- Chiral N-heterocyclic carbene-iridium complexes for asymmetric reduction of prochiral ketimines
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Enantioselective reduction of imines to the corresponding chiral secondary amines has been studied using a series of chiral half-sandwich iridium complexes. Chiral N-heterocyclic carbene (NHC) ligands in these complexes were synthesized from readily available, naturally occurring amino acids. Inexpensive phenylsilane was used as a convenient hydrogen donor. Under the optimized conditions, Ir-NHC complexes could reduce ketimines in good yields, albeit with moderate enantiomeric excess (ee). The phenylglycine derived chiral NHC was shown to give the best Ir catalyst and it also gave the maximum ee compared to catalysts prepared from other NHCs in this series. The opposite enantiomer of the reduction product was always obtained while using the Ir complex bearing a valine based NHC. The yields were consistently high with a variety of imine substrates having different steric and electronic demands.
- Kathuria, Lakshay,Samuelson, Ashoka G.
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supporting information
(2020/12/28)
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- Palladium supported on magnesium hydroxyl fluoride: An effective acid catalyst for the hydrogenation of imines and N-heterocycles
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Palladium catalysts supported on acidic fluorinated magnesium hydroxide Pd/MgF2-x(OH)x were prepared through precipitation or impregnation methods. Applications to the hydrogenation of various aldimines and ketimines resulted in good catalytic activities at mild temperatures using one atmosphere of hydrogen. Quinolines, pyridines and other N-heterocycles were successfully hydrogenated at higher temperature and hydrogen pressure using low palladium loadings and without the use of any acid additive. Such reactivity trend confirmed the positive effect of the Br?nsted and Lewis acid sites from the fluorinated magnesium hydroxide support resulting in the effective pre-activation of N-heterocycle substrates and therefore in the good catalytic activity of the palladium nanoparticles during the hydrogenations. As demonstrated in the hydrogenation of imines, the catalyst was recycled up to 10 times without either loss of activity or palladium leaching. This journal is
- Agbossou-Niedercorn, Francine,Corre, Yann,Dongare, Mohan K.,Kemnitz, Erhard,Kokane, Reshma,Michon, Christophe,Umbarkar, Shubhangi B.
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supporting information
p. 19572 - 19583
(2021/11/04)
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- Sustainable Production of Benzylamines from Lignin
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Catalytic conversion of lignin into heteroatom functionalized chemicals is of great importance to bring the biorefinery concept into reality. Herein, a new strategy was designed for direct transformation of lignin β-O-4 model compounds into benzylamines and phenols in moderate to excellent yields in the presence of organic amines. The transformation involves dehydrogenation of Cα?OH, hydrogenolysis of the Cβ?O bond and reductive amination in the presence of Pd/C catalyst. Experimental data suggest that the dehydrogenation reaction proceeds over the other two reactions and secondary amines serve as both reducing agents and amine sources in the transformation. Moreover, the concept of “lignin to benzylamines” was demonstrated by a two-step process. This work represents a first example of synthesis of benzylamines from lignin, thus providing a new opportunity for the sustainable synthesis of benzylamines from renewable biomass, and expanding the products pool of biomass conversion to meet future biorefinery demands.
- Guo, Tenglong,Kühn, Fritz E.,Li, Changzhi,Liu, Yuxuan,Wang, Chao,Xiao, Jianliang,Zhang, Bo,Zhang, Tao,Zhao, Zongbao K.
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supporting information
p. 20666 - 20671
(2021/08/25)
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- Diethylsilane as a Powerful Reagent in Au Nanoparticle-Catalyzed Reductive Transformations
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Diethylsilane (Et2SiH2), a simple and readily available dihydrosilane, that exhibits superior reactivity, as compared to monohydrosilanes, in a series of reductive transformations catalyzed by recyclable and reusable Au nanoparticles (1 mol-%) supported on TiO2. It reduces aldehydes or ketones almost instantaneously at ambient conditions. It can be used in a one pot rapid reductive amination procedure, in which premixing of aldehyde and amine is required prior to the addition of the reducing agent and the catalyst, even in a protic solvent. An unprecedented method for the synthesis of N-arylisoindolines is also shown in the reductive amination between o-phthalaldehyde and anilines. In this transformation, it is proposed that the intermediate N,2-diphenylisoindolin-1-imines are reduced stepwise to the isoindolines. Finally, Et2SiH2 readily reduces amides into amines in excellent yields and shorter reaction times relative to previously known analogous nano Au(0)-catalyzed protocols.
