- Selective hydrogenation of nitriles to secondary amines catalyzed by a pyridyl-functionalized and alkenyl-tethered NHC-Ru(II) complex
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A set of Co(III) and Ru(II) compounds are synthesized bearing pyridyl-functionalized and alkenyl-tethered N-heterocyclic carbene (NHC) ligand (L1). [CoIII(L1)3](PF6)3 (1) was synthesized by the reaction of [L1H]PF6, Co(OAc)2.4H2O, K2CO3 in tetrahydrofuran (THF) under refluxing condition. [RuIIL1(η6-p-cymene)Cl]PF6 (2) was synthesized via transmetallation method. For both compounds, the NHC ligand chelates the metal through carbene carbon and pyridyl nitrogen whereas the butenyl unit remains free. Compound 2 hydrogenates organic nitriles efficiently providing selectively secondary amines. In the presence of external amines, unsymmetrical secondary amines are also obtained.
- Saha, Sayantani,Kaur, Mandeep,Singh, Kuldeep,Bera, Jitendra K.
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- Stereoselective pinacol coupling of planar chiral (benzaldehyde)Cr(Co)3, (benzaldimine)Cr(CO)3, ferrocenecarboxaldehyde and (dienal)Fe(CO)3 complexes with samarium diiodide
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An intermolecular pinacol coupling of the Planar chiral tricarbonylchromium complexes of o-substituted benzaldehydes or benzaldimines with samarium(II) diiodide in THF produces exclusively threo 1.2-diols or 1,2-diamines in an optically pure form, while the corresponding racemic o- substituted benzaldehyde or benzaldimine chromium complexes give a mixture of threo and erythro pinacol coupling products in a various ratio depending upon the nature of o-substituent. Similarly, planar chiral 2-substituted ferrocenecarboxaldehydes and (dienal)Fe(CO)3 produce the corresponding 1.2- diols with high stereoselectivity. The generated transition metal-complexed ketyl radical intermediates are configurationally stable with restriction to a rotation about C(α)-C(ipso) bond.
- Taniguchi, Nobukazu,Uemura, Motokazu
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- Design of a bifunctional Ir-Zr based metal-organic framework heterogeneous catalyst for the N-alkylation of amines with alcohols
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The direct N-alkylation of amines with alcohols was performed with an Ir-Zr-based metal-organic framework multifunctional heterogeneous catalyst. This system is efficient and environmentally benign for the synthesis of various organic amines in air in the absence of a base. The catalyst was recovered and reused without significant loss of activity, and only water was produced as a byproduct. Better be direct than elusive: The direct N-alkylation of amines with alcohols is performed with an Ir-Zr-based metal-organic framework multifunctional heterogeneous catalyst. This system is efficient and environmentally benign for the synthesis of various organic amines in air in the absence of a base. The catalyst is recovered and reused without significant loss of activity, and only water is produced as a byproduct.
- Rasero-Almansa,Corma,Iglesias,Sanchez
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- First example of direct reductive amination of aldehydes with primary and secondary amines catalyzed by water-soluble transition metal catalysts
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An unprecedented efficient and highly selective direct reductive amination of aldehydes with primary and secondary amines in water using gaseous hydrogen and water-soluble catalysts is developed. The catalytic system formed in situ from Pd(PhCN)2Cl2 and 2,2′-biquinoline-4,4′-dicarboxylic acid dipotassium salt (BQC), allows full conversion of aldehydes and the formation of desired alkylated amines with excellent yields and selectivities. The catalytic system is stable and can be recycled and reused three times without loss of activity.
- Robichaud, André,Nait Ajjou, Abdelaziz
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- Stereodynamics of 2-(diethylamino)propane and 2-(dibenzylamino)propane. 1H and 13C{1H} DNMR studies. Molecular mechanics calculations
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2-(Diethylamino)propane (DEAP) and 2-(dibenzylamino)propane (DBAP) possess similar molecular symmetries. Interconversion among the stable equilibrium conformations occurs by inversion-rotation at the pyramidal nitrogen and by isolated rotation about carbon-nitrogen bonds. In DEAP and DBAP, the fact that stable equilibrium conformations cannot have destabilizing syn-1,5 interactions between methyl or phenyl groups limits the number of equilibrium conformations that will be present at concentrations high enough to be NMR detectable. The 1H and 13C{1H} NMR spectra of DEAP at 100 K show two diastereomeric pairs of enantiomeric conformations. One pair of enantiomers has the isopropyl methine proton and both ethyl methyl groups gauche to the lone pair (75%). The other pair has the methine proton anti to the lone pair with the ethyl methyl groups respectively gauche and anti to the lone pair (25%). The barrier to inversion-rotation in DEAP (ΔG? = 6.4 kcal/mol) is higher than barriers to isolated rotation about carbon-nitrogen bonds (ΔG? = 5.3-5.7 kcal/mol). The 1H and 13C{1H} NMR spectra of DBAP at 100 K show just one pair of enantiomeric conformations that have the isopropyl methine proton and both phenyl groups gauche to the lone pair. There is no evidence in the NMR spectrum at 100 K for those conformations of DBAP that have a phenyl group anti to the lone pair. The barrier to inversion-rotation in DBAP (ΔG? = 6.4 kcal/mol) is higher than the barrier to racemization via isolated rotation about carbon-nitrogen bonds (ΔG? = 5.5 kcal/mol). Molecular mechanics calculations of conformational energies are in good agreement with the observed conformational preferences.
