- CO2-Assisted asymmetric hydrogenation of prochiral allylamines
-
A new methodology for the asymmetric hydrogenation of allylamines takes advantage of a reversible reaction between amines and carbon dioxide (CO2) to suppress unwanted side reactions. The effects of various parameters (pressure, time, solvent, and base additives) on the enantioselectivity and conversion of the reaction were studied. The homogeneously-catalyzed asymmetric hydrogenation of 2-arylprop- 2-en-1-amine resulted in complete conversion and up to 82% enantiomeric excess (ee). Added base, if chosen carefully, improves the enantioselectivity and chemoselectivity of the overall reaction.
- Alridge, Christopher J.,De Winter, Tamara M.,Ho, Jaddie,Jessop, Philip G.
-
p. 6755 - 6761
(2022/03/31)
-
- Direct Access to Primary Amines from Alkenes by Selective Metal-Free Hydroamination
-
Direct and selective synthesis of primary amines from easily available precursors is attractive yet challenging. Herein, we report the rapid synthesis of primary amines from alkenes via metal-free regioselective hydroamination at room temperature. Ammonium carbonate was used as ammonia surrogate for the first time, allowing for efficient conversion of terminal and internal alkenes into linear, α-branched, and α-tertiary primary amines under mild conditions. This method provides a straightforward and powerful approach to a wide spectrum of advanced, highly functionalized primary amines which are of particular interest in pharmaceutical chemistry and other areas.
- Du, Yi-Dan,Chen, Bi-Hong,Shu, Wei
-
supporting information
p. 9875 - 9880
(2021/03/29)
-
- Iron-Catalyzed Diastereoselective Synthesis of Disubstituted Morpholines via C-O or C-N Bond Formation
-
The diastereoselective synthesis of 2,6- and 3,5-disubstituted morpholines was achieved from 1,2-amino ethers and 1,2-hydroxy amines substituted by an allylic alcohol using an iron(III) catalyst. The morpholines were obtained either by C-O or C-N bond formation. A plausible mechanism is suggested, involving a thermodynamic equilibrium to explain the formation of the cis diastereoisomer as the major product.
- Aubineau, Thomas,Dupas, Alexandre,Zeng, Tian,Cossy, Janine
-
supporting information
p. 525 - 531
(2020/08/28)
-
- Facile synthesis of controllable graphene-co-shelled reusable Ni/NiO nanoparticles and their application in the synthesis of amines under mild conditions
-
The primary objective of many researchers in chemical synthesis is the development of recyclable and easily accessible catalysts. These catalysts should preferably be made from Earth-abundant metals and have the ability to be utilised in the synthesis of pharmaceutically important compounds. Amines are classified as privileged compounds, and are used extensively in the fine and bulk chemical industries, as well as in pharmaceutical and materials research. In many laboratories and in industry, transition metal catalysed reductive amination of carbonyl compounds is performed using predominantly ammonia and H2. However, these reactions usually require precious metal-based catalysts or RANEY nickel, and require harsh reaction conditions and yield low selectivity for the desired products. Herein, we describe a simple and environmentally friendly method for the preparation of thin graphene spheres that encapsulate uniform Ni/NiO nanoalloy catalysts (Ni/NiO?C) using nickel citrate as the precursor. The resulting catalysts are stable and reusable and were successfully used for the synthesis of primary, secondary, tertiary, and N-methylamines (more than 62 examples). The reaction couples easily accessible carbonyl compounds (aldehydes and ketones) with ammonia, amines, and H2 under very mild industrially viable and scalable conditions (80 °C and 1 MPa H2 pressure, 4 h), offering cost-effective access to numerous functionalized, structurally diverse linear and branched benzylic, heterocyclic, and aliphatic amines including drugs and steroid derivatives. We have also demonstrated the scale-up of the heterogeneous amination protocol to gram-scale synthesis. Furthermore, the catalyst can be immobilized on a magnetic stirring bar and be conveniently recycled up to five times without any significant loss of catalytic activity and selectivity for the product.
