- Direct reductive coupling of secondary amides: Chemoselective formation of vicinal diamines and vicinal amino alcohols
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We report the first one-pot reductive homocoupling reaction of secondary amides and cross-coupling reaction of secondary amides with ketones to give secondary vicinal diamines and amino alcohols. This method relies on the direct generation of α-amino carb
- Huang, Pei-Qiang,Lang, Qi-Wei,Wang, Ai-E,Zheng, Jian-Feng
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supporting information
p. 1096 - 1099
(2015/02/19)
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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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- Iminopinacol coupling with lithium: Electron-transfer mediators
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The addition of tert-butyl borate or ethyl formate to N-alkylbenzalimines directs the reaction pathway from the Birch reduction to the pinacol-type coupling with lithium in THF; an analogous reaction with a dimethylimmonium salt requires a trace titanium catalyst as the electron-transfer mediator.
- Mistryukov, Electron A.
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p. 230 - 231
(2007/10/03)
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- Samarium diiodide/nickel diiodide an efficient system for homo and heterocoupling reactions of imines
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Samarium diiodide in the presence of a catalytic amount of nickel diiodide mediates a very fast dimerization of imines into vicinal diamines and the mixed coupling of imines and ketones to give β-amino alcohols.
- Machrouhi, Fouzia,Namy, Jean-Louis
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p. 1315 - 1318
(2007/10/03)
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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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p. 12775 - 12788
(2007/10/03)
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- Cp2VCl2-catalyzed meso-selective pinacol coupling reaction of aldimines in the presence of chlorosilane and zinc metal
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A catalytic reductive coupling of aldimines was achieved by using a catalyst Cp2VCl2/PhMe2SiCl/Zn system. The influence of the catalyst, chlorosilane, co-reductant, solvent, and temperature on both the yield and diastereoselectivity of the coupling products was investigated in detail. As a result, the present Cp2VCl2-catalyzed reductive coupling of aldimines in the presence of PhMe2-SiCl and zinc metal provided the corresponding 1,2- diamines in good yield with high meso selectivity (up to 92% meso), while the reductive coupling of aldehydes, ketones, and aldimines by the hitherto known catalytic methods leads to the preferential formation of dl isomers of the coupling products.
- Hatano, Bunpei,Ogawa, Akiya,Hirao, Toshikazu
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p. 9421 - 9424
(2007/10/03)
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- Practical and efficient synthesis of C2 symmetrical diamines with Zn / Me3SiCl
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C2 symmetrical diamines are efficiently obtained by reductive coupling of imines with the couple Zn/Me3SiCl. This high yielding method is very practical and cheap for large scale preparation.
- Alexakis, Alexandre,Aujard, Isabelle,Mangeney, Pierre
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p. 873 - 874
(2007/10/03)
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- A new coupling reaction between β-lactones and electrophiles mediated by a SmI2/(NiI2 catalytic) system
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β-lactones react with ketones aldehydes and imines in the presence of a SmI2/(NiI2 catalytic) system to afford substituted tetrahydrofuranones and pyrrolidinones.
- Machrouhi, Fouzia,Namy, Jean-Louis
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p. 11111 - 11122
(2007/10/03)
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- Organic reaction in water. Part 1. A convenient method for reduction of imines using zinc powder
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Reduction of imines was performed with zinc powder in 5% aqNaOH solution without any organic solvents under mild conditions, and the corresponding amines were obtained in good yields.
- Tsukinoki, Takehito,Mitoma, Yoshiharu,Nagashima, Satoko,Kawaji, Takatoshi,Hashimoto, Iwao,Tashiro, Masashi
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p. 8873 - 8876
(2007/10/03)
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- Synthesis of Enantiomerically Pure 1,2-Diamines by Reductive Coupling of Tricarbony(benzaldimine)chromium Complexes
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Enantiomerically pure 1,2-diamines are prepared by intermolecular pinacol coupling of planar chiral (benzaldimine)Cr(CO)3 complexes with samarium(II) diiodide.
- Taniguchi, Nobukazu,Uemura, Motokazu
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