- C(sp3)-F bond activation of CF3-substituted anilines with catalytically generated silicon cations: Spectroscopic evidence for a hydride-bridged Ru-S dimer in the catalytic cycle
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Heterolytic splitting of the Si-H bond mediated by a Ru-S bond forms a sulfur-stabilized silicon cation that is sufficiently electrophilic to abstract fluoride from CF3 groups attached to selected anilines. The ability of the Ru-H complex, generated in the cooperative activation step, to intramolecularly transfer its hydride to the intermediate carbenium ion (stabilized in the form of a cationic thioether complex) is markedly dependent on the electronic nature of its phosphine ligand. An electron-deficient phosphine thwarts the reduction step but, based on the Ru-S catalyst, half of an equivalent of an added alkoxide not only facilitates but also accelerates the catalysis. The intriguing effect is rationalized by the formation of a hydride-bridged Ru-S dimer that was detected by 1H NMR spectroscopy. A refined catalytic cycle is proposed.
- Stahl, Timo,Klare, Hendrik F. T.,Oestreich, Martin
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p. 1248 - 1251
(2013/03/29)
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- Homogeneous catalytic hydrogenation of amides to amines
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Hydrogenation of amides in the presence of [Ru(acac)3] (acacH=2,4-pentanedione), triphos [1,1,1-tris- (diphenylphosphinomethyl)ethane] and methanesulfonic acid (MSA) produces secondary and tertiary amines with selectivities as high as 93 % provided that there is at least one aromatic ring on N. The system is also active for the synthesis of primary amines. In an attempt to probe the role of MSA and the mechanism of the reaction, a range of methanesulfonato complexes has been prepared from prepared from [Ru(acac) 3], triphos and MSA, or from reactions of [RuX-(OAc)(triphos)] (X=H or OAc) or [RuH2(CO)(triphos)] with MSA. Crys-tallographically characterised complexes include: [Ru(OAc-κ1O) 2(H2O)-(triphos)], [Ru(OAc-κ2O,O') (CH3SO3-κ1O)(triphos)], [Ru(CH 3SO3-κ1O)2-(H 2O)(triphos)] and [Ru2(μ-CH3SO 3)3-(triphos)2][CH3SO3], whereas other complexes, such as [Ru(OAc-κ1O)(OAc- κ2O,O')(triphos)],[Ru(CH3SO3- κ1O)(CH3SO3-κ2O,O')- (triphos)], H[Ru(CH3SO3-κ1O) 3-(triphos)], [RuH(CH3SO3-κ1O) (CO)-(triphos)] and [RuH(CH3SO3-k2O,O')- (triphos)] have been characterised spectroscopically. The interactions between these various complexes and their relevance to the catalytic reactions are discussed.
- Coetzee, Jacorien,Dodds, Deborah L.,Klankermayer, Jürgen,Brosinski, Sandra,Leitner, Walter,Slawin, Alexandra M. Z.,Cole-Hamilton, David J.
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supporting information
p. 11039 - 11050
(2013/09/02)
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- One-pot photo-reductive N-alkylation of aniline and nitroarene derivatives with primary alcohols over Au-TiO2
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We report the photo-catalytic N-alkylation of aniline by Au-TiO 2. We successfully alkylate aniline with several primary alcohols. The combined selectivities of mono- and di-alkylated products were always in excess of 70% and dependent on the alkylating alcohol used. A one-pot reaction from nitrobenzene was found to be possible with several substrates. Preliminary experiments showed that this approach could be adopted for the production of lactams using terminal amino-alcohols. The Royal Society of Chemistry 2013.
- Stibal, David,Sa, Jacinto,Bokhoven, Jeroen A. Van
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- Selective N-alkylation of amines using nitriles under hydrogenation conditions: Facile synthesis of secondary and tertiary amines
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Nitriles were found to be highly effective alkylating reagents for the selective N-alkylation of amines under catalytic hydrogenation conditions. For the aromatic primary amines, the corresponding secondary amines were selectively obtained under Pd/C-catalyzed hydrogenation conditions. Although the use of electron poor aromatic amines or bulky nitriles showed a lower reactivity toward the reductive alkylation, the addition of NH4OAc enhanced the reactivity to give secondary aromatic amines in good to excellent yields. Under the same reaction conditions, aromatic nitro compounds instead of the aromatic primary amines could be directly transformed into secondary amines via a domino reaction involving the one-pot hydrogenation of the nitro group and the reductive alkylation of the amines. While aliphatic amines were effectively converted to the corresponding tertiary amines under Pd/C-catalyzed conditions, Rh/C was a highly effective catalyst for the N-monoalkylation of aliphatic primary amines without over-alkylation to the tertiary amines. Furthermore, the combination of the Rh/C-catalyzed N-monoalkylation of the aliphatic primary amines and additional Pd/C-catalyzed alkylation of the resulting secondary aliphatic amines could selectively prepare aliphatic tertiary amines possessing three different alkyl groups. According to the mechanistic studies, it seems reasonable to conclude that nitriles were reduced to aldimines before the nucleophilic attack of the amine during the first step of the reaction.
