100319-40-2Relevant articles and documents
From p-Xylene to Ibuprofen in Flow: Three-Step Synthesis by a Unified Sequence of Chemoselective C?H Metalations
Lee, Hyune-Jea,Kim, Heejin,Kim, Dong-Pyo
, p. 11641 - 11645 (2019)
Ibuprofen was prepared from an inactive and inexpensive p-xylene by three-step flow functionalizations through chemoselective metalations of benzyl positions in sequence using an in situ generated LICKOR-type superbase. The flow approach in the microreactor facilitated the comprehensive exploration of over 100 conditions in the first-step reaction by varying concentrations, temperatures, solvents, and equivalents of reagents, enabling optimal conditions to be found with 95 % yield by significantly suppressing the formation of byproducts, followed by the second C?H metalation step in 95 % yield. Moreover, gram-scale synthesis of ibuprofen in the final step was achieved by biphasic flow reaction of solution-phase intermediate with CO2, isolating 2.3 g for 10 min of operation time.
Investigations in sono-enzymatic degradation of ibuprofen
Chakma, Sankar,Moholkar, Vijayanand S.
, p. 485 - 494 (2016)
The drug ibuprofen (IBP) appears frequently in the wastewater discharge from pharmaceutical industries. This paper reports studies in degradation of IBP employing hybrid technique of sono-enzymatic treatment. This paper also establishes synergy between individual mechanisms of enzyme and sonolysis for IBP degradation by identification of degradation intermediates, and Arrhenius & thermodynamic analysis of the experimental data. Positive synergy between sonolysis and enzyme treatment is attributed to formation of hydrophilic intermediates during degradation. These intermediates form due to hydroxylation and oxidation reactions induced by radicals formed during transient cavitation. Activation energy and enthalpy change in sono-enzymatic treatment are lower as compared to enzyme treatment, while frequency factor and entropy change are higher as compared to sonolysis. Degradation of IBP in sono-enzymatic treatment is revealed to be comparable with other hybrid techniques like photo-Fenton, sono-photocatalysis, and sono-Fenton.
Regiocontrolled Photooxygenation of Ibuprofen by Pyrimidopteridinetetrone- and Anthraquinone-Oxygen Systems
Sako, Magoichi,Oyabu, Iwao,Hirota, Kosaku,Maki, Yoshifumi
, p. 601 - 602 (1991)
Ibuprofen 4 underwent regiocontrolled photooxygenation on the propionic acid and isobutyl moieties in the presence of pyrimidopteridinetetrone 1- and anthraquinone 3- oxygen systems.
Synthesis of Pt compounds containing chiral (2S,4S)-pentane-2,4-diyl-bis(5H-dibenzo[b]phosphindole) as ligand and their use in asymmetric hydroformylation of styrene derivatives
Toth, Imre,Elsevier, Cornelis J.,De Vries, Johannes G.,Bakos, Jozsef,Smeets, Wilberth J. J.,Spek, Anthony L.
, p. 15 - 25 (1997)
Unlike bis(diphenyl)phosphine derivatives in general, (2S,4S)-pentane-2,4-diyl-bis(5H-dibenzo[b]phosphindole), S,S-BDBPP, gives a trans oligomeric compound [PtCl2(S,S-BDBPP)]n, 1, in reaction with dichloro-Pt precursors such as PtCl2(PhCN)2, PtCl2(CH3CN)2 and PtCl2(COD) at room temperature. Compound 1, which could be readily isolated, slowly rearranges in solutions at room temperature to the expected cis-monomer PtCl2(S,S-BDBPP), 3. Heating or the presence of PtCl2(COD) accelerates the transformation of compound 1 to 3. SnCl2 adducts of both compounds, trans-[PtCl(SnCl3)(S,S-BDBPP)]n, 2, and cis-PtCl(SnCl3)(S,S-BDBPP), 4, as well as the known cis-PtCl(SnCl3)(S,S-BDPP), 5, (S,S-BDPP = (2S,4S)-2,4-bis(diphenylphosphino)pentane) have been tested as catalysts in the asymmetric hydroformylation of p-isobutylstyrene. The phenyl analog 5 provides up to 75% e.e. but moderate yields to chiral 2-(4-isobutylphenyl)-2-propanal. Compared to this, the regioselectivity to the branched aldehyde is remarkably increased; however, the enantioselectivity is drastically decreased by the use of both dibenzophosphole derivatives 2 and 4. The similarities in the selectivities provided by 2 and 4 indicate that the trans oligomer 2 transforms to the cis-monomer 4 during the catalytic process. X-ray crystal structure determination of compound 3 shows a half-chair conformation for the chelate ring with a symmetric arrangement of dibenzophosphole groups. Besides a preference for the latter achiral conformation, the planar structure of the dibenzophosphole groups can also be considered as reason for the moderate enantioselectivities provided by 4.
