- Decarboxylative Cross-Coupling of Acyl Fluorides with Potassium Perfluorobenzoates
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We report the transition metal-free decarboxylative cross-coupling reactions of acyl fluorides with potassium perfluorobenzoates. Compared with traditional transition metal-catalyzed cross-couplings, this protocol presents an extremely environmentally ben
- Fu, Liyan,Chen, Qiang,Nishihara, Yasushi
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supporting information
p. 6388 - 6393
(2020/08/24)
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- Chiral octahedral complexes of Co(iii) as catalysts for asymmetric epoxidation of chalcones under phase transfer conditions
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Stereochemically inert and positively charged chiral complexes of Co(iii) were shown to catalyze the asymmetric epoxidation of chalcones with H2O2 under phase transfer conditions. The reaction products had enantiomeric purities of up to 55%. It was also shown that complex 1a I- catalyzed the coupling reaction of a resulting epoxide with CO2 (conversion 72%).
- Larionov, Vladimir A.,Markelova, Elina P.,Smol'yakov, Alexander F.,Savel'yeva, Tat'yana F.,Maleev, Victor I.,Belokon, Yuri N.
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p. 72764 - 72771
(2015/09/15)
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- Dehydrogenation of perfluoroalkyl ketones by using a recyclable oxoammonium salt
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A novel dehydrogenation reaction of perfluoroalkyl ketones by the oxoammonium salt 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (4-NHAc-TEMPO+BF4-, Bobbitt's salt, 1) is described. The reaction proceeds under mildly basic conditions and appears to be unique to perfluoroalkyl ketones. A proposed mechanism for this unusual transformation is given. The byproduct of the reaction, 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy (1a), can easily be recovered and used to regenerate the oxoammonium salt. The dehydrogenation of perfluoroalkyl ketones by using an oxoammonium salt is reported. The reaction proceeds under mildly basic conditions and affords α,β-unsaturated products in fair to excellent yields. The reaction likely proceeds through a two-step sequence. The spent oxidant can easily be recovered and used to regenerate the oxoammonium salt. Copyright
- Hamlin, Trevor A.,Kelly, Christopher B.,Leadbeater, Nicholas E.
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supporting information
p. 3658 - 3661
(2013/07/19)
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- Reactions of polyfluorinated chalcones with o-aminobenzenethiol and its zinc salt
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The reactions of polyfluorochalcones with o-aminothiophenol in methanol in the presence of HCl afford polyfluorine-substituted 2,3-dihydrobenzo[b][1,5] thiazepines. In some cases, the cyclization is accompanied by fluorine substitution in the perfluorophenyl ring. Probably, the formation of thiazepines proceeds through the Michael thia-adduct. The Zn salt of o-aminothiophenol reacts with chalcones in DMF exclusively via fluorine substitution.
- Shmuilovich,Orlova,Beregovaya,Shelkovnikov
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experimental part
p. 361 - 367
(2011/11/05)
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- Graphite oxide as an auto-tandem oxidation-hydration-aldol coupling catalyst
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Graphite oxide (GO) was found to function as an auto-tandem oxidation-hydration-aldol coupling catalyst for the formation of chalcones in a single reaction vessel. Various alkynes or alcohols were hydrated or oxidized in situ to their corresponding methyl ketones or aldehydes, respectively, which underwent a subsequent Claisen-Schmidt condensation. Each of the aforementioned reactions proceeded in the absence of metals (confirmed by inductively coupled plasma mass spectrometry, ICP-MS) and afforded a range of chalcone products in good to excellent yields from commercially available starting materials.
- Jia, Hong-Peng,Dreyer, Daniel R.,Bielawski, Christopher W.
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supporting information; experimental part
p. 528 - 532
(2011/04/24)
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- Predicting the photoinduced electron transfer thermodynamics in polyfluorinated 1,3,5-triarylpyrazolines based on multiple linear free energy relationships
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The photophysical properties of 1,3,5-triarylpyrazolines are strongly influenced by the nature and position of substituents attached to the aryl-rings, rendering this fluorophore platform well suited for the design of fluorescent probes utilizing a photoinduced electron transfer (PET) switching mechanism. To explore the tunability of two key parameters that govern the PET thermodynamics, the excited state energy ΔE00 and the acceptor potential E(A/A-), a library of polyfluoro-substituted 1,3-diaryl-5-phenyl-pyrazolines was synthesized and characterized. The observed trends for the PET parameters were effectively captured through multiple Hammett linear free energy relationships (LFER) using a set of independent substituent constants for each of the two aryl rings. Given the lack of experimental Hammett constants for polyfluoro-substituted aromatics, theoretically derived constants based on the electrostatic potential at the nucleus (EPN) of carbon atoms were employed as quantum chemical descriptors. The performance of the LFER was evaluated with a set of compounds that were not included in the training set, yielding a mean unsigned error of 0.05 eV for the prediction of the combined PET parameters. The outlined LFER approach should be well suited for designing and optimizing the performance of cation-responsive 1,3,5-triarylpyrazolines.
- Verma, Manjusha,Chaudhry, Aneese F.,Fahrni, Christoph J.
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experimental part
p. 1536 - 1546
(2009/06/28)
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- Synthesis and biological evaluation of aromatic enones related to curcumin
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Curcumin, a natural product isolated from the spice turmeric, has been shown to exhibit a wide range of pharmacological activities including certain anti-cancer properties. It has been specifically shown to be an effective inhibitor of angiogenesis both in vitro and in vivo. Using curcumin as a lead compound for anti-angiogenic analog design, a series of structurally related compounds utilizing a substituted chalcone backbone have been synthesized and tested via an established SVR cell proliferation assay. The results have yielded a wide range of compounds that equal or exceed curcumin's ability to inhibit endothelial cell growth in vitro. Due to both their commercial availability and their fairly straightforward synthetic preparation, these low molecular weight compounds are attractive leads for developing future angiogenic inhibitors.
- Robinson, Thomas Philip,Hubbard IV, Richard B.,Ehlers, Tedman J.,Arbiser, Jack L.,Goldsmith, David J.,Bowen, J. Phillip
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p. 4007 - 4013
(2007/10/03)
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- Silver compounds in synthetic chemistry. Part 2: A convenient synthesis of 2,3,4,5,6-pentafluorophenones, C6F5COR, from pentafluorophenylsilver, AgC6F5, and the corresponding acid chlorides, RCOCl
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2,3,4,5,6-Pentafluorophenones are formed selectively from the reactions of pentafluorophenylsilver and carboxylic acid chlorides in moderate to excellent yields.
- Kremlev, Mikhail M.,Tyrra, Wieland,Naumann, Dieter,Yagupolskii, Yurii L.
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p. 1327 - 1331
(2007/10/03)
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- Aryl palladium carbene complexes and carbene-aryl coupling reactions
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Transmetalation of an aminocarbene moiety from [W(CO) 5{C(NEt2)R}] to palladium leads to isolable monoaminocarbene palladium aryl complexes [{Pd(μ-Br)Pf[C(NEt 2)R]}2] (R = Me, Ph; Pf = C6F5). When [W(CO)5{C(OMe)R}] is used, the corresponding palladium carbenes cannot be isolated since these putative, more electrophilic carbenes undergo a fast migratory insertion process to give alkyl palladium complexes. These complexes could be stabilized in the η3-allylic form for R = 2-phenylethenyl or in the less stable η3-benzylic fashion for R = Ph. Hydrolysis products and a pentafluorophenylvinylic methyl ether (when R = Me) were also observed. The monoaminocarbenes slowly decompose through carbene-aryl coupling to produce the corresponding iminium salts and, depending on the reaction conditions, the corresponding hydrolysis products. The electrophilicity of the carbene carbon, which is mainly determined by the nature of the heteroatom group, controls the ease of evolution by carbene-aryl coupling. Accordingly, no carbene-aryl coupling was observed for a diaminocarbene palladium aryl complex.
- Albeniz, Ana C.,Espinet, Pablo,Manrique, Raul,Perez-Mateo, Alberto
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p. 1565 - 1573
(2007/10/03)
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- Syntheses and UV-visible spectroscopic properties of new 'fluorophilic' fluorine-and perfluoroalkyl-substituted solvatochromic pyridinium N-phenolate betaine dyes
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Syntheses and negative solvatochromism of three new 'fluorophilic' fluorine- and perfluoroalkyl- substituted pyridinium N-phenolate betaine dyes 3-5 are described in order to obtain new zwitterionic dyes which should be less basic and better soluble in perfluorinated solvents than the solvatochromic standard betaine dyes 1 and 2, used to establish an empirical scale of solvent polarity, called the ET (30) or ETN scale. The new betaine dyes 3-5 were designed to allow an extension of the existing ET (30) scale to new solvents. Copyright
- Reichardt, Christian,Eschner, Michael,Schaefer, Gerhard
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p. 737 - 751
(2007/10/03)
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