- Catalyst-Free and Transition-Metal-Free Approach to 1,2-Diketones via Aerobic Alkyne Oxidation
-
A catalyst-free and transition-metal-free method for the synthesis of 1,2-diketones from aerobic alkyne oxidation was reported. The oxidation of various internal alkynes, especially more challenging aryl-alkyl acetylenes, proceeded smoothly with inexpensive, easily handled, and commercially available potassium persulfate and an ambient air balloon, achieving the corresponding 1,2-diketones with up to 85% yields. Meanwhile, mechanistic studies indicated a radical process, and the two oxygen atoms in the 1,2-diketons were most likely from persulfate salts and molecular oxygen, respectively, rather than water.
- Shen, Duyi,Wang, Hongyan,Zheng, Yanan,Zhu, Xinjing,Gong, Peiwei,Wang, Bin,You, Jinmao,Zhao, Yulei,Chao, Mianran
-
p. 5354 - 5361
(2021/05/05)
-
- Tetraaryl Cyclopentadienones: Experimental and Theoretical Insights into Negative Solvatochromism and Electrochemistry
-
The synthesis of a series of tetraaryl cyclopentadienones comprising different substitution patterns is reported. Their photophysical and electrochemical properties are investigated by UV/Vis spectroscopy and cyclic voltammetry as well as by supporting quantum chemical simulations and reveal a distinct effect of substituents on the redox behavior of the molecules as well as the absorption properties of this class of compounds. While electrochemical data display a shift in reduction potential of up to 200 mV between the differently substituted cyclopentadienones, their photophysical investigations in differently polar solvents suggest a negative solvatochromic effect, although protic solvents induce a bathochromic shift. Crystal structure analyses of some derivatives confirm similarity with related cyclopentadienones while providing insight into intermolecular C–H···O and C–H···π interactions in the solid state.
- Meitinger, Nicolas,Mengele, Alexander K.,Witas, Kamil,Kupfer, Stephan,Rau, Sven,Nauroozi, Djawed
-
p. 6555 - 6562
(2020/10/02)
-
- Two-Photon Absorption Enhancement by the Inclusion of a Tropone Ring in Distorted Nanographene Ribbons
-
A new family of distorted ribbon-shaped nanographenes was designed, synthesized, and their optical and electrochemical properties were evaluated, pointing out an unprecedented correlation between their structural characteristics and the two-photon absorption (TPA) responses and electrochemical band gaps. Three nanographene ribbons have been prepared: a seven-membered-ring-containing nanographene presenting a tropone moiety at the edge, its full-carbon analogue, and a purely hexagonal one. We have found that the TPA cross-sections and the electrochemical band gaps of the seven-membered-ring-containing compounds are higher and lower, respectively, than those of the fully hexagonal polycyclic aromatic hydrocarbon (PAH). Interestingly, the inclusion of additional curvature has a positive effect in terms of non-linear optical properties of those ribbons.
- Campa?a, Araceli G.,Castro-Fernández, Silvia,Cruz, Carlos M.,Cuerva, Juan M.,Jiménez, Vicente G.,Márquez, Irene R.,Ma??as, Ermelinda,Mariz, Inês F. A.,Palomino-Ruiz, Lucía
-
p. 7139 - 7145
(2020/04/17)
-
- Substituent Effect in the Synthesis of α,α-Dibromoketones, 1,2-Dibromalkenes, and 1,2-Diketones from the Reaction of Alkynes and Dibromoisocyanuric Acid
-
Internal alkynes reacted with dibromoisocyanuric acid/H2O to afford α,α-dibromoketone and 1,2-diketone derivatives. Diarylalkynes with activating groups provided 1,2-diketone derivatives as the major products, whereas diarylalkynes with a non-activating group or alkylarylalkynes gave α,α-dibromoketone derivatives as the major products. In addition, diarylalkynes with deactivating groups provided 1,2-dibromoalkenes. The reaction was conducted at room temperature and showed good yields in most cases. Reaction pathways have been proposed on the basis of experimental observations and density functional theory (DFT) calculations. (Figure presented.).
- Cho, Eunjeong,Jayaraman, Aravindan,Lee, Junseong,Ko, Kyoung Chul,Lee, Sunwoo
-
p. 1846 - 1858
(2019/03/07)
-
- Electronic Communication across Porphyrin Hexabenzocoronene Isomers
-
Single-molecule electronic components (SMECs) are envisioned as next-generation building blocks in quantum circuit systems. However, challenges such as the reproducibility of the electrode attachment to the individual molecules hamper their fundamental in
- Martin, Max M.,Lungerich, Dominik,Haines, Philipp,Hampel, Frank,Jux, Norbert
-
supporting information
p. 8932 - 8937
(2019/05/29)
-
- Oxa[7]superhelicene: A π-Extended Helical Chromophore Based on Hexa-peri-hexabenzocoronenes
-
A novel π-extended “superhelicene” based on hexa-peri-hexabenzocoronenes (HBCs) has been synthesized by an efficient four-step synthetic procedure starting from diphenyl ether. Comprehensive structural analysis of the helicene was performed by NMR spectroscopy and mass spectrometry measurements together with X-ray analysis. Physicochemical analysis of the superhelicene and suitable HBC references revealed it had outstanding fluorescent features with quantum yields of over 80 %.