- Cui, Zhibing,Liu, Jianguo,Liu, Qiying,Ma, Longlong,Singh, Thishana,Wang, Chenguang,Wang, Nan,Zhu, Yuting
-
supporting information
p. 7387 - 7397
(2020/11/19)
-
- Quinazoline derivatives and its preparation method and application
-
The invention relates to quinazoline derivatives and its preparation method and application. The quinazoline derivatives with The structural formula, the quinazoline derivative to gefitinib for the positive control, the result shows that compared with the gefitinib has good activity; and lead compound OTS514 compared, equivalent activity, PBK/TOPK inhibitors for further transformation and the discovery of new anti-tumor medicine phenological shopping has higher learning with the reference value. The invention also provides a preparation method of the quinazoline derivatives and the preparation of PBK/TOPK inhibitor and an anticancer drug.
- -
-
Paragraph 0041-0045
(2019/07/08)
-
- Enantioselective Synthesis of β-Methyl Amines via Iridium-Catalyzed Asymmetric Hydrogenation of N-Sulfonyl Allyl Amines
-
The iridium-catalyzed asymmetric hydrogenation of several N-sulfonyl allyl amines is reported. All substrates can be easily obtained by the Ir-catalyzed isomerization of N-tosylaziridines reported previously. The commercially available threonine-derived phosphinite (UbaPHOX) iridium complex has been found to be the best catalyst for this catalytic application, affording β-methyl amines with good to excellent ee values (up to 94%). The synthetic potential of this novel methodology was demonstrated by the formal synthesis of Lorcaserin and LY-404187. (Figure presented.).
- Cabré, Albert,Verdaguer, Xavier,Riera, Antoni
-
p. 4196 - 4200
(2019/08/16)
-
- Rhodium-catalyzed asymmetric hydrogenation of β-branched enamides for the synthesis of β-stereogenic amines
-
Using a rhodium complex of a bisphosphine ligand (R)-SDP, β-branched simple enamides with a (Z)-configuration were hydrogenated to β-stereogenic amines in quantitative yields and with excellent enantioselectivities (88-96% ee).
- Zhang, Jian,Liu, Chong,Wang, Xingguang,Chen, Jianzhong,Zhang, Zhenfeng,Zhang, Wanbin
-
p. 6024 - 6027
(2018/06/18)
-
- New insights into the catalytic reduction of aliphatic nitro compounds with hypophosphites under ultrasonic irradiation
-
This work describes an efficient process for the reduction of nitro compounds to the corresponding amines with a catalytic amount of Pd/C (0.6 mol%), and a mixture of sodium hypophosphite and hypophosphorous acid as a reducing agent in H2O/2-MeTHF at 60 °C. The reaction was optimized under silent conditions. The conditions for the in situ production of H2 using the mixture NaH2PO2/H3PO2 were studied. The influence of ultrasonic activation was investigated both in terms of efficiency and kinetics. The reaction was shown to be efficient in water, at 70 °C with a quantitative conversion and a maximal yield in only 15 min thanks to the ultrasonic activation. Finally, ultrasound was proved to act as a physical agent of phase transfer.
- Letort,Lejeune,Kardos,Métay,Popowycz,Lemaire,Draye
-
p. 4583 - 4590
(2017/10/13)
-
- Reduction of selenoamides to amines using SmI2-H2O
-
Selenoamides are selectively reduced to amines by SmI2 with H2O. The process is general for primary, secondary, and tertiary aryl and alkyl selenoamide substrates and selectively delivers amine products. The reduction proceeds under mild conditions using SmI2 activated by straightforward addition of H2O, and does not require an additional Lewis base additive.
- Thurow, Samuel,Lenardo, Eder J.,Just-Baringo, Xavier,Procter, David J.
-
-
- Enantioselective Hydroaminomethylation of Olefins Enabled by Rh/Br?nsted Acid Relay Catalysis
-
Herein, by employing a rhodium catalyst with a commercial ligand and a phosphoric acid catalyst, highly chemo-, regio-, and enantioselective hydroaminomethylation of olefins is realized through a relay catalytic hydroformylation/dynamic kinetic reductive amination process. The method features mild conditions (1 bar of syngas, room temperature in most cases), high yields (up to 99%), and high enantioselectivities (up to >99.5:0.5 er). Besides styrenes, acrylamides also provided the products with high yields and enantioselectivities. Aliphatic alkenes and vinyl esters are also applicable for the current method, albeit lower yields and enantioselectivities were obtained.
