. Even glucosamine, which contains multiple hydroxyl groups, is selectively N-protected in methanol.
- Hashimoto, Yoshimitsu,Morita, Nobuyoshi,Suzuki, Tomoyuki,Tamura, Osamu,Tanaka, Kosaku
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p. 899 - 902
(2020/05/28)
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- Organic/inorganic Fe3O4@MCM-41@Zr-piperazine: An impressive magnetite nanocatalyst for N-Tert-Butoxycarbonylation of amines
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Fe3O4@MCM-41@Zirconium magnetic nanoparticles modified with piperazine (Fe3O4@MCM-41@Zr-piperazine), as a newly reported catalyst, shows excellent catalytic activity in N-tertbutoxycarbonylation of amines under the mild and solvent-free conditions. Accordingly, different derivatives of N-tert-butylcarbamates owning diverse aliphatic, aromatic and heteroaromatic amines were prepared efficiently. Good performance of this method for the majority of used complex or acidsensitive substrates and facile separation of this nanocatalyst due to its superparamagnetic nature from the reaction mixture via an external magnetic field for several times are the most important striking features of this protocol.
- Pourhasan-Kisomi, Reyhaneh,Shirini, Farhad,Golshekan, Mostafa
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p. 3859 - 3870
(2019/05/08)
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- Tert-Butyl(3-cyano-4,6-dimethylpyridin-2-yl)carbonate as a green and chemoselective N-tert-butoxycarbonylation reagent
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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)
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- Reductions of Imines Using Zirconocene Chloride Hydride
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Herein, we describe the fast, chemoselective, and clean reduction of imines with zirconocene chloride hydride. The reaction works well on aromatic and enolizable aliphatic aldimines, as well as ketimines. A range of N-protecting groups and various functio
- Vargová, Denisa,Mudráková, Brigita,Némethová, Ivana,?ebesta, Radovan
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p. 7606 - 7612
(2019/12/03)
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- Unlocking the potential of phenacyl protecting groups: CO2-based formation and photocatalytic release of caged amines
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Orthogonal protection and deprotection of amines remain important tools in synthetic design as well as in chemical biology and material research applications. A robust, highly efficient, and sustainable method for the formation of phenacyl-based carbamate esters was developed using CO2 for the in situ preparation of the intermediate carbamates. Our mild and broadly applicable protocol allows for the formation of phenacyl urethanes of anilines, primary amines, including amino acids, and secondary amines in high to excellent yields. Moreover, we demonstrate the utility by a mild and convenient photocatalytic deprotection protocol using visible light. A key feature of the [Ru(bpy)3](PF6)2-catalyzed method is the use of ascorbic acid as reductive quencher in a neutral, buffered, two-phase acetonitrile/water mixture, granting fast and highly selective deprotection for all presented examples.
- Speckmeier, Elisabeth,Klimkait, Michael,Zeitler, Kirsten
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p. 3738 - 3745
(2018/04/14)
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- Highly Selective Syn Addition of 1,3-Diones to Internal Ynamides Catalyzed by Zinc Iodide
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1,3-Diones are already established as nucleophiles to perform additions to ynamides; the highly selective hydroalkoxylation of internal ynamides is now described. Several catalytic systems have been compared to perform this transformation, including transition-metal-based catalysts and Lewis acids. ZnI2 was found to be both very active and highly selective providing only E adducts through a syn addition. Investigation of the scope and limitations showed that this catalyst was compatible with various functional groups. In addition to seventeen examples of ynamide hydroalkoxylation, one example of ynamide hydroarylation is reported.
- Plamont, Rémi,Graux, Lionel V.,Clavier, Hervé
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supporting information
p. 1372 - 1376
(2018/04/02)
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- Chemoselective: N-tert -butyloxycarbonylation of amines in glycerol
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A catalyst-free, efficient and green protocol has been developed for the chemoselective N-Boc protection of amines by using glycerol as a solvent at room temperature. A variety of functionalized amines, such as aliphatic, aromatic as well as heteroaromatic were protected using the developed protocol. N-tert-Butyloxycarbonylation derivatives were formed without the formation of isocyanate, urea, N,N-di-t-Boc, or oxazolidinone as side products. The operational simplicity, cleaner reaction, rapid reaction convergence, functional group tolerance, excellent yield, high selectivity, catalyst-free feature and solvent recyclability are the distinct advantages of this protocol. Owing to these merits, this protocol is feasible, economical and environmentally benign.
