- Degradation of fluorescent whitening agents in sunlit natural waters
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Stilbene-type fluorescent whitening agents (FWAs), such as the distyryl biphenyl (DSBP) and the diaminostilbene types (DAS 1 and DAS 2), are commonly used in detergents and papers. They are not readily biodegradable, but due to their ability to absorb part of the terrestrial sunlight, they can be photochemically degraded in natural surface waters. Following a fast preceding photoisomerization, the three compounds are degraded by direct photochemical processes yielding mainly aldehydes and alcohols. Their degradation quantum yields are similar, about 10"SUP -4" . Nevertheless, in samples of a eutrophic Swiss lake water, DSBP is photochemically degraded three times faster (t"SUB 1/2" =87 min) in summer noon terrestrial sunlight at 25 degrees C than DAS 1 and DAS 2 (t"SUB 1/2" =278 and 313 min) because of a higher rate of sunlight absorption by the DSBP isomer mixture. All FWAs are degraded faster if the oxygen concentration is increased. Dissolved natural organic material partly inhibits the degradation of DSBP in the reaction with molecular oxygen. The behavior of these compounds illustrates the influence of a preceding isomer equilibrium on degradation rate coefficients. (Authors)
- Kramer,Canonica,Hoigne,Kaschig
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Read Online
- Mn(OAc) 3Induced C-4 Arylations of Quinazoline 3-Oxides with Arylboronic Acids
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The use of manganese triacetate as an oxidant component in the C-4 arylations of 2-aryl-quinazoline 3-oxides with arylboronic acids is reported. The new protocol was applied to prepare new 2,4-diarylated quinazoline 3-oxides in good to high yields. The me
- Samandram, Rashinikumar,Koruk?u, Meliha ?etin,Co?kun, Necdet
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p. 210 - 216
(2021/09/13)
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- Pd-catalyzed oxidative homocoupling of arylboronic acids in WEPA: A sustainable access to symmetrical biaryls under added base and ligand-free ambient conditions
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Symmetrical and unsymmetrical biaryls comprises a diverse class of biologically eloquent organic compounds. We herein report, a quick and eco-friendly protocol for the synthesis of biaryls by an oxidative (aerobic) homocoupling of arylboronic acids (ABAs) using Pd(OAc)2 in water extract of pomogranate ash (WEPA) as an efficient agro-waste(bio)-derived aqueous (basic) media. The reactions were executed at ambient aerobic conditions in the absence of external base and ligand to result symmetrical biaryls in excellent yields. The use of renewable media with an effective exploitation of waste, short reaction times, excellent yields of products, easy separation of the products, unnecessating the external base, oxidant, ligand or volatile organic solvents and ambient reaction conditions are the vital insights of the present protocol.
- Appa, Rama Moorthy,Lakshmidevi, Jangam,Naidu, Bandameeda Ramesh,Venkateswarlu, Katta
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- Oxidative and Reductive Cross-Coupling Reactions Catalyzed by an Anionic "ligandless" Palladium Complex
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The anionic complex [NBu4][Pd(DMSO)Cl3], which can be synthesized on a gram scale in a single step starting from commercially available starting materials, has been shown to be an active catalyst in the Mizoroki-Heck reaction of aryl halides. We present two new catalytic applications of this complex: the base-free oxidative Heck reaction and the reductive homodimerization of aryl halides. This complex outperformed other palladium salts. In the latter reaction, the catalyst loading could be reduced to 0.01 mol %. The scope of the reactions has been explored, demonstrating the potential of the anionic palladium complex in these catalytic transformations.
- Schroeter, Felix,Lerch, Swantje,Strassner, Thomas
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supporting information
p. 1614 - 1621
(2019/01/04)
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- Palladium-metalated porous organic polymers as recyclable catalysts for chemoselective decarbonylation of aldehydes
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A novel palladium nanoparticle (NP)-metalated porous organic ligand (Pd NPs/POL-xantphos) has been prepared for the chemoselective decarbonylation of aldehydes. This heterogenous catalyst not only has excellent catalytic activity and chemoselectivity, but also holds high activity after 10 runs of reuse. The effective usage of this method is demonstrated through the synthesis of biofuels such as furfuryl alcohol (FFA) via the highly chemoselective decarbonylation of biomass-derived 5-hydroxy-methylfurfural (HMF) with a TON up to 1540. More importantly, 9-fluorenone could be obtained in one step through the decarbonylation of 2-bromobenzaldehyde by using this heterogeneous catalyst.