- Meng, Jing,Li, Xing-Han,Han, Zhi-Yong
-
p. 1076 - 1079
(2017/03/15)
-
- MOF-derived cobalt nanoparticles catalyze a general synthesis of amines
-
The development of base metal catalysts for the synthesis of pharmaceutically relevant compounds remains an important goal of chemical research. Here, we report that cobalt nanoparticles encapsulated by a graphitic shell are broadly effective reductive amination catalysts. Their convenient and practical preparation entailed template assembly of cobaltdiamine- dicarboxylic acid metal organic frameworks on carbon and subsequent pyrolysis under inert atmosphere.The resulting stable and reusable catalysts were active for synthesis of primary, secondary, tertiary, and N-methylamines (more than 140 examples).The reaction couples easily accessible carbonyl compounds (aldehydes and ketones) with ammonia, amines, or nitro compounds, and molecular hydrogen under industrially viable and scalable conditions, offering cost-effective access to numerous amines, amino acid derivatives, and more complex drug targets.
- Jagadeesh, Rajenahally V.,Murugesan, Kathiravan,Alshammari, Ahmad S.,Neumann, Helfried,Pohl, Marga-Martina,Radnik, J?rg,Beller, Matthias
-
p. 326 - 332
(2017/09/28)
-
- Biocatalytic Formal Anti-Markovnikov Hydroamination and Hydration of Aryl Alkenes
-
Biocatalytic anti-Markovnikov alkene hydroamination and hydration were achieved based on two concepts involving enzyme cascades: epoxidation-isomerization-amination for hydroamination and epoxidation-isomerization-reduction for hydration. An Escherichia coli strain coexpressing styrene monooxygenase (SMO), styrene oxide isomerase (SOI), ω-transaminase (CvTA), and alanine dehydrogenase (AlaDH) catalyzed the hydroamination of 12 aryl alkenes to give the corresponding valuable terminal amines in high conversion (many ≥86%) and exclusive anti-Markovnikov selectivity (>99:1). Another E. coli strain coexpressing SMO, SOI, and phenylacetaldehyde reductase (PAR) catalyzed the hydration of 12 aryl alkenes to the corresponding useful terminal alcohols in high conversion (many ≥80%) and very high anti-Markovnikov selectivity (>99:1). Importantly, SOI was discovered for stereoselective isomerization of a chiral epoxide to a chiral aldehyde, providing some insights on enzymatic epoxide rearrangement. Harnessing this stereoselective rearrangement, highly enantioselective anti-Markovnikov hydroamination and hydration were demonstrated to convert α-methylstyrene to the corresponding (S)-amine and (S)-alcohol in 84-81% conversion with 97-92% ee, respectively. The biocatalytic anti-Markovnikov hydroamination and hydration of alkenes, utilizing cheap and nontoxic chemicals (O2, NH3, and glucose) and cells, provide an environmentally friendly, highly selective, and high-yielding synthesis of terminal amines and alcohols.
- Wu, Shuke,Liu, Ji,Li, Zhi
-
p. 5225 - 5233
(2017/08/17)
-
- METHOD OF RACEMISATION OF UNDESIRED ENANTIOMERS
-
The present invention provides a very simple, efficient and economic technology for racemisation of amines, alcohols or thioalcohols where the chiral carbon (benzylic position) is located at the β-position of the heteroatom (amino, hydroxyl or mercapto group) or even more distant therefrom. Special focus is oriented in efficient and simple racemisation of an undesired enantiomer of a chiral pharmaceutically active ingredient, preferably lorcaserin or a salt thereof, preferably the hydrochloride salt thereof. The approach according to the invention enables a use of cheaper and shorter racemic synthetic schemes not requiring expensive and toxic reagents and catalysts. Present methodology enables industrialy convenient process.
