13364-16-4Relevant articles and documents
Synthesis of Chiral Amines via a Bi-Enzymatic Cascade Using an Ene-Reductase and Amine Dehydrogenase
Jongkind, Ewald P. J.,Fossey-Jouenne, Aurélie,Mayol, Ombeline,Zaparucha, Anne,Vergne-Vaxelaire, Carine,Paul, Caroline E.
, (2021/12/23)
Access to chiral amines with more than one stereocentre remains challenging, although an increasing number of methods are emerging. Here we developed a proof-of-concept bi-enzymatic cascade, consisting of an ene reductase and amine dehydrogenase (AmDH), to afford chiral diastereomerically enriched amines in one pot. The asymmetric reduction of unsaturated ketones and aldehydes by ene reductases from the Old Yellow Enzyme family (OYE) was adapted to reaction conditions for the reductive amination by amine dehydrogenases. By studying the substrate profiles of both reported biocatalysts, thirteen unsaturated carbonyl substrates were assayed against the best duo OYE/AmDH. Low (5 %) to high (97 %) conversion rates were obtained with enantiomeric and diastereomeric excess of up to 99 %. We expect our established bi-enzymatic cascade to allow access to chiral amines with both high enantiomeric and diastereomeric excess from varying alkene substrates depending on the combination of enzymes.
Remote Regioselective Radical C-H Functionalization of Unactivated C-H Bonds in Amides: The Synthesis of gem-Difluoroalkenes
Hu, Qu-Ping,Cheng, Jing,Wang, Ying,Shi, Jie,Wang, Bi-Qin,Hu, Ping,Zhao, Ke-Qing,Pan, Fei
supporting information, p. 4457 - 4462 (2021/05/26)
The site-selective functionalization of unactivated aliphatic amines is an attractive and challenging synthetic approach. We herein report a general strategy for the remote site-selective functionalization of unactivated C(sp3)-H bonds in amides by photogenerated amidyl radicals to form gem-difluoroalkenes with trifluoromethyl-substituted alkenes. The site selectivity is controlled by a 1,5-hydrogen atom transfer (HAT) process of the amide. This photocatalyzed transformation shows both chemo- and site-selectivity, facilitating the formation of a secondary, tertiary, or quaternary carbon center.
One-pot reductive amination of carboxylic acids: a sustainable method for primary amine synthesis
Coeck, Robin,De Vos, Dirk E.
supporting information, p. 5105 - 5114 (2020/08/25)
The reductive amination of carboxylic acids is a very green, efficient and sustainable method for the production of (bio-based) amines. However, with current technology, this reaction requires two to three reaction steps. Here, we report the first (heterogeneous) catalytic system for the one-pot reductive amination of carboxylic acids to amines, with solely H2 and NH3 as the reactants. This reaction can be performed with relatively cheap ruthenium-tungsten bimetallic catalysts in the green and benign solvent cyclopentyl methyl ether (CPME). Selectivities of up to 99% for the primary amine could be achieved at high conversions. Additionally, the catalyst is recyclable and tolerant for common impurities such as water and cations (e.g. sodium carboxylate).
Synthesis of β-Chiral Amines by Dynamic Kinetic Resolution of α-Branched Aldehydes Applying Imine Reductases
Matzel, Philipp,Wenske, Sebastian,Merdivan, Simon,Günther, Sebastian,H?hne, Matthias
, p. 4281 - 4285 (2019/08/20)
Imine reductases (IREDs) allow the one-step preparation of optically active secondary and tertiary amines by reductive amination of ketones. Until now, mainly α-chiral amines have been prepared by this route. In this study, we explored the possibility of synthesizing β-chiral amines, a class of compounds which is also frequently found as structural motif in pharmaceuticals but much more challenging to prepare due to the following reasons: (i) The aldehyde substrate already contains the chiral center and needs to be racemized to enable full conversion. (ii) Because the intermediate imine bears the stereo center two carbon atoms remote to the imine nitrogen, it is more challenging to achieve high enantioselectivity compared to α-chiral amine synthesis. For investigating the proof of concept, we first confirmed that different IREDs are able to convert a variety of α-branched aldehydes when combined with five different amine substrates. The IRED from Streptomyces ipomoeae was a suitable enzyme facilitating the dynamic kinetic resolution of 2-phenylpropanal and a substituted 2-methyl-3-phenylpropanal: the corresponding N-methylated β-chiral amines were obtained with '95 % conversion and 78 and 95 %ee. Other amines were formed with low to moderate enantiomeric excess. This exemplifies the potential of IREDs for the one-step synthesis of secondary β-chiral amines, but also the challenge to identify highly selective enzymes for a desired amine product.
The facile preparation of primary and secondary amines via an improved Fukuyama-Mitsunobu procedure. Application to the synthesis of a lung-targeted gene delivery agent
Guisado, Cristina,Waterhouse, Jodie E.,Price, Wayne S.,Jorgensen, Michael R.,Miller, Andrew D.