- Ingale, Ajit P.,More, Vishal K.,Gangarde, Uddhav S.,Shinde, Sandeep V.
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supporting information
p. 10142 - 10147
(2018/06/18)
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- Aminolithiation–arylation consecutive cyclization of N-(2-fluorophenyl)methylaminoalkylstyryls giving aryl-substituted pyrido[1,2-b]isoquinolines
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Aminolithiation–arylation tandem cyclization of N-(2-fluorophenyl)methylaminoalkylstyryls proceeded smoothly to give hexahydro-2H-pyrido[1,2-b]isoquinoline using a stoichiometric amount of n-BuLi with high trans selectivity. The arylation reaction was highly accelerated by the addition of HMPA. Both pyrido- and pyrrolo-[1,2-b]isoquinoline were successfully constructed by this tandem reaction.
- Yamamoto, Yasutomo,Nakanishi, Yasue,Yamada, Ken-ichi,Tomioka, Kiyoshi
-
supporting information
p. 5309 - 5318
(2018/06/11)
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- Decarboxylative Negishi Coupling of Redox-Active Aliphatic Esters by Cobalt Catalysis
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A cobalt-catalyzed decarboxylative Negishi coupling reaction of redox-active aliphatic esters with organozinc reagents was developed. The method enabled efficient alkyl–aryl, alkyl–alkenyl, and alkyl–alkynyl coupling reactions under mild reaction conditions with no external ligand or additive needed. The success of an in situ activation protocol and the facile synthesis of the drug molecule (±)-preclamol highlight the synthetic potential of this method. Mechanistic studies indicated that a radical mechanism is involved.
- Liu, Xu-Ge,Zhou, Chu-Jun,Lin,Han, Xiang-Lei,Zhang, Shang-Shi,Li, Qingjiang,Wang, Honggen
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p. 13096 - 13100
(2018/09/21)
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- Enantioselective Synthesis of anti-1,2-Diamines by Cu-Catalyzed Reductive Couplings of Azadienes with Aldimines and Ketimines
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Here we report highly efficient and chemoselective azadiene-imine reductive couplings catalyzed by (Ph-BPE)Cu-H that afford anti-1,2-diamines. In all cases, reactions take place with either aldimine or ketimine electrophiles to deliver a single diastereom
- Shao, Xinxin,Li, Kangnan,Malcolmson, Steven J.
-
supporting information
p. 7083 - 7087
(2018/05/29)
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- Method for selective removal of t-butyloxycarboryl from nitrogen
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The invention discloses a method for selective removal of t-butyloxycarboryl from nitrogen. According to the synthesis method, directed at a reaction substrate having t-butyloxycarboryl and another acyl protecting group on a molecular nitrogen atom, in the presence of a selectfluor reagent, reaction is carried out in a solution for selective removal of t-butyloxycarboryl and retention of another acyl protecting group. The synthesis method provided by the invention is novel and efficient, is not reported in literature, and can be widely used in total synthesis and drug intermediate synthesis.
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-
Paragraph 0024-0025; 0026-0028; 0053-0055
(2018/03/26)
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- Efficient and expeditious chemoselective BOC protection of amines in catalyst and solvent-free media
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A green and eco-friendly route for the almost quantitative BOC protection of a large variety of aliphatic and aromatic amines, amino acids, and amino alcohols is reported in catalyst and solvent-free media under mild reaction conditions. The products were confirmed by 1H, 13C NMR, IR spectroscopy, and in some cases, elemental analysis. This protocol does not require any water quenches, solvent separations, and purification steps, such as recrystallization and column chromatography.
- Viswanadham, Balaga,Mahomed, Abdul S.,Friedrich, Holger B.,Singh, Sooboo
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p. 1355 - 1363
(2017/02/15)
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- Sustainable and chemoselective N-Boc protection of amines in biodegradable deep eutectic solvent
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Abstract: A green and practical approach for the chemoselective N-tert-butyloxycarbonylation of structurally diverse amines with di-tert-butyl dicarbonate (Boc2O) is described. Selective N-Boc protection was achieved in excellent yields in urea-choline chloride deep eutectic solvent (DES) as the most promising environmentally benign and cost-effective solvent under mild reaction condition. DES can protect various aromatic and aliphatic amines using Boc2O in good to excellent yields in short reaction times without any side products. Graphical abstract: [Figure not available: see fulltext.].