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-
Page/Page column 22; 23
(2015/02/02)
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- Characterization of a novel amine transaminase from Halomonas elongata
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Chiral amines are indispensable building blocks in the production of biologically active compounds. They are fundamental for the pharmaceutical industry, both as active molecules themselves and as chiral auxiliaries in asymmetric synthesis; however, the available synthetic strategies often present disadvantages. ω-Transaminases (ω-TAs) appear as an attractive alternative by driving the stereoselective amination of prochiral ketones. HEWT is a novel amine transaminase from the moderate halophilic bacterium, Halomonas elongata DSM 2581, which is highly (S)-selective, being able to fully convert (S)-1-phenylethylamine to acetophenone and showing no activity with the corresponding (R)-1-phenylethylamine. HEWT has a broad substrate scope, active with a range of amino donors and acceptors, and naturally accepts isopropylamine (IPA) as amino donor in asymmetric synthesis providing a 41% conversion of pyruvate in 24 h at 37°C starting with 1:1 molar ratio between the reagents. HEWT also accepts ortho-xylylenediamine as amino donor in for amine synthesis, in particular, with benzaldehyde yielding high conversions between 90 and 95%. The enzyme is also tolerant to the presence of cosolvents up to 20% making it a promising candidate for industrial applications.
- Cerioli, Lorenzo,Planchestainer, Matteo,Cassidy, Jennifer,Tessaro, Davide,Paradisi, Francesca
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p. 141 - 150
(2015/09/01)
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- Electron transfer reduction of nitriles using SmI2-Et 3N-H2O: Synthetic utility and mechanism
-
The first general reduction of nitriles to primary amines under single electron transfer conditions is demonstrated using SmI2 (Kagan's reagent) activated with Lewis bases. The reaction features excellent functional group tolerance and represents an attractive alternative to the use of pyrophoric alkali metal hydrides. Notably, the electron transfer from Sm(II) to CN functional groups generates imidoyl-type radicals from bench stable nitrile precursors.
- Szostak, Michal,Sautier, Brice,Spain, Malcolm,Procter, David J.
-
supporting information
p. 1092 - 1095
(2014/03/21)
-
- Dynamic kinetic resolution of 2-phenylpropanal derivatives to yield β-chiral primary amines via bioamination
-
The amination of racemic α-chiral aldehydes, 2-phenylpropanal derivatives, was investigated employing ω-transaminases. By medium and substrate engineering the optical purity of the resulting β-chiral chiral amine could be enhanced to reach optical purities up to 99% ee. Using enantiocomplementary ω-transaminases allowed us to access the (R)- as well as the (S)-enantiomer in most cases. It is important to note that the stereopreference of the ω-transaminases found for α-chiral aldehydes did not correlate with the stereopreference previously observed for the amination of methyl ketones. In one case the stereopreference switched even upon exchanging a methyl substituent to a methoxy group.
- Fuchs, Christine S.,Hollauf, Manuel,Meissner, Maximilian,Simon, Robert C.,Besset, Tatiana,Reek, Joost N. H.,Riethorst, Waander,Zepeck, Ferdinand,Kroutil, Wolfgang
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p. 2257 - 2265
(2014/07/21)
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- One-pot anti-markovnikov hydroamination of unactivated alkenes by hydrozirconation and amination
-
A one-pot anti-Markovnikov hydroamination of alkenes is reported. The synthesis of primary and secondary amines from unactivated olefins was accomplished in the presence of a variety of functional groups. Hydrozirconation, followed by amination with nitrogen electrophiles, provides exclusive anti-Markovnikov selectivity. Most products are isolated in high yields without the use of column chromatography.
- Strom, Alexandra E.,Hartwig, John F.
-
p. 8909 - 8914
(2013/09/24)
-
- Highly efficient one step synthesis of primary amines from B-Chlorodialkylboranes
-
A convenient and simple method for synthesis of primary amines has been developed by direct amination of B-Chlorodialkylboranes. This general procedure has been applied to synthesize acyclic, cyclic, hindered and chiral amines in very high yields using both hydroxylamine-O-sulfonic acid and monochloroamine as reagents.
- Malhotra, Sanjay V.,Brown, Herbert C.
-
experimental part
p. 383 - 385
(2012/08/28)
-
- Resolution of (±)-β-methylphenylethylamine by a novel chiral stationary phase for Pirkle-type column chromatography
-
In this study, a new Pirkle-type chiral column stationary phase for resolution of β-methylphenylethyl amine was described by using activated Sepharose 4B as a matrix, L-tyrosine as a spacer arm, and an aromatic amine derivative of L-glutamic acid as a ligand. The binding capacities of the stationary phase were determined at different pH values (pH = 6, 7, and 8) using buffer solutions as mobile phase, and enantiomeric excess (ee) was determined by HPLC equipped with chiral column. The ee was found to be 47%.
