2164-19-4Relevant academic research and scientific papers
Simultaneous Preparation of (S)-2-Aminobutane and d -Alanine or d -Homoalanine via Biocatalytic Transamination at High Substrate Concentration
Li, Jianjiong,Wang, Yingang,Wu, Qiaqing,Yao, Peiyuan,Yu, Shanshan,Zhu, Dunming
supporting information, (2022/03/01)
(S)-2-Aminobutane, d-alanine, and d-homoalanine are important intermediates for the production of various active pharmaceutical ingredients and food additives. The preparation of these small chiral amine or amino acids with high water solubility still demands searching for efficient methods. In this work, we identified an ω-transaminase (ω-TA) from Sinirhodobacter hungdaonensis (ShdTA) that catalyzed the kinetic resolution of racemic 2-aminobutane at a concentration of 800 mM using pyruvate as the amino acceptor, leading to the simultaneous isolation of enantiopure (S)-2-aminobutane and d-alanine in 46% and 90% yield, respectively. In addition, (S)-2-aminobutane (98% ee) and d-homoalanine (99% ee) were isolated in 45% and 93% yield, respectively, in the kinetic resolution of racemic 2-aminobutane at a concentration of 400 mM coupled with deamination of l-threonine by threonine deaminase. We thus developed a biocatalytic process for the practical synthesis of these valuable small chiral amine and d-amino acids.
Ni-Catalyzed reductive amination of phenols with ammonia or amines into cyclohexylamines
Cuypers, Thomas,Morias, Thomas,Windels, Simon,Marquez, Carlos,Van Goethem, Cédric,Vankelecom, Ivo,De Vos, Dirk E.
, p. 1884 - 1893 (2020/04/07)
Phenol and its derivatives, which naturally occur in lignocellulose, can be considered as a renewable feedstock not only for aromatic, but also for alicyclic compounds, such as primary and N-substituted cyclohexylamines. So far, the latter are mostly produced from non-renewable starting materials like benzene via problematic nitration/reduction or cross-coupling routes. Herein, an efficient reductive amination of phenol with ammonia or amines is demonstrated, for the first time without the need for rare and expensive noble metals and without using any additives. Various supported Ni catalysts were screened and we elucidated the influence of the key parameters, including the acid-base properties of the supporting material. Acquired knowledge was then applied to different phenol-ammonia/amine combinations, resulting in the synthesis of various primary, secondary and tertiary cyclohexylamines in fair to very high yields.
Enhanced Selectivity in the Hydrogenation of Anilines to Cyclo-aliphatic Primary Amines over Lithium-Modified Ru/CNT Catalysts
Tomkins, Patrick,Müller, Thomas E.
, p. 1438 - 1445 (2018/03/30)
The hydrogenation of aromatic amines to the corresponding cycloaliphatic primary amines is an important industrial reaction. However, secondary amine formation and other side reactions are frequently observed, resulting in reduced selectivity. The side products are formed mostly on the support, yet support effects are little understood at present. This study describes the facile modification of Ru/CNT catalysts with LiOH, by this means significantly improving catalyst selectivity in toluidine hydrogenation without decreasing the activity of the catalysts. The effect is explained by LiOH diminishing acidic sites on the catalyst support and enhancing the adsorption of the aromatic ring on the metallic ruthenium nanoparticles. With the LiOH-modified Ru/CNT catalyst, other substrates, such as methylnitrobenzenes, are also converted efficiently. This study thus describes an improved catalyst for the preparation of cyclohexylamines and provides guidelines for future catalyst design.
The Rhodium Catalysed Direct Conversion of Phenols to Primary Cyclohexylamines
Tomkins, Patrick,Valgaeren, Carlot,Adriaensen, Koen,Cuypers, Thomas,Vos, Dirk E. De
, p. 3689 - 3693 (2018/07/31)
Cyclohexylamines are important intermediates in chemical industry, which are currently produced from petrochemical sources. Phenols, however, are an attractive sustainable feedstock. We here demonstrate the transformation of phenols with ammonia to primary cyclohexylamines. In contrast to previously reported chemistry which used palladium catalysts, we here show that rhodium is an excellent catalyst for the formation of primary cyclohexylamines. Different parameters were studied and it was shown that the reaction is applicable to a scope of phenolic compounds providing high selectivity.
Stereochemistry of hydrodenitrogenation: The mechanism of elimination of the amino group from cyclohexylamines over sulfided Ni-Mo/γ-Al2O3 catalysts
Prins,Ranade,Rota,Ranade
, p. 389 - 399 (2007/10/03)
HDS and HDN are among the most significant catalytic processes in the petroleum industry, because during these processes sulfur and nitrogen are removed in the form of H2S and ammonia from oil fractions. The HDN of cyclohexylamine and of the diastereomers of 2-methylcyclohexylamine and 2,6-dimethylcyclohexylamine was studied at 200°-350°C and 50 bar over a sulfided Ni-Mo/γ-Al2O3 catalyst. The rate of HDN of alkyl-substituted cyclohexylamines over sulfided Ni-Mo catalysts depended on the number of β hydrogen atoms and on their stereochemical relation to the amino group. Isomerization of olefinic products and the amines prevented meaningful mechanistic studies at 350°C. The cis diastereomers reacted faster than the trans diastereomers, because they allowed for an anti geometric relationship in the chair conformation between the amino group and a hydrogen atom on a β carbon atom. The syn elimination occurred to a considerable extent at higher temperatures in molecules that were unable to undergo anti elimination. The activation energy of anti elimination was lower than that of syn elimination, and the activation energy of anti elimination involving a hydrogen atom attached to a tertiary β carbon atom was lower than that involving a hydrogen atom attached to secondary β carbon atom.
REDUCTION OF CONJUGATED CYCLOHEXENONE OXIMES WITH ALUMINIUM HYDRIDE
Zaidlewicz, Marek,Uzarewicz, Ireneusz G.
, p. 143 - 150 (2007/10/02)
The reduction of representative conjugated cyclohexenone oximes with aluminium hydride in tetrahydrofuran yields 2-cyclohexenylamines and saturated aziridines - 7-azabicycloheptane derivatives, as the main reaction products.Small quantities of cyclohexylamines and perhydroazepines are also formed.Regioselectivity of the reduction depends on oxime configuration.Higher yields of 2-cyclohexenylamines are obtained from E than Z isomers.The reaction mechanism is proposed.
HIGHLY STEREOSELECTIVE SYNTHESIS OF CYCLIC PRIMARY AMINES VIA HYDRIDE REDUCTIONS.
Hutchins, Robert O.,Su, Wei-Yang
, p. 695 - 698 (2007/10/02)
The reduction of p,p'-dimethoxybenzhydryl imines of substituted cyclohexanones with lithium tri-sec-butyl or tri-ethylborohydride and subsequent cleavage of the resulting secondary amines with formic acid affords the corresponding axial cyclohexyl primary amines with high stereoselectivity.