- Azizi, Najmedin,Shirdel, Fatemeh
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p. 1069 - 1074
(2017/05/12)
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- Copper nanoparticles catalyzed N-H functionalization: An efficient solvent-free N-tert-butyloxycarbonylation strategy
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A chemoselective transformation of amines to their tert-butyloxycarbonyl (Boc) protected derivatives (NBoc) is described using Cu-NPs under solvent-free conditions. Simple method, rapid reaction rate, mild conditions, tolerance of a wide range of functional groups, excellent yield, ease recovery and high catalytic turnover are the salient features of this approach. tert-Butyloxycarbonylation of chiral amino acid esters and amino alcohols were performed without racemization.
- Deb, Barnali,Debnath, Sudipto,Deb, Anindita,Maiti, Dilip K.,Majumdar, Swapan
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supporting information
p. 629 - 633
(2017/01/25)
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- Nickel-catalyzed synthesis of stereochemically defined enamides via Bi- and tricomponent coupling reaction
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The stereoselective synthesis of (E)-trisubstituted tertiary enamides is documented via site-selective Ni-catalyzed β-arylation of allenamides with boronic acids in high yields (up to 89%). The nucleophilic character of the "organo-Ni" intermediates is further exploited to implement a one-pot tricomponent procedure involving the final allylation of aldehydes (yields up to 93%). Mechanistic insights and efficiency on a gram scale process were also documented.
- Liu,De Nisi,Cerveri,Monari,Bandini
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supporting information
p. 5034 - 5037
(2017/11/06)
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- Alpha-oxidation of amine derivatives by bis(2,2,2-tri-chloroethyl) azodicarboxylate and application of its products as iminium ion equivalents
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Alpha-oxidation of amine derivatives by azodicarboxylate was examined. Among several azodicarboxylate esters and amides tested, bis(2,2,2-trichloroethyl) azodicarboxylate, that has highly electrophilic 2,2,2-trichloroethoxycarbonyl functional groups, was found to have excellent oxidation reactivity. Acylated or carbamoylated amines were suitable substrates for this reaction condition. Tertially amines could react in the same manner, but spontaneous elimination of hydrazinyl group occurred to give dimerized products. The reaction products were found to react with nucleophiles in the presence of Lewis or Br?nsted acid catalyst. This strongly suggests that the reaction products, alpha-hydrazinated amine derivatives, might serve as carbonyl group equivalents, very useful intermediates in synthetic organic chemistry.
- Honzawa, Shinobu,Uchida, Mitsuaki,Tashiro, Takuya,Sugihara, Takumichi
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p. 994 - 1029
(2017/07/27)
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- Pathways in the Degradation of Geminal Diazides
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The degradation of geminal diazides is described. We show that diazido acetates are converted into tetrazoles through the treatment with bases. The reaction of dichloro ketones with azide anions provides acyl azides, through in situ formation of diazido ketones. We present experimental and theoretical evidence that both fragmentations may involve the generation of acyl cyanide intermediates. The controlled degradation of terminal alkynes into amides (by loss of one carbon) or ureas (by loss of two carbons) is also shown.
- Holzschneider, Kristina,H?ring, Andreas P.,Haack, Alexander,Corey, Daniel J.,Benter, Thorsten,Kirsch, Stefan F.
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p. 8242 - 8250
(2017/08/14)
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- Efficient chemoselective hydrogenation of organic azides catalyzed by palladium nanoparticles with alkyne-derived homogeneous supports
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Catalytic chemoselective hydrogenation of organic azides using palladium nanoparticles stabilized by alkyne derivatives was studied. A broad range of aromatic and aliphatic azides were smoothly reduced to the corresponding amines in excellent yields with a quite small amount of the catalyst. Hydrogenation of 3-phenylpropylazide gave 3-phenylpropylamine almost quantitatively with a substrate-to-palladium molar ratio (S/Pd) of 12,900 under 8?atm of H2. The reaction under 1?atm of H2also proceeded smoothly with an S/Pd of 1000. Several reduction-sensitive functional groups, such as carbonyl, halide, benzylic OH, and aliphatic nitro were well tolerated under the reaction conditions.