- Brown, Jay H.,Bushweller, C. Hackett
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- Expanding Water/Base Tolerant Frustrated Lewis Pair Chemistry to Alkylamines Enables Broad Scope Reductive Aminations
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Lower Lewis acidity boranes demonstrate greater tolerance to combinations of water/strong Br?nsted bases than B(C6F5)3, this enables Si?H bond activation by a frustrated Lewis pair (FLP) mechanism to proceed in the presence of H2O/alkylamines. Specifically, BPh3has improved water tolerance in the presence of alkylamines as the Br?nsted acidic adduct H2O–BPh3does not undergo irreversible deprotonation with aliphatic amines in contrast to H2O–B(C6F5)3. Therefore BPh3is a catalyst for the reductive amination of aldehydes and ketones with alkylamines using silanes as reductants. A range of amines inaccessible using B(C6F5)3as catalyst, were accessible by reductive amination catalysed by BPh3via an operationally simple methodology requiring no purification of BPh3or reagents/solvent. BPh3has a complementary reductive amination scope to B(C6F5)3with the former not an effective catalyst for the reductive amination of arylamines, while the latter is not an effective catalyst for the reductive amination of alkylamines. This disparity is due to the different pKavalues of the water–borane adducts and the greater susceptibility of BPh3species towards protodeboronation. An understanding of the deactivation processes occurring using B(C6F5)3and BPh3as reductive amination catalysts led to the identification of a third triarylborane, B(3,5-Cl2C6H3)3, that has a broader substrate scope being able to catalyse the reductive amination of both aryl and alkyl amines with carbonyls.
- Fasano, Valerio,Ingleson, Michael J.
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- Additive-free selective methylation of secondary amines with formic acid over a Pd/In2O3 catalyst
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Formic acid is used as the sole carbon and hydrogen source in the methylation of aromatic and aliphatic amines to methylamines. The reaction proceeds via a formylation/transfer hydrogenation pathway over a solid Pd/In2O3 catalyst without the need for any additive.
- Benaissa, Idir,Cantat, Thibault,Genre, Caroline,Godou, Timothé,Pinault, Mathieu
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- BF3·Et2O as a metal-free catalyst for direct reductive amination of aldehydes with amines using formic acid as a reductant
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A versatile metal- and base-free direct reductive amination of aldehydes with amines using formic acid as a reductant under the catalysis of inexpensive BF3·Et2O has been developed. A wide range of primary and secondary amines and diversely substituted aldehydes are compatible with this transformation, allowing facile access to various secondary and tertiary amines in high yields with wide functional group tolerance. Moreover, the method is convenient for the late-stage functionalization of bioactive compounds and preparation of commercialized drug molecules and biologically relevant N-heterocycles. The procedure has the advantages of simple operation and workup and easy scale-up, and does not require dry conditions, an inert atmosphere or a water scavenger. Mechanistic studies reveal the involvement of imine activation by BF3and hydride transfer from formic acid.
- Fan, Qing-Hua,Liu, Xintong,Luo, Zhenli,Pan, Yixiao,Xu, Lijin,Yang, Ji,Yao, Zhen,Zhang, Xin
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supporting information
p. 5205 - 5211
(2021/07/29)
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- Imine reduction with me2s-bh3
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Although there exists a variety of different catalysts for hydroboration of organic substrates such as aldehydes, ketones, imines, nitriles etc., recent evidence suggests that tetra-coordinate borohydride species, formed by activation, redistribution, or decomposition of boron reagents, are the true hydride donors. We then proposed that Me2S-BH3 could also act as a hydride donor for the reduction of various imines, as similar compounds have been observed to reduce carbonyl substrates. This boron reagent was shown to be an effective and chemoselective hydroboration reagent for a wide variety of imines.
- Kamal, Mohammad M.,Liu, Zhizhou,Vidovi?, Dragoslav,Zhai, Siyuan
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- Trimethyl Borate-Catalyzed, Solvent-Free Reductive Amination
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Solvent-free reductive amination of aldehydes and ketones with aliphatic and aromatic amines in high-to-excellent yields has been achieved with sub-stoichiometric trimethyl borate as promoter and ammonia borane as reductant.