, p. 1049 - 1057 (2007/10/03)
An efficient modification of the Fukuyama-Mitsunobu procedure has been developed whereby primary or secondary amines can be synthesized from alkyl alcohols and the corresponding nosyl-protected/activated amine. Most importantly, the use of the DTBAD and diphenylpyridinylphosphine, as Mitsunobu reagents, generates reaction by-products that can be easily removed, providing a remarkably clean product mixture. This improved technique was implemented in the synthesis of a complex lipopeptide designed to target α 9β1-integrin proteins predominant on upper airway epithelial cells. The Royal Society of Chemistry 2005.
Development of chiral N-alkylcarbamates as new leads for potent and selective H3-receptor antagonists: Synthesis, capillary electrophoresis, and in vitro and oral in vivo activity
Sasse, Astrid,Kiec-Kononowicz, Katarzyna,Stark, Holger,Motyl, Malgorzata,Reidemeister, Sibylle,Ganellin, C. Robin,Ligneau, Xavier,Schwartz, Jean-Charles,Schunack, Walter
, p. 593 - 600 (2007/10/03)
Novel carbamates as derivatives of 3-(1H-imidazol-4-yl)propanol with an N-alkyl chain were prepared as histamine H3-receptor antagonists. Branching of the N-alkyl side chain with methyl groups led to chiral compounds which were synthesized stereospecifically by a Mitsunobu protocol adapted Gabriel synthesis. The optical purity of some of the chiral compounds was determined (ee > 95%) by capillary electrophoresis (CE). The investigated compounds showed pronounced to high antagonist activity (K(i) values of 4.1-316 nM) in a functional test for histamine H3 receptors on rat cerebral cortex synaptosomes. Similar H3-receptor antagonist activities were observed in a peripheral model on guinea pig ileum. No stereoselective discrimination for the H3 receptor for the chiral antagonists was found with the in vitro assays. All compounds were also screened for central H3-receptor antagonist activity in vivo in mice after po administration. Most compounds were potent agents of the H3-receptor-mediated enhancement of brain N(τ)- methylhistamine levels. The enantiomers of the N-2-heptylcarbamate showed a stereoselective differentiation in their pharmacological effect in vivo (ED50 of 0.39 mg/kg for the (S)-derivative vs 1.5 mg/kg for the (R)- derivative) most probably caused by differences in pharmacokinetic parameters. H1- and H2-receptor activities were determined for some of the novel carbamates, demonstrating that they have a highly selective action at the histamine H3 receptor.
PREPARATION OF ISOMERICALLY PURE ALKYLAMINES VIA THE REACTION OF DIMETHYLALKYLBORANES WITH CHLORAMINE
Kabalka, George W.,Wang, Zhe,Goudgaon, Nganna M.
, p. 2409 - 2414 (2007/10/02)
Dimethylborane was used to hydroborate alkenes regiospecifically.The resultant dimethylalkylboranes react with ammonium hydrochloride and sodium hypochlorite to yield isomerically pure alkylamines.
ORGANOBORANES FOR SYNTHESIS. 7. AN IMPROVED GENERAL SYNTHESIS OF PRIMARY AMINES FROM ALKENES via HYDROBORATION-ORGANOBORANE CHEMISTRY
Brown, Herbert C.,Kim, Kee-Won,Srebnik, Morris,Singaram, Bakthan
, p. 4071 - 4078 (2007/10/02)
Triorganylboranes, R3B, and diorganylborinicesters, R2BOR', react readily with preformed chloramine or hydroxylamine-O-sulfonic acid to produce the corresponding primary amines, RNH2.However, the product of the reaction following hydrolysis is the boronic acid, RB(OH)2, limiting the yield to 67percent for R3B and to 50percent for R2BOR'.This problem has now been overcome with the help of lithium dimethylborohydride, readily converted in situ to dimethylborane.The hydroboration of representative alkenes by dimethylborane provides the corresponding monoorganyldimethylborane, RMe2B.Treatment of this intermediate with hydroxylamine-O-sulfonic acid provides the desired amines, RNH2, in isolated yields of 73percent to 95percent.The reaction proceeds with complete retention, reproducing the precise structure of the organic group in the organoboranes, RMe2B.
Stereochemistry of Aliphatic Carbocations, 14. Alkyl Shifts from Secondary to Primary Carbon Atoms
Kirmse, Wolfgang,Guenther, Bernd-Rainer,Knist, Johannes,Kratz, Sigrid,Loosen, Karin,et al.
, p. 2127 - 2139 (2007/10/02)
Alkyl shifts from secondary to primary carbon atoms have been induced by the nitrous acid deamination of suitable amines (4, 22, 39, 51); they include sequential rearrangements (-CH3,CH3 and -CH3,H).Predominant although incomplete inversion at the migration origin has been observed (Me 70percent, Et 62-64percent, nPr 65percent, iPr 64percent, tBu 55percent).Our results require the intervention of open secondary carbocations which may be preceded by less stable bridged intermediates.
