583-59-5Relevant articles and documents
Isomer and enantiomer separation of 2- and 4-alkyl-cyclohexanols by stereoselective complex formation with O,O′-dibenzoyl-(2R,3R)-tartaric acid
Kassai,Balint,Juvancz,Fogassy,Kozma
, p. 1715 - 1719 (2001)
Stereoisomeric mixtures of 2- and 4-alkyl-cyclohexanols form complex with O,O′-dibenzoyl-(2R,3R)-tartaric acid. The diastereoisomer complex formation can be used for isomer and enatiomer separation as it is trans- and enantioselective in the case of 2-alkyl-cyclohexanols and trans-selective in the case of 4-alkyl-cyclohexanols.
Selective Reductions. 38. Reaction of Thexylchloroborane-Methyl Sulfide Complex in Methylene Chloride with Selected Organic Compounds Containing Representative Functional Groups. Comparison of the Reducing Characteristics of Thexylchloroborane, Thexylborane, and Diborane
Brown, Herbert C.,Nazer, Behrooz,Cha, Jim Soon,Sikorski, James A.
, p. 5264 - 5270 (1986)
The approximate rate and stoichiometry of the reaction of excess thexylchloroborane-methyl sulfide complex, ThxBHCL*SMe2, with 56 selected organic compounds containing representative functional groups under standard conditions (methylene chloride, 0 deg C) were determined order to define the characteristics of the reagent for selective reductions.The selectivity of the reagent was also compared to the selectivities of thexylborane and diborane.Alcohols and phenol react with the reagent at a fast rate to evolve an equivalent of hydrogen without any further reduction .Amines and aliphatic thiols do not form any hydrogen, while benzenethiol shows partial hydrogen formation.Aldehydes and ketones are reduced rapidly and quantitatively to give the corresponding alcohols.Unlike thexylborane and diborane, the reagent shows good stereoselectivity toward cyclic ketones.For example, 2-methylcyclohexanone is reduced to the less stable isomer, cis-2-methylcyclohexanol, in a high ratio (99.9percent cis isomer at -78 deg C).Cinnamaldehyde is reduced rapidly to cinnamyl alcohol, and any further reduction of the double bond is very slow under these conditions. p-Benzoquinone reacts only partially with the reagent while anthraquinone is totally unreactive.Carboxylic acids liberate 1 equiv of hydrogen rapidly and are further reduced to the corresponding aldehydes in good yields and purity.Acid chlorides react sluggishly with the reagent to use 2 equiv of hydride, while acetic anhydride utilizes 3 equiv of hydride to yield acetaldehyde and ethanol.On the other hand, cyclic anhydrides, such as succinic anhydride and phthalic anhydride, react very slowly with the reagent.Esters are almost inert toward thexylchloroborane. γ-Butyrolactone and phthalide are only partially reduced under the reaction conditions.Isopropenyl acetate utilizes 3 equiv og hydride to yield the corresponding acetaldehyde and presumably the hydroboration product of propylene.Only a partial reduction of epoxides can be observed.Primary amides like caproamide and benzamide evolve 1 equiv of hydrogen, but further reaction is very slow.Tertiary amides are almost inert under these conditions.Capronitrile reacts with the reagent to use 2 equiv of hydride in less than 24 h, while the reaction between benzonitrile and thexylchloroborane is sluggish.Nitrobenzene and 1-nitropropane do not react with the reagent, while azobenzene reacts only partially.Azoxybenzene consumes 2 equiv of hydride in 48 h.Only a sluggish reaction between thexylchloroborane and cyclohexanone oxime or phenyl isocyanate can be observed.Pyridine does not react, while pyridine N-oxide utilizes 3 equiv of hydride.Of the sulfur compounds tested, only dimethyl sulfoxide is reduced by the reagent to form the corresponding sulfide, while other sulfur compounds, such as disulfide, sulfide, and sulfone, are inert under these conditions.Altough sulfonic acids evolve hydrogen, no further reduction is observed.