- Louka, Anastasia,Kidonakis, Marios,Saridakis, Iakovos,Zantioti-Chatzouda, Elisavet-Maria,Stratakis, Manolis
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p. 3508 - 3514
(2020/06/02)
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- Enantioselective reduction of: N -alkyl ketimines with frustrated Lewis pair catalysis using chiral borenium ions
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Enantioselective reduction of ketimines was demonstrated using chiral N-heterocyclic carbene (NHC)-stabilised borenium ions in frustrated Lewis pair catalysis. High levels of enantioselectivity were achieved for substrates featuring secondary N-alkyl substituents. Comparative reactivity and mechanistic studies identify key determinants required to achieve useful enantioselectivity and represent a step forward in the further development of enantioselective FLP methodologies.
- Mercea, Dan M.,Howlett, Michael G.,Piascik, Adam D.,Scott, Daniel J.,Steven, Alan,Ashley, Andrew E.,Fuchter, Matthew J.
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supporting information
p. 7077 - 7080
(2019/06/20)
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- GROUP 5 METAL COMPLEXES FOR CATALYTIC AMINE FUNCTIONALIZATION
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This application pertains to group 5 metal complexes having the structure of Formula I; and their potential utility in catalyzing α-alkylation of secondary amine-containing moieties.
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Page/Page column 47-50
(2018/12/14)
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- Asymmetric Reductive Amination of Ketones Catalyzed by Imine Reductases
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Biocatalysis employing imine reductases is a promising approach for the one-step generation of chiral amines from ketones. The enzymes reported for this process suffer from low activity and moderate stereoselectivity. We identified a set of enzymes that facilitate this reaction with high to quantitative conversions from a library of 28 imine reductases. This enabled the conversion of ketones with ammonia, methylamine, or butylamine into the corresponding amines. Most importantly, we performed preparative (>100 mg) scale syntheses of amines such as (1S,3R)-N,3-dimethylcyclohexylamine and (R)-N-methyl-2-aminohexane with excellent stereochemical purities (98 % de, 96 % ee) in good yields.
- Wetzl, Dennis,Gand, Martin,Ross, Alfred,Müller, Hubertus,Matzel, Philipp,Hanlon, Steven P.,Müller, Michael,Wirz, Beat,H?hne, Matthias,Iding, Hans
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p. 2023 - 2026
(2016/07/07)
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- Efficient hydrosilylation of imines using catalysts based on iridium(iii) metallacycles
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Ir(iii) metallacycles were applied as catalysts for the hydrosilylation of various ketimines and aldimines with sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate, NaBArF24, as an additive. By using a slight excess of the organosilane reagent, the reactions proceeded rapidly and efficiently, at low catalyst loadings and at room temperature. Several examples of cationic Ir(iii) catalysts could be synthesised, characterized and tested. In situ-generated catalysts proved to be more active as compared to isolated ones and species with non-coordinating BArF24 counterion gave the highest catalytic activities.
- Corre,Iali,Hamdaoui,Trivelli,Djukic,Agbossou-Niedercorn,Michon
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p. 1452 - 1458
(2015/04/14)
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- Highly chemoselective reduction of imines using a AuNPore/PhMe2SiH/water system and its application to reductive amination
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Abstract An unusually strong affinity of unsupported nanoporous gold (AuNPore) towards aldimines and ketimines has been demonstrated. By using PhMe2SiH and water as a hydrogen source and AuNPore as a catalyst, ketimines and aldimines can be reduced to the corresponding amines in high chemical yields under mild conditions. This system was also applied to the reductive amination of aldehydes and ketones.
