- Fe2Mn(μ3-O)(COO)6 Cluster Based Stable MOF for Oxidative Coupling of Amines via Heterometallic Synergy
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The direct catalytic oxidative coupling of amines is one of the attracting methods for the synthesis of a variety of pharmaceutical or industrial needed imines. Numerous earth-abundant manganese based salts, oxides, and complexes have been applied in this reaction. However, these compounds suffered from difficult separation, large catalyst loading, complicated reactivation or indeterminate activity. Considering the facts that metal-organic frameworks (MOFs) with crystalline structure, precise composition, and enormous surface area have superior performance in heterogeneous catalytic reactions, herein, we introduced Mn into [Fe3(μ3-O)(CH3COO)6], one of the precursors for the preparation of stable MOFs, and got [Fe2Mn(μ3-O)(CH3COO)6] cluster. After ligand replacement with biphenyl-3,4’,5-tricarboxylic acid (BPTC), heterometallic cluster-based [Fe2Mn(μ3-O)(BPTC)2(DMF)2(H2O)] (1) was obtained. As expected, 1 is stable and able to catalyze the homo- or cross-coupling of amines effectively and selectively with 0.9 mol% catalyst loading at room temperature. Control experiments indicated that the catalytic activity of 1 mainly stems from Mn sites and that Fe synergistically contributes to the stability. Additionally, 1 is recyclable and can be reused easily for at least 8 runs without obvious decrease in catalytic ability. To our knowledge, 1 should be the first heterometallic cluster-based MOF with defined structure suitable for the synthesis of diverse imines from oxidative coupling of amines under mild conditions, which may shed light on the easy preparation of effective heterogeneous catalysts for organic synthesis.
- Wang, Ying-Xia,Wang, Hui-Min,Meng, Pan,Song, Dong-Xia,Qi, Zhikai,Zhang, Xian-Ming
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supporting information
p. 2983 - 2989
(2021/08/30)
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- Biocatalytic N-Alkylation of Amines Using Either Primary Alcohols or Carboxylic Acids via Reductive Aminase Cascades
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The alkylation of amines with either alcohols or carboxylic acids represents a mild and safe alternative to the use of genotoxic alkyl halides and sulfonate esters. Here we report two complementary one-pot systems in which the reductive aminase (RedAm) from Aspergillus oryzae is combined with either (i) a 1° alcohol/alcohol oxidase (AO) or (ii) carboxylic acid/carboxylic acid reductase (CAR) to affect N-alkylation reactions. The application of both approaches has been exemplified with respect to substrate scope and also preparative scale synthesis. These new biocatalytic methods address issues facing alternative traditional synthetic protocols such as harsh conditions, overalkylation and complicated workup procedures.
- Ramsden, Jeremy I.,Heath, Rachel S.,Derrington, Sasha R.,Montgomery, Sarah L.,Mangas-Sanchez, Juan,Mulholland, Keith R.,Turner, Nicholas J.
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p. 1201 - 1206
(2019/01/21)
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- Visible light photocatalytic aerobic oxidative synthesis of imines from alcohols and amines on dye-sensitized TiO2
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A general visible light photocatalytic protocol for the synthesis of imines via a two-step one-pot route on alizarin red S (ARS)-sensitized TiO2 was uncovered. This efficient synthesis protocol involves one step of the highly selective formation of aldehydes from the oxidation of alcohols with O2 on ARS-sensitized TiO2 photocatalyst, and a subsequent step of condensation of newly formed aldehydes with various amines on TiO2 to afford imines in one pot. Anatase TiO2 provides a versatile platform for catalytic amounts of ARS (0.67 mol%) to facilitate the electron transfer from dye traversing its conduction band to O2 under green LED irradiation. Moreover, the Lewis acid sites of TiO2 can promote the formation of imines from aldehydes and amines in very high isolated yields. We took advantage of both the photocatalytic and catalytic properties of TiO2 to significantly expand the scope of imines. Our work suggests that the synthetic applications of TiO2 photocatalysis can be achievable under mild conditions by exploring the excellent functionalities of TiO2.
- Xu, Hui,Shi, Ji-Long,Hao, Huimin,Li, Xia,Lang, Xianjun
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p. 128 - 135
(2019/01/04)
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- A General Way to Construct Arene-Fused Seven-Membered Nitrogen Heterocycles
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Imines react with seven-membered cyclic anhydrides (prepared from the corresponding dicarboxylic acids by a recently discovered in-situ cyclodehydration protocol) by the Castagnoli–Cushman reaction pathway to give privileged seven-membered arene-fused nitrogen-heterocyclic compounds with reagent-controlled diversity of the skeleton and peripheral groups.
