- Ring-opening reactions of nonactivated aziridines catalyzed by tris(pentafluorophenyl)borane
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The ring-opening reactions of nonactivated aziridines with amine nucleophiles are efficiently catalyzed by tris(pentafluorophenyl)borane leading to derivatives of trans-1,2-diamines in high yields. A mechanistic investigation of the reaction suggests that in situ formed [(C6F5)3B(OH2)]· H2O catalyzes the opening through a Bronsted acid manifold.
- Watson, Iain D. G.,Yudin, Andrei K.
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- An efficient synthesis of 2-amino alcohols by silica gel catalysed opening of epoxide rings by amines
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Silica gel (60-120 mesh) efficiently catalyses the opening of epoxide rings by amines at rt under solvent-free conditions providing an easy method for the synthesis of 2-amino alcohols. Aromatic and aliphatic amines react with cyclohexene oxide with exclu
- Chakraborti, Asit K.,Rudrawar, Santosh,Kondaskar, Atul
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- Synthesis and enantioselectivity of optically active 1- and 3-substituted 4-phenyl-1,2,3,4-tetrahydroisoquinolin-4-ols and related compounds as norepinephrine potentiators
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Optically active 1,2-dimethyl-4-phenyl-1,2,3,4-tetrahydroisoquinolin-4- ols (1R,4R-3a and 1S,4S-3b, 1S,4R-4a, and 1R,4S-4b) and 2-methyl-4-phenyl- 1,2,3,4-tetrahydroisoquinolines (4S-5a and 4R-5b) were prepared in order to examine the effects of the 1-, 3-, and 4-substituents of 2-methyl-4-phenyl- 1,2,3,4-tetrahydroisoquinolin-4-ol (PI-OH) (1) on the enantioselectivity for norepinephrine (NE) potentiating activity. The conformations and absolute configurations of 3-5 were determined from their 1H-NMR and circular dichroism (CD) spectra and by single-crystal X-ray diffractometric analysis. The NE potentiating activity of the optically active 3-5 and previously prepared 3-methyl derivatives (3R,4R-6a and 3S,4S-6b) of PI-OH were tested. The results show that compounds 3, 4, and 6 had high enantioselectivity for NE potentiation: the 4R series of the enantiomers exhibited activity but not the 4S-enantiomers. The activity of the 4-desoxy compound 5 also resided exclusively in the 4S-enantiomer. These findings suggest the presence of a specific receptor for NE uptake, and the enantiomers 3a, 4a, 5a, and 6a may be antagonistic at this NE uptake receptor.
- Kihara,Ikeuchi,Adachi,Nagao,Moritoki,Yamaguchi,Taira
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- Scope and limitations of montmorillonite K 10 catalysed opening of epoxide rings by amines
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Montmorillonite K 10 efficiently catalyses the opening of epoxide rings by amines in high yields with excellent regio- and diastereo-selectivities under solvent-free conditions at room temperature affording an improved process for synthesis of 2-amino alcohols. Reaction of cyclohexene oxide with aryl/alkyl amines leads to the formation of trans-2-aryl/alkylaminocyclohexanols. For unsymmetrical epoxides, the regioselectivity is controlled by the electronic and steric factors associated with the epoxide and the amine. Selective nucleophilic attack at the benzylic carbon of styrene oxide takes place with aromatic amines, whereas, aliphatic amines exhibit preferential nucleophilic attack at the terminal carbon. Aniline reacts selectively at the less hindered carbon of other unsymmetrical epoxides. The difference in the internal strain energy of the epoxide ring in cycloalkene oxides and alkene oxides led to selective nucleophilic opening of cyclohexene oxide by aniline in the presence of styrene oxide. Due to the chelation effect, selective activation of the epoxide ring in 3-phenoxy propylene oxide takes place in the presence of styrene oxide leading to preferential cleavage of the epoxide ring in 3-phenoxy propylene oxide by aniline.
- Chakraborti, Asit K.,Kondaskar, Atul,Rudrawar, Santosh
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- Stereospecific rearrangement of β-amino alcohols catalyzed by H 2SO4
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Highly enantioselective rearrangement of β-amino alcohols was realized by using a catalytic amount of H2SO4. Georg Thieme Verlag Stuttgart.
- Métro, Thomas-Xavier,Pardo, Domingo Gomez,Cossy, Janine
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- An efficient protocol for regioselective ring opening of epoxides using sulfated tungstate: Application in synthesis of active pharmaceutical ingredients atenolol, propranolol and ranolazine
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Sulfated tungstate was found to be a new and highly efficient catalyst for opening of epoxide rings by amines to give β-amino alcohols with high regioselectivity. Various advantages associated with this novel and environmental friendly protocol include solvent-free conditions, short reaction times, high product yields, simple workup procedure and easy recovery and reusability of the catalyst. This protocol has been applied for the synthesis of active pharmaceutical ingredients atenolol, propranolol and ranolazine.
- Pathare, Sagar P.,Akamanchi, Krishnacharya G.