- Yilmaz, Hayrullah,Topal, Giray,Cakmak, Resit,Hosgoren, Halil
-
experimental part
p. 252 - 257
(2010/12/18)
-
- COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
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Page/Page column 45-49; 62
(2010/12/31)
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- AMPA RECEPTOR POTENTIATORS
-
The present invention relates to a compound of Formula (I) or a pharmaceutically acceptable salt thereof which is useful for the treatment of conditions associated with glutamate hypofunction, such as psychiatric and neurological disorders.
- -
-
Page/Page column 7-8
(2008/12/06)
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- Notable coordination effects of 2-pyridinesulfonamides leading to efficient aziridination and selective aziridine ring opening
-
(Chemical Equation Presented) We have developed, on the basis of a chelation-strategy, an efficient copper-catalyzed aziridination protocol with the use of 5-methyl-2-pyridinesulfonamide and Phl(OAc)2. The reaction proceeds smoothly under mild conditions to give aziridines in moderate to good yields in the absence of external ligands or bases. The coordination-assisted approach offers the additional benefits that efficient deprotection of the N-substituent and selective aziridine ring-opening are effectively achieved.
- Han, Hoon,Bae, Imhyuck,Eun, Jeong Yoo,Lee, Junseong,Do, Youngkyu,Chang, Sukbok
-
p. 4109 - 4112
(2007/10/03)
-
- METHOD FOR PRODUCING AN OPTICALLY ACTIVE NITRO COMPOUND
-
An optically active nitro compound having two hydrogen atoms on its α-cabon atom and having β-asymmetric carbon atom can be produced by making α, β-unsaturated nitroolefin having a hydrogen atom on its α-cabon atom react with at least two organosilicon compounds having at lest one silicon-hydrogen bond in the molecule in the presence of an asymmetric copper complex, or react with an organosilicon compound having at least one silicon-hydrogen bond in the molecule in the presence of an asymmetric copper complex and water.
- -
-
-
- Lipase-catalyzed enantioselective reaction of amines with carboxylic acids under reduced pressure in non-solvent system and in ionic liquids
-
Lipase-catalyzed enantioselective acylation of 1-phenylethylamine and 2-phenyl-1-propylamine was performed by reacting the amines with carboxylic acids in a non-solvent system or in ionic liquids as reaction media. The reaction equilibrium was shifted toward amide synthesis by the removal of formed water under reduced pressure.
- Irimescu, Roxana,Kato, Katsuya
-
p. 523 - 525
(2007/10/03)
-
- Sulfonamide derivatives
-
The present invention relates to a compound of formula (Ia) or a pharmaceutically acceptable salt thereof which is useful for the treatment of conditions associated with glutamate hypofunction, such as psychiatric and neurological disorders. 1
- -
-
-
- Heterocyclic sulfonamide derivatives
-
The present invention provides certain heterocyclic sulfonamide derivatives of formula (I): useful for potentiating glutamate receptor function in a patient and therefore, useful for treating a wide variety of conditions, such as psychiatric and neurological disorders.
- -
-
-
- Sulfonamide derivatives
-
The present invention relates to a compound of formula (I) or a pharmaceutically acceptable salt thereof which is useful for the treatment of conditions associated with glutamate hypofunction, such as psychiatric and neurological disorders.
- -
-
-
- Combination therapy for treatment of depression
-
The present invention provides a method for treating depression, comprising administering to a patient an effective amount of a first component which is a suitable antidepressant, in combination with an effective amount of a second component which is a suitable AMPA receptor potentiator.
- -
-
-
- Catalytic Enantioselective Conjugate Reduction of β,β -Disubstituted Nitroalkenes
-
Efficient addition: Bisphosphane-CuI complexes catalyze the enantioselective reduction of β,β-disubstituted nitroalkenes, giving chiral β,β-disubstituted nitroalkanes in useful yields and selectivities (see scheme). The reaction can be carried out with as little as 0.1 mol % of complex, rendering the process among one of the more efficient methods for conjugate addition chemistry.
- Czekelius, Constantin,Carreira, Erick M.
-
p. 4793 - 4795
(2007/10/03)
-
- An α-aminomethyl carbanion equivalent via a novel Barbier reaction: (1H-naphtho[ 1,8-de]-1,2,3-triazin-2-yl)methyl anion
-
A novel sonication-promoted Barbier reaction putatively generated the titled species from the corresponding naphthotriazinylmethyl chloride and magnesium in THF: its formal addition to a variety of carbonyl compounds in situ occurred in excellent yields. Subsequent catalytic hydrogenolysis of the triazine moiety demasked the amine, thus defining a route to various phenylethylamines (including the alkaloid 'mescaline'), or ethanolamines (in two cases), in excellent overall yields. (C) 2000 Elsevier Science Ltd.
- Chandrasekhar, Sosale,Sridhar, Malayalam
-
p. 4685 - 4688
(2007/10/03)
-
- The stereoselectivity of inhibition of rat liver mitochondrial MAO-A and MAO-B by the enantiomers of 2-phenylpropylamine and their derivatives
-
As part of a study of the stereoselectivity of inhibition of the different forms of monoamine oxidase (MAO-A and MAO-B), the enantiomers of 2- phenylpropylamine, N-methyl-2-phenylpropylamine and N-methyl-N-propargyl-2- phenylpropylamine have been prepared. The K(i) values for each enantiomer when competitively inhibiting both MAO-A and MAO-B are reported. The enantiomers of N-methyl-N-propargyl-2-phenylpropylamine were also evaluated as irreversible inhibitors (first order rate constant [k2] for formation of the covalent adduct). These compounds represent a series of enantiomers in which asymmetry is due to the presence of a hydrophobic (-CH3) substituent at the carbon atom β to the amino function. The results are discussed in comparison to previous studies of similar enantiomeric compounds in which the asymmetry was present at the carbon atom α to the amino function.
- Bocchinfuso, Ronald,Robinson, J. Barry
-
p. 293 - 300
(2007/10/03)
-
- Enantioselective synthesis of β-substituted primary and secondary amines by alkylation of (R)-phenylglycinol amide enolates
-
General and convenient syntheses of optically active β-substituted secondary or primary amines 4 and 8 are described. The method is based on diastereoselective alkylation of amides 1 and 5 derived from R-(-)-phenylglycinol followed by reduction and removal of the chiral appendage. This procedure has also been applied to the preparation of 1,4-amino alcohols 12 and γ-amino esters 14.
- Jullian, Valérie,Quirion, Jean-Charles,Husson, Henri-Philippe
-
p. 1091 - 1097
(2007/10/03)
-
- Die Isocyanid-Cyanid-Umlagerung - Mechanismus und praeparative Anwendung
-
Bis vor kurzem war die Isocyanid-Cyanid-Umlagerung hauptsaechlich als Beispiel fuer eine unimolekular verlaufende Gasphasenreaktion bekannt und nur fuer einfache Systeme kinetisch untersucht.Kinetikstudien in Loesung wurden erst moeglich, als man eine ueberlagerte, zum gleichen Produkt fuehrende Radikalkette erkannte und diese inhibieren konnte.Die Geschwindigkeit der Isomerisierung erwies sich als kaum von der Struktur und von Substituenten abhaengig.Allenfalls starke sterische Hinderung in drei Dimensionen wie in tris-α-substituierten Triptylcylisocyaniden fuehrt zu einer deutlichen Erhoehung der Aktivierungsenthalpie.Die Ergebnisse lassen sich mit einem rein sigmatropen Mechanismus deuten und sind damit in Einklang mit Voraussagen aus ab-initio-Rechnungen.Auch praeparativ laesst sich diese Umlagerung inzwischen nutzen.Bei der Blitzpyrolyse sind die Ausbeuten an Cyanid nahezu quantitativ.Allylisocyanide reagieren ohne Allylisomerisierung und optisch aktive Isocyanide unter vollstaendiger Retention.Die Umlagerung kann sowohl Bestandteil wirtschaftlich interessanter Synthesen, z.B. der Entzuendungshemmer Ibuprofen und (S)-Naproxen, sein als auch beim Aufbau optisch aktiver β-Acyloxycyanide, die nuetzliche Synthesebausteine sind, aus optisch aktiven α-Aminosaeuren helfen.