Photocatalytic degradation of Rhodamine B and Ibuprofen with upconversion luminescence in Ag-BaMoO4: Er3+/Yb3+/K+ microcrystals
Ray, Schindra Kumar,Kshetri, Yuwaraj K.,Dhakal, Dipesh,Regmi, Chhabilal,Lee, Soo Wohn
, p. 36 - 48 (2017)
Silver dispersed BaMoO4 octahedron microcrystals doped with Er3+, Yb3+, and K+ were synthesized by microwave hydrothermal process. The photocatalytic activity of different samples toward the degradation of Rhodamine B (Rh B) dye and Ibuprofen (IBP) drug were carried in solar light and visible light irradiation, respectively. The sample, Ag-BaMoO4: Er3+/Yb3+, degraded the Rh B within 90?min about 99.60%, which is nearly 30 times as compared to the host material BaMoO4. Similarly, Ag-BaMoO4: Er3+/Yb3+, degraded the IBP within 90?min about 41.49%, which is nearly 31 times as compared to the host in visible light. IBP photodegradation intermediates were identified by high-resolution quadrupole-time of flight-electrospray ionization-mass spectrometry (HR-QTOF ESI/MS) in negative ion mode and detailed degradation pathway mechanism was proposed. Under 980?nm excitation, two strong green emission peaks (526?nm and 555?nm) and a less intense red emission peak (661?nm) were observed, which are assigned to the 2H11/2?→?4I15/2, 4S3/2?→?4I15/2, and 4F9/2?→?4I15/2 transitions of the Er3+ ions, respectively. Two photons upconversion process for green emission was observed. The upconversion luminescence intensity was increased by two-fold in magnitude by the addition of K+ ion in Er3+/Yb3+ doped BaMoO4. Moreover, silver particles were found to favor the photocatalytic activity while K+ ions significantly enhanced upconversion. The photocatalytic as well as upconversion mechanism was explained. The combination of efficient photocatalytic activity and upconversion emission of the Ag-BaMoO4: Er3+/Yb3+/K+ make the material suitable for the multifunctional application.
Photocarboxylation of Benzylic C-H Bonds
Meng, Qing-Yuan,Schirmer, Tobias E.,Berger, Anna Lucia,Donabauer, Karsten,K?nig, Burkhard
, p. 11393 - 11397 (2019)
The carboxylation of sp3-hybridized C-H bonds with CO2 is a challenging transformation. Herein, we report a visible-light-mediated carboxylation of benzylic C-H bonds with CO2 into 2-arylpropionic acids under metal-free conditions. Photo-oxidized triisopropylsilanethiol was used as the hydrogen atom transfer catalyst to afford a benzylic radical that accepts an electron from the reduced form of 2,3,4,6-tetra(9H-carbazol-9-yl)-5-(1-phenylethyl)benzonitrile generated in situ. The resulting benzylic carbanion reacts with CO2 to generate the corresponding carboxylic acid after protonation. The reaction proceeded without the addition of any sacrificial electron donor, electron acceptor or stoichiometric additives. Moderate to good yields of the desired products were obtained in a broad substrate scope. Several drugs were successfully synthesized using the novel strategy.
Tuning the support adsorption properties of Pd/SiO2 by silylation to improve the selective hydrogenation of aromatic ketones
Quintanilla,Bakker,Kreutzer,Moulijn,Kapteijn
, p. 55 - 63 (2008)
Silylation of Pd/SiO2 catalysts increases the selectivity toward alcohols in the reduction of aromatic ketones. This work demonstrates that the selectivity is directly related to the adsorption strength of the alcohol on the surface of the support relative to the adsorption strength of the ketone. This observation can be explained by interaction of the support coverage with the metal coverage. Silylation yields a more hydrophobic support, on which the aromatic alcohol adsorbs more weakly relative to the ketone, in turn decreasing the amount of the alcohol adsorbed on the metal and thus suppressing the consecutive reduction of the alcohol. Silylation was carried out by using di-alkyl (dichlorodimethylsilane) and tri-alkyl (hexamethyldisilazane and hexamethyldisilane) silylating agents. Hexamethyldisilazane provided to be the most effective agent in terms of incorporation of methyl groups, catalyst hydrophobicity, and stability. Selective hydrogenation of 4-isobutyl acetophenone (4-IBAP) to 4-isobutylphenyl ethanol (4-IBPE) revealed that not only was the fresh hexamethyldisilazane-silylated Pd/SiO2 catalyst more selective than the untreated catalyst, but also the silylated catalyst was much more selective after a deactivation-regeneration cycle than the untreated Pd/SiO2 catalyst. The change in selectivity can be explained by a change in the relative adsorption strength of 4-IBPE over 4-IBAP on silylation.
Heterogeneous Cu-catalysts for the reductive deoxygenation of aromatic ketones without additives
Zaccheria, Federica,Ravasio, Nicoletta,Ercoli, Mauro,Allegrini, Pietro
, p. 7743 - 7745 (2005)
Carbonyl groups conjugated with aromatic systems can be selectively converted into methylene ones under extremely mild conditions and without the need of any acidic additive over a heterogeneous Cu/SiO2 catalyst.
Improving Catalytic Hydrogenation Performance of Pd Nanoparticles by Electronic Modulation Using Phosphine Ligands
Guo, Miao,Li, He,Ren, Yiqi,Ren, Xiaomin,Yang, Qihua,Li, Can
, p. 6476 - 6485 (2018)
Tuning the activity and selectivity of metal nanoparticles (NPs) is a long-term pursuit in the field of catalysis. Herein, we report successfully improving both the activity and chemoselectivity of Pd NPs (1.1 nm) with triphenylphosphine (PPh3) cross-linked in the nanopore of FDU-12. The electron-donating effect of PPh3 increases the surface electronic density of Pd NPs and weakens the Pd-H bond, as evidenced by the results of XPS, in situ FT-IR adsorption of CO, and H2-D2 exchange reactions. Consequently, Pd NPs modified with PPh3 obtain >99% selectivity to 1-phenylethanol in acetophenone hydrogenation and 94% selectivity to styrene in phenylacetylene hydrogenation. Furthermore, the activity of Pd NPs is enhanced and suppressed by PPh3, respectively, in the hydrogenation of electrophilic nitro compounds and nucleophilic carbonyl substrates. Our primary results shed some light on judiciously choosing organic ligands for modifying the catalytic performance of metal NPs toward specific chemical transformations.
Catalytic Intermolecular C(sp3)-H Amination: Selective Functionalization of Tertiary C-H Bonds vs Activated Benzylic C-H Bonds
Brunard, Erwan,Boquet, Vincent,Van Elslande, Elsa,Saget, Tanguy,Dauban, Philippe
, p. 6407 - 6412 (2021/05/29)
A catalytic intermolecular amination of nonactivated tertiary C(sp3)-H bonds (BDE of 96 kcal·mol-1) is reported for substrates displaying an activated benzylic site (BDE of 85 kcal·mol-1). The tertiary C(sp3)-H bond is selectively functionalized to afford α,α,α-Trisubstituted amides in high yields. This unusual site-selectivity results from the synergistic combination of Rh2(S-Tfpttl)4, a rhodium(II) complex with a well-defined catalytic pocket, with tert-butylphenol sulfamate (TBPhsNH2), which leads to a discriminating rhodium-bound nitrene species under mild oxidative conditions. This catalytic system is very robust, and the reaction was performed on a 50 mmol scale with only 0.01 mol % of catalyst. The TBPhs group can be removed under mild conditions to afford the corresponding NH-free amines.