- Bakulina, Olga,Chizhova, Maria,Dar'in, Dmitry,Krasavin, Mikhail
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p. 362 - 371
(2018/01/27)
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- Novel transition bimetal-organic frameworks: Recyclable catalyst for the oxidative coupling of primary amines to imines at mild conditions
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A novel type of transition bimetal-organic frameworks was described as a heterogeneous catalyst for the oxidative coupling of amines to imines under mild conditions, which was easily synthesized by the coordination assembly of manganese(ii) and cobalt(ii) with 1,3,5-benzenetricarboxylic acid (H3BTC) for the first time. The metal-organic framework material was characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetry and N2 sorption. As an environmentally benign heterogeneous catalyst, the catalytic ability of the metal-organic framework material was then detected to be excellent for the tert-butyl hydroperoxide (TBHP) promoted direct oxidative coupling of benzylamines to imines in excellent yields (up to 100%) in methanol for 3 h. More importantly, it could be recycled up to six runs, while still maintaining its high catalytic activity.
- Ge, Danhua,Qu, Genlong,Li, Xinming,Geng, Kaiming,Cao, Xueqin,Gu, Hongwei
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p. 5531 - 5536
(2016/07/06)
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- Reversible C-C bond activation enables stereocontrol in Rh-catalyzed carbonylative cycloadditions of aminocyclopropanes
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Upon exposure to neutral or cationic Rh(I)-catalyst systems, amino-substituted cyclopropanes undergo carbonylative cycloaddition with tethered alkenes to provide stereochemically complex N-heterocyclic scaffolds. These processes rely upon the generation and trapping of rhodacyclopentanone intermediates, which arise by regioselective, Cbz-directed insertion of Rh and CO into one of the two proximal aminocyclopropane C-C bonds. For cyclizations using cationic Rh(I)-systems, synthetic and mechanistic studies indicate that rhodacyclopentanone formation is reversible and that the alkene insertion step determines product diastereoselectivity. This regime facilitates high levels of stereocontrol with respect to substituents on the alkene tether. The option of generating rhodacyclopentanones dynamically provides a new facet to a growing area of catalysis and may find use as a (stereo)control strategy in other processes.
- Shaw, Megan H.,McCreanor, Niall G.,Whittingham, William G.,Bower, John F.
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p. 463 - 468
(2015/01/30)
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- Effect of N-Bound Organic Moiety in Dithiocarbamate (R2NCS-2) and trans Influence of Triphenylphosphine on NiS2PN Chromophore
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Three square planar Ni(II) complexes of the composition [Ni(bzcprdtc)2](1), [Ni(bzcprdtc)(NCS)(PPh3)](2) and [Ni(bzcprdtc)(PPh3)2]ClO4 (3)[(where bzcprdtc = N-benzyl-N-cyclopropyl-dithiocarbamate)] ha
- Sathiyaraj, Ethiraj,Valarmathi, Panneerselvam,Thirumaran, Subbiah,Ciattini, Samuele,Gupta, Vivek K.,Kant, Rajni
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p. 1127 - 1137
(2015/08/04)
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- Directing group enhanced carbonylative ring expansions of amino-substituted cyclopropanes: Rhodium-catalyzed multicomponent synthesis of N-heterobicyclic enones
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Aminocyclopropanes equipped with suitable N-directing groups undergo efficient and regioselective Rh-catalyzed carbonylative C-C bond activation. Trapping of the resultant metallacycles with tethered alkynes provides an atom-economic entry to diverse N-heterobicyclic enones. These studies provide a blueprint for myriad N-heterocyclic methodologies.
- Shaw, Megan H.,Melikhova, Ekaterina Y.,Kloer, Daniel P.,Whittingham, William G.,Bower, John F.
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supporting information
p. 4992 - 4995
(2013/05/22)
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- Substituted 4-Oxo-1,2,3,4-tetrahydroquinoline-3-carboxylic esters by a tandem imine addition-SNAr reaction
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A tandem imine addition-SNAr annulation reaction has been developed as a new approach to the synthesis of 4-oxo-1,2,3,4- tetrahydroquinoline-3-carboxylic esters. A series of these structures has been generated by reacting selected imines with tert-butyl 2-fluoro-5- nitrobenzoylacetate. Structural variations in the final products are accomplished by changing the substituents on the imine and the alkyl group of the ester. The title compounds are isolated as their enols in 55-97% yield without the need for added base or catalysts. The synthesis of the starting materials as well as mechanistic studies and further synthetic conversions of the products are presented.
