- Ferric ion concentration-controlled aerobic photo-oxidation of benzylic C–H bond with high selectivity and conversion
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A Fe(III)-promoted highly selective photo-oxidation of benzylic C–H bond delivering relative carbonyl products is reported. By altering the concentration of ferric salt, methylarenes can be selectively oxidized under UV irradiation to furnish aromatic aldehydes or acids, respectively. By this protocol, the oxidation of ethylarenes provides the corresponding acetophenones. The reaction is inferred to involve divergent pathways in different concentrations of catalyst for the alternative selectivity between aldehydes and aicds. The reusable catalyst, high conversion and selectivity make this oxidation a green and economic protocol for the synthesis of aromatic carbonyl compounds.
- Bu, Hongzhong,Gu, Jiefan,Li, Yufeng,Ma, Hongfei,Wan, Yuting,Wu, Zheng-Guang,Zhang, Weijian,Zhou, Ying'ao,Zhu, Hongjun
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- Scrutinizing ligand exchange reactions in the formation of the precious group metal-organic framework RuII,II-HKUST-1: The impact of diruthenium tetracarboxylate precursor and modulator choice
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The precious group metal (PGM) analogues of the iconic metal-organic framework [Cu3(BTC)2] (HKUST-1; BTC = 1,3,5 benzenetricarboxylate) still represent a synthetic challenge, especially if targeting the univalent and ideally defect-free RuII,IIvariant. Herein we present a systematic study employing the controlled secondary building unit approach (CSA) by using a variety of diruthenium tetracarboxylate complexes [Ru2(RCO2)4] as precursors in the synthesis of univalent Ru-HKUST-1 samples. Carboxylate ligand exchange test reactions suggest the importance of a pKamatch between precursor ligand and BTC linker. For example,l-mandelate substituted precursors resulted in the most “perfect” samples of the investigated series with a fourfold increase in crystalline domain sizes compared to the established acetate route (according to PXRD and HR-TEM), high compositional purity (FT-IR, Raman, TGA and elemental analysis) and feature a so far unprecedentedly high BET surface area of 1789 m2g?1with the expected pore size distribution and total pore volume all similar to the ideal HKUST-1 parent structure.
- Heinz, Werner R.,Staude, Dominik,Mayer, David,Bunzen, Hana,Fischer, Roland A.
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supporting information
p. 5226 - 5235
(2021/04/26)
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- Milled Dry Ice as a C1 Source for the Carboxylation of Aryl Halides
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The use of carbon dioxide as a C1 chemical feedstock remains an active field of research. Here we showcase the use of milled dry ice as a method to promote the availability of CO 2in a reaction solution, permitting practical synthesis of arylcarboxylic acids. Notably, the use of milled dry ice produces marked increases in yields relative to those obtained with gaseous CO 2, as previously reported in the literature.
- O'Brien, Connor J.,Nicewicz, David A.
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supporting information
p. 814 - 816
(2021/03/01)
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- Aqueous Flow Hydroxycarbonylation of Aryl Halides Catalyzed by an Amphiphilic Polymer-Supported Palladium-Diphenylphosphine Catalyst
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An aqueous continuous-flow reaction system is developed for the palladium-catalyzed hydroxycarbonylation of aryl halides. Flow hydroxycarbonylation of aryl halides in aqueous solution proceeds efficiently in a flow reactor containing a palladium-diphenylphosphine complex immobilized on an amphiphilic polystyrene-poly(ethylene glycol) resin to give the corresponding benzoic acids in excellent yields.
- Osako, Takao,Kaiser, Reinhard,Torii, Kaoru,Uozumi, Yasuhiro
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p. 961 - 966
(2019/05/10)
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- An Aerobic Alternative to Oxidative Ozonolysis of Styrenes
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A general, selective and extremely efficient procedure for the aerobic cleavage of aromatic alkenes is presented. TON values in the range 6,000,000-10,000,000 are obtained for this nickel-catalyzed reaction performed in polyethylene glycol 400 under 1 atm of molecular oxygen. Mono-, di-, tri- and tetrasubstituted styrene derivatives are oxidatively cleaved by this reproducible protocol, also suitable for larger scale (1.5 g) reactions. The presence of several functional groups (alkyl, alkoxy, halogen, trifluoromethyl) is tolerated in the substrates. The mechanistic proposal to explain the selective generation of carboxylic acids and ketones from aromatic alkenes involves the participation of the polyol solvent in the presented oxidative process.
- Urgoitia, Garazi,Sanmartin, Raul,Herrero, María Teresa,Domínguez, Esther
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supporting information
p. 1150 - 1156
(2016/04/09)
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- Laccase-Mediator System for Alcohol Oxidation to Carbonyls or Carboxylic Acids: Toward a Sustainable Synthesis of Profens
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By combining two green and efficient catalysts, such as the commercially available enzyme laccase from Trametes versicolor and the stable free radical 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), the oxidation in water of some primary alcohols to the corresponding carboxylic acids or aldehydes and of selected secondary alcohols to ketones can be accomplished. The range of applicability of bio-oxidation is widened by applying the optimized protocol to the oxidation of enantiomerically pure 2-arylpropanols (profenols) into the corresponding 2-arylpropionic acids (profens), in high yields and with complete retention of configuration.