- Takale, Balaram S.,Tao, Shanmou,Yu, Xiaoqiang,Feng, Xiujuan,Jin, Tienan,Bao, Ming,Yamamoto, Yoshinori
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p. 7154 - 7158
(2015/08/24)
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- Disulfonimide-Catalyzed Asymmetric Reduction of N-Alkyl Imines
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A chiral disulfonimide (DSI)-catalyzed asymmetric reduction of N-alkyl imines with Hantzsch esters as a hydrogen source in the presence of Boc2O has been developed. The reaction delivers Boc-protected N-alkyl amines with excellent yields and enantioselectivity. The method tolerates a large variety of alkyl amines, thus illustrating potential for a general reductive cross-coupling of ketones with diverse amines, and it was applied in the synthesis of the pharmaceuticals (S)-Rivastigmine, NPS R-568 Hydrochloride, and (R)-Fendiline. A chiral disulfonimide (DSI)-catalyzed asymmetric reduction of N-alkyl imines with Hantzsch esters as a hydrogen source in the presence of Boc2O was developed. The reaction delivers Boc-protected N-alkyl amines with excellent yields and enantioselectivity. The method was successfully applied to the synthesis of the pharmaceuticals (S)-Rivastigmine, NPS R-568 Hydrochloride, and (R)-Fendiline.
- Wakchaure, Vijay N.,Kaib, Philip S. J.,Leutzsch, Markus,List, Benjamin
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supporting information
p. 11852 - 11856
(2015/10/05)
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- Liquid chromatographic resolution of fendiline and its analogues on a chiral stationary phase based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid
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Fendiline, an effective anti-anginal drug for the treatment of coronary heart diseases, and its sixteen analogues were resolved on a CSP based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid. Fendiline was resolved quite well with the separation factor (α) of 1.25 and resolution (RS ) of 1.55 when a mobile phase consisting of methanol-acetonitrile-trifluoroacetic acid-triethylamine at a ratio of 80/20/0.1/0.5 (v/v/v/v) was used. The comparison of the chromatographic behaviors for the resolution of fendiline and its analogues indicated that the 3,3-diphenylpropyl group bonded to the secondary amino group of fendiline is important in the chiral recognition and the difference in the steric bulkiness between the phenyl group and the methyl group at the chiral center of fendiline is also important in the chiral recognition.
- Lee, Ga Ram,Hyun, Myung Ho
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p. 21386 - 21397
(2015/02/19)
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- Selective N-alkylation of primary amines with R-NH2·HBr and alkyl bromides using a competitive deprotonation/protonation strategy
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Monoalkylation of primary amines using amine hydrobromides and alkyl bromides has been carried out. Under controlled reaction conditions the reactant primary amine was selectively deprotonated and made available for reaction, while the newly generated secondary amine remained protonated, and did not participate in alkylation further. Reaction was carried out under mild reaction conditions and was applicable to a wide range of primary amines and alkyl bromides.
- Bhattacharyya, Shubhankar,Pathak, Uma,Mathur, Sweta,Vishnoi, Subodh,Jain, Rajeev
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p. 18229 - 18233
(2014/05/20)
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- METHOD FOR PRODUCING N-SUBSTITUTED AMINE COMPOUNDS THROUGH CATALYZED ALKYLATION
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The invention relates to a method for producing a N-substituted amine compound by catalyzed alkylation. The method uses amine and alcohol or two kinds of amines as the reaction materials, employs composite metal oxides catalyst at a reaction temperature of 80-180° C. to catalyze the reaction for 6-36 hours, so as to produce the N-substituted amine compound. The reaction condition of the method of the invention is relatively moderate, using a catalyst made of cheap non-noble metals, which is non-caustic and easy to be separated and reused. The reaction does not need any medium and has relatively high conversion rate and selectivity.
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Paragraph 0044
(2014/02/16)
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- Copper-catalyzed reductive amination of aromatic and aliphatic ketones with anilines using environmental-friendly molecular hydrogen
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A convenient and practical copper-catalyzed reductive amination was discovered. In the presence of easily available and inexpensive Cu(OAc) 2 various ketones react with anilines and molecular hydrogen to give the desired amines in high yields.