- Ramachandran, P. Veeraraghavan,Choudhary, Shivani,Singh, Aman
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p. 4274 - 4280
(2021/03/09)
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- Hydrogenation of Secondary Amides using Phosphane Oxide and Frustrated Lewis Pair Catalysis
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The metal-free catalytic hydrogenation of secondary carboxylic acid amides is developed. The reduction is realized by two new catalytic reactions. First, the amide is converted into the imidoyl chloride by triphosgene (CO(OCCl3)2) using novel phosphorus(V) catalysts. Second, the in situ generated imidoyl chlorides are hydrogenated in high yields by an FLP-catalyst. Mechanistic and quantum mechanical calculations support an autoinduced catalytic cycle for the hydrogenation with chloride acting as unusual Lewis base for FLP-mediated H2-activation.
- K?ring, Laura,Sitte, Nikolai A.,Bursch, Markus,Grimme, Stefan,Paradies, Jan
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p. 14179 - 14183
(2021/09/03)
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- Poisoning effect of N-containing compounds on performance of Raney nickel in transfer hydrogenation
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The effect of amines, imines and heterocycle compounds on conversion has been studied in transfer hydrogenation of camphor and 2-PrOH catalyzed by Raney nickel. Small amount (5 mol% to nickel) of N-containing compound significantly decreases catalyst activity. It has been shown that the poisoning effect mostly depends on molecular size of amines and heterocyclic compounds. For aniline and cyclohexylamine the dependence of camphor conversion on poison/nickel ratio was obtained. Additionally, benzaldehyde, cinnamaldehyde demonstrated higher reactivity compared corresponding imines under transfer hydrogenation conditions. Obtained data explain low activity of nickel-based catalysts when N-containing compounds are presented in reaction mixture.
- Martyanov, Oleg N.,Philippov, Alexey A.
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- Sulfonium ion-promoted traceless Schmidt reaction of alkyl azides
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Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction through 1,2-migration of C-H and C-C bonds was accessible to the one-pot substitution reaction.
- Ardiansah, Bayu,Kakiuchi, Kiyomi,Morimoto, Tsumoru,Tanimoto, Hiroki,Tomohiro, Takenori
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supporting information
p. 8738 - 8741
(2021/09/08)
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- Reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3as a reductant
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Herein, we report the first example of efficient reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3 as a catalyst and a reductant under mild conditions, affording various tertiary and secondary amines in excellent yields. A mechanistic study indicates that BH3N(C2H5)3 plays a dual function role of promoting imine and iminium formation and serving as a reductant in reductive amination. This journal is
- Zou, Qizhuang,Liu, Fei,Zhao, Tianxiang,Hu, Xingbang
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supporting information
p. 8588 - 8591
(2021/09/04)
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- INHIBITORS OF INDOLEAMINE 2,3-DIOXYGENASE AND METHODS OF THEIR USE
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The present invention provides compounds of formula (I): wherein all of the variables are as defined herein. These compounds are inhibitors of indoleamine 2,3-dioxygenase (IDO), which may be used as medicaments for the treatment of proliferative disorders, such as cancer, viral infections and/or autoimmune diseases.
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Page/Page column 167-168
(2020/02/16)
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- Method for synthesizing N-isopropylbenzylamine
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The invention provides a method for synthesizing N-isopropylbenzylamine, which comprises subjecting benzyl chloride as a raw material and isopropylamine to ammonolysis reaction under the action of a catalyst to obtain the N-isopropylbenzylamine. The process is simple in synthetic route, the reaction is easy to control, less three wastes are generated, and the green and environment-friendly requirements are met. The produced N-isopropylbenzylamine is high in purity and excellent in quality, and is an excellent industrialization route.
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Paragraph 0114-0116
(2020/07/06)
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- Cine-Silylative Ring-Opening of α-Methyl Azacycles Enabled by the Silylium-Induced C-N Bond Cleavage
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Described herein is the development of a borane-catalyzed cine-silylative ring-opening of α-methyl azacycles. This transformation involves four-step cascade processes: (i) exo-dehydrogenation of alicyclic amine, (ii) hydrosilylation of the resultant enamine, (iii) silylium-induced cis-β-amino elimination to open the ring skeleton, and (iv) hydrosilylation of the terminal olefin. The present borane catalysis also works efficiently for the C-N bond cleavage of acyclic tertiary amines. On the basis of experimental and computational studies, the silicon atom was elucidated to play a pivotal role in the β-amino elimination step.
- Zhang, Jianbo,Chang, Sukbok
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supporting information
p. 12585 - 12590
(2020/08/21)
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- Unlocking the catalytic potential of tris(3,4,5-trifluorophenyl)borane with microwave irradiation
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The catalytic activity of tris(3,4,5-trifluorophenyl)borane has been explored in the 1,2-hydroboration reactions of unsaturated substrates. Under conventional conditions, the borane was found to be active only in the hydroboration of aldehyde, ketone and imine substrates, with alkenes and alkynes not being reduced effectively. The use of microwave irradiation on the other hand has permitted alkenes and alkynes to be hydroborated in good yields.
- Carden, Jamie L.,Gierlichs, Lukas J.,Wass, Duncan F.,Browne, Duncan L.,Melen, Rebecca L.