- Ikawa, Takashi,Fujita, Yuki,Mizusaki, Tomoteru,Betsuin, Sae,Takamatsu, Haruki,Maegawa, Tomohiro,Monguchi, Yasunari,Sajiki, Hironao
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supporting information; experimental part
p. 293 - 304
(2012/02/01)
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- Cu(ii)-catalyzed C-H (SP3) oxidation and C-N cleavage: Base-switched methylenation and formylation using tetramethylethylenediamine as a carbon source
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Base-switched methylenation and formylation using tetramethylethylenediamine (TMEDA) as a carbon source have been achieved under mild conditions, catalyzed by CuCl2, with atmospheric oxygen as oxidant. Bisindolylmethanes, diphenylmethanes and 3-formylindoles were synthesized with excellent regioselectivity and good yield.
- Zhang, Lei,Peng, Chen,Zhao, Dan,Wang, Yue,Fu, Hai-Jian,Shen, Qi,Li, Jian-Xin
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supporting information; experimental part
p. 5928 - 5930
(2012/07/27)
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- Mechanistic studies of the copper-catalyzed electrophilic amination of diorganozinc reagents and development of a zinc-free protocol
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Equation Presented An SN2 mechanism for the copper-catalyzed amination of diorganozinc reagents by O-benzoyl-N,N-dialkylhydroxyamines is supported by following stereochemically defined organometallics through the reaction and by employing the endocyclic restriction test. A copper-catalyzed electrophilic amination of organomagnesium compounds is also described in which the use of zinc halides has been eliminated.
- Campbell, Matthew J.,Johnson, Jeffrey S.
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p. 1521 - 1524
(2008/02/02)
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- Copper-catalyzed electrophilic amination of organozinc nucleophiles: Documentation of O-benzoyl hydroxylamines as broadly useful R2N(+) and RHN(+) synthons
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This paper details new copper-catalyzed electrophilic amination reactions of diorganozinc reagents using O-benzoyl hydroxylamines as electrophilic nitrogen sources that may be accessed in one step. Simple and functionalized aryl, heteroaryl-, benzyl, n-alkyl, sec-alkyl, and tert-alkyl nucleophiles couple with R2NOC(O)Ph and RHNOC(O)Ph reagents in the presence of catalytic quantities of copper salts to provide tertiary and secondary amines, respectively, in generally good yields. In many cases, the product may be isolated analytically pure after a simple extractive workup. The amination process is shown to tolerate a significant degree of steric demand. The amination of nominally unreactive Caryl-H bonds via a sequential directed ortho metalation/transmetalation/catalytic amination reaction sequence is detailed. The direct Cu-catalyzed amination of Grignard reagents using cocatalysis by ZnCl2 is described.
- Herman, Ashley M.,Johnson, Jeffrey S.
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p. 219 - 224
(2007/10/03)
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- Copper-Catalyzed Electrophilic Amination of Diorganozinc Reagents
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The copper-catalyzed electrophilic amination of diorganozinc reagents employing O-acyl N,N-dialkyl hydroxylamine derivatives as aminating agents is described. This reaction offers a general method for the preparation of tertiary amines in high yields and is noteworthy for its convenience both in terms of reaction conditions employed (room temperature, ≤1 h) and ease of product isolation (acid/base extractive workup). Copyright
- Berman, Ashley M.,Johnson, Jeffrey S.
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p. 5680 - 5681
(2007/10/03)
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- PALLADIUM-CATALYZED AROMATIC AMINATION OF ARYL BROMIDES WITH N,N-DIETHYLAMINO-TRIBUTYLTIN
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The reaction of N,N-diethylamino-tributyltin with aryl bromides in the presence of a catalytic amount of PdCl2(o-tolyl3P)2 gave N,N-diethylaminobenzene derivatives.The reaction is a new kind of amination different from ones through aryne or SRN1 mechanism.
- Kosugi, Masanori,Kameyama,Masayuki,Migita, Toshihiko
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p. 927 - 928
(2007/10/02)
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