57680-93-0Relevant academic research and scientific papers
Microwave-Enhanced Asymmetric Transfer Hydrogenation of N-(tert-Butylsulfinyl)imines
Pablo, Oscar,Guijarro, David,Yus, Miguel
, p. 7034 - 7038 (2016/02/19)
Microwave irradiation has considerably enhanced the efficiency of the asymmetric transfer hydrogenation of N-(tert-butylsulfinyl)imines in isopropyl alcohol catalyzed by a ruthenium complex bearing the achiral ligand 2-amino-2-methylpropan-1-ol. In addition to shortening reaction times for the transfer hydrogenation processes to only 30 min, the amounts of ruthenium catalyst and isopropyl alcohol can be considerably reduced in comparison with our previous procedure assisted by conventional heating, which diminishes the environmental impact of this new protocol. This methodology can be applied to aromatic, heteroaromatic and aliphatic N-(tert-butylsulfinyl)ketimines, leading, after desulfinylation, to the expected primary amines in excellent yields and with enantiomeric excesses of up to 96 %. Microwave irradiation promotes the asymmetric transfer hydrogenation of N-(tert-butylsulfinyl)imines in 2-propanol catalysed by a ruthenium complex bearing an achiral β-amino alcohol as ligand. After desulfinylation, α-branched primary amines containing aromatic, heteroaromatic and aliphatic substituents are obtained in excellent yields and with enantiomeric excesses of up to 96 %.
Ritter reaction in subcritical water: An efficient and green method for amides synthesis
Jiang, Shengqian,Wang, Zhouyu,Jiang, Zhenju,Li, Jianhui,Zhou, Shulin,Pu, Long
experimental part, p. 24 - 28 (2012/08/08)
Ritter reaction was carried out efficiently in subcritical water with catalytic amount of trifluoromethanesulfonic acid. The amides were formed in good to excellent yields from secondary alcohols and tert-butanol with various nitriles.
Asymmetric synthesis of chiral primary amines by transfer hydrogenation of N -(tert -Butanesulfinyl)ketimines
Guijarro, David,Pablo, Oscar,Yus, Miguel
supporting information; experimental part, p. 5265 - 5270 (2010/10/21)
(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.
Aziridines. 77: cis-trans pair of a N-benzoylaziridine: Dependence of carbonyl reactivity on nitrogen pyramid
Falkenstein, Reinhard,Stamm, Helmut
, p. 195 - 196 (2007/10/03)
In a multistep process, anthracenide and both 1-benzoyl-2-methyl-3-phenylaziridines 1a form carbanion 4a that abstracts a proton from the solvent THF. The steep N pyramid of cis-1a makes attack of 4a on C=O of cis-1a fast enough to compete with proton abs
HOMOLYTIC AZIRIDINE OPENING (AZA VARIANT OF CYCLOPROPYLCARBINYL-HOMOALLYL REARRANGEMENT) BY ADDITION OF TRIBUTYLTIN RADICAL TO N-ACYLAZIRIDINES. FACTORS CONTRIBUTING TO THE REGIOSELECTIVITY
Werry, Juergen,Stamm, Helmut,Lin, Pen-Yuan,Falkenstein, Reinhard,Gries, Stefan,Irngartinger, Hermann
, p. 5015 - 5028 (2007/10/02)
AIBN initiated reaction of N-acylaziridines 1 with Bu3SnH in refluxing benzene provided products 5 and 8 of reductive ring opening.Yields (practically quantitative in most cases) fell drastically with steric hindrance of the addition of Bu3Sn to the acyl oxygen of 1.They depended to some extent on the experimental conditions for hydrogen capturing when aziridine homolysis provided a primary radical 3 or 6.The regioselectivity of (probably reversible) ring homolysis can be understood in terms of the stability of the arising radical (3, 6), of stereoelectronic control (e.g. 1i as compared to 1h) and of frontier orbital interactions (1j).A possible difference in bond lengths as explanation for the formation of the primary radical from 1j did not find support from an X-ray structure analysis of N-tosyl-2-methyl-aziridine 11.Isomeric products were obtained only twice (1i, 1j) with a dependence of the ratio 5j:8j on concentration and hydrogen isotope of Bu3SnH.No such dependence was found for the ratio 5:14 (reduction without and with an intervening cyclization of 3 leading to a pyrrolidone) obtained from the N-cinnamoylaziridine 1l.This ratio (1:9 for 1l and 1:3 for 1n) must reflect the E-Z isomers in 3.The observed preference for the formation of E-3 from 2 can be explained by stereoelectronic and steric effects.A cinnamoyl double bond in 5 was saturated depending on experimental conditions.
Von der basenkatalysierten Ringoeffnung von 2H-Azirinen zu einer α-Alkylierungsmethode von primaeren Aminen
Schulthess, Adrian Heinz,Hansen, Hans-Juergen
, p. 1322 - 1336 (2007/10/02)
It is shown than fluorene-9'-spiro-2-(3-phenyl-2H-azirine) (1) on treatment with various alcohols in the presence of the corresponding alkoxide ions yields N-(9'-fluorenyl)benzimidates 2a-d (Scheme 1). 2,2,3-Triphenyl-2H-aziridine (3) reacts with methanol in a similar manner (Scheme 2).Benzimidates 2a (Scheme 3), 8 (Scheme 4) and 10 (Scheme 5) can easily be deprotonated by butyllithium (BuLi) or lithium diisopropylamide (LDA) in tetrahydrofuran (THF) to 1-methoxy-2-aza-allylanions, that can be alkylated, at C(3), exclusively, by various electrophiles (e.g.R-X (X = I, Br), RCHO or methyl acrylate (see also Scheme 6)).As the acidic hydrolyses (1 N HCl) of benzimidates 9 and 11 leads to the corresponding α-alkylated free amines 15 and 18 (Scheme 7 and 8), benzoyl derivatives 16 and 19 are obtained from the hydrolysis under basic conditions.On the other hand it is observed that a catalyzed Chapman rearrangement of 9 and 11 results in the formation of N-benzoyl-N-methyl derivatives 17 and 20 (Scheme 7 and 8).The described reactions offer a simple method for the α-alkylation of actived primary amines.