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p. 318 - 321
(2019/01/09)
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- Catalyst-Free Reductive Coupling of Aromatic and Aliphatic Nitro Compounds with Organohalides
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A rare reductive coupling of nitro compounds with organohalides has been realized. The reaction is initiated by a partial reduction of the nitro group to a nitrenoid intermediate. Therefore, not only aromatic but also aliphatic nitro compounds are efficiently transformed into monoalkylated amines, with organohalides as the alkylating agent. Given the innate reactivity of the nitrenoid, a catalyst is not required, resulting in a high tolerance for aryl halide substituents in both starting materials.
- Rauser, Marian,Eckert, Raphael,Gerbershagen, Max,Niggemann, Meike
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supporting information
p. 6713 - 6717
(2019/04/14)
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- Direct Reductive Amination of Carbonyl Compounds Catalyzed by a Moisture Tolerant Tin(IV) Lewis Acid
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Despite the ever-broadening applications of main-group ‘frustrated Lewis pair’ (FLP) chemistry to both new and established reactions, their typical intolerance of water, especially at elevated temperatures (>100 °C), represents a key barrier to their mainstream adoption. Herein we report that FLPs based on the Lewis acid iPr3SnOTf are moisture tolerant in the presence of moderately strong nitrogenous bases, even under high temperature regimes, allowing them to operate as simple and effective catalysts for the reductive amination of organic carbonyls, including for challenging bulky amine and carbonyl substrate partners. (Figure presented.).
- Sapsford, Joshua S.,Scott, Daniel J.,Allcock, Nathan J.,Fuchter, Matthew J.,Tighe, Christopher J.,Ashley, Andrew E.
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supporting information
p. 1066 - 1071
(2018/01/27)
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- Direct Reductive N-Functionalization of Aliphatic Nitro Compounds
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The first general protocol for the direct reductive N-functionalization of aliphatic nitro compounds is presented. The nitro group is partially reduced to a nitrenoid, with a mild and readily available combination of B2pin2 and zinc organyls. Thereby, the formation of an unstable nitroso intermediate is avoided, which has so far severely limited reductive transformations of aliphatic nitro compounds. The reaction is concluded by an electrophilic amination of zinc organyls.
- Rauser, Marian,Ascheberg, Christoph,Niggemann, Meike
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p. 3970 - 3974
(2018/02/26)
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- CLEAVABLE TETRAZINE USED IN BIO-ORTHOGONAL DRUG ACTIVATION
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Disclosed is an advancement in provoked chemical cleavage. Thereby the invention provides the use of a diene as a chemically cleavable group attached to a Construct, and the use of a dienophile to provoke the release of the Construct by allowing the diene to react with a dienophile capable of undergoing an inverse electron demand Diels Alder reaction with the diene. The invention includes a kit for releasing a Construct CA bound to a Trigger TR, the kit comprising a tetrazine and a dienophile, wherein the Trigger is the tetrazine. The invention also includes the use of the formation of a pyridazine by reacting a tetrazine comprising a Construct CA bound thereto and a dienophile, as a chemical tool for the release, in a chemical, biological or physiological environment, of said Construct.
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- HEAT SHOCK PROTEIN 90 INHIBITORS
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Substituted aromatic compounds of formula (I) shown below: (formula I) The definition of each variable in formula (I) appears in the Specification. Also disclosed is a pharmaceutical composition containing one of the substituted aromatic compounds. Further disclosed is a method of using one of these compounds for treating a medical condition associated with HSP90.
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Page/Page column 19; 33; 35; 42
(2018/10/19)
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- Synthesis of β-Lactams by Palladium(0)-Catalyzed C(sp3)?H Carbamoylation
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A general and user-friendly synthesis of β-lactams is reported that makes use of Pd0-catalyzed carbamoylation of C(sp3)?H bonds, and operates under stoichiometric carbon monoxide in a two-chamber reactor. This reaction is compatible with a range of primary, secondary and activated tertiary C?H bonds, in contrast to previous methods based on C(sp3)?H activation. In addition, the feasibility of an enantioselective version using a chiral phosphonite ligand is demonstrated. Finally, this method can be employed to synthesize valuable enantiopure free β-lactams and β-amino acids.
- Dailler, David,Rocaboy, Ronan,Baudoin, Olivier
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supporting information
p. 7218 - 7222
(2017/06/13)
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- Improved Buchner reaction selectivity in the copper-catalyzed reactions of ethyl 3-arylmethylamino-2-diazo-3-oxopropanoates
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Ethyl 3-alkyl(arylmethyl)amino-2-diazo-3-oxopropanoates (diazo amidoacetates) generate generally both cyclohepta[c]pyrrolones (Buchner products) and β-lactams (1,4-insertion products), and show obvious N-substituent-controlled chemoselectivity between the intramolecular Buchner reaction and aliphatic 1,4-C-H insertion under the catalysis of copper salts. The less steric N-alkyl substituents in the amide moiety generally favor the aliphatic 1,4-C-H insertion, while the more steric N-alkyl substituents generally favor the Buchner reaction. Compared with rhodium and ruthenium-catalyzed conditions, the current copper-catalyzed conditions improved the Buchner reaction selectivity of ethyl 3-alkyl(arylmethyl)amino-2-diazo-3-oxopropanoates.
