2328-24-7Relevant academic research and scientific papers
Spontaneous oscillatory in vitro chiral conversion of simple carboxylic acids and its possible mechanism
Sajewicz, Mieczyslaw,Matlengiewicz, Marek,Leda, Marcin,Gontarska, Monika,Kronenbach, Dorota,Kowalska, Teresa,Epstein, Irving R.
, p. 1066 - 1073 (2010)
In earlier studies, we have collected experimental evidence (mostly from thin-layer chromatography and polarimetry) on the spontaneous oscillatory in vitro chiral conversion of simple carboxylic acids dissolved in 70% aqueous ethanol. To elucidate this phenomenon, we developed a simple theoretical model of two linked Templators. Recently, we have obtained additional experimental evidence of the spontaneous condensation of chiral carboxylic acids, based on the biuret test (amino acids), high performance liquid chromatography, and 13C NMR spectroscopy (profens and hydroxy acids). We briefly describe our experimental results in the context of the existing literature and outline an improved theoretical model for these phenomena. Our system resembles in some respects the reported oscillatory condensation of organic silanols. Here, the key reaction is the formation of carboxylic acid-derived enols. Finally, we discuss the importance of the oscillatory chiral conversion of simple carboxylic acids for biochemistry, pharmacology, and related life sciences. Copyright
A Novel Enzymatic Decarboxylation Proceeds via a Thiol Ester Intermediate
Kawasaki, Takayasu,Watanabe, Masakatsu,Ohta, Hiromichi
, p. 2017 - 2020 (1995)
It is proposed that arylmalonate decarboxylase (AMDase)-catalyzed decarboxylation proceeds via a thiol ester intermediate.Kinetics and CD spectra indicated that α-bromohenylacetate is a competititve inhibitor.TOF mass data indicated that the inhibitor bound with the enzyme through a thiol ester bond which was formed between a cysteine residue of the enzyme and the carboxyl group of the inhibitor.This result was also supported by reactivation of the enzyme by the addition of 2-mercaptoethanol, which is expected to cleave the enzyme-inhibitor bond via nucleophilic attack on the thiol ester linkage.
Effects of alkali halide salts on hydrocarboxylation of styrene catalyzed by water-soluble palladium phosphine complexes
He, Zhenhong,Hou, Zhenshan,Luo, Yanping,Zhou, Liang,Liu, Yuanfeng,Eli, Wumanjiang
, p. 289 - 297 (2013)
Hydrocarboxylation of styrene catalyzed by water-soluble Pd-TPPTS complexes was investigated. The reaction conditions, including reaction pressure, temperature, time and etc. have a significant influence on the catalytic performance. It was found that the yield of total acids and the selectivity towards 3-phenylpropionic acid were enhanced by adding a suitable amount of alkali metal halide salts. In addition, the reaction mechanism and the role of alkali metal halide salts in the reaction were discussed on the basis of the characterization of 1H NMR and 31P NMR.
Highly Regioselective Iron-Promoted Hydrocarboxylation of Styrene
Brunet, Jean-Jacques,Neibecker, Denis,Srivastava, Radhey S.
, p. 2759 - 2762 (1993)
The reaction of Li with styrene under carbon monoxide (1 atm) in a H2O/i-PrOH/LiOH system promotes a highly regioselective (98percent) hydrocarboxylation to 2-phenylpropionic acid.In contrast, when conducted under argon, the reaction predominantly (90percent) leads to 3-phenylpropionic acid.
Nickel-catalyzed asymmetric allylation of alkyl Grignard reagents, effect of ligands, leaving groups and a kinetic resolution with a hard nucleophile
Nomura, Nobuyoshi,RajanBabu
, p. 1713 - 1716 (1997)
Enantioselective addition of Grignard reagents to methyl 1,3-diphenylallyl ether in the presence of Ni(0)-phosphine catalysts is reported. Kinetic resolution (79% ee) observed in the addition of MeMgBr has important implications for the mechanism and further development of this reaction as a valuable synthetic reaction.
Synthesis of Mn-doped TiO2 by novel route and photocatalytic mineralization/intermediate studies of organic pollutants
Umar, Khalid,Ibrahim, Mohamad Nasir Mohamad,Ahmad, Akil,Rafatullah, Mohd
, p. 2927 - 2945 (2019)
The doping of TiO2 particles with various manganese (Mn) concentrations (0.25–1.0%) were synthesized using simple sol–gel and modified sol–gel technique. The characteristics of synthesized particles were found employing standard analytical techniques such as X-ray diffraction, scanning electron microscopy and UV–Vis spectroscopy. The photocatalytic activity of the synthesized particles was compared by investigating the mineralization of two selected organic pollutants like ketoprofen and chlorothalonil. The photocatalysts which were produced by improved sol–gel technique show the lower value of band gap energy and small size crystallite and, hence, exhibit better photocatalytic activity. The outcomes also designate that the concentration of dopant Mn 0.75% indicated the highest photocatalytic activity than other concentrations of dopant in the mineralization of both the compounds. The mineralization kinetics of both compounds was studied under various situations like reaction pH and catalyst dosage. The mineralization rates were highly affected by all the above parameters. An effort has also been performed to highlight the intermediates produced during the photooxidation of both the compounds using the GC–MS analysis method. Both compounds show the production of several intermediates. A possible pathway for the production of different products has been suggested.