- Li, Wen-Hao,Li, Cun-Yao,Li, Yan,Tang, Hai-Tao,Wang, Heng-Shan,Pan, Ying-Ming,Ding, Yun-Jie
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supporting information
p. 8446 - 8449
(2018/08/28)
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- Palladium(II) complexes with diaminomaleonitrile-based Schiff-base ligands: Synthesis, characterization and application as Suzuki–Miyaura coupling catalysts
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The characterization of synthesized Schiff base ligands (L1–L5); (where L1?=?N-salicyliden- 2,3-diamino-cis-2-butenedinitrile, L2?=?3- methoxy-N-salicyliden-2,3-diamino-cis-2-butenedinitrile, L3?=?5-bromo-N-salicyliden-2,3-diamino-cis-2-butenedinitrile, L4?=?5-nitro-N-salicyliden-2,3-diamino-cis-2-butenedinitrile, and L5?=?5-methoxy-N-salicyliden-2,3-diamino-cis-2-butenedinitrile) and their palladium complexes [PdL(PPh3)] (L1–L5) were carried out by FT-IR, UV–vis, 1H NMR, 13C NMR and elemental analysis. The coordination geometry of [PdL3(PPh3)] was determined by single crystal X-ray crystallography. In this structure the palladium center was in a partially distorted NNOP square planar coordination environment. The catalytic potential of the synthesized complexes was evaluated in Suzuki–Miyaura cross-coupling reaction by choosing different arylhalides and phenylboronic acid. The results showed that arylhalides with electron withdrawing substituents were more appropriate in this reaction. In all cases, the desired product of cross coupling Suzuki reaction was the major product. It is also worth to mention that the product of homo-coupling reaction was also observed as a minor product. In this regards, a blank reaction with just phenylboronic acid was performed and the results showed the occurrence of the homo-coupling product in a good yield.
- Beigi, Zeinab,Kianfar, Ali Hossein,Mohammadnezhad, Gholamhossein,G?rls, Helmar,Plass, Winfried
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- Exfoliation effect of PEG-type surfactant on Pd supported GO (SE-Pd(nanoparticle)/GO) in cascade synthesis of amides: A comparison with Pd(nanoparticle)/rGO
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In the presence investigation, a cascade method for the synthesis of primary amides is discussed by the catalysis of Pd supported onto graphene oxide (Pd/GO) nanosheets. Also, the effect of different polyethyleneglycol-type (PEG-type) polyethers including PEG-300, P123 and F127 on the catalytic activity of Pd/rGO is studied in the the reaction of aldehyde and hydroxylamine hydrochloride to give benzamide. Addition of PEG-type polyethers played an important role in raising the catalytic power of Pd(nanoparticle)/GO by exfoliation of GO sheets. The present paper introduces Pd(nanoparticle)/GO as first Pd supported GO for the synthesis of primary amides through this method. This catalyst was highly active, efficient, tolerant, and environmentally benign in one-pot conditions with recyclability at least for 8 runs. Also, this study suggests the prevailing catalytic activity of Pd(nanoparticle)/GO rather to Pd(nanoparticle)/rGO in a comparitive experiment.