- Liu, Jing,Tu, Jianzhuo,Yang, Zhanhui,Pak, Chol-Ung,Xu, Jiaxi
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p. 4616 - 4626
(2017/07/11)
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- REACTIONS OF STANNYL CATIONS
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The present invention relates to a method of reducing, cleaving and/or coupling at least one C=O, C-O, C=C or C=N bond of a compound, using a reagent comprising a stannyl cation.
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Page/Page column 22
(2018/01/17)
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- Long-chain NHC-stabilized RuNPs as versatile catalysts for one-pot oxidation/hydrogenation reactions
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The synthesis and catalytic activity of long-chain NHC-stabilized RuNPs are presented. Full characterization of these novel nanostructures including surface state studies show that the ligand influences the number and the location of Ru active sites which impacts the NP catalytic activity, especially in hydrogenation reactions. The high stability and versatility of these nanosystems make them successful catalysts for both oxidation and hydrogenation reactions that can even be performed successively in a one pot-fashion.
- Martínez-Prieto,Ferry,Rakers,Richter,Lecante,Philippot,Chaudret,Glorius
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supporting information
p. 4768 - 4771
(2016/04/09)
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- Mild Metal-Free Hydrosilylation of Secondary Amides to Amines
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The combination of amide activation by Tf2O with B(C6F5)3-catalyzed hydrosilylation with TMDS constitutes a method for the one-pot reduction of secondary amides to amines under mild conditions. The method displays a broad applicability for the reduction of many types of substrates, and shows good compatibility and excellent chemoselectivity for many sensitive functional groups. Reductions of a multifunctionalized α,β-unsaturated amide obtained from another synthetic methodology, and a C-H functionalization product produced the corresponding amines in good to excellent yield. Chemoselective reduction of enantiomeric pure (ee >99%) tetrahydro-5-oxo-2-furaneamides yielded 5-(aminomethyl)dihydrofuran-2(3H)-ones in a racemization-free manner. The latter were converted in one pot to N-protected 5-hydroxypiperidin-2-ones, which are building blocks for the synthesis of many natural products. Further elaboration of an intermediate led to a concise four-step synthesis of -epi-pseudoconhydrine.
- Huang, Pei-Qiang,Lang, Qi-Wei,Wang, Yan-Rong
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p. 4235 - 4243
(2016/06/09)
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- SPIROCYCLIC HAT INHIBITORS AND METHODS FOR THEIR USE
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Compounds having a structure of Formula (IX) or a stereoisomer, tautomer or pharmaceutically acceptable salt thereof, wherein R1, R2a, R2b, R3a, R3b, R4a, R4b, Q1----Q2, R6, R7, A, B, W, x, and y are as defined herein and are provided. Pharmaceutical compositions comprising such compounds and methods for treating various HAT-related conditions or diseases, including cancer, by administration of such compounds are also provided.
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Page/Page column 575
(2016/04/10)
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- Transformation of N,N-diisopropylarylmethylamines into N-isopropylarylmethylamines with molecular iodine
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N,N-Diisopropylarylmethylamines were smoothly converted into the corresponding N-isopropylarylmethylamines by the reaction with molecular iodine in the presence of Na2CO3 in chloroform at 60 °C. Other related tertiary amines were also transformed into the corresponding secondary amines by the reaction with molecular iodine under the same reaction conditions.
- Ezawa, Masatoshi,Moriyama, Katsuhiko,Togo, Hideo
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p. 6689 - 6692
(2016/02/03)
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- Off-rate screening (ORS) by surface plasmon resonance. An efficient method to kinetically sample hit to lead chemical space from unpurified reaction products
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The dissociation rate constant kd (off-rate) is the component of ligand-protein binding with the most significant potential to enhance compound potency. Here we provide theoretical and empirical data to show that this parameter can be determined accurately from unpurified reaction products containing designed test compounds. This screening protocol is amenable to parallel chemistry, provides efficiencies of time and materials, and complements existing methodologies for the hit-to-lead phase in fragment-based drug discovery.
- Murray, James B.,Roughley, Stephen D.,Matassova, Natalia,Brough, Paul A.
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supporting information
p. 2845 - 2850
(2014/05/06)
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- Dearomative radical spirocyclization from N-ce: Raghubenzyltrichloroacetamides revisited using a copper(I)-mediated atom transfer reaction leading to 2-azaspiro[4.5]decanes
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An atom transfer radical dearomatizing spirocyclization from N-benzyltrichloroacetamides using CuCl regioselectively leads to 2-azaspiro[4.5]decadienes, in which the labile allylic chlorine atom is easily replaced by a hydroxyl group in aqueous medium or by quenching with methanol or allylamine. After oxidation of the target compound, the N-tert-butyl group can be removed from the resulting spirocyclohexanedienone.
