- Conversion of racemic alcohols to optically pure amine precursors enabled by catalyst dynamic kinetic resolution: Experiment and computation
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An unprecedented base metal catalysed asymmetric synthesis of α-chiral amine precursors from racemic alcohols is reported. This redox-neutral reaction utilises a bench-stable manganese complex and Ellman's sulfinamide as a versatile ammonia surrogate. DFT
- Azofra, Luis Miguel,Tran, Mai Anh,Zubar, Viktoriia,Cavallo, Luigi,Rueping, Magnus,El-Sepelgy, Osama
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supporting information
p. 9094 - 9097
(2020/10/02)
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- Method for synthesizing chiral amine
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The invention discloses a method for synthesizing chiral amine. According to the method, a catalytic amount of ketone is used as a self-catalyst, alkali which is cheap and easy to get is used as a synergistic catalyst, a 1-aryl-alcoho compound is used as
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Paragraph 0038; 0039; 0040; 0041
(2019/01/16)
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- Iridium-catalyzed diastereoselective amination of alcohols with chiral: Tert-butanesulfinamide by the use of a borrowing hydrogen methodology
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An iridium-catalyzed diastereoselective amination of alcohols with chiral tert-butanesulfinamide was developed under basic conditions, affording the optically active secondary sulfinamides in high yields and diastereoselectivities. The removal of the sulfinyl group from sulfonamides allowed a facile access to a wide range of α-chiral primary amines. This synthetic strategy was further applied in the synthesis of the marketed pharmaceuticals (S)-rivastigmine and NPS R-568.
- Xi, Xiaomei,Li, Yongjie,Wang, Guannan,Xu, Guangda,Shang, Lina,Zhang, Yao,Xia, Lixin
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supporting information
p. 7651 - 7654
(2019/08/30)
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- Transition-Metal-Free Hydrogen Autotransfer: Diastereoselective N-Alkylation of Amines with Racemic Alcohols
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A practical method for the synthesis of α-chiral amines by alkylation of amines with alcohols in the absence of any transition-metal catalysts has been developed. Under the co-catalysis of a ketone and NaOH, racemic secondary alcohols reacted with Ellman's chiral tert-butanesulfinamide by a hydrogen autotransfer process to afford chiral amines with high diastereoselectivities (up to >99:1). Broad substrate scope and up to a 10 gram scale production of chiral amines were demonstrated. The method was applied to the synthesis of chiral deuterium-labelled amines with high deuterium incorporation and optical purity, including examples of chiral deuterated drugs. The configuration of amine products is found to be determined solely by the configuration of the chiral tert-butanesulfinamide regardless of that of alcohols, and this is corroborated by DFT calculations. Further mechanistic studies showed that the reaction is initiated by the ketone catalyst and involves a transition state similar to that proposed for the Meerwein–Ponndorf–Verley (MPV) reduction, and importantly, it is the interaction of the sodium cation of the base with both the nitrogen and oxygen atoms of the sulfinamide moiety that makes feasible, and determines the diastereoselectivity of, the reaction.
- Xiao, Miao,Yue, Xin,Xu, Ruirui,Tang, Weijun,Xue, Dong,Li, Chaoqun,Lei, Ming,Xiao, Jianliang,Wang, Chao
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supporting information
p. 10528 - 10536
(2019/07/17)
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- From racemic alcohols to enantiopure amines: Ru-catalyzed diastereoselective amination
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A commercially available ruthenium(II) PNP-type pincer catalyst (Ru-Macho) promotes the formation of α-chiral tert-butanesulfinylamines from racemic secondary alcohols and Ellmans chiral tert-butanesulfinamide via a hydrogen borrowing strategy. The formation of α-chiral tert-butanesulfinylamines occurs in yields ranging from 31% to 89% with most examples giving >95:5 dr.
- Oldenhuis, Nathan J.,Dong, Vy M.,Guan, Zhibin
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supporting information
p. 12548 - 12551
(2014/12/10)
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- A versatile Ru catalyst for the asymmetric transfer hydrogenation of both aromatic and aliphatic sulfinylimines
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A highly efficient Ru catalyst based on an achiral, very simple, and inexpensive amino alcohol ligand (2-amino-2-methylpropan-1-ol) has been developed for the asymmetric transfer hydrogenation (ATH) of chiral N-(tert-butylsulfinyl)imines. This complex is able to catalyze the ATH of both aromatic and the most challenging aliphatic sulfinylimines by using isopropyl alcohol as the hydrogen source. The diastereoselective reduction of aromatic, heteroaromatic, and aliphatic sulfinylketimines, including sterically congested cases, over short reaction times (1-4 h), followed by desulfinylation of the nitrogen atom, affords the corresponding highly enantiomerically enriched (ee up to >99%) α-branched primary amines in excellent yields. The same ligand was equally effective for the synthesis of both (R)- and (S)-amines by using the appropriate absolute configuration in the iminic substrate. DFT mechanistic studies show that the hydrogen-transfer process is stepwise. Moreover, the origin of the diastereoselectivity has been rationalized.