Hydrogen-atom and oxygen-atom transfer reactivities of iron(
Banerjee, Sridhar,Haukka, Matti,Hossain, Md. Kamal,Huelsmann, Ricardo Dagnoni,Martendal, Edmar,Munshi, Sandip,Nordlander, Ebbe,Paine, Tapan K.,Peralta, Rosely,Singh, Reena,Sinha, Arup,Valiati, Andrei Felipe,Wendt, Ola F.,Xavier, Fernando,Yiga, Solomon
supporting information, p. 870 - 884 (2022/02/01)
A series of iron(ii) complexes with the general formula [FeII(L2-Qn)(L)]n+ (n = 1, L = F?, Cl?; n = 2, L = NCMe, H2O) have been isolated and characterized. The X-ray crystallographic data reveals that
Synthesis and structural elucidation of (pyridyl)imine Fe(II) complexes and their applications as catalysts in transfer hydrogenation of ketones
Tsaulwayo, Nokwanda,Kumah, Robert T.,Ojwach, Stephen O.
, (2021/01/25)
Reactions of (pyridyl)imine ligands: 2,6-diisopropyl-N-[(pyridine-2-yl)methylene]aniline (L1), 2,6-diisopropyl-N-[(pyridine-2-yl)ethylidene]aniline (L2), 2,6-dimethyl-N-[(pyridine-2-yl)methylene]aniline (L3), 2,6-dimethyl-N-[(pyridine-2-yl)ethylidene]aniline (L4) and N-[(pyridine-2-yl)methylene]aniline (L5) with FeCl2 salt afforded the corresponding paramagnetic Fe(II) complexes [Fe(L1)2Cl][FeCl4] (Fe1), [Fe(L2)2Cl][FeCl4] (Fe2), [Fe(L3)2Cl][FeCl4] (Fe3), [Fe(L4)2Cl][FeCl4], (Fe4), [Fe(L5)2Cl2] (Fe5) in good yields. On the other hand, reactions of L1 with FeCl2 in the presence of NaPF6 afforded complex [Fe(L1)2Cl][PF6] (Fe6) in moderate yields. Molecular structures of complexes Fe1 and Fe2 reveal the formation of cationic species containing two N^N bidentate ligands and one chlorido co-ligand to give five-coordinate geometry with [FeCl4]? as counter-anion. On the other hand, complex Fe5, is an octahedral neutral species containing two bidentate L5 and two chlorido ligands. All the complexes (Fe1–Fe6) formed active catalysts in the transfer hydrogenation of ketones affording average yields of about 85%. The ligand architecture, reaction conditions and nature of substrate influenced the catalytic activities of the complexes. Mercury and subs-stoichiometric poisoning tests pointed to the existence of both Fe(0) nanoparticles and homogeneous Fe(II) species as the active intermediates.
Application of robust ketoreductase from Hansenula polymorpha for the reduction of carbonyl compounds
Petrovi?ová, Tatiana,Gyuranová, Dominika,Pl?, Michal,Myrtollari, Kamela,Smonou, Ioulia,Rebro?, Martin
, (2021/02/05)
Enzyme-catalysed asymmetric reduction of ketones is an attractive tool for the production of chiral building blocks or precursors for the synthesis of bioactive compounds. Expression of robust ketoreductase (KRED) from Hansenula polymorpha was upscaled and applied for the asymmetric reduction of 31 prochiral carbonyl compounds (aliphatic and aromatic ketones, diketones and β-keto esters) to the corresponding optically pure hydroxy compounds. Biotransformations were performed with the purified recombinant KRED together with NADP+ recycling glucose dehydrogenase (GDH, Bacillus megaterium), both overexpressed in Escherichia coli BL21(DE3). Maximum activity of KRED for biotransformation of ethyl-2-methylacetoacetate achieved by the high cell density cultivation was 2499.7 ± 234 U g–1DCW and 8.47 ± 0.40 U·mg–1E, respectively. The KRED from Hansenula polymorpha is a very versatile enzyme with broad substrate specificity and high activity towards carbonyl substrates with various structural features. Among the 36 carbonyl substrates screened in this study, the KRED showed activity with 31, with high enantioselectivity in most cases. With several ketones, the Hansenula polymorpha KRED catalysed preferentially the formation of the (R)-secondary alcohols, which is highly valued.