- Arai, Noriyoshi,Onodera, Nozomi,Ohkuma, Takeshi
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p. 4183 - 4186
(2016/08/24)
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- Heterobimetallic dinuclear lanthanide alkoxide complexes as acid-base bifunctional catalysts for synthesis of carbamates under solvent-free conditions
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Heterobimetallic dinuclear lanthanide alkoxide complexes Ln2Na8(OCH2CH2NMe2)12(OH)2 [Ln: I (Nd), II (Sm), III (Yb) and IV (Y)] were used as efficient acid-base bifunctional catalysts for the synthesis of carbamates from dialkyl carbonates and amines as well as the N-Boc protection of amines. The cooperative catalysts showed high catalytic activity and a wide scope of substrates with good to excellent yields under solvent-free conditions. The systems have shown higher catalytic activities due to the noteworthy synergistic interactions of Lewis acid center-Br?nsted basic center. The comparison of catalytic efficiency between mono- and dinuclear heterobimetallic lanthanide alkoxide analogues was also investigated.
- Zeng, Ruijie,Bao, Linquan,Sheng, Hongting,Sun, Lili,Chen, Man,Feng, Yan,Zhu, Manzhou
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p. 78576 - 78584
(2016/09/09)
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- Efficient N-Boc protection of amines by a reusable heterogeneous solid acid nanocatalyst at room temperature
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An efficient and rapid protocol for chemoselective N-Boc protection of various structurally different aryl, aliphatic, and heterocyclic amines is reported with (Boc)2O using mesoporous silica phenylsulfonic acid (SBA-15-Ph-SO3H) as a recyclable and heterogeneous solid acid nanocatalyst under solvent-free condition at ambient temperature. The catalyst can be easily recovered and reused for ten reaction cycles for protection of amines without considerable loss of activity. The advantages of this green method are simplicity, easy workup, chemoselectivity, short reaction time, and excellent yield.
- Veisi, Hojat,Sedrpoushan, Alireza,Ghazizadeh, Habibollah,Hemmati, Saba
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p. 1451 - 1461
(2016/04/26)
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- Diamine precursor process for the production of compounds
-
Provided is an inexpensive, simple, and efficient method for preparing, from a starting material, a nitro compound constituting a diamine precursor compound which is a starting material for producing a polyamic acid and/or polyimide. Compound (1) is reacted according to reaction formula (1) with di-tert-butyl dicarbonate ((Boc)2O) to produce compound (2) (1) (where R1 represents -CH2COOR or -CH2Ph(-Z)m (where Z is a substituent group for a phenyl group (Ph) and m ranges from 0 to 5), and R represents a lower alkyl group or alkali metal atom), compound (2) is then reacted according to reaction formula (2) with H-A-CH2-X to produce compound (3) (2) (where A represents -C=C- or -CH=CH-, and X represents a leaving substituent group), and compound (3) is then subjected to a coupling reaction according to reaction formula (3) with compound (4) to produce compound (5) (3) (where Y represents a leaving substituent group).
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-
Paragraph 0197; 0198; 0199; 0200; 0201; 0202
(2016/10/07)
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- Expanding the scope of Et3B/O2-mediated coupling reactions of O,Te-acetal
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Et3B/O2-mediated radical coupling reactions of O,Te-acetal 2 were explored using diverse electrophilic double bonds. Ethyl radical derived from Et3B under air cleaved the C–Te bond of 2 to generate α-alkoxy bridgehead radi
- Kamimura, Daigo,Nagatomo, Masanori,Urabe, Daisuke,Inoue, Masayuki
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p. 7839 - 7848
(2016/11/17)
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- Aqueous MW eco-friendly protocol for amino group protection
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In this paper a new catalyst-free and on-water method for protection of amines and amino acids with di-tert-butyl dicarbonate, 9-fluorenylmethoxycarbonyl chloride, acetyl chloride and tosyl chloride is presented. The protection can be realized in a few minutes under microwave-assistance. The reaction proved to be chemoselective in presence of ambident nucleophiles and water solution of di-tert-butyl carboxylic acid or chloride acid are the only wastes produced.
