- Regioselective hydroboration-oxidation and -amination of fluoro-substituted styrenes
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Hydroboration of fluorinated styrenes with common hydroborating agents results in polymerization. However, regioselective hydroboration has been achieved by utilizing iodoborane-dimethyl sulfide. A series of fluorinated β-phenethyl alcohols and amines were synthesized via this methodology.
- Ramachandran, P. Veeraraghavan,Madhi, Sateesh,O'Donnell, Martin J.
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Read Online
- Bi-enzymatic Conversion of Cinnamic Acids to 2-Arylethylamines
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The conversion of carboxylic acids, such as acrylic acids, to amines is a transformation that remains challenging in synthetic organic chemistry. Despite the ubiquity of similar moieties in natural metabolic pathways, biocatalytic routes seem to have been overlooked for this purpose. Herein we present the conception and optimisation of a two-enzyme system, allowing the synthesis of β-phenylethylamine derivatives from readily-available ring-substituted cinnamic acids. After characterisation of both parts of the reaction in a two-step approach, a set of conditions allowing the one-pot biotransformation was optimised. This combination of a reversible deaminating and irreversible decarboxylating enzyme, both specific for the amino acid intermediate in tandem, represents a general method by which new strategies for the conversion of carboxylic acids to amines could be designed.
- Weise, Nicholas J.,Thapa, Prasansa,Ahmed, Syed T.,Heath, Rachel S.,Parmeggiani, Fabio,Turner, Nicholas J.,Flitsch, Sabine L.
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p. 995 - 998
(2020/01/21)
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- PERIPHERAL ALKYL AND ALKENYL CHAINS EXTENDED BENZENE DERIVATIVES AND PHARMACEUTICAL COMPOSITION INCLUDING THE SAME
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The compounds represented by Formula (I), which are peripheral alkyl and alkenyl chains extended benzene derivatives, are useful as dual autotaxin (ATX) / histone deacetylase (HD AC) inhibitors. These compounds may be included in a pharmaceutical composition along with a pharmaceutically acceptable carrier, and be used in a therapeutically effective amount for prophylaxis or treatment of various diseases and disorders.
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- Benzimidazole fragment containing Mn-complex catalyzed hydrosilylation of ketones and nitriles
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The synthesis of a new bidentate (NN)–Mn(I) complex is reported and its catalytic activity towards the reduction of ketones and nitriles is studied. On comparing the reactivity of various other Mn(I) complexes supported by benzimidazole ligand, it was observed that the Mn(I) complexes bearing 6-methylpyridine and benzimidazole fragments exhibited the highest catalytic activity towards monohydrosilylation of ketones and dihydrosilylation of nitriles. Using this protocol, a wide range of ketones were selectively reduced to the corresponding silyl ethers. In case of unsaturated ketones, the chemoselective reduction of carbonyl group over olefinic bonds was observed. Additionally, selective dihydrosilylation of several nitriles were also achieved using this complex. Mechanistic investigations with radical scavengers suggested the involvement of radical species during the catalytic reaction. Stoichiometric reaction of the Mn(I) complex with phenylsilane revealed the formation of a new Mn(I) complex.
- Ganguli, Kasturi,Mandal, Adarsha,Sarkar, Bidisha,Kundu, Sabuj
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supporting information
(2020/08/13)
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- Biocatalytic Formal Anti-Markovnikov Hydroamination and Hydration of Aryl Alkenes
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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
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p. 5225 - 5233
(2017/08/17)
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- Electron transfer reduction of nitriles using SmI2-Et 3N-H2O: Synthetic utility and mechanism
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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.
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supporting information
p. 1092 - 1095
(2014/03/21)
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- Activation of electrophilicity of stable Y-delocalized carbamate cations in intramolecular aromatic substitution reaction: Evidence for formation of diprotonated carbamates leading to generation of isocyanates
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Although cations with three heteroatoms, such as monoprotonated guanidine and urea, are stabilized by Y-shaped conjugation and such Y-conjugated cations are sufficiently basic to be further protonated (or protosolvated) to dications in strongly acid media, only O-monoprotonated species have been detected in the case of carbamates even in magic acid. We found that the trifluoromethanesulfonic acid-catalyzed cyclization of arylethylcarbamates proceeds to afford dihydroisoquinolones in high yield. In strong acids, methyl carbamates are fully O-monoprotonated, and these monocations do not undergo cyclization even under heating. But, as the acidity of the reaction medium is further increased, the cyclization reaction of methyl phenethylcarbamates starts to proceed as a first-order reaction, with a linear relationship between rate and acidity. The sign and magnitude of the entropy of activation ΔS ? were found to be similar to those of other AAc1 reactions. These results strongly support the idea that further protonation of the O-protonated carbamates is involved in the cyclization, but the concentration of the dications is very low and suggests that the rate-determining step is dissociation of methanol from the diprotonated carbamate to generate protonated isocyanate, which reacts with the aromatic ring. Therefore, O-protonated carbamates are weak bases in sharp contrast to other Y-shaped monocations.
- Kurouchi, Hiroaki,Kawamoto, Kyoko,Sugimoto, Hiromichi,Nakamura, Satoshi,Otani, Yuko,Ohwada, Tomohiko
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p. 9313 - 9328,16
(2012/12/11)
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- Enhanced reduction of C-N multiple bonds using sodium borohydride and an amorphous nickel catalyst
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Amorphous nickel powder (Ni0) was utilised as a catalyst under mild, aqueous, basic conditions for enhancing the sodium borohydride-mediated reduction of C-N multiple bonds such as oximes, imines, hydrazones and nitriles to produce the corresponding amines in good to excellent yields.
- Liu, Shouxin,Yang, Yihua,Zhen, Xiaoli,Li, Junzhang,He, Huimin,Feng, Juan,Whiting, Andrew
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experimental part
p. 663 - 670
(2012/01/15)
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- Structure-activity relationships in the binding of chemically derivatized CD4 to gp120 from human immunodeficiency virus
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The first step in HIV infection is the binding of the envelope glycoprotein gp120 to the host cell receptor CD4. An interfacial "Phe43 cavity" in gp120, adjacent to residue Phe43 of gp120-bound CD4, has been suggested as a potential target for therapeutic intervention. We designed a CD4 mutant (D1D2F43C) for site-specific coupling of compounds for screening against the cavity. Altogether, 81 cysteine-reactive compounds were designed, synthesized, and tested. Eight derivatives exceeded the affinity of native D1D2 for gp120. Structure-activity relationships (SAR) for derivatized CD4 binding to gp120 revealed significant plasticity of the Phe43 cavity and a narrow entrance. The primary contacts for compound recognition inside the cavity were found to be van der Waals interactions, whereas hydrophilic interactions were detected in the entrance. This first SAR on ligand binding to an interior cavity of gp120 may provide a starting point for structure-based assembly of small molecules targeting gp120-CD4 interaction.
- Xie, Hui,Ng, Danny,Savinov, Sergey N.,Dey, Barna,Kwong, Peter D.,Wyatt, Richard,Smith III, Amos B.,Hendrickson, Wayne A.
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p. 4898 - 4908
(2008/03/11)
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- Instantaneous SmI2/H2O/amine mediated reduction of nitroalkanes and α,β-unsaturated nitroalkenes
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A rapid method for efficient reduction of nitroalkanes and α,β-unsaturated nitroalkenes using SmI2/H2O/amine has been developed.
- Ankner, Tobias,Hilmersson, G?ran
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p. 5707 - 5710
(2008/02/10)
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- 2-aminobenzoxazole derivatives and combinatorial libraries thereof
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The present invention relates to novel 2-aminobenzoxazole derivative compounds of the following formula: wherein R1 to R4 and Z have the meanings provided herein. The invention further relates to combinatorial libraries containing two or more such compounds, as well as methods of preparing 2-aminobenzoxazole derivative compounds.
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- 2-aminopyridine derivatives and combinatorial libraries thereof
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The present invention relates to novel 2-aminopyridine derivative compounds of the following formula: wherein R1to R5have the meanings provided herein. The invention further relates to combinatorial libraries containing two or more such compounds, as well as methods of preparing 2-aminopyridine derivative compounds.
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- Design and synthesis of N-nonpolar nucleobase dipeptides: Application of the Ugi reaction for the preparation of dipeptides havingfluoroarylalkyl groups appended to the nitrogen atom
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A single-step one-pot synthesis based on the Ugi four-component condensation of previously unknown dipeptides, 2,3,4 and 5, having afluoroaromatic group appended to the nitrogen atom, is described. The series of dipeptides produced here can be viewed as nonpolar nucleobase dipeptides since the difluorotoluene nucleoside 1 is a well known nonpolar analogue of natural thymidine. A mixture of N-protected amino acids 7, fluorophenethylamines 6, isocyanides 8, and acetone or paraformaldehyde are stirred in methanol in the presence of 3 A molecular sieves to furnish the N-fluoroarylethyl-Aib- or -Gly-containing dipeptides 2 or 3, in moderate yields. The dipeptides 2d and 3b, having a cyclohex-1-enamide moiety, are deprotected readily with 3 M HCl in THF to a3ord the free dipeptides in high yields. The N-fluoroarylmethyl-Aib- or -Gly-containingβ-alanyl dipeptides 4 or 5, designed based on the structure of 2′,5′-linked isoDNA, are also synthesized in a similar fashion to the preparation of 2, in moderate to good yields as both protected and free dipeptides.
- Das, Biplab Kumar,Shibata, Norio,Takeuchi, Yoshio
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p. 197 - 206
(2007/10/03)
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- Process for preparing fluorine-containing phenethylamines and novel fluorine-containing β-iminovinyl-and β-iminoethylbenzenes
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The present invention relates to a process for preparing fluorine-containing phenethylamines which is characterized in that, in a first step, a substituted bromobenzene is reacted with an N-vinylimide in the presence of a palladium catalyst, in a second step, the resulting substituted β-iminovinylbenzene is hydrogenated catalytically and in a third step, the substituted β-iminovinylbenzene obtained in the second step is cleaved. This process also provides access to novel β-iminovinyl- and β-iminoethylbenzenes.
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- Process for the preparation of (8As,12AS,13AS)-decahydroisoquino ((2,1-G) (1,6)-naphthyridin-8-one derivatives
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The invention provides a process for preparing single enantiomers of compounds represented by the formula: STR1 and chiral acid addition salts thereof; wherein: X and Y are independently hydrogen; lower alkyl; lower alkoxy; or halo; or X and Y taken together is methylenedioxy or ethylene-1,2-dioxy; which includes reduction of a compound represented by the formula: STR2 to give a mixture of stereoisomers represented by the formula: STR3 wherein each wavy line independently represents a bond in either the α or β position; followed by dissolving the mixture of stereoisomers and a chiral resolving acid in a suitable solvent and allowing the solution to crystallize, giving a salt of the desired enantiomer.
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