- Rostamnia, Sadegh,Doustkhah, Esmail,Zeynizadeh, Behzad
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- Water mediated Heck and Ullmann couplings by supported palladium nanoparticles: Importance of surface polarity of the carbon spheres
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Heterogeneous palladium nanoparticle catalysts that are supported on amphiphilic carbon spheres (Pd@CSP) have been utilized for water-mediated Heck coupling reactions of aryl halides with different alkenes under phosphine free as well as aerobic conditions. Furthermore, a variety of Heck coupling reactions using different bases and solvents, including organic polar and non-polar solvents, have been explored. Aryl bromides are also well activated in Heck coupling reactions in organic polar solvent and as well as in water. In addition, Ullmann coupling reactions of aryl iodides have been catalyzed in water with the aid of phase transfer catalysts (PTC) in moderate yields. A plausible mechanism for the catalytic activity of Pd@CSP in the case of the Ullmann reaction is also established. It has been demonstrated that the hydrophobic effects of the catalyst surface play an important role in catalyst activity in water. In addition, the E-factor analysis verified that our present protocol is significantly comparable with other catalytic systems and explains the improved greenness. Moreover, the catalyst described in this process is not only greener, but also retains its significant activity for up to four catalytic cycles for the Heck coupling reactions. The surface polarity of the amphiphilic carbon spheres results in higher activity under these conditions.
- Kamal, Ahmed,Srinivasulu, Vunnam,Seshadri,Markandeya, Nagula,Alarifi,Shankaraiah, Nagula
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p. 2513 - 2522
(2013/02/21)
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- Mild and ligand-free Pd(II)-catalyzed conjugate additions to hindered γ-substituted cyclohexenones
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Ligand-free cationic Pd(II) catalyst with NaNO3 as an additive is a highly active catalytic system for conjugate additions to sterically hindered γ-substituted cyclohexenones. More challenging γγ- and βγ-substrates also react well to produce products with quaternary centers in good dr. The conjugate additions occur in a diastereoselective fashion under mild, practical and air-stable conditions, using readily available commercial reagents.
- Jordan-Hore, James A.,Sanderson, James N.,Lee, Ai-Lan
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supporting information; experimental part
p. 2508 - 2511
(2012/07/03)
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- Sunlight promoted palladium catalysed Mizoroki-Heck, Suzuki-Miyaura and Sonogashira reactions
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The palladium catalysed Mizoroki-Heck, Suzuki-Miyaura and Sonogashira reactions were successfully carried out under irradiation with sunlight. The Heck reaction gives considerable amount of Z product due to photochemical isomerization of initially formed E alkenes. Reaction of methyl 2-iodobenzoate with acrylamide under solar condition furnished 2H-2-benzazepine-1,3-dione rather than the expected derivative of cinnamate while the same reaction with ethyl 2-iodobenzoate gave the desired cinnamide.
- Chaudhary, Anju R.,Bedekar, Ashutosh V.
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p. 6100 - 6103,4
(2020/08/20)
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- [Pd(L)Cl2]-catalyzed selective hydroxylation of arylboronic acids to phenols
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The palladium complex [Pd(L)Cl2] (1) has been prepared by the reaction of Pd(COD)Cl2 (COD = 1,5-cyclooctadiene) with L [N,N′-bis(diphenylphosphanyl)-2-(diphenylphosphanyl)ethanamine]. The ligand L and complex 1 have been characterized by elemental analysis, mass spectrometry and 1H/31P NMR spectroscopy. In the presence of O2, 1 selectively catalyzes the hydroxylation of a variety of arylboronic acids to the corresponding phenol derivatives in solvents with low-dielectric constants at 298 K, although in solvents with high dielectric constants the same reaction leads to the formation of both phenol and the coupled product, i.e. biaryl. The mechanistic aspects of the selective phenol formation from arylboronic acid with 1 have been addressed.
- Chowdhury, Abhishek Dutta,Mobin, Shaikh M.,Mukherjee, Soumen,Bhaduri, Sumit,Lahiri, Goutam Kumar
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experimental part
p. 3232 - 3239
(2011/08/07)
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- Tetraarylphosphonium salts as soluble supports for oxidative catalysts and reagents
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(Figure Presented) Tetraarylphosphonium (TAP)-supported DMSO, TEMPO, and DIB reagents were synthesized and used for the oxidation of alcohols, including Swern oxidation and for the R-acetoxylation of ketones. By taking advantage of the predictable solubility properties of the TAP unit, simple precipitation and filtration of the phosphonium moiety permit complete separation of the desired oxidation products. This paper describes the preparation of these three TAP-supported oxidative reagents and their activity in the aforementioned oxidative transformations. Furthermore, we have demonstrated that these reagents can be recycled directly when used in catalytic processes and following regeneration when used in stoichiometric processes. 2009 American Chemical Society.