- Diaba, Fa?za,Montiel, Juan A.,Martínez-Laporta, Agustín,Bonjoch, Josep
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p. 2619 - 2622
(2013/06/05)
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- Scope and mechanistic studies of catalytic hydrosilylation with a high-valent nitridoruthenium(VI)
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Hydrosilylation catalyzed by a high-valent nitridoruthenium(VI) compound, [RuN(saldach)(CH3OH)]+[ClO4]- (1, where saldach is the dianion of racemic N,N'-cyclohexan-diyl- bis(salicylideneimine)) is described. Using phenylsilane as reductant, a variety of unsaturated organic substrates, including aldehydes, ketones, and imines, are effectively reduced to alcohols and amines, respectively, accompanied by the redistribution of PhSiH3 at silicon. Mechanistic studies indicate that the catalysis proceeds via silane activation rather than carbonyl activation, and the silane is likely activated via multiple pathways, including a radical-based pathway.
- Abbina, Srinivas,Bian, Shi,Oian, Casey,Du, Guodong
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supporting information
p. 678 - 684
(2013/05/21)
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- N-alkylation of amines by homogeneous ruthenium complexes in the presence of free diphosphines
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Chemoselective N-alkylation of amines by ruthenium complexes in the presence of free diphosphine ligands under mild conditions is described. Octyl amine and aniline were chosen as aliphatic and aromatic amines to investigate the effect of different phosphines, reaction times, and temperature on conversion, as well as selectivity towards related secondary and tertiary amines. After optimization of the reaction conditions, this catalytic system was used for N-alkylation of other amines and has shown moderate to very good yields. The reaction products were monitored by GC-MS. The crystal structure of [Ru(NO3)2CO(PPh3)2] with a monodentate and a bidentate nitrate was determined by X-ray crystallographic analysis.
- Tamaddoni Jahromi, Bahareh,Kharat, Ali Nemati
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p. 3498 - 3508
(2014/01/06)
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- Ruthenium-catalyzed transfer hydrogenation of nitriles: Reduction and subsequent N-monoalkylation to secondary amines
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The selective synthesis of amines continues to be of importance because of their application in the bulk and fine chemical industries. Herein, domino ruthenium-catalyzed transfer hydrogenation of nitriles with subsequent N-monoalkylation by using alcohols is described. With this novel approach, various nitriles were reductively N-monoalkylated in excellent yields. A simple method for the synthesis of secondary amines starting directly from nitriles by using a ruthenium catalyst is described. With this novel domino system, various nitriles were reduced and subsequently N-monoalkylated in excellent yields (up to 99 %). In addition to isopropanol, other alcohols were also used as a reductant and N-monoalkylation reagent. Copyright
- Werkmeister, Svenja,Bornschein, Christoph,Junge, Kathrin,Beller, Matthias
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supporting information
p. 3671 - 3674
(2013/07/19)
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- Synthesis, reactivities, and catalytic properties of iodo-bridged polymeric iridium complexes with flexible carbon chain-bridged bis(tetramethylcyclopentadienyl) ligands
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Dinuclear iridium complexes [(C5Me4)(CH 2)n(C5Me4)][Ir(COD)]2 (2a: n = 2; 2b: n = 3; 2c: n = 4) are obtained from the reactions of the corresponding dilithium salts Li2/sub
- Tan, Xing,Li, Bin,Xu, Shansheng,Song, Haibin,Wang, Baiquan
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p. 3253 - 3261
(2013/07/19)
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- Catalyst-free one-pot reductive alkylation of primary and secondary amines and N,N-dimethylation of amino acids using sodium borohydride in 2,2,2-trifluoroethanol
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A simple and convenient procedure for the reductive alkylation of primary and secondary amines and N,N-dimethylation of amino acids is described using sodium borohydride as a reducing agent in 2,2,2- trifluoroethanol without use of a catalyst or any other additive. The solvent can be readily recovered from reaction products in excellent purity for direct reuse. Georg Thieme Verlag Stuttgart - New York.
- Tajbakhsh, Mahmood,Hosseinzadeh, Rahman,Alinezhad, Heshmatollah,Ghahari, Somayeh,Heydari, Akbar,Khaksar, Samad
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experimental part
p. 490 - 496
(2011/03/20)
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- Synthesis and reactivity of non-activated 2-(chloromethyl)aziridines
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An efficient synthesis of non-activated 2-(chloromethyl)aziridines and 2-chloromethyl-2-methylaziridines as new representatives of the class of 2-(halomethyl)aziridines was developed. Furthermore, the reactivity of these azaheterocycles was assessed and compared to that of their brominated counterparts, pointing to a similar profile for 2-(chloromethyl)aziridines and 2-(bromomethyl)aziridines on the one hand, and a different behaviour of 2-chloromethyl-2-methylaziridines versus 2-bromomethyl-2-methylaziridines concerning their aptitude towards ring expansion to azetidines on the other hand.