- Pablo, Oscar,Guijarro, David,Kovacs, Gabor,Lledos, Agusti,Ujaque, Gregori,Yus, Miguel
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p. 1969 - 1983
(2012/03/26)
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- Impregnated ruthenium on magnetite as a recyclable catalyst for the N-alkylation of amines, sulfonamides, sulfinamides, and nitroarenes using alcohols as electrophiles by a hydrogen autotransfer process
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Various impregnated metallic salts on magnetite have been prepared, including cobalt, nickel, copper, ruthenium, and palladium salts, as well as a bimetallic palladium - copper derivative. Impregnated ruthenium catalyst is a versatile, inexpensive, and simple system for the selective N-monoalkylation of amino derivatives with poor nucleophilic character, such as aromatic and heteroaromatic amines, sulfonamides, sulfinamides, and nitroarenes, using in all cases alcohols as the initial source of the electrophile, through a hydrogen autotransfer process. In the case of sulfinamides, this is the first time that these amino compounds have been alkylated following this strategy, allowing the use of chiral sulfinamides and secondary alcohols to give the alkylated compound with a diastereomeric ratio of 92:8. In these cases, after alkylation, a simple acid deprotection gave the expected primary amines in good yields. The ruthenium catalyst is quite sensitive, and small modifications of the reaction medium can change the final product. The alkylation o amines using potassium hydroxide renders the N-monoalkylated amines, and the same protocol using sodium hydroxide yields the related imines. The catalyst can be easily removed by a simple magnet and can be reused up to ten times, showing the same activity.
- Cano, Rafael,Ramon, Diego J.,Yus, Miguel
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experimental part
p. 5547 - 5557
(2011/08/10)
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- Asymmetric synthesis of chiral primary amines by transfer hydrogenation of N -(tert -Butanesulfinyl)ketimines
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(Figure presented) The diastereoselective reduction of (R)-N-(tert- butanesulfinyl)ketimines by a ruthenium-catalyzed asymmetric transfer hydrogenation process in isopropyl alcohol, followed by desulfinylation of the nitrogen atom, is an excellent method to prepare highly enantiomerically enriched α-branched primary amines (up to >99% ee) in short reaction times (1-4 h). (1S,2R)-1-Amino-2-indanol has been shown to be a very efficient ligand to perform this transformation. Ketimines bearing either an aryl or a heteroaryl group and an alkyl group as substituents of the iminic carbon atom are very good substrates for this process. The reduction of a dialkyl ketimine could also be achieved, affording the expected amine with moderate optical purity (69% ee). Some amines which are precursors of very interesting biologically and pharmacologically active compounds have been prepared in excellent yields and enantiomeric excesses.
- Guijarro, David,Pablo, Oscar,Yus, Miguel
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supporting information; scheme or table
p. 5265 - 5270
(2010/10/21)
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- Synthesis of highly enantiomerically enriched amines by the diastereoselective addition of triorganozincates to N-(tert-butanesulfinyl)imines
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The reaction of triorganozincates with (R)-N-(tert-butanesulfinyl) imines gives the expected α-branched sulfinamides in good to excellent yields with diastereomeric ratios of up to 98:2. The N-sulfinyl group of the products can be easily removed by acidic treatment, affording the corresponding chiral primary amines in enantiomeric excesses of up to 96%. The reactivity and the selectivity shown by the triorganozincates are different from the ones observed with the corresponding Grignard reagents, which allows, in several cases, the preparation of both enantiomers of an amine from the same imine substrate. When mixed triorganozincates are used, one can take advantage of the slow transfer rate of the methyl group to use it as a non-transferable one. Both aromatic and aliphatic aldimines, as well as activated ketimines, are good substrates for these addition reactions.
- Almansa, Raquel,Guijarro, David,Yus, Miguel
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experimental part
p. 2484 - 2491
(2009/04/11)
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- One-pot asymmetric synthesis of either diastereomer of tert-butanesulfinyl- protected amines from ketones
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A one-pot method for the asymmetric synthesis of tert-butanesulfinyl- protected amines is described. Condensation of aryl alkyl and dialkyl ketones with tert-butanesulfinamide followed by in situ reduction with the appropriate reagent provides either dias
- Tanuwidjaja, Jessica,Peltier, Hillary M.,Ellman, Jonathan A.
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p. 626 - 629
(2007/10/03)
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- Reversal of diastereofacial selectivity in hydride reductions of N-tert-butanesulfinyl imines
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A variety of N-tert-butanesulfinyl imines were reduced with NaBH 4 in THF containing 2% water to provide the corresponding secondary sulfinamides in high yield and diastereoselectivity. By using the same sulfinyl imine starting materials and changing the reductant to L-Selectride, the stereoselectivity could be efficiently reversed to afford the opposite product diastereomer in high yield and selectivity.
- Colyer, John T.,Andersen, Neil G.,Tedrow, Jason S.,Soukup, Troy S.,Faul, Margaret M.
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p. 6859 - 6862
(2007/10/03)
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- One-pot asymmetric synthesis of tert-butanesulfinyl-protected amines from ketones by the in situ reduction of tert-butanesulfinyl ketimines
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A one-pot method for the asymmetric synthesis of tert-butanesulfinyl-protected amines is described. The ketones 2 are condensed with (R)-tert-butanesulfinamide 1 and the tert-butanesulfinyl imine intermediates reduced in situ with NaBH4 to affo
- Borg, George,Cogan, Derek A.,Ellman, Jonathan A.
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p. 6709 - 6712
(2007/10/03)
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