- Extended Catalytic Scope of a Well-Known Enzyme: Asymmetric Reduction of Iminium Substrates by Glucose Dehydrogenase
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NADP(H)-dependent imine reductases (IREDs) are of interest in biocatalytic research due to their ability to generate chiral amines from imine/iminium substrates. In reaction protocols involving IREDs, glucose dehydrogenase (GDH) is generally used to regenerate the expensive cofactor NADPH by oxidation of d-glucose to gluconolactone. We have characterized different IREDs with regard to reduction of a set of bicyclic iminium compounds and have utilized 1H NMR and GC analyses to determine degree of substrate conversion and product enantiomeric excess (ee). All IREDs reduced the tested iminium compounds to the corresponding chiral amines. Blank experiments without IREDs also showed substrate conversion, however, thus suggesting an iminium reductase activity of GDH. This unexpected observation was confirmed by additional experiments with GDHs of different origin. The reduction of C=N bonds with good levels of conversion (>50 %) and excellent enantioselectivity (up to >99 % ee) by GDH represents a promiscuous catalytic activity of this enzyme.
- Roth, Sebastian,Pr?g, Andreas,Wechsler, Cindy,Marolt, Marija,Ferlaino, Sascha,Lüdeke, Steffen,Sandon, Nicolas,Wetzl, Dennis,Iding, Hans,Wirz, Beat,Müller, Michael
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- Oxidation of Trialkylamines by BrCCl3: Scope, Applications and Mechanistic Aspects
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The catalyst-free photochemical reaction of trialkylamines and BrCCl3 induced by visible light was investigated. The outcome of the reaction was found to depend strongly on the nature of the amine substrates. N-Methyl-1,2,3,4-tetrahydroisoquino
- Nauth, Alexander M.,Orejarena Pacheco, Julio Cesar,Pusch, Stefan,Opatz, Till
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supporting information
p. 6966 - 6974
(2017/12/26)
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- A chemo-enzymatic route to enantiomerically pure cyclic tertiary amines
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Deracemization of racemic chiral tertiary amines has been achieved by combination of an enantioselective amine oxidase, obtained through directed evolution, and ammonia borane in a one-pot process. Copyright
- Dunsmore, Colin J.,Carr, Reuben,Fleming, Toni,Turner, Nicholas J.
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p. 2224 - 2225
(2007/10/03)
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- Metallation of benzylic amines via amine-borane complexes
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Formation of borane complexes of N,N-dimethylbenzylamine, N,N- dimethyl(1-naphthyl)methylamine, N,N-dimethyl(2-naphthyl)methylamine, N- methyltetrahydroisoquinoline and N-methylisoindoline facilitates regioselective metallation of these systems using BuLi, giving intermediate benzylic anions which react with a range of electrophiles to give products in good yield.
- Ebden, Mark R.,Simpkins, Nigel S.,Fox, David N.A.
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p. 12923 - 12952
(2007/10/03)
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- A highly efficient synthesis of 1-methyl-, 1-benzyl-, and 1-phenyl-1,2,3,4-tetrahydroisoquinolines by a modified pummerer reaction
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(±)-1-Methyl- (13b), (±)-1-benzyl- (13c), and (±)-1-phenyl- (13d)-1,2,3,4-tetrahydroisoquinolines, which are supposed to participate in the pathogenesis of Parkinson's disease, were prepared by using a modified Pummerer reaction as a key step in excellent overall yields from the commercially available ketones (4b-c).
- Shinohara, Tatsumi,Takeda, Akira,Toda, Jun,Terasawa, Noriyo,Sano, Takehiro
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p. 555 - 565
(2007/10/03)
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- Activation of Benzylic Amines Towards Regioselective Metallation by Borane Complex Formation
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Formation of borane complexes of N,N-dimethylbenzylamine 4 and N-methyltetrahydroisoquinoline 1 facilitates regioselective metallation of these systems using BuLi, giving benzylic anions which react with a range of electrophiles.
- Ebden, Mark R.,Simpkins, Nigel S.,Fox, David N. A.
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p. 8697 - 8700
(2007/10/02)
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- Lewis Acid Complexed Heteroatom Carbanions; A New Concept for α-Metallation of Tertiary Amines
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BF3 complexes of typical benzylic, allylic and saturated N-methyl tertiary amines were α-lithiated, with lithium tetramethylpiperidide (LTMP) or sec-butyllithium, and were treated with electrophiles.
- Kessar, Satinder V.,Singh, Paramjit,Vohra, Rahul,Kaur, Nachhattar Pal,Singh, Kamal Nain
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p. 568 - 570
(2007/10/02)
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- A New Method of α-Functionalization for Tertiary Amines by Nucleophilic Substitution of α-Siloxy Amines
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α-Siloxy amines, which were easily prepared by "silicon Polonovski reaction" of tertiary amine N-oxides with trialkylsilyl trifluoromethanesulfonate, were treated with various nucleophiles to give the corresponding α-functionalized tertiary amines in moderate to good yields.This new method has to the advantage that it enables the α-substitution of amines not only by alkyl groups but also by alkenyl and aryl groups with sp2 carbon as a reaction center, since the introduction of such groups is difficult in electrophilic substitution of dipole-stabilized α-lithio amines.Besides the organometallics such as Grignard and organoaluminum reagents, trimethylsilyl cyanide and silyl enol ether could also be employed as nucleophiles in the presence of an appropriate Lewis acid.
- Tokitoh, Norihiro,Okazaki, Renji
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p. 735 - 740
(2007/10/02)
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- Tetrahydroisoquinolines. Part 3. Stereoselective Synthesis of cis- and trans-1,4-Disubstituted N-Methyl-1,2,3,4-tetrahydroisoquinolines as their Tricarbonylchromium Complexes
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The 1-exo proton of tricarbonyl-4-exo-methyl- or tricarbonyl-4-exo-ethyl-2-methyl-1,2,3,4-tetrahydroisoquinolinechromium (6) and (7) can be regio- and stereo-selectively removed by t-butyl-lithium and replaced with a variety of electrophiles to give cis-1,4-disubstituted 2-methyl-1,2,3,4-tetrahydroisoquinoline complexes.Oxidative decomplexation generates the corresponding cis-1,4-disubstituted tetrahydroisoquinolines.Similar methodology applied to tricarbonyl (4-exo-trimethylsilyl-2-methyl-1,2,3,4-tetrahydroisoquinoline)chromium (15) gives, after desilylation, 1-exo-substituted tetrahydroisoquinoline complexes.
- Blagg, Julian,Coote, Steven J.,Davies, Stephen G.,Middlemiss, David,Naylor, Alan
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p. 689 - 694
(2007/10/02)
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