- Stankovic, Sonja,D'Hooghe, Matthias,Dewulf, Jo,Bogaert, Piet,Jolie, Robrecht,De Kimpe, Norbert
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scheme or table
p. 4529 - 4532
(2011/09/20)
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- Microwave-assisted regioselective ring opening of non-activated aziridines by lithium aluminium hydride
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A new synthetic protocol for the LiAlH4-promoted reduction of non-activated aziridines under microwave conditions was developed. Thus, ring opening of 2-(acetoxymethyl)aziridines provided the corresponding β-amino alcohols, which were then used as eligible substrates in the synthesis of 5-methylmorpholin-2-ones via condensation with glyoxal in THF. The same procedure was applied for the preparation of novel 5(R)- and 5(S)-methylmorpholin-2-ones starting from the corresponding enantiopure 2-(hydroxymethyl)aziridines. Additionally, 2-(methoxymethyl)- and 2-(phenoxymethyl)aziridines were treated with LiAlH4 under microwave irradiation, giving rise to either isopropylamines or 1-methoxypropan-2-amines depending on the reaction conditions.
- Stankovic, Sonja,D'Hooghe, Matthias,De Kimpe, Norbert
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scheme or table
p. 4266 - 4273
(2010/11/18)
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- Zinc-promoted, iridium catalyzed reductive alkylation of primary amines with aliphatic ketones in aqueous medium
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The reductive alkylation of primary aromatic and aliphatic amines with aliphatic ketones has been achieved in aqueous acidic medium using commercially available, non-activated zinc dust catalyzed by a very small quantity of iridium bromide. Anilines react well in aqueous formic acid, whereas monoalkylamines require 1,4-dioxane as a co-solvent and sulfuric acid as the proton source. A plausible mechanism via low-valent iridium hydride species is proposed.
- da Silva, Renato A.,Bieber, Lothar W.
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scheme or table
p. 689 - 691
(2010/04/02)
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- Monoalkylation of primary amines and N-sulfinylamides
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An efficient monoalkylation of primary amines with primary or secondary alcohols catalyzed by Ra-Ni under mild conditions is described. The Royal Society of Chemistry.
- García Ruano, José Luis,Parra, Alejandro,Alemán, José,Yuste, Francisco,Mastranzo, Virginia M.
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supporting information; experimental part
p. 404 - 406
(2009/05/06)
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- A novel series of urea-based peptidomimetic calpain inhibitors
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A series of peptide aldehyde derivatives in which the P2 chiral carbon has been replaced with nitrogen were synthesized as urea-based peptidomimetic inhibitors of μ-calpain. The compounds mirrored the general SAR of peptidyl aldehyde calpain inhibitors but displayed greater selectivity for μ-calpain over cathepsin B.
- Sanders, M. Lee,Donkor, Isaac O.
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p. 1965 - 1968
(2007/10/03)
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- Pd(OAc)2-catalyzed carbonylation of amines
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A phosphine-free catalytic system [Pd(OAc)2-Cu(OAc) 2-air] induced a substrate-specific carbonylation of amines in boiling toluene under CO gas (1 atm). Symmetrical N,N′-dialkylureas were obtained by the carbonylation of primary amines. N,N,N′-Trialkylureas were selectively formed by addition of a secondary amine to the above reaction vessel. Secondary amines did not give tetraalkylureas. However, dialkylamines with a phenyl group on their alkyl chains, such as N-monoalkylated benzylic amine or phenethylamine derivatives, underwent a direct aromatic carbonylation to afford five- or six-membered benzolactams. In the carbonylation, the chelation effect or steric repulsion between Pd(II) and the meta-substituent in the ortho-palladation and the ring sizes of cyclopalladation products that were formed prior to carbonylation were found to generate good site selectivity and increase the reaction rate. In contrast, carbonylation of ω- arylalkylamines with a hydroxyl group gave neither ureas nor benzolactams but instead produced 1,3-oxazolidinones smoothly. Hydrochlorides of amines also underwent carbonylation to afford the corresponding amides under the conditions used. This procedure made it possible to prepare ureas of amino acid esters and N-alkylcarbamates in practical yields.
- Orito, Kazuhiko,Miyazawa, Mamoru,Nakamura, Takatoshi,Horibata, Akiyoshi,Ushito, Harumi,Nagasaki, Hideo,Yuguchi, Motoki,Yamashita, Satoshi,Yamazaki, Tetsuro,Tokuda, Masao
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p. 5951 - 5958
(2007/10/03)
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- Reduction of carboxylic acid derivatives using diphenylsilane in the presence of a Rh-PPh3 complex
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Reductions of carboxylic acid derivatives by silanes in the presence of rhodium complexes were studied. Carboxylic esters were reduced to alcohols by diphenylsilane catalyzed by [RhCl(cod)]2/4PPh3 or [RhCl(PPh3)3] at room temperature in up to 99% yields. For example, ethyl decanoate and ethyl phenylacetate were converted to decanol and 2-phenylethanol in 98 and 92% yields, respectively. Carboxylic acids were also reduced by this reducing system to the corresponding alcohols in high yields. Furthermore, N-monosubstituted amides were reduced to secondary amines in moderate to good yields. For sterically hindered amides, the yields were moderate, and imines were produced in competitive yields.