- Nardi,Cano, N. Herrera,Costanzo,Oliverio,Sindona,Procopio
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p. 18751 - 18760
(2015/06/15)
-
- Intramolecular carbolithiation of heterosubstituted alkynes: An experimental and theoretical study
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A series of heterosubstitued alkynes was successfully submitted to the intramolecular carbolithiation of their triple bond. We show that the addition is stereoselective because of the control exerted by the terminal substituent X on the geometry of the transition state. A complementary DFT study suggests that the addition is anti when a strong Li-X interaction occurs.
- Lhermet, Rudy,Ahmad, Maha,Hauduc, Clémence,Fressigné, Catherine,Durandetti, Muriel,Maddaluno, Jacques
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supporting information
p. 8105 - 8111
(2015/05/27)
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- Preparation, characterization and application of succinimidinium hydrogensulfate ([H-Suc]HSO4) as an efficient ionic liquid catalyst for the N-Boc protection of amines
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In this work, succinimidinium hydrogensulfate ([H-Suc]HSO4), as a novel Bronsted acidic ionic liquid is prepared and characterized by studying its FT-IR, 1H NMR, 13C NMR, mass and SEM. This reagent can be used as an efficient catalyst for the N-Boc protection of amines at room temperature and neat conditions. This new method consistently has the advantages of excellent yields and short reaction times. Further, this ionic liquid can be recovered and reused for several times. This journal is
- Shirini, Farhad,Jolodar, Omid Goli,Seddighi, Mohadeseh,Borujeni, Hojatollah Takbiri
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p. 19790 - 19798
(2015/03/18)
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- MgBr 2 · OEt 2: A Lewis Acid Catalyst for the O - And N -Boc Protection of Phenols and Amines
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MgBr2 · OEt2 efficiently catalyzes the O- and N-tert-butoxycarbonylation of functionalized phenols and amines. The presented procedure is operationally simple and done under solvent-free conditions. GRAPHICAL ABSTRACT.
- Schechter, Aaron,Goldrich, David,Chapman, Jessica R.,Uberheide, Beatrix M.,Lim, Daniel
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supporting information
p. 653 - 660
(2015/10/29)
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- PRMT5 INHIBITORS AND USES THEREOF
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Described herein are compounds of Formula (I)-(XIII), pharmaceutically acceptable salts thereof, and pharmaceutical compositions thereof. Compounds of the present invention are useful for inhibiting PRMT5 activity. Methods of using the compounds for treating PRMT5-mediated disorders are also described.
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Paragraph 00475
(2016/01/12)
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- N-Substitution dependent stereoselectivity switch in palladium catalyzed hydroalkynylation of ynamides: A regio and stereoselective synthesis of ynenamides
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A highly general palladium catalysed regioselective hydroalkynylation of ynamides for versatile enamide building blocks with an alkyne tether is achieved with an N-substitution dependent stereoselectivity switch under very mild reaction conditions.
- Dwivedi, Vikas,Hari Babu, Madala,Kant, Ruchir,Sridhar Reddy, Maddi
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supporting information
p. 14996 - 14999
(2015/10/12)
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- Direct Amidation of N-Boc- and N-Cbz-Protected Amines via Rhodium-Catalyzed Coupling of Arylboroxines and Carbamates
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N-Boc- and N-Cbz-protected amines are directly converted into amides by a novel rhodium-catalyzed coupling of arylboroxines and carbamates, replacing the traditional two-step deprotection-condensation sequence. Both protected anilines and aliphatic amines are efficiently transformed into a wide variety of secondary benzamides, including sterically hindered and electron-deficient amides, as well as in the presence of acid-labile and reducible functional groups.
- Lim, Diane S. W.,Lew, Tedrick T. S.,Zhang, Yugen
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supporting information
p. 6054 - 6057
(2016/01/09)
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- General solvent-free highly selective N-tert-butyloxycarbonylation strategy using protic ionic liquid as an efficient catalyst
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A simple, rapid and solvent-free protocol is described for the chemo-selective transformation of amines to tert-butyloxycarbonyl protected derivatives (NHBoc) using Boc2O and imidazolium trifluoroacetate protic ionic liquid (5-20 mol%). Unwanted side products such as isocyanate, urea or N,N-di-Boc were not detected. The scope of the protection strategy was successfully explored for substrate alcohols, phenols and thiol at elevated temperatures. Optically pure amino acids, amino acid esters and amino alcohols were efficiently converted to the corresponding N-Boc protected derivatives in excellent yields without racemization at the chiral center. The distinct advantages of this method are: operational simplicity, cleaner reaction, high selectivity, excellent yield, rapid reaction convergence, easy preparation and recyclability of the catalyst.