- Reger, David,Haines, Philipp,Heinemann, Frank W.,Guldi, Dirk M.,Jux, Norbert
-
supporting information
p. 5938 - 5942
(2018/04/26)
-
- Chiral Frustrated Lewis Pairs Catalyzed Highly Enantioselective Hydrosilylations of 1,2-Dicarbonyl Compounds
-
A highly enantioselective hydrosilylation of 1,2-dicarbonyl compounds was successfully realized for the first time utilizing the combination of tricyclohexylphosphine and chiral alkenylborane derived in situ from diyne as a frustrated Lewis pair catalyst. A variety of optically active α-hydroxy ketones and esters were obtained in 52-98% yields with 86-99% ee's.
- Ren, Xiaoyu,Du, Haifeng
-
p. 810 - 813
(2016/02/09)
-
- Superbenzene-Porphyrin Conjugates
-
A free-base porphyrin carrying two hexabenzocoronene (HBC) substituents in a trans arrangement and its zinc complex have been prepared. The compounds were characterized extensively and found to form tricationic dimers in the gas phase. X-ray crystallography confirms for the zinc complex a profound π-stacking of the HBC moieties. In contrast, the free-base porphyrin incarcerates n-heptane which essentially prevents π-stacking. Upon excitation of the HBC substituents, efficient energy transfer to the central porphyrin is observed. Super size me! The first porphyrin conjugate with two superbenzene units shows properties induced by the superbenzene and porphyrin moieties, but also behavior that differs distinctly from that of the individual buildung blocks. The molecule is characterized by standard spectroscopic methods and modern mass spectrometry, and the first X-ray structure of such a conjugate is presented.
- Lungerich, Dominik,Hitzenberger, Jakob F.,Marcia, Mario,Hampel, Frank,Drewello, Thomas,Jux, Norbert
-
supporting information
p. 12231 - 12235
(2016/02/23)
-
- Synthesis and spectral characterisation of dicyanopyrazine-related cyanoheterocycles
-
Four dicyanopyrazine-related cyanoheterocycles have been synthesised and characterised; they show different absorption maxima values and molar absorptivity in absorption spectra. HOMO and LUMO energy levels have been obtained by electrochemical measurements and DMol3 calculation and show little difference in HOMO values but big differences in LUMO values. Their UV-Vis absorbance and fluorescence spectra have been investigated in chloroform and toluene and their aggregation decreases as the concentration decreases in toluene.
- Song, Cheol Jun,Jang, Chun Keun,Yao, Wang,Jaung, Jae Yun
-
p. 268 - 272
(2013/07/27)
-
- Nanosized Mn(acac)3 anchored on amino functionalized silica for the selective oxidative synthesis of 2-arylbenzimidazoles, 2-arylbenzothiazoles and aerobic oxidation of benzoins in water
-
Silica functionalized Mn(acac)3 was prepared and employed for the one-pot oxidative synthesis of 2-arylbenzimidazoles, 2-arylbenzothiazoles; and oxidation of benzoins to benzils under air atmosphere using water as the reaction medium. Environmentally friendly procedure, chemoselectivity and excellent yields are main advantages of this procedure. In all the cases, the catalyst was found to be highly active and selective; passes hot filtration test successfully; and could be recycled several times with a slight loss of activity. Graphical Abstract: SiO2-Mn(acac)3 catalyzed synthesis of 2-arylbenzimidazoles, 2-arylbenzothiazoles and oxidation of benzoins in air [Figure not available: see fulltext.]
- Sodhi, Ravinderpal Kour,Paul, Satya
-
experimental part
p. 608 - 615
(2012/01/13)
-
- Reversed-polarity synthesis of diaryl ketones via palladium-catalyzed cross-coupling of acylsilanes
-
Acylsilanes serve as acyl anion equivalents in a palladium-catalyzed cross-coupling reaction with aryl bromides to give unsymmetrical diaryl ketones. Water plays a unique and crucial activating role in these reactions. High-throughput experimentation techniques provided successful reaction conditions initially involving phosphites as ligands. Ultimately, 1,3,5,7-tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane was identified as giving a longer-lived catalyst with higher turnover numbers. Its use, in conjunction with a palladacycle precatalyst, led to optimal reaction rates and yields. Scope and limitations of this novel method are presented along with initial mechanistic insight.
- Schmink, Jason R.,Krska, Shane W.