- Ohta, Tetsuo,Kamiya, Masahiro,Nobutomo, Mami,Kusui, Keisuke,Furukawa, Isao
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p. 1856 - 1861
(2007/10/03)
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- A mild and convenient procedure for desulfinylation of p-toluenesulfinyl amines
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Reaction of p-toluenesulfinyl amines with thiophenol in the presence of catalytic amount of ZnCl2 provides the corresponding desulfinylated amines in high yield. Georg Thieme Verlag Stuttgart.
- Li, Bin Feng,Yuan, Ke,Dai, Li Xin,Hou, Xue Long
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p. 535 - 537
(2007/10/03)
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- TACHYKININ RECEPTOR ANTAGONISTS
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The present invention relates to selective NK-1 receptor antagonists of Formula (I) or a pharmaceutically acceptable salt thereof, for the treatment of disorders associated with an excess of tachykinins.
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- Exploring SmBr2-, SmI2-, and YbI2-mediated reactions assisted by microwave irradiation
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The use of microwave heating in lanthanide(II) halide (LnX2 = SmBr2, SmI2, and YbI2) mediated reduction and coupling reactions has been investigated for a variety of functional groups including α,β-unsaturated esters, aldehydes, ketones, imines, and alkyl halides. Good to quantitative transformations were obtained within a few minutes without the addition of any co-solvents, such as hexamethyl phosphoramide (HMPA). The redox potential of YbI2 in tetrahydrofuran (THF) has been determined as -1.02± 0.05 V (versus Ag/AgNO3) by cyclic voltammetry. A large selectivity difference in various reactions was observed depending on the redox potential of the LnX2 reagent. The more powerful reductant, SmBr2, afforded mainly pinacol-coupling products of ketones whereas the weaker reductant YbI2 afforded mainly reduction products. The results indicate that the reducing power of LnX 2 has a large impact on not only the pinacol coupling/reduction product ratio of ketones but also on other substrates in which there are competing coupling and reduction reactions. The use of in situ generated LnX2 has also been explored and proven useful in many of these reactions.
- Dahlen, Anders,Prasad, Edamana,Flowers II, Robert A.,Hilmersson, Goeran
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p. 3279 - 3284
(2007/10/03)
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- Hydroamination of carbonyl compounds with oximes
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N-alkyl(cycloalkyl)benzylamines, p-fluorobenzylamines, (1-phenylethyl) amines, [1-(p-fluorophenyl)ethyl]amines were synthesized by hydroamination of aldehydes and ketones with oximes.
- Tarasevich,Kozlov
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p. 379 - 383
(2007/10/03)
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- Instantaneous SmI2/H2O/amine-mediated reductions in THF
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The SmI2-mediated reductions of ketones, imines, and α,β-unsaturated esters have been shown to be instantaneous in the presence of H2O and an amine in THF. The SmI2-mediated reductions are not only shown to be fast and quantitative by the addition of H2O and an amine, but the workup procedures are also simplified. Competing experiments with SmI2/H2O/amine confirmed that α,β-unsaturated esters could be selectively reduced in the presence of ketones or imines. Comparison of analogue ligands showed that nitrogen and phosphorus ligands are superior to oxygen and sulfur ligands in these reductions. The trialkylphosphine 1,2-bis(dimethylphosphino)ethane (DMPE) provided a primary kinetic isotope effect, yielding a kH/kD of 4.5.
- Dahlen, Anders,Hilmersson, Goeran
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p. 1123 - 1128
(2007/10/03)
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- Two new methodologies for the deoxygenation and reduction of nitrones based on the use of lithium and DTBB (cat.)
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A variety of nitrones undergo deoxygenation when treated with an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB) (10 mol%) in THF at room temperature to give the corresponding imines. The Li/DTBB system, when combined with nickel(II) chloride dihydrate allows the reduction of a series of nitrones to secondary amines. The use of the deuterium oxide-containing nickel(II) salt transforms the starting nitrones to deuterated secondary amines.
- Radivoy,Alonso,Yus
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p. 427 - 430
(2007/10/03)
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- Chemoselective reductive amination of aldehydes and ketones by dibutylchlorotin hydride-HMPA complex
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Reductive amination of various aldehydes and ketones has been performed effectively by pentacoordinate chloro-substituted tin hydride complex, Bu2SnClH-HMPA. The tin reagent worked particularly well for the case using weakly basic aromatic amines as starting substrates. Stoichiometric amounts of a substrate and a reducing agent were adequate for the reaction. The Sn-Cl bond in the complex plays an important role for both steps of imine formation and subsequent reduction. Highly chemoselective reduction of carbonyls could be achieved regardless of other functionalities such as halogen, carbon- carbon double bond and hydroxyl groups in the starting carbonyls and amines.
- Suwa, Toshihiro,Sugiyama, Erika,Shibata, Ikuya,Baba, Akio
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p. 789 - 800
(2007/10/03)
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