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- Solid lithium perchlorate as a powerful catalyst for the synthesis of β-aminoalcohols under solvent-free conditions
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Lithium perchlorate catalyzed the ring opening of epoxides with amines to provide the corresponding β-aminoalcohols in excellent yields with high regioselectivity. The reaction proceeds rapidly under mild and neutral conditions and worked well with primary, secondary, aliphatic, aromatic, and hindered amines in short times at room temperature, in the absence of solvent.
- Azizi, Najmodin,Saidi, Mohammad R.
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- Nickel-Catalyzed Regio- And Stereospecific C-H Coupling of Benzamides with Aziridines
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A nickel-catalyzed C-H coupling of 8-aminoquinoline-derived benzamides with aryl- and alkyl-substituted aziridines has been disclosed. The current strategy provides direct access to benzolactams by the C-H alkylation-intramolecular amidation cascade event with the concomitant removal of the aminoquinoline auxiliary. The regioselectivity of ring opening of aziridines can be controlled by the substituents. The reaction with chiral aziridines proceeds with inversion of configuration, thus suggesting an SN2-type nucleophilic ring-opening pathway.
- Hirano, Koji,Miura, Masahiro,Xu, Shibo
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p. 5471 - 5475
(2021/07/26)
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- Synthesis, characterization and catalytic application of Bi2S3 microspheres for Suzuki-Miyaura cross-coupling reaction and chemoselective ring opening of epoxides
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Bismuth sulfide (Bi2S3) prepared using L-cysteine, which served as both the sulfur source and the directing molecule for the formation of Bi2S3 as heterogeneous catalyst through solvothermal method. The prepared catalyst was examined by various techniques such as XRD, BET, FE-SEM, TEM, and TGA analysis. The results and analysis revealed that bismuth microspheres have better catalytic behavior for the preparation of biphenyl in water as a greenest solvent and for the ring opening of epoxides by nucleophiles including amines, alcohol, and thiol compared to pure Bi(NO3)3. 3H2O under solvent-free condition. Moreover, the novel catalyst could be recovered and reusedat least four times without loss of its catalytic activity.
- Ghorbani-Choghamarani, Arash,Taherinia, Zahra
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- Amine grafted Fe3O4 immobilized graphene oxide as a recyclable and effectual nanocomposite for the regioselective ring opening reaction
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This work describes the synthesis of magnetic graphene oxide (MGO), where iron oxide (Fe3O4) nanoparticles were uniformly deposited over the sheets of the graphene oxide (GO). Further, the introduction of aminopropyltrimethoxysilane (APTMS) on the surface of MGO was successfully done and results in the formation of amine-functionalized magnetic graphene oxide (MGO–NH2). The synthesized heterogeneous magnetic nanocomposite was characterized by numerous physicochemical and morphological techniques such as powder X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, transmission electron microscopy, vibrating sample magnetometer, scanning electron microscopy, CHN analyzer, and energy-dispersive X-ray analysis. The synthesized nanocomposite was proved to be an effectual catalyst in the nucleophilic ring opening reactions of styrene oxide with derivatives of amines under green solvent. The present catalyst displayed good catalytic activity, short reaction time, higher regioselectivity, excellent yields and could be reutilized up to seven catalytic rounds with no substantial loss in its activity. The excellent properties of the catalyst are due to the dual character of acidic groups (existence of carboxyl groups on the sheet edges) and basic groups (amine groups anchored on the surface of GO). On completion of the reaction, the prepared nanocomposite could be effortlessly recovered from the reaction mixture by utilizing an external magnet, owing to the ferromagnetic property of Fe3O4. Graphical Abstract: [Figure not available: see fulltext.].
- Gupta, Padmini,Garkoti, Charu,Shabir, Javaid,Surabhi,Sah, Digvijay,Mozumdar, Subho
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p. 4013 - 4028
(2021/06/25)
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- Highly regioselective ring-opening of epoxides with amines: A metal- A nd solvent-free protocol for the synthesis of β-amino alcohols
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We herein report a metal- A nd solvent-free acetic acid-mediated ring-opening reaction of epoxides with amines. This process provides β-amino alcohols in high yields with excellent regioselectivity. Importantly, this epoxide ring-opening protocol can be used for the introduction of amines in natural products during late-stage transformations.
- Li, Dong,Wang, Jing,Yu, Shibo,Ye, Silei,Zou, Wenjie,Zhang, Hongbin,Chen, Jingbo
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supporting information
p. 2256 - 2259
(2020/03/04)
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- M-Type SrFe12O19Ferrite: An Efficient Catalyst for the Synthesis of Amino Alcohols under Solvent-Free Conditions
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Magnetically separable strontium hexaferrite SrFe12O19 was prepared using the chemical coprecipitation method, and the nanostructured material was characterized by X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and BET analysis. The SEM images showed the homogeneity of the chemical composition of SrFe12O19 and uniform distribution of size and morphology. The pore size of the nanomaterial and its specific area were determined by BET measurements. Strontium hexaferrite SrFe12O19 exhibited a strong magnetic field, which is highly suitable in the heterogeneous catalysis as it can be efficiently separated from the reaction. The magnetic nanocatalyst showed high activity and environmentally benign heterogeneous catalysts for the epoxide ring-opening with amines affording β-amino alcohols under solvent-free conditions. When unsymmetrical epoxides were treated in the presence of aromatics amines, the regioselectivity was influenced by the electronic and steric factors. Total regioselectivity was observed for the reactions performed with aliphatic amines. The magnetically SrFe12O19 nanocatalyst showed excellent recyclability with continuously good catalytic activities after four cycles.