-
supporting information; experimental part
p. 19574 - 19577
(2012/01/13)
-
- An effective synthesis of N,N-dimethylamides from carboxylic acids and a new route from N,N-dimethylamides to 1,2-diaryl-1,2-diketones
-
Carboxylic acids were heated at 150 °C in DMF in the presence of 1.25 equiv of thionyl chloride to give corresponding N,N-dimethylamides in good yields. Tandem chlorination and amidation reactions occurred in the one-pot procedure. Dicarboxylic acids needed prolonged reaction time to produce bisamides in good yields. Some benzamides were efficiently converted into corresponding 1,2-diaryl-1,2-diketones (benzils) under acyloin condensation conditions in the presence of 4,4′-di-tert-butylbiphenyl (DBB) in THF. Ultrasonic irradiation effectively accelerates the reaction, but it is not critical. However, the presence of DBB is fatal to the reaction. Although a few synthetic methods for benzils from benzoic acids have been reported so far, this method is one of the most convenient and highly reproducible procedures.
- Kumagai, Takashi,Anki, Tomohiro,Ebi, Takahiro,Konishi, Akihito,Matsumoto, Kouzou,Kurata, Hiroyuki,Kubo, Takashi,Katsumoto, Kenta,Kitamura, Chitoshi,Kawase, Takeshi
-
experimental part
p. 8968 - 8973
(2011/01/04)
-
- 5,6-Diphenyl-1,2,4-Triazinic Dimeric Derivatives and the Use Thereof in the Form of Sun-Protective Agents
-
The invention relates to 5,6-diphenyl-1,2,4-triazinic compounds of general formula (I), wherein identical or different R1, R2, R3 and R4 represent a hydrogen, fluoride, chloride or bromine atom, C1 to C12 linear or branched alkyl, C1 A C18 linear or branched hydroxy, alkoxy poly(ethoxy)-alkoxy with a C1 to C4 alkyl fragment and an ethoxy number ranging from 1 to 4, amino or mono or di-alkylamino with a C1 to C4 alkyl fragment group, X is ortho-, meta- or paraphenylene, 4,4′-biphenylene, 2,4- or 2,6- or 3,4- or 3,5-pyridinylene, 2,2′-bipyridinylene, meta- or paraphenylenediamino, ethylenediamine, 2,2′-piperazinylene, diacyl of formula -(R4CO)2-, wherein r represents a phenyl radical, a 3 to 10 carbon, phenanthrene or anthracene atoms alkyl chain except 1,4-bis(5,6-diphenyl-1,2,4-triazin-3-yl)benzene of 2,4-bis(5,6-diphenyl-1,2,4-triazin-3-yl)pyridine and of 2,6-bis(5,6-diphenyl-1,2,4-triazin-3-yl)pyridine, to cosmetic compositions containing said compounds and to the use thereof in the form of sun filters or light-protective agents.
- -
-
Page/Page column 12
(2008/12/04)
-
- Syntheses of hexabenzocoronene derivatives
-
The syntheses of four hexabenzo[bc,ef,hi,kl,no,qr]coronene (HBC) derivatives have been carried out. Double Knoevenagel condensation of the benzil 5 with the ketone 6 gave the 2,3,4,5-tetrakis(4-tert-butylphenyl)cyclopenta-2,4-dien-1-one (7). Diels-Alder a
- Sadhukhan, Subir K.,Viala, Christine,Gourdon, Andre
-
p. 1521 - 1525
(2007/10/03)
-
- Indium-mediated reductive coupling of acyl cyanides: A convenient synthesis of 1,2-diketones
-
The indium-mediated reductive coupling of acyl cyanides afforded the corresponding 1,2-diketones in moderate to good yields under neutral and mild conditions. (C) 2000 Elsevier Science Ltd.
- Baek,Lee,Yoo,Ko,Kim,Kim
-
p. 8097 - 8099
(2007/10/03)
-
- Electrosynthesis of 1,2 diketones by reduction of aromatic esters at freshly metal coated electrodes: A novel coupling reaction
-
The one-step electrosynthesis of 1,2 aryldiketones has been achieved by constant current electrolysis of aromatic esters in an undivided cell fitted with a cadmium coated cathode and a sacrificial magnesium anode. Evidence is given for a role of Mg2+ ions in the pathway of the reaction.
- Heintz, Monique,Devaud, Marguerite,Hebri, Hassan,Dunach, Elisabet,Troupel, Michel
-
p. 2249 - 2252
(2007/10/02)
-
- A novel synthesis of aromatic α-diketones from electron transfer reactions of aromatic acids with either lithium 4,4'-di-t-butylbiphenyl radical anion or lithium metal
-
Some aromatic α-diketones were directly synthesized in high yields from ultrasound-promoted reactions of the corresponding acids with excess lithium in dry THF. Use of a catalytic amount of 4,4'-di-t-butylphenyl (DBB) enhanced the coupling reaction rate.
- Karaman,Fry
-
p. 6267 - 6270
(2007/10/02)
-
- CATALYTIC CARBONYLATION OF DIARYLIODONIUM SALTS PROMOTED BY PALLADