- Photometric Characterization of the Reductive Amination Scope of the Imine Reductases from Streptomyces tsukubaensis and Streptomyces ipomoeae
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Imine reductases (IREDs) have emerged as promising enzymes for the asymmetric synthesis of secondary and tertiary amines starting from carbonyl substrates. Screening the substrate specificity of the reductive amination reaction is usually performed by time-consuming GC analytics. We found two highly active IREDs in our enzyme collection, IR-20 from Streptomyces tsukubaensis and IR-Sip from Streptomyces ipomoeae, that allowed a comprehensive substrate screening with a photometric NADPH assay. We screened 39 carbonyl substrates combined with 17 amines as nucleophiles. Activity data from 663 combinations provided a clear picture about substrate specificity and capabilities in the reductive amination of these enzymes. Besides aliphatic aldehydes, the IREDs accepted various cyclic (C4–C8) and acyclic ketones, preferentially with methylamine. IR-Sip also accepted a range of primary and secondary amines as nucleophiles. In biocatalytic reactions, IR-Sip converted (R)-3-methylcyclohexanone with dimethylamine or pyrrolidine with high diastereoselectivity (>94–96 % de). The nucleophile acceptor spectrum depended on the carbonyl substrate employed. The conversion of well-accepted substrates could also be detected if crude lysates were employed as the enzyme source.
- Matzel, Philipp,Krautschick, Lukas,H?hne, Matthias
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p. 2022 - 2027
(2017/10/07)
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- Preparation de nouveaux β-aminoacides a longue chaine et leur conversion en carboxybetaines bicatenaires F-alkylees
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The synthesis of amphoteric F-alkylated bitailed surfactants derived from new β-aminoacid intermediates is described. N-alkyl N-benzyl amines or N-alkyl N-methyl amines are added to acrylic acid. The β-amino acids obtained are quaternized by 2-F-alkyl ethyl acetates or thioacetate bromides to produce the F-alkylated double-chain carboxybetaines.
- Enjalbert,Bassilana,Krier,Szoenyi,Cambon
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p. 145 - 152
(2007/10/03)
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- ELECTROCHEMICAL REDUCTIVE AMINATION. II. AMINATION OF ALIPHATIC ALDEHYDES WITH PRIMARY AMINES
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The formation of a secondary amine by the electrolysis of an aqueous solution containing an aldehyde and a primary amine was studied.The formation of the secondary amines passes through the intermediate stage of an aldimine.The highest yield of secondary amine is attained at a molar ratio of primary amine to aldehyde of 1.2:1.As electrode material lead, cadmium, zinc, and copper may be used.As supporting electrolyte a phosphate buffer with a pH close to the pKa of the primary amine is recommended.By the method developed 32 amines with various structures were synthesized.
- Smirnov, Yu. D.,Pavlichenko, V. F.,Tomilov, A. P.
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p. 374 - 380
(2007/10/02)
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- Physostigmine derivatives.
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Physostigmine derivatives are described of the general formula: in which R is a linear or branched alkyl with three to nine C atoms, or benzyl, and their slats with pharmaceutically acceptable acids, which are particularly useful for the preparation of pharmaceutical compositions having a acetylcholinesterase inhibiting function
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- Competing Hydride Transfer and Ene Reactions in the Aminoalkylation of 1-Alkenes with N,N-Dimethylmethyleniminium Ions. A Literature Correction
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A literature report that N,N-dimethylmethyleniminium ion (2) reacts with propylene and styrene to form unsaturated tertiary amines is shown to be incorrect.The major products are the secondary amines 1-(methylamino)butane and 1-(methylamino)-3-phenylpropane in which N-demethylation has occurred along with the saturation of the alkene.Analogous major products are formed with 1-butene, 1-hexene, 1-octene, 1-dodecene, 1-tetradecene, p-methylstyrene, and m-nitrostyrene as substrates.When the substrates are isobutylene, 2-ethyl-1-hexene, α-methylstyrene, and p-methoxystyrene, the major products are tertiary amines, but the secondary amines are also formed in smaller yields.The small yields of tertiary amines obtained in the cases of styrene and p-methylstyrene were increased by going from solvent acetic acid to acetonitrile and by increasing the branching of the alkyl groups on nitrogen.The internal olefins 5-decene and cyclohexene were far less reactive, giving only 3-4percent of amine products that were mainly tertiary in the former case and secondary in the latter.It is concluded that tertiary amine products are favored by an alkene structure and a solvent that favors the formation of a stable carbenium ion intermediate or a transition state with substantial carbenium ion character upon electrophilic attack of the iminium ion on the alkene.The secondary amine products are favored when a carbenium ion is of low stability and when the β-carbon atom of the olefin and/or the alkyl group attached to nitrogen is sterically unhindered; such hindrance decreases the rate of hydride ion transfer that is believed to occur in the production of secondary amines.
- Cohen, Theodore,Onopchenko, Anatoli
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p. 4531 - 4537
(2007/10/02)
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