- Laayati, Mouhsine,Hasnaoui, Ali,Abdallah, Nayad,Oubaassine, Saadia,Fkhar, Lahcen,Mounkachi, Omar,El Houssame, Soufiane,Ait Ali, Mustapha,El Firdoussi, Larbi
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- OLIGONUCLEOTIDE AND NUCLEIC ACID SYNTHESIS
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The present invention relates to methods for the high fidelity synthesis of oligonucleotides and polynucleotides on a solid surface. In particular, the invention relates to methods of synthesising oligonucleotides, polynucleotides, and doublestranded polynucleotides/nucleic acids, such as DNA and XNA, wherein the process comprises thermally controlled deprotection steps at the 5'-OH of previously coupled nucleosides or nucleotides at selected sites on the surface of the substrate.
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Page/Page column 124; 125
(2019/08/12)
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- THERMALLY-CLEAVABLE PROTECTING AND LINKER GROUPS
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The present invention relates to chemical linkers and protecting groups, compounds and compositions containing the chemical linkers or protecting groups, and intermediates and processes that can be used to prepare them. The chemical linkers and protecting groups are based on pyrrolidine and piperidine activating groups, which undergo intramolecular cyclisation upon heating with release of carbon dioxide, thereby releasing the organic compound from a substrate. In particular, those chemical linkers and protecting groups are useful in the solid phase synthesis of oligonucleotides according to the following representative schemes.
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Page/Page column 56; 57
(2018/11/10)
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- β-amino alcohols and their respective 2-phenyl-N-alkyl aziridines as potential DNA minor groove binders
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It is known that aziridines and nitrogen mustards exert their biological activities, especially in chemotherapy, via DNA alkylation. The studied scaffold, 2-phenyl-1-aziridine, provides a distinct conformation compared to commonly used aziridines, and the
- Vaidergorn, Miguel M.,Carneiro, Zumira A.,Lopes, Carla D.,de Albuquerque, Sérgio,Reis, Felipe C.C.,Nikolaou, Sofia,Mello, Juliana F.R. e,Genesi, Giovani L.,Trossini, Gustavo H.G.,Ganesan,Emery, Flavio S.
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p. 657 - 664
(2018/08/23)
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- Visible-Light-Promoted Metal-Free Aerobic Hydroxyazidation of Alkenes
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A highly efficient visible-light-promoted metal-free aerobic hydroxyazidation of alkenes has been developed. This protocol was operationally simple with broad substrate scope using relatively simple and readily available starting materials, such as alkene
- Yang, Bo,Lu, Zhan
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p. 8362 - 8365
(2017/12/08)
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- Direct catalytic synthesis of unprotected 2-amino-1-phenylethanols from alkenes by using iron(II) phthalocyanine
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Aryl-substituted amino alcohols are privileged scaffolds in medicinal chemistry and natural products. Herein, we report that an exceptionally simple and inexpensive FeII complex efficiently catalyzes the direct transformation of simple alkenes into unprotected amino alcohols in good yield and perfect regioselectivity. This new catalytic method was applied in the expedient synthesis of bioactive molecules and could be extended to aminoetherification.
- Legnani, Luca,Morandi, Bill
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supporting information
p. 2248 - 2251
(2016/02/18)
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- Green Regio- and Enantioselective Aminolysis Catalyzed by Graphite and Graphene Oxide under Solvent-Free Conditions
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The ring-opening reactions of epoxides with amines were efficiently and regioselectively catalyzed by high-surface-area graphite and graphene oxide under metal-free and solvent-free conditions. For epoxides without aryl groups, catalytic activity was observed only for graphene oxide, and hence, the activity must have been due to its acidic groups. For styrene oxide, instead, graphite and graphene oxide exhibited rather similar catalytic activities, and hence, the activity was mainly due to activation of the electrophilic epoxide by π-stacking interactions with the graphitic π system. The described aminolysis procedure is green and cheap because the catalyst can be recovered and recycled without loss of efficiency. Moreover, these heterogeneous catalysts exert high stereoselective control in the presence of nonracemic epoxides and provide chiral β-amino alcohols with enantiomeric excess values up to 99 %.
- Acocella, Maria Rosaria,D'Urso, Luciana,Maggio, Mario,Guerra, Gaetano
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p. 1915 - 1920
(2016/07/06)
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- Greener aminolysis of epoxides on BiCl3/SiO2
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The remarkable catalytic activity of BiCl3/SiO2 for the ring-opening of epoxides with aromatic and aliphatic amines under microwave and thermal heating was observed. This eco-friendly heterogeneous catalyst displayed high to excellent regioselectivity in the synthesis of β-amino alcohols under solvent-free conditions. High turnover frequency (TOF) values under microwave heating and excellent reusability of the catalyst may significantly contribute to applied chemistry.