- Bunce, Richard A.,Schammerhorn, James E.,Sigle, Jessica
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p. 373 - 380
(2013/06/04)
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- Synthesis of iminonitriles by oxone/tbab-mediated one-pot oxidative three-component strecker reaction
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Oxidative three-component reaction of aldehydes, amines, and TMSCN in a biphasic solvent system (toluene/H2O) containing Oxone, tetra-n-butylammonium bromide (TBAB) and sodium bicarbonate afforded α-iminonitriles in good to excellent yields. This oxidative Strecker reaction was applicable to a wide range of aldehydes and amines, aromatic or aliphatic, of different electronic and steric properties. Substituted 1-aza-2-cyano-1,3-dienes were also accessible using α,β-unsaturated aldehydes as inputs.
- Gualtierotti, Jean-Baptiste,Schumacher, Xavier,Wang, Qian,Zhu, Jieping
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p. 1380 - 1386
(2013/07/05)
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- Synthesis, biological activities and DFT calculation of aα-aminophosphonate containing cyclopropane moiety
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Five new aα-aminophosphonate derivatives containing cyclopropane moiety have been synthesized via conventional and microwave irradiation methods under solvent- and catalysis-free condition. The structures of the aα-aminophosphonate compounds have been confirmed by 1H NMR, 31P NMR, FT-IR, EI-MS and FTICR-MS studies. Their herbicidal activities were evaluated in vivo and in vitro. The results showed some compounds were found to exhibit moderate herbicidal activities against Brassica campestris at 100 and 10 ppm. Theoretical calculation of 2c was carried out with B3LYP/6-31G (d,p). The full geometry optimization was carried out using 6-31G(d,p) basis set and the structure-activity relationship was also studied by frontier orbital energy.
- Liu, Xing-Hai,Weng, Jian-Quan,Tan, Cheng-Xia,Pan, Li,Wang, Bao-Lei,Li, Zheng-Ming
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experimental part
p. 4031 - 4036
(2012/01/14)
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- Synthesis of C-aryl-N-cyclopropylnitrones
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Synthesis of C-aryl-N-cyclopropylnitrones is described. Preparations were performed either by condensation of the appropriate aldehyde with N-cyclopropyl-hydroxylamine, or oxidation of N-substituted N-cyclopropylamines with sodium tungstate/hydrogen perox
- Vukics, Krisztina,Tarkanyi, Gabor,Dravecz, Ferenc,Fischer, Janos
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p. 3419 - 3425
(2007/10/03)
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- N1,N10-Ethylene-bridged high-potential flavins: Synthesis, characterization, and reactivity
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N1,N10-Ethyleneisoalloxazinium chloride and its 8-Cl-, 7-CF3-, and 3-CH3-7-CF3-substituted analogs were synthesized for the purpose of exhibiting thermal reactivity with organic substrates. The new flavins were characterized spectroscopically and electrochemically, and were found to react with amines, thiols, and phenylhydrazine, the latter case exhibiting catalytic aerobic recycling. Reactions of aliphatic benzylic and cyclopropyl amines with the 7-CF3 analog were also compared to their oxidations by tris(phenanthroline)iron(III). All reactions of the flavinium salts appear to occur through heterolytic rather than homolytic mechanisms.
- Li, Wen-Shan,Zhang, Nanjing,Sayre, Lawrence M.
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p. 4507 - 4522
(2007/10/03)
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- Phosphatase inhibitors. III. Benzylaminophosphonic acids as potent inhibitors of human prostatic acid phosphatase
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Further investigation of the structural requirements of a series of benzylphosphonic acid inhibitors of human prostatic acid phosphatase has led to the highly potent series of α-aminobenzylphosphonic acids. The α-benzylaminobenzylphosphonic acid, with an IC50 = 4 nM, exhibited a 3500-fold improvement in potency over the carbon analogue, α-phenylethyl. The enhanced potency may be due to a combination of four favorable interactions including those with the phosphate binding region, the presence the hydrophobic moieties of the benzylamino and phenylphosphonic acid, and a rigid conformer produced by an internal salt bridge between the phosphonate and the α-amino group. Replacement of the phosphonic acid moiety with a phosphinic or carboxylic acid as well as deletion of the benzyl substitution on the α-amino group led to great reductions in potency.
- Beers, Scott A.,Schwender, Charles F.,Loughney, Deborah A.,Malloy, Elizabeth,Demarest, Keith,Jordan, Jerold
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p. 1693 - 1701
(2007/10/03)
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