- Galletti, Paola,Pori, Matteo,Funiciello, Federica,Soldati, Roberto,Ballardini, Alberto,Giacomini, Daria
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p. 2684 - 2689
(2016/12/23)
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- Visible light photoredox-catalyzed deoxygenation of alcohols
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Carbon-oxygen single bonds are ubiquitous in natural products whereas efficient methods for their reductive defunctionalization are rare. In this work an environmentally benign protocol for the activation of carbon-oxygen single bonds of alcohols towards a reductive bond cleavage under visible light photocatalysis was developed. Alcohols were activated as 3,5-bis(trifluoromethyl)-substituted benzoates and irradiation with blue light in the presence of [Ir(ppy)2( dtb-bpy)](PF6 ) as visible light photocatalyst and Hünig's base as sacrificial electron donor in an acetonitrile/water mixture generally gave good to excellent yields of the desired defunctionalized compounds. Functional group tolerance is high but the protocol developed is limited to benzylic, α-carbonyl, and α-cyanoalcohols; with other alcohols a slow partial C-F bond reduction in the 3,5-bis(trifluoromethyl)benzoate moiety occurs.
- Rackl, Daniel,Kais, Viktor,Kreitmeier, Peter,Reiser, Oliver
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p. 2157 - 2165
(2015/01/09)
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- Direct carboxylation of simple arenes with CO2 through a rhodium-catalyzed C-H bond activation
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Direct carboxylation of simple arenes under atmospheric pressure of CO2 is achieved through a rhodium-catalyzed C-H bond activation without the assistance of a directing group. Various arenes such as benzene, toluene, xylene, electron-rich or electron-deficient benzene derivatives, and heteroaromatics are directly carboxylated with high TONs. This journal is
- Suga, Takuya,Mizuno, Hajime,Takaya, Jun,Iwasawa, Nobuharu
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supporting information
p. 14360 - 14363
(2015/02/19)
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- Method for estimating SN1 rate constants: Solvolytic reactivity of benzoates
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Nucleofugalities of pentafluorobenzoate (PFB) and 2,4,6-trifluorobenzoate (TFB) leaving groups have been derived from the solvolysis rate constants of X,Y-substituted benzhydryl PFBs and TFBs measured in a series of aqueous solvents, by applying the LFER equation: log k = sf(Ef + Nf). The heterolysis rate constants of dianisylmethyl PFB and TFB, and those determined for 10 more dianisylmethyl benzoates in aqueous ethanol, constitute a set of reference benzoates whose experimental ΔG ? have been correlated with the ΔH? (calculated by PCM quantum-chemical method) of the model epoxy ring formation. Because of the excellent correlation (r = 0.997), the method for calculating the nucleofugalities of substituted benzoate LGs have been established, ultimately providing a method for determination of the SN1 reactivity for any benzoate in a given solvent. Using the ΔG? vs ΔH? correlation, and taking sf based on similarity, the nucleofugality parameters for about 70 benzoates have been determined in 90%, 80%, and 70% aqueous ethanol. The calculated intrinsic barriers for substituted benzoate leaving groups show that substrates producing more stabilized LGs proceed over lower intrinsic barriers. Substituents on the phenyl ring affect the solvolysis rate of benzhydryl benzoates by both field and inductive effects.
- Matic, Mirela,Denegri, Bernard,Kronja, Olga
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supporting information
p. 8986 - 8998,13
(2012/12/12)
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- Protolytic defluorination of trifluoromethyl-substituted arenes
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A series of trifluoromethyl-substituted arenes were studied in their reactions with Bronsted superacids. The products from these reactions suggest the formation of reactive electrophiles, such as carbocations, acylium cations or equivalent electrophilic species. As such, Friedel-Crafts-type reactions occur between these species and arene nucleophiles. NMR studies were done, and the results suggest the formation of an acyl group from the trifluoromethyl groups in the superacid.
- Kethe, Anila,Tracy, Adam F.,Klumpp, Douglas A.
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experimental part
p. 4545 - 4549
(2011/07/29)
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- HIGH-PURITY (FLUOROALKYL)BENZENE DERIVATIVE AND PROCESS FOR PRODUCING THE SAME
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The process for producing a (fluoroalkyl)benzene derivative according to the present invention comprises a step of reducing the total content of group 3 to group 12 transition metals in an alkylbenzene derivative to 500 ppm or less in terms of metal atoms; a step of halogenating the branched alkyl group of the purified alkylbenzene derivative by a photohalogenation to obtain a (haloalkyl)benzene derivative; and a step of subjecting the (haloalkyl)benzene derivative to a halogen-fluorine exchange using HF in an amount of 10 mol or higher per one mole of the (haloalkyl)benzene derivative. The (fluoroalkyl)benzene derivative produced by the process is reduced in the content of impurities such as residual halogens and residual metals, and is useful as intermediates for functional chemical products for use in applications such as medicines and electronic materials.