- Mohsenzadeh, Farshid,Aghapoor, Kioumars,Darabi, Hossein Reza,Jalali, Mohammad Reza,Halvagar, Mohammad Reza
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p. 978 - 985
(2016/08/08)
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- Chemical fixation of CO2 to cyclic carbonates using Al(III) β-aminoalcohol based efficient catalysts: An experimental and computational studies
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A series of Al(III) unsymmetrical β-aminoalcohol based complexes 1-6 were synthesized via metalation of the corresponding ligands 1′-6′ those were prepared by the reaction of benzylamine with readily available epoxides viz., styrene oxide, 1,2-epoxy-3-phenoxypropane, 4-tertbutylphenyl glycidyl ether, 4-chlorophenyl glycidyl ether, glycidyl 2-methylphenyl ether and 1,2-epoxyhexane. Among these complexes, the complex 2 was found to be most effective in the cycloaddition of aryloxy/aliphatic terminal epoxides with CO2 under atmospheric pressure to get corresponding cyclic carbonates with high conversion and selectivity (up to >99%) in the presence of tetrabutylammonium bromide as a co-catalyst. The DFT calculations revealed the important role played by counter-ion in the co-catalyst during cycloaddition reaction of CO2 with the substituted epoxides.
- Verma, Shailesh,Si, Mrinal Kanti,Kureshy, Rukhsana I.,Nazish, Mohd,Kumar, Manish,Khan, Noor-Ul H.,Abdi, Sayed H.R.,Bajaj, Hari C.,Ganguly, Bishwajit
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p. 135 - 144
(2016/04/04)
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- Catalytic activity of graphite-based nanofillers on cure reaction of epoxy resins
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The strong influence of graphite oxide (GO) nanofiller on the glass transition temperature (Tg) of epoxy resins, generally attributed to restricted molecular mobility of the epoxy matrix by the nanofiller or to the crosslinking of GO layers via the epoxy chains, is investigated. The study confirms that large increases of the glass transition temperature of the nanocomposite can be observed in presence of GO. However, similar Tg increases are observed, when the filler is a high-surface-area graphite (HSAG), lacking oxidized groups. Moreover, these Tg differences tend to disappear as a consequence of aging or thermal annealing. These results suggest that the observed Tg increases are mainly due to a catalytic activity of graphitic layers on the crosslinking reaction between the epoxy resin components (epoxide oligomer and di-amine), rather than to reaction of the epoxide groups with functional groups of GO. This hypothesis is supported by investigating the catalytic activity of graphite-based materials on reactions between analogous monofunctional epoxide and amine compounds.
- Mauro, Marco,Acocella, Maria Rosaria,Corcione, Carola Esposito,Maffezzoli, Alfonso,Guerra, Gaetano
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supporting information
p. 5612 - 5615
(2014/12/10)
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- MORPHOLINE-SPIROCYCLIC PIPERIDINE AMIDES AS MODULATORS OF ION CHANNELS
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The invention relates to morpholine spirocyclic piperidine amide compounds useful as inhibitors of ion channels. The invention also provides pharmaceutically acceptable compositions comprising the compounds of the invention and methods of using the compositions in the treatment of various disorders.
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Page/Page column 96
(2012/10/07)
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- Catalytic, enantioselective N-acylation of lactams and thiolactams using amidine-based catalysts
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In contrast to alcohols and amines, racemic lactams and thiolactams cannot be resolved directly via enzymatic acylation or classical resolution. Asymmetric N-acylation promoted by amidine-based catalysts, particularly Cl-PIQ 2 and BTM 3, provides a convenient method for the kinetic resolution of these valuable compounds and often achieves excellent levels of enantioselectivity in this process. Density functional theory calculations indicate that the reaction occurs via N-acylation of the lactim tautomer and that cation-π interactions play a key role in the chiral recognition of lactam substrates.
- Yang, Xing,Bumbu, Valentina D.,Liu, Peng,Li, Ximin,Jiang, Hui,Uffman, Eric W.,Guo, Lei,Zhang, Wei,Jiang, Xuntian,Houk,Birman, Vladimir B.
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supporting information
p. 17605 - 17612
(2013/01/15)
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- Efficient preparation of α-ketoacetals
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The Weinreb amides 2a,b were prepared from the a,a-dimethoxyacetic acids 1c,d. A number of representative nucleophilic additions (RMgX and RLi) on 2 afforded a-ketoacetals 3a-j in 70-99% yield. These compounds represent a versatile arrangement of functional groups of significant synthetic value, as demonstrated in the synthesis of (±)-salbutamol.
- Ayala-Mata, Francisco,Barrera-Mendoza, Citlalli,Jimenez-Vazquez, Hugo A.,Vargas-Diaz, Elena,Zepeda, L. Gerardo
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p. 13864 - 13878
(2013/03/13)
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- Palladium-catalyzed double carbonylation using near stoichiometric carbon monoxide: Expedient access to substituted 13C2-labeled phenethylamines
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A novel and general approach for 13C2- and 2H-labeled phenethylamine derivatives has been developed, based on a highly convergent single-step assembly of the carbon skeleton. The efficient incorporation of two carbon-13 isotopes into phenethylamines was accomplished using a palladium-catalyzed double carbonylation of aryl iodides with near stoichiometric carbon monoxide.
- Nielsen, Dennis U.,Neumann, Karoline,Taaning, Rolf H.,Lindhardt, Anders T.,Modvig, Amalie,Skrydstrup, Troels
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p. 6155 - 6165
(2012/09/21)
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- Identification of novel 2-((1-(benzyl(2-hydroxy-2-phenylethyl)amino)-1-oxo- 3-phenylpropan-2-yl)carbamoyl)benzoic acid analogues as BMP-2 stimulators
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The synthesis and SAR studies of 10 new chemical entities (NCEs) that have shown BMP-2 stimulation and osteoblast differentiation are reported. Among these, 2-((1-(benzyl(2-hydroxy-2-phenylethyl)amino)-1-oxo-3-phenylpropan-2-yl) carbamoyl)benzoic acid (11) was the most effective while its analogue 13 also showed good activity in inducing osteoblast BMP-2 production. Compound 11 induced osteoblast differentiation in vitro, and this effect was abrogated by a physiological BMP-2 inhibitor, noggin. It also exhibited dose dependent increase in nascent bone formation (2.16- and 3.12-fold more than the control at 1 and 5 mg/kg dose, respectively) at the fracture site in rats. At the maximum osteogenic concentration, compound 11 significantly inhibited osteoblastic proteosomal activity. This compound was safe, as it had no effect on BMP synthesis in cardiovascular tissue.
- Balaramnavar, Vishal M.,Khan, Imran A.,Siddiqui, Jawed Akhtar,Khan, Mohd Parvez,Chakravarti, Bandana,Sharan, Kunal,Swarnkar, Gaurav,Rastogi, Namrata,Siddiqui,Mishra, Durga Prasad,Chattopadhyay, Naibedya,Saxena, Anil K.
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p. 8248 - 8259
(2013/01/15)
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- A Dieckmann cyclization route to piperazine-2,5-diones
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Piperazine-2,5-diones are formed by Dieckmann cyclization (NaH, THF) of substructures of the type CH2-N(R)C(O)CH2N(R′) CO2Ph in which the terminal methylene (CH2) that is adjacent to nitrogen closes onto the carbonyl group of the phenyl carbamate unit at the other end of the chain. R and R′ are alkyl groups, and the terminal methylene is activated by a ketone carbonyl, a nitrile, an ester, or a phosphoryl group. The starting materials are assembled by standard acylation and oxidation processes, starting from a β-(alkylamino)alcohol, an (alkylamino)acetonitrile, an (alkylamino) ester, or an (alkylamino)methyl phosphonate.
- Aboussafy, Claude Larrivee,Clive, Derrick L. J.
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scheme or table
p. 5125 - 5131
(2012/07/03)
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- Synthesis and 2D QSAR of O-sulphonated β-aminols derivatives as novel antifungal and antibacterial agents
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Synthesis of a series of b-aminol derivatives using regioselective opening reaction catalyzed by SiO2 (60-120 mesh) and O-sulphonation in THF-KOH system, comprising tert-butoxycarbonyl at secondary nitrogen and evaluate for various stains of bacteria and fungi. SAR study of synthesized compound using backward regression analysis.
- Saxena, Anil K.,Sharma, Sugandha,Pandey, Atindra K.,Shukla, Praveen K.
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supporting information; experimental part
p. 6476 - 6481
(2011/11/29)
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- Zinc tetrafluoroborate hydrate as a mild catalyst for epoxide ring opening with amines: Scope and limitations of metal tetrafluoroborates and applications in the synthesis of antihypertensive drugs (RS)/(R)/(S)-metoprolols
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The scope and limitations of metal tetrafluoroborates have been studied for epoxide ring-opening reaction with amines, and Zn(BF4) 2?xH2O has been found to be a mild and efficient catalyst affording high yields under solvent-free conditions at rt with excellent chemo-, regio-, and stereoselectivities. The catalytic efficiency followed the order Zn(BF4)2?xH2O ? Cu(BF4)2?xH2O > Co(BF4) 2?6H2O ? Fe(BF4)2? 6H2O > LiBF4 for reactions with cyclohexene oxide and Zn(BF4)2?xH2O ? Co(BF4) 2?6H2O ? Fe(BF4)2? 6H2O > Cu(BF4)2?xH2O for stilbene oxide, but AgBF4 was ineffective. For reaction of styrene oxide with aniline, the metal tetrafluoroborates exhibited comparable regioselectivity (1:99-7:93) with preferential reaction at the benzylic carbon of the epoxide ring. A reversal of regioselectivity (91:1-69:31) in favor of the reaction at the terminal carbon of the epoxide ring was observed for reaction with morpholine. The regioselectivity was dependent on the electronic and steric factors of the epoxide and the pKa of the amine and independent of amine nucleophilicity. The role of the metal tetrafluoroborates is envisaged as "electrophile nucleophile dual activation" through cooperativity of coordination, charge-charge interaction, and hydrogen-bond formation that rationalizes the catalytic efficiency, substrate reactivity, and regioselectivity. The methodology was used for synthesis of cardiovascular drug metoprolol as racemic and enriched enantiomeric forms.
- Pujala, Brahmam,Rana, Shivani,Chakraborti, Asit K.
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experimental part
p. 8768 - 8780
(2011/12/04)
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- Synthesis of N-substituted Clausenamide analogues
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A practical synthesis of N-substituted Clausenamide analogues, including (-) and (+) CM1, Piracetam analogue 1 and Nefiracetam analogue 2, have been developed.
- Li, Xingzhou,Zhu, Chuangjiang,Li, Changhui,Wu, Kemei,Huang, Daofei,Huang, Liang
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experimental part
p. 5531 - 5538
(2010/12/25)
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- Rearrangement of N-alkyl 1,2-amino alcohols. Synthesis of (S)-toliprolol and (S)-propanolol
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N-alkyl 1,2-amino alcohols were rearranged stereospecifically by using TFAA/Et3N. This rearrangement has been used to synthesize N-isopropyl-3-(aryloxy)-2-hydroxypropylamines, β-adrenergic blocking agents such as (S)-toliprolol and (S)-propanolol.
- Duthion, Béranger,Métro, Thomas-Xavier,Gomez Pardo, Domingo,Cossy, Janine
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scheme or table
p. 6696 - 6706
(2011/02/26)
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- Heterogeneous Lewis acid catalysis with self-organized polymeric rare earth arylsulfonates under solvent-free conditions
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Polymeric rare earth arylsulfonates, easily prepared from rare earth triisopropoxides and biphenyl-4,4'-disulfonic acid (BPDSA) or 1,3,5-triphenylbenzene trisulfonic acid (TPTSA) in a self-organization manner, were found to work as an efficient heterogene
- Furuno, Hiroshi,Ishida, Shuichi,Suzuki, Shoko,Hayano, Tetsuji,Onitsuka, Satoaki,Inanaga, Junji
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scheme or table
p. 1007 - 1018
(2010/10/03)
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- Highly efficient and versatile chemoselective addition of amines to epoxides in water catalyzed by erbium(III) triflate
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Er(OTf)3 is proposed as a highly efficient and reusable catalyst for the opening of epoxides in water with aliphatic as well as aromatic amines leading to the synthesis of β-amino alcohols. The aqueous conditions employed in the present method will make it 'environmentally friendly' and potentially useful for industrial applications.
- Procopio, Antonio,Gaspari, Marco,Nardi, Monica,Oliverio, Manuela,Rosati, Ornelio
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p. 2289 - 2293
(2008/09/18)
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- Microwave-enhanced sulphated zirconia and SZ/MCM-41 catalyzed regioselective synthesis of β-amino alcohols under solvent-free conditions
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A solvent-free approach for the regioselective synthesis of β-amino alcohols in shorter reaction times and higher yields, compared to conventional heating is described. It involves microwave (MW) exposure of undiluted reactants in the presence of sulphated zirconia (SZ) or sulphated zirconia over MCM-41 (SZM) as catalyst. Both acid materials can be easily recovered and reused.
- Negron-Silva, Guillermo,Hernandez-Reyes, C. Xochitl,Angeles-Beltran, Deyanira,Lomas-Romero, Leticia,Gonzalez-Zamora, Eduardo
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p. 977 - 985
(2008/09/18)
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- Sn(OTf)2 catalysed regioselective styrene oxide ring opening with aromatic amines
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Sn(OTf)2 is an efficient and versatile catalyst for the highly regioselective opening of styrene oxide with aromatic amines, which allowed for the preparation of fourteen 2-arylamino-2-phenylethanols, some of them described here for the first time (6g, 6i, 6j, 6k and 6m). Sn(OTf)2 also catalyses the opening of styrene oxide with aliphatic amines in moderate to high yields but with a lower degree of regioselectivity. 2-Akylamino-1-phenylethanols are the predominant products when moderate to high regioselectivity is observed (compounds 4b, 4c and 4d). This is the first report of the use of Sn(OTf)2 to catalyse the opening of an epoxide by aliphatic amines.
- Mancilla, Gabriela,Femenía-Ríos, Marienca,Macías-Sánchez, Antonio J.,Collado, Isidro G.
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experimental part
p. 11732 - 11737
(2009/04/11)
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- Comparative study of the regioselective synthesis of β-aminoalcohols under solventless conditions catalyzed by sulfated zirconia and SZ/MCM-41
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Sulfated zirconia and SZ/MCM-41 were used as catalysts for the synthesis of β-aminoalcohols via epoxide aminolysis. Sulfated zirconia was prepared by sol-gel and SZ/MCM-41 was obtained by impregnation. Solid catalysts were characterized by XRD, SEM-EDS, UV-Vis, FT-IR pyridine desorption and Nitrogen physisorption. Both acid materials were useful as catalysts, even when they were recycled several times. The β-aminoalcohols were characterized by FT-IR, 1H- and 13C-NMR and GC-MS.