- Roy, Marie-Noelle,Poupon, Jean-Christophe,Charette, Andre B.
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supporting information; experimental part
p. 8510 - 8515
(2009/12/28)
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- Soluble gold and palladium complexes heterogenized on MCM-41 are effective and versatile catalysts
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Chiral Schiff base-gold and -palladium complexes were immobilized on ordered mesoporous silica supports (MCM-41), and their catalytic hydrogenation ability is studied and compared with that of their homogeneous counterparts. The high accessibility introduced by the structure of the supports allows the preparation of highly efficient immobilized catalysts with TOFs of up to 6000 h-1 for the hydrogenation of diethyl itaconate. The easily recoverable immobilized catalysts duplicate the activity of their homogeneous analogues, and no deactivation of the catalysts is observed after repeated recycling. Gold(III) homogeneous or heterogenized complexes also catalyze the homocoupling of arylboronic acids or alkynes to afford symmetrical biaryls, whereas the respective gold(I) and palladium(II) complexes catalyze the corresponding cross-coupling reaction. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Gonzalez-Arellano, Camino,Corma, Avelino,Iglesias, Marta,Sanchez, Felix
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scheme or table
p. 1107 - 1115
(2009/02/05)
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- Removal, recovery, and recycling of triarylphosphonium-supported tin reagents for various organic transformations
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Phosphonium-supported tin reagents and catalysts were prepared and were shown to be effective in Stille couplings, radical dehalogenations, radical cyclizations, and carbonyl allylations. Not only could the tin residues be removed from the crude reaction mixture through a phase separation process but also they could be recovered and recycled.
- Poupon, Jean-Christophe,Marcoux, David,Cloarec, Jean-Manuel,Charette, Andre B.
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p. 3591 - 3594
(2008/02/12)
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- Gold (I) and (III) catalyze Suzuki cross-coupling and homocoupling, respectively
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Trinuclear triphenylphosphine 1,2Au(I) complexes with the [N,N,O]-tridentate unsymmetrical Schiff bases (1,2) catalyze the Suzuki cross-coupling reaction to afford nonsymmetrical biaryls in good yields, whereas the 1,2Au(III) complexes give only arylboronic homocoupling.
- Gonzalez-Arellano,Corma,Iglesias,Sanchez
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p. 497 - 501
(2007/10/03)
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- Palladium-catalyzed inter- and intramolecular coupling reactions of aryl and vinyl halides mediated by indium
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(Chemical Equation Presented) Treatment of aryl and vinyl halides with 50 mol % of 100 mesh indium, 2.5 mol % of Pd-C, and 1.5 equiv of LiCl under mild conditions (DMF, 100°C, 1-3 h) could produce coupling products efficiently in good to excellent yields in which the Csp2-Csp2 bond was formed. This reagent worked equally well with both intermolecular and intramolecular coupling reactions, producing a variety of biaryls, 1,3-dienes, and cyclic compounds.
- Phil, Ho Lee,Seomoon, Dong,Lee, Kooyeon
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p. 343 - 345
(2007/10/03)
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- Preparation of aromatic organozinc compounds and composition therefor
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The invention relates to a technique for preparing aromatic organozinc compounds and to a composition therefore. This composition constitutes a reactant that can be used to carry out the synthesis of organozinc compounds, and comprises a cobalt salt, a zinc salt, a polar aprotic solvent and elemental zinc in divided form, the elemental zinc being in solid form, the other elements being in a form dissolved in the solvent. Application to organic synthesis.
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- New chemical synthesis of functionalized arylzinc compounds from aromatic or thienyl bromides under mild conditions using a simple cobalt catalyst and zinc dust
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A new chemical method for the preparation of arylzinc intermediates is described in acetonitrile, on the basis of the activation of aryl bromides by low-valent cobalt species arising from the reduction of cobalt halide by zinc dust. This procedure allows for the synthesis of a variety of functionalized aryl- and thienylzinc species in good to excellent yields. The versatility and the simplicity of that original method represent an alternative to most known procedures.