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- CETP INHIBITORS AND METABOLITES THEREOF
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Compounds resulting from the administration of torcetrapib to a mammal, and the use of such compounds as an indicator or biomarker to the presence or exposure of torcetrapib in the plasma of a mammal including humans. The invention is also directed to cholesteryl ester transfer protein (CET P) inhibitors, pharmaceutical compositions containing such inhibitors and the usi-, of such inhibitors to elevate cert in plasma lipid levels, including high den~;ity lipoprotein (HDL)-cholesterol and t lower certain other plasma lipid levels, such as low density lipoprotein (LDL)-chole terol and triglycerides.
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Page/Page column 31
(2010/02/11)
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- An improved preparation of 3,5-bis(trifluoromethyl)acetophenone and safety considerations in the preparation of 3,5-bis(trifluoromethyl)phenyl Grignard reagent
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An improved and efficient bromination of 3,5-bis(trifluoromethyl)benzene was developed. A safe and reliable preparation of the potentially explosive 3,5-bis(trifluoromethyl)phenyl Grignard and 3-trifluoromethylphenyl Grignard reagents, from the precursor bromides, is described. Reaction System Screening Tool (RSST) and Differential Thermal Analysis (DTA) studies suggest these trifluoromethylphenyl Grignard reagents can detonate on loss of solvent contact or upon moderate heating. When prepared and handled according to the methods described herein, these Grignard reagents can be safely prepared and carried on to advanced intermediates.
- Leazer Jr., Johnnie L.,Cvetovich, Raymond,Tsay, Fuh-Rong,Dolling, Ulf,Vickery, Thomas,Bachert, Donald
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p. 3695 - 3698
(2007/10/03)
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- Crystallization-induced asymmetric transformation: stereospecific synthesis of L-768,673
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A highly convergent, asymmetric synthesis of L-768,673, an Iks Class III antiarrythmic drug candidate, is described. Synthesis of the racemic 1-trifluoroethyl-3-amino-5-phenyl benzodiazepinone was achieved by Ru-catalyzed hydrogenation of the corresponding oxime that was derived from commercially available 1-trifluoroethyl-5-phenyl benzodiazepine in 76 percent overall yield. An efficient one-pot resolution-racemization of (+/-)-amine provided the desired (+)-amine as its mandelate salt in 92 percent yield and 99.4 percent ee. Regioselective ortho-lithiation of 1,3-bis(trifluoromethyl)benzene with n-BuLi in the presence of a catalytic amount of 2,2',6,6'-tetramethylpiperidine afforded its aryl lithium. Subsequent transmetalation and alkylation with allyl bromide produced the corresponding olefin. Ru-catalyzed oxidative cleavage of the terminated double bond of the olefin provided the desired 2,4-bis(trifluoromethyl)phenylacetic acid in 35 percent overall yield. A modified Schotten-Baumman procedure was developed for coupling of (+)-amine and the acid to produce L-768,673 in 92 percent yield without racemization. - Keywords: Asymmetric synthesis; Benzodiazepines; Oximes; Resolution-racemization
- Shi, Yao-Jun,Wells, Kenneth M.,Pye, Philip J.,Choi, Woo-Baeg,Churchill, Hywyn R. O.,et al.
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p. 909 - 918
(2007/10/03)
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- Bis- and oligo(trifluoromethyl)benzenes: Hydrogen/metal exchange rates and gas-phase acidities
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The proton mobilities (kinetic acidities) of bis- and tris(trifluoromethyl)benzene are dictated to a large extent by steric factors; the trifluoromethyl group is a fairly bulky substituent that can seriously impede the approach of the metalating reagent. Most Satisfactory results in terms of yields and selectivities have been achieved with lithium 2,2,6,6-tetramethylpiperidide or with methyllithium in the presence of potassium tert-butoxide, a slim version of the standard superbase. The rates of deprotonation under irreversible conditions do not parallel the thermodynamic (equilibrium) acidities. Substituent effects on the deprotonation energies in the gas phase appear to be additive: each trifluoromethyl group lowers it by 13 kcal mol-1 when located ortho with respect to the carbanion, and by 10 kcal mol-1 when located in a meta or para position.
- Schlosser, Manfred,Mongin,Porwisiak, Jacek,Dmowski, Wojciech,Bueker, Heinz H.,Nibbering, Nico M. M.
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p. 1281 - 1286
(2007/10/03)
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- 1-bromo-3,5-bis(trifhioromethyl)benzene: A versatile starting material for organometallic synthesis
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1-Bromo-3,5-bis(trifluoromethyl)benzene (1) can be selectively prepared by treatment of 1,3-bis(fluorornethyl)benzene with N,N′-dibromo-5,5-dimethylhydantoin in strongly acidic media. A number of synthetically useful reactions via 3,5bis{trifluoromethyl)phenylmagnesium, -lithium, and -copper intermediates were accomplished. VCH Verlagsgesellschaft mbH, , 1996.
- Porwisiak, Jacek,Schlosser, Manfred
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p. 233 - 235
(2007/10/02)
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