- Negron-Silva, Guillermo,Hernandez-Reyes, C. Xochitl,Angeles-Beltran, Deyanira,Lomas-Romero, Leticia,Gonzalez-Zamora, Eduardo,Mendez-Vivar, Juan
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p. 2515 - 2532
(2008/03/15)
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- Zinc(II) perchlorate hexahydrate catalyzed opening of epoxide ring by amines: Applications to synthesis of (RS)/(R)-propranolols and (RS)/(R)/(S)-naftopidils
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(Figure Presented) Commercially available zinc(II) Perchlorate hexahydrate [Zn(ClO4)2·6H2O] was found to be a new and highly efficient catalyst for opening of epoxide rings by amines affording 2-amino alcohols in high yields under solvent-free conditions and with excellent chemo-, regio-, and stereoselectivities. For unsymmetrical epoxides, the regioselectivity was influenced by the electronic and steric factors associated with the epoxides and the amines. A complementarity in the regioselectivity was observed during the reaction of styrene oxide with aromatic and aliphatic amines: aromatic amines provided amino alcohols from nucleophilic attack at the benzylic carbon as major products whereas aliphatic amines resulted in formation of the amino alcohols through reaction at the terminal carbon atom of the epoxide ring as the major/sole products. Reaction of aniline with various glycidic ethers gave the amino alcohols by regioselective nucleophilic attack at the terminal carbon atom of the epoxide ring as the only/major product. Zinc(II) Perchlorate hexahydrate was found to be the best catalyst compared to other metal Perchlorates. The counteranion modulated the catalytic property of the various Zn(II) compounds that followed the order Zn(ClO4) 2·6H2O Zn(BF4)2 ～ Zn(OTf)2 ZnI2 > ZnBr2 > ZnCl2 > Zn(OAc)2 > Zn(CO3)2 in parallelism with the acidic strength of the corresponding protic acids (except for TfOH). The applicability of the methodology was demonstrated by the synthesis of cardiovascular drugs propranolol and naftopidil as racemates and optically active enantiomers.
- Shivani,Pujala, Brahmam,Chakraborti, Asit K.
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p. 3713 - 3722
(2008/02/05)
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- Regioselectivity in a highly efficient, microwave-assisted epoxide aminolysis
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We have developed a microwave-assisted aminolysis of epoxides as an efficient method for synthesizing a number of β-amino alcohols. In most cases, including in reactions of amines with a trisubstituted epoxide, only one equivalent of amine is required to
- Desai, Hinal,D'Souza, Brendan R.,Foether, Devin,Johnson, Benjamin F.,Lindsay, Harriet A.
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p. 902 - 910
(2008/01/06)
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- N-substituted 5-aryl-1,3-oxazolidin-2-ones from arylethylene oxides
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Substituted 5-aryl-1,3-oxazolidin-2-ones can be efficiently prepared from arylethylene oxides and tert-butyl alkylcarbamates in the presence of catalytic amount of potassium tert-butoxide as a base. Their further hydrolysis under basic conditions provides aryl substituted aminoethanols in high yields.
- Wrobel,Bobin,Karczewski
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p. 907 - 912
(2007/10/03)
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- CATALYZED ENANTIOSELECTIVE TRANSFORMATION OF ALKENES
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Enantioselective catalytic reactions that operate directly on unactivated alkenes for the preparation of chiral organic building blocks and new materials. More particularly, a catalyzed enantioselective reaction that operates on an unsaturated hydrocarbon, such as an alkene, to provide an enantiomerically enriched reactive organometallic intermediate, which can be converted to a variety of multifunctional optically active reaction products.
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Page/Page column 60
(2010/02/10)
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- Highly chemoselective addition of amines to epoxides in water
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(Chemical Equation Presented) Aminolysis of a variety of epoxides by aliphatic and aromatic amines in water, in the absence of any catalyst with high yields, is reported. β-Amino alcohols were formed under mild conditions with high selectivity and in excellent yields.
- Azizi, Najmodin,Saidi, Mohammad R.
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p. 3649 - 3651
(2007/10/03)
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- Scandium triflate as an efficient and useful catalyst for the synthesis of β-amino alcohols by regioselective ring opening of epoxides with amines under solvent-free conditions
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A simple and efficient method has been developed for the synthesis of β-amino alcohols by ring opening of epoxides in the presence of a catalytic amount of Sc(OTf)3 at room temperature under solvent-free conditions. The reaction works well with both aromatic and aliphatic amines. High regio-, and diastereoselectivity can be considered as a noteworthy advantage of this method.
- Placzek, Andrew T.,Donelson, James L.,Trivedi, Rushi,Gibbs, Richard A.,De, Surya K.
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p. 9029 - 9034
(2007/10/03)
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- Calcium trifluoromethanesulfonate-catalysed aminolysis of epoxides
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Aminolysis of epoxides catalysed by calcium trifluoromethanesulfonate under mild reaction conditions is described. The novel method is very efficient in the synthesis of wide variety of β-amino alcohols with high regio- and stereoselectivity.