- Werkmeister, Svenja,Junge, Kathrin,Beller, Matthias
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supporting information
p. 2371 - 2374
(2013/02/21)
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- Borrowing hydrogen methodology for amine synthesis under solvent-free microwave conditions
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Application of microwave heating to the Borrowing Hydrogen strategy to form C-N bonds from alcohols and amines is presented, removing the need for solvent and reducing the reaction times while still yielding results comparable with those using thermal heating.
- Watson, Andrew J. A.,Maxwell, Aoife C.,Williams, Jonathan M. J.
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supporting information; experimental part
p. 2328 - 2331
(2011/05/17)
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- A versatile catalyst for reductive animation by transfer hydrogenation
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An iridium catalyst enables the reductive amination of carbonyl groups with unprecedented substrate scope, selectivity, and activity using formic acid as the hydrogen source (see scheme) The catalyst system provides significant improvement over commonly used boron hydrides.
- Wang, Chao,Pettman, Alan,Basca, John,Xiao, Jianliang
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supporting information; experimental part
p. 7548 - 7552
(2010/12/19)
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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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- Salt-free synthesis of tertiary amines by ruthenium-catalyzed amination of alcohols
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The amination of secondary alcohols to give tertiary amines in the presence of different in situ generated ruthenium catalysts has been investigated in detail. By applying a combination of [Ru3(CO)12] and N-phenyl-2-(dicyclohexylphosphanyl) pyrrole as the catalyst, cyclic amines can be alkylated with different alcohols in high yield, whereas aliphatic amines gave transalkylation side products. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Tillack, Annegret,Hollmann, Dirk,Mevius, Kathleen,Michalik, Dirk,Baehn, Sebastian,Beller, Matthias
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body text
p. 4745 - 4750
(2009/05/07)
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- Novel domino elimination-rearrangement-addition reaction of N-alkoxy(arylmethyl)amines to N-alkyl arylamines
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A new domino reaction of N-alkoxy(arylmethyl)amines to N-alkyl arylamines, consisting of three types of reactions: elimination of alcohol, rearrangement of the aryl group, and addition of an organolithium or a magnesium reagent, has been developed for the first time. Georg Thieme Verlag Stuttgart.
- Miyata, Okiko,Ishikawa, Tatsuya,Ueda, Masafumi,Naito, Takeaki
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p. 2219 - 2222
(2007/10/03)
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- Synthesis of ruthenium hydride complexes containing beta-aminophosphine ligands derived from amino acids and their use in the H2- hydrogenation of ketones and imines
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The new complexes RuHCl(PPh2CH2-CHRNH 2)2 and RuHCl(PPh2CH2CHRNH 2)(R-binap), R = H (Pgly), R = Me [(R)-Pala] were prepared by the substitution of the PPh3 ligands in RuHCl(PPh3) 3 or RuHCl(PPh3)[(R)-binap] with beta-aminophosphines derived from amino acids. The complex trans-RuHCl(Pgly)[(R)-binap] has been characterized by X-ray crystallography. The complex trans-RuHCl[(S)-Ppro] 2 where (5)-Ppro is derived from proline was also prepared and characterized by X-ray crystallography. These were used as catalyst precursors in the presence of a base (KOPr-i or KOBu-t) for the hydrogenation of various ketones and imines to the respective alcohols and amines with H2 gas (1-11 atm) at room temperature. Acetophenone was hydrogenated to (S)-1-phenylethanol in low ee (up to 40%) when catalyzed by the enantiomerically pure complexes. These complexes are especially active in the hydrogenation of sterically congested and electronically deactivated ketones and imines and are selective for the hydrogenation of C=O bonds over C=C bonds.