- Majumdar, Swapan,De, Jhinuk,Chakraborty, Ankita,Maiti, Dilip K.
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p. 24544 - 24550
(2014/07/07)
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- N-Protection of amines using pyridinium 2,2,2-trifluoroacetate ionic liquid as an efficient and reusable catalyst
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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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- Rice husk: Introduction of a green, cheap and reusable catalyst for the protection of alcohols, phenols, amines and thiols
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A mild, efficient and eco-friendly protocol for the chemoselective protection of benzylic and primary and less hindered secondary aliphatic alcohols and phenols as trimethylsilyl ethers and different types of amines as N-tert-butylcarbamates is developed using rice husk (RiH) as the catalyst. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols and amines with acetic anhydride. Easy work-up, relatively short reaction times, excellent yields and low cost, availability and reusability of the catalyst are the striking features of this methodology, which can be considered to be one of the best and general methods for the protection of alcohols, phenols, thiols and amines. In addition, the use of a green reagent in the above-mentioned reactions results in a reduction of environmental pollution and of the cost of the applied methods.
- Shirini, Farhad,Akbari-Dadamahaleh, Somayeh,Mohammad-Khah, Ali,Aliakbar, Ali-Reza
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p. 164 - 170
(2014/03/21)
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- Bromine and iodine-cucurbit[6]uril complexes: Preparation and applications in synthetic organic chemistry
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Iodine and bromine inclusion compounds were easily prepared by gas diffusion of the halogens using finely powdered CB[6]. A brown powder consisting of I2-CB[6]·4H2O and an orange one of (Br 2)4-CB[6]·10H2O were employed in several different reactions. I2-CB[6] can be used in catalytic reactions giving yields comparable to those reported in the literature. Br 2-CB[6] was effectively applied in electrophilic bromination of benzene and formation of bromohydrin. However, the radical substitution at cyclohexene could not be performed. Overall, based on these results, several applications can be envisioned for these complexes. This journal is the Partner Organisations 2014.
- Reddy,Cavallini,Demets,Silva
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supporting information
p. 2262 - 2264
(2014/06/09)
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- Simple, chemoselective, catalytic olefin isomerization
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Catalytic amounts of Co(SaltBu,tBu)Cl and organosilane irreversibly isomerize terminal alkenes by one position. The same catalysts effect cycloisomerization of dienes and retrocycloisomerization of strained rings. Strong Lewis bases like amines and imidazoles, and labile functionalities like epoxides, are tolerated.
- Crossley, Steven W. M.,Barabé, Francis,Shenvi, Ryan A.
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supporting information
p. 16788 - 16791
(2015/01/09)
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- A simple, rapid, and efficient N-Boc protection of amines under ultrasound irradiation and catalyst-free conditions
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A green and simple approach for the N-Boc protection on structurally diverse amines under ultrasound irradiation is described. Selective N-Boc protection was achieved in excellent isolated yield in a short reaction time at room temperature. Mild conditions, inexpensive and an easily available reagent, and absence of any auxiliary substances are the main advantages of this procedure. Graphical abstract: [Figure not available: see fulltext.]
- Amira, Aicha,K'Tir, Hacene,Berredjem, Malika,Aouf, Nour-Eddine
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p. 509 - 515
(2014/03/21)
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- Photocatalytic decarboxylative reduction of carboxylic acids and its application in asymmetric synthesis
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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)
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- Palladium-mediated [2+1] cycloaddition of norbornene derivatives with ynamides
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An efficient palladium-catalyzed [2+1] cycloaddition between ynamides and norbornenes or norbornadienes is reported. Both phosphapalladacycles and palladium/secondary phosphine oxide catalytic systems were found to be competent for the transformation allowing the preparation of aminomethylenecyclopropanes. The reaction showed general applicability to various functionalized bicyclo[2.2.1]hept-2-enes and ynamides. A chiral phosphapalladacycle was tested to carry out this transformation in an enantioselective fashion.
- Clavier, Herve,Lepronier, Aymeric,Bengobesse-Mintsa, Nathalie,Gatineau, David,Pellissier, Helene,Giordano, Laurent,Tenaglia, Alphonse,Buono, Gerard
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supporting information
p. 403 - 408
(2013/05/22)
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