- Cepanec, Ivica,Litvi?, Mladen,Mikulda?, Hrvoje,Bartolin?i?, Anamarija,Vinkovi?, Vladimir
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p. 2435 - 2439
(2007/10/03)
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- Zinc-catalyzed aminolysis of epoxides
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A series of amino alcohols has been prepared by a novel zinc-catalyzed nucleophilic opening of epoxide rings by amines.
- Pachón, Laura Durán,Gamez, Patrick,Van Brussel, Jos J. M.,Reedijk, Jan
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p. 6025 - 6027
(2007/10/03)
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- ZrCl4 as a new and efficient catalyst for the opening of epoxide rings by amines
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Zirconium(IV) chloride catalyses the nucleophilic opening of epoxide rings by amines leading to the efficient synthesis of β-amino alcohols. The reaction works well with aromatic and aliphatic amines in short times at room temperature in the absence of solvent. Exclusive trans stereoselectivity is observed for cyclic epoxides. Aromatic amines exhibit excellent regioselectivity for preferential nucleophilic attack at the sterically less hindered position during the reaction with unsymmetrical epoxides. However, in case of styrene oxide, selective formation of the benzylic amine was observed during the reactions with aromatic amines.
- Chakraborti, Asit K.,Kondaskar, Atul
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p. 8315 - 8319
(2007/10/03)
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- Solid-phase synthesis of arylalkanolamines
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A versatile method for the solid-phase synthesis of differentially substituted arylalkanolamines has been developed using immobilized carbamates. The method has been successfully used for the synthesis of arylethanolamines and arylpropanolamines in high yields and purities.
- Srinivasan,Gupta,Kundu
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p. 5993 - 5995
(2007/10/03)
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- Enantioselective synthesis of β-hydroxy amines and aziridines using asymmetric transfer hydrogenation of α-amino ketones
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Enantioselective transfer hydrogenation of α-amino ketones is an effective method for the asymmetric synthesis of β-hydroxy amines and aziridines.
- Kawamoto,Wills
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p. 1916 - 1928
(2007/10/03)
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- 1,4-benzodioxin derivatives
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PCT No. PCT/JP96/01252 Sec. 371 Date Nov. 12, 1997 Sec. 102(e) Date Nov. 12, 1997 PCT Filed May 13, 1996 PCT Pub. No. WO96/35685 PCT Pub. Date Nov. 14, 1996A 1,4-benzodioxin derivative represented by formula (I) wherein A is an aryl group or a (C3-C8)cycloalkyl group, R1 and R2 individually are a hydrogen atom, a halogen atom, an alkyl group, a trifluoromethyl group, an alkoxy group, an aryl group, an aryloxy group, or R1 and R2 together form a methylenedioxy group, R3 is a hydrogen atom or an alkyl group, R4 is a hydrogen atom or CO2R5, R5 is a hydrogen atom or an alkyl group, X is a radical of formula (II) or (III) wherein n is 1 or 2. The compounds are useful for a prophylactic or therapeutic agent for diabetes, hyperglycemia and obesity.
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- Stereocontrol between remote atom centers in acyclic substrates. Anti addition of hydride to 1,5-, 1,6-, and 1,7-hydroxy ketones
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For conformationally unconstrained, acyclic organic compounds, the control of stereogenic centers at remote positions of a chain, that is, at a distance of four or more atom centers, remains a challenging problem in asymmetric synthesis. We report on our
- Zhang, Han-Cheng,Harris, Bruce D.,Costanzo, Michael J.,Lawson, Edward C.,Maryanoff, Cynthia A.,Maryanoff, Bruce E.
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p. 7964 - 7981
(2007/10/03)
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- Synthesis of chiral α-substituted N-[((2S)-2-hydroxy-2-phenyl)-ethyl]-2-phenylglycine derivatives by diastereocontrolled alkylation of (6R)-2,3,5,6-tetrahydro-3,6-diaryl-N-[(2'R)-(2'-methyl)phenyl-methyl]-4H-1,4 -oxazin-2-ones
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The synthesis of α-substituted N-[((2S)-2-hydroxy-2-phenyl)-ethyl]-2-phenylglycine derivatives is reported, The key step of the sequence is the highly diastereoselective alkylation of (6R)-2,3,5,6-tetrahydro-3,6-diaryl-N-[(2'R)-(2'-methyl)phenylmethyl]-4H-1,4 -oxazin-2-ones after deprotonation with t-BuOK. Opening of the resulting oxazinone with ethanolic KOH, followed by hydrogenolysis of the corresponding N-[(2R)-(2-methyl)phenylmethyl] compound to furnish the expected 2-phenylglycine derivative, is also described.
- Remuzon, Philippe,Soumeillant, Maxime,Dussy, Christian,Bouzard, Daniel
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p. 17711 - 17726
(2007/10/03)
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- Lithium trifluoromethanesulfonate-catalysed aminolysis of oxiranes
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The aminolysis of oxiranes was found to be catalysed by lithium trifluoromethanesulfonate in acetonitrile solutions. This salt turned out to be an excellent substitute for the unsafe lithium perchlorate.
- Auge, Jacques,Leroy, Frederic
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p. 7715 - 7716
(2007/10/03)
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