- Abdur-Rashid, Kamaluddin,Guo, Rongwei,Lough, Alan J.,Morris, Robert H.,Song, Datong
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p. 571 - 579
(2007/10/03)
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- Role of noncovalent interactions in the enantioselective reduction of aromatic ketimines with trichlorosilane
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Asymmetric reduction of ketimines 1 with trichlorosilane can be catalyzed by a new N-methyl L-valine derived Lewis basic organocatalyst, such as 4d, with high enantioselectivity. The structure-reactivity investigation suggests hydrogen bonding and arene-arene interactions between the catalyst and the incoming imine as the main factor determining the enantiofacial selectivity.
- Malkov, Andrei V.,Mariani, Andrea,MacDougall, Kenneth N.,Kocovsky, Pavel
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p. 2253 - 2256
(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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- Displacements at the Nitrogen of Lithioalkoxylamides by Organometallic Reagents
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The conversions of N-(o-bromobenzyl)methoxylamine to N-acetylbenzoazetine (1), of N-methoxylamine to N-acetyltetrahydroquinoline (2), and N-methoxylamine to N-acetylbenzazapine (3) illustrate the use of this displacement reaction to form nitrogencontaining rings in an exocyclic reaction mode.An X-ray structural determination is reported for 1.The formations of anilides by amination of aromatic organolithium reagents with lithium methoxylamide is also reported.Lithium reagents are found to be more effective than Grignard, copper, or zinc reagents in these displacement, and the yields decrease as the size of the substituents around nitrogen increases.The endocyclic restriction test is used to show that this displacement on nitrogen cannot occur within the endocyclic confines of a seven-membered ring.A SN2 reaction pathway in a lithium complex is considered to be supported by these results.
- Beak, Peter,Selling, Gordon W.
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p. 5574 - 5580
(2007/10/02)
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- The Geometry of Displacements at Nonstereogenic Atoms: The Formal Displacement of Alkoxide from Alkoxyamines by Organolithium Reagents
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Amination of organolithium regents can be achieved by reaction with methyllithium-alkoxyamines.Details of the methodology and analysis of the reaction mechanism are presented.Reactions of methyl-, ethyl-, n-butyl-, sec-butyl-, tert-butyl-, phenyl-, and (o-methoxyphenyl)lithium with methyllithium-methoxyamine give the corresponding amines, isolated as the benzamides, in yields of 71-97percent.Lower yields are obtained with o-lithio-N,N-diisopropylbenzamide, 4-lithiodibenzothiophene, n-butylmagnesium bromide, and phenylmagnesium bromide.Reactions of n-butyl, sec-butyl-, tert-butyl-, and phenyllithium with methyllithium-N-methylmethoxyamine provide the corresponding N-methyl-amines, isolated as the benzamides, in yields of 30-70percent.Retention of the N-methyl group in these reactions is considered to rule out a nitrene intermediate.Involvement of a lithium alkoxyamide is suggested by the formation and substitution of that species by two different routes.Dilithiation of N-methoxy-N-amine (17) gives, after an intramolecular reaction and addition of acetyl chloride, N-acetylindoline, in 78percent yield.Dilithiation of N-methyl-N-amine (19) gives N-methyl-N-acetamide (20), after rection with acetyl chloride.The nitrogen transfer in this conversion is shown by a double labeling experiment to be intermolecular.This results is taken to suggest that the bond angles required for displacement cannot be achieved in a six-membered ring, and the mechanism of the reaction involves a complex in which displacement occurs via an SN2-like transition state.The exocyclic-endocyclic intramolecular-intermolecular test is noted to provide a general approach for determination of the geomatry of reactions at nonstereogenic centers.
- Beak, Peter,Basha, Anwer,Kokko, Bruce,Loo, DeKai
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p. 6016 - 6023
(2007/10/02)
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- THE ELECTROPHILIC AMINATION OF ORGANOLITHIUMS WITH METHYLLITHIUM COMPLEXES OF N-SUBSTITUTED METHOXYAMINES
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Three N-alkyl methoxyamine derivatives are shown to be effective as electrophilic reagents for the conversion of organolithiums to secondary amines.
- Kokko, Bruce J.,Beak, Peter
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p. 561 - 564
(2007/10/02)
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