- Ruechardt, Christoph,Meier, Michael,Haaf, Klaus,Pakusch, Joachim,Wolber, Erwin K. A.,Mueller, Barbara
-
p. 907 - 915
(2007/10/02)
-
- PREPARATION OF ISOMERICALLY PURE ALKYLAMINES VIA THE REACTION OF DIMETHYLALKYLBORANES WITH CHLORAMINE
-
Dimethylborane was used to hydroborate alkenes regiospecifically.The resultant dimethylalkylboranes react with ammonium hydrochloride and sodium hypochlorite to yield isomerically pure alkylamines.
- Kabalka, George W.,Wang, Zhe,Goudgaon, Nganna M.
-
p. 2409 - 2414
(2007/10/02)
-
- THE REACTION OF ORGANOBORANES WITH TRIMETHYLSILYL AZIDE IN A NEUTRAL MEDIUM: SYNTHESIS OF PRIMARY AMINES
-
A facile method for the preparation of primary amines using trimethylsilyl azide and trialkylboranes in a neutral protic solvent is described.
- Kabalka, George W.,Goudgaon, Naganna M.,Liang, Yanhong
-
p. 1363 - 1370
(2007/10/02)
-
- Asymmetric Hydrogenation of 2-Aryl-1-nitropropenes by Fermenting Bakers'Yeast
-
2-Aryl-1-nitropropenes were enantioselectively hydrogenated on C=C double bonds by incubation with fermenting bakers' yeast to afford optically active 2-aryl-1-nitopropanes.
- Ohta, Hiromichi,Ozaki, Kazuhiko,Tsuchihashi, Gen-ichi
-
p. 191 - 192
(2007/10/02)
-
- ORGANOBORANES FOR SYNTHESIS. 7. AN IMPROVED GENERAL SYNTHESIS OF PRIMARY AMINES FROM ALKENES via HYDROBORATION-ORGANOBORANE CHEMISTRY
-
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.
- Brown, Herbert C.,Kim, Kee-Won,Srebnik, Morris,Singaram, Bakthan
-
p. 4071 - 4078
(2007/10/02)
-
- REACTIONS OF METHYLCOPPER AND CHIRAL ORGANOCUPRATES WITH 1-NITRO-2-PHENYLETHENE AND OF LITHIUM DIMETHYLCUPRATE WITH METHYL 3(NITROPHENYL)PROPENOATES
-
Organocopper compounds like methylcopper, lithium dimethylcuprate, chiral lithium methyl-(S)-2(1-dimethylaminoethyl)-phenylcuprate and lithium menthoxy(methyl)cuprate react with 1-nitro-2-phenylethene to give the conjugate addition product 1-nitro-2-phenylpropane in moderate yields.In the reaction with lithium methyl-(S)-2(1-dimethylaminoethyl)phenylcuprate 2percent asymmetric induction was obtained.The reaction between lithium dimethylcuprate and methyl 3(4-nitrophenyl)propenoate gave the corresponding azoxy compound and no conjugate addition product, while methyl 3(3-nitrophenyl)propenoate gave some conjugate addition.
- Hansson, A.-T.,Nilsson, M.
-
p. 389 - 391
(2007/10/02)
-
- Stereochemistry of Aliphatic Carbocations, 15. Rearrangements in 2-Arylalkyl Systems
-
Phenyl shifts from secondary to primary carbon proceed with virtually complete inversion at the migration origin, regardless whether they are induced by solvolysis of the aryl sulfonate 25 or by deamination of the amines 12, 17, 26, and 43.Sequential rearrangements (Ph, CH3 and Ph, H) are likewise stereo- and regiospecific.These results strongly support the intervention of phenonium ions.In contrast, the competitive alkyl shifts (deamination only) from benzylic to primary carbon produce but a small excess of inversion (Me 27percent, Et 13percent, iPr 20percent, tBu 3percent).Obviously, benzyl cations are the predominant intermediates.
- Kirmse, Wolfgang,Guenther, Bernd-Rainer,Loosen, Karin
-
p. 2140 - 2153
(2007/10/02)
-