Enantioselective Synthesis of Chiral Carboxylic Acids from Alkynes and Formic Acid by Nickel-Catalyzed Cascade Reactions: Facile Synthesis of Profens
Fu, Kaiyue,Ma, Yu,Sun, Yaxin,Tang, Bo,Yang, Guang,Yang, Peng,Yue, Jieyu,Zhang, Li,Zhou, Jianrong Steve
supporting information, (2021/11/22)
We report a stereoselective conversion of terminal alkynes to α-chiral carboxylic acids using a nickel-catalyzed domino hydrocarboxylation-transfer hydrogenation reaction. A simple nickel/BenzP* catalyst displayed high activity in both steps of regioselective hydrocarboxylation of alkynes and subsequent asymmetric transfer hydrogenation. The reaction was successfully applied in enantioselective preparation of three nonsteroidal anti-inflammatory profens (>90 % ees) and the chiral fragment of AZD2716.
Dynamic Kinetic Resolution of I-Substituted Cyclic β-Ketoesters via Asymmetric Hydrogenation: Constructing Chiral Cyclic β-Hydroxyesters with Three Contiguous Stereocenters
Yang, Dan,Wu, Xiong,Zheng, Xiao-Jie,Xie, Jian-Hua,Zhou, Qi-Lin
supporting information, p. 5153 - 5157 (2021/07/20)
An efficient asymmetric hydrogenation of racemic I-substituted cyclic β-ketoesters via dynamic kinetic resolution to provide chiral cyclic β-hydroxy esters with three contiguous stereocenters is reported. Using a chiral spiro iridium catalyst (R)-5 (Ir-SpiroSAP), a series of racemic I-Aryl/alkyl substituted cyclic β-ketoesters were hydrogenated to the corresponding chiral cyclic β-hydroxy esters in high yields (84-97%) with good to excellent enantioselectivities (69->99% ee) and cis,cis-selectivities (up to >99:1).
Catalytic α-Deracemization of Ketones Enabled by Photoredox Deprotonation and Enantioselective Protonation
Chen, Shuming,Gao, Anthony Z.,Ivlev, Sergei I.,Meggers, Eric,Nie, Xin,Ye, Chen-Xi,Zhang, Chenhao
supporting information, p. 13393 - 13400 (2021/09/03)
This study reports the catalytic deracemization of ketones bearing stereocenters in the α-position in a single reaction via deprotonation, followed by enantioselective protonation. The principle of microscopic reversibility, which has previously rendered this strategy elusive, is overcome by a photoredox deprotonation through single electron transfer and subsequent hydrogen atom transfer (HAT). Specifically, the irradiation of racemic pyridylketones in the presence of a single photocatalyst and a tertiary amine provides nonracemic carbonyl compounds with up to 97% enantiomeric excess. The photocatalyst harvests the visible light, induces the redox process, and is responsible for the asymmetric induction, while the amine serves as a single electron donor, HAT reagent, and proton source. This conceptually simple light-driven strategy of coupling a photoredox deprotonation with a stereocontrolled protonation, in conjunction with an enrichment process, serves as a blueprint for other deracemizations of ubiquitous carbonyl compounds.
Insertion of Diazo Esters into C-F Bonds toward Diastereoselective One-Carbon Elongation of Benzylic Fluorides: Unprecedented BF3Catalysis with C-F Bond Cleavage and Re-formation
Wang, Fei,Nishimoto, Yoshihiro,Yasuda, Makoto
supporting information, p. 20616 - 20621 (2021/11/23)
Selective transformation of C-F bonds remains a significant goal in organic chemistry, but C-F insertion of a one-carbon-atom unit has never been established. Herein we report the BF3-catalyzed formal insertion of diazo esters as one-carbon-atom sources into C-F bonds to accomplish one-carbon elongation of benzylic fluorides. A DFT calculation study revealed that the BF3 catalyst could contribute to both C-F bond cleavage and re-formation. This elongation provided α-fluoro-α,β-diaryl esters with a high level of diastereoselectivity. Various benzylic fluorides and diazo esters were applicable. The synthetic utility of this method was demonstrated by the synthesis of a fluoro analogue of a compound that is used as a transient receptor and potential canonical channel inhibitor.