- Fillon, Hyacinthe,Gosmini, Corinne,Perichon, Jacques
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p. 3867 - 3870
(2007/10/03)
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- N-(4-biphenylmethyl)imidazoles as potential therapeutics for the treatment of prostate cancer: Metabolic robustness due to fluorine substitution?
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3,3′,5,5′- And 2,2′,6,6′-tetrafluoro-substituted 1-[(1,1′-biphenyl]-4-yl)methyl]-1H-imidazoles were synthesized as inhibitors of 17α-hydroxylase-C17,20-lyase (P450 17, CYP 17). P450 17 is the key enzyme of androgen biosynthesis. Its inhibition is a novel
- Leroux, Frederic,Hutschenreuter, Tilman U.,Charriere, Celine,Scopelliti, Rosario,Hartmann, Rolf W.
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p. 2671 - 2686
(2007/10/03)
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- Highly chemoselective heterogeneous Pd-catalyzed biaryl synthesis from haloarenes: Reaction in an oil-in-water microemulsion
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Heterogeneous Pd/C-catalyzed reductive coupling of substituted haloarenes to the respective biaryls is effected with very high chemoselectivity in an oil-in-water microemulsion, using a reducing agent such as formate and a base, NaOH, in the presence of a catalytic amount of tetrabutylammonium bromide (TBAB) at 75°C. Almost 100% biphenyl selectivity is obtained with iodobenzene. High coupling yields are achieved with 4-chlorotoluene and 4-chlorobenzaldehyde as the substrate. The competitive reduction reaction becomes predominant when the water-in-oil microemulsion is used as the solvent medium.
- Mukhopadhyay, Sudip,Yaghmur, Anan,Baidossi, Mubeen,Kundu, Buddhadeb,Sasson, Yoel
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p. 641 - 643
(2013/09/05)
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- Influence of Conformation and Proton-Transfer Dynamics in the Dibenzyl σ-Complex on Regioselectivity in Gattermann-Koch Formylation via Intracomplex Reaction
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The Gattermann-Koch formylations of diphenyl, diphenylmethane, dibenzyl, and 1,3-diphenyl- propane were studied in HF-SbF5, -TaF5, -BF3, -NbF5, and CF3SO3H-SbF5. While usual high para regioselectivity was obtained for diphenyl, diphenylmethane, and 1,3-diphenylpropane, unprecedented ortho regioselectivity was observed for dibenzyl which increased with decreasing the SbF5/dibenzyl molar ratio and with strength of Lewis acids used in HF. A sandwich-like complex for monoprotonated dibenzyl resulting in ortho regioselectivity via the intracomplex reaction was suggested; therefore, the conformations of protonated diphenylmethane, dibenzyl, and 1,3- diphenylpropane and their proton-transfer dynamics were probed by semiempirical calculation (PM3). The calculation predicted that ortho monoprotonation was slightly preferable for dibenzyl, and remarkable preference of dibenzyl over other aromatic compounds was observed in ortho- ortho intramolecular inter-ring proton transfer via a fan-shaped complex rather than a sandwich- like complex. The experimental and theoretical data for dibenzyl are compatible with the intracomplex reaction, whereby CO is protonated by the ortho σ-complex undergoing rapid inter- ring proton transfer to generate formyl cation in the vicinity of the ortho position leading to ortho regioselectivity.
- Tanaka, Mutsuo,Fujiwara, Masahiro,Xu, Qiang,Ando, Hisanori,Raeker, Todd J.
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p. 4408 - 4412
(2007/10/03)
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- Activation of Reducing Agents. Sodium Hydride Containing Complex Reducing Agents. 32. NiCRAL's as Very Efficient Agents in Promoting Cross-Coupling of Aryl Halides
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Nickel-containing complex reducing agents NiCRA-bpy are shown to be the first nickel reagents able to efficiently perform cross-coupling of aryl halides.The presence of KI in the reaction medium generally improves the procedure.The mechanism and influence of the structures of the substrates are discused.
- Lourak, Mouhsine,Vanderesse, Regis,Fort, Yves,Caubere, Paul
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p. 4844 - 4848
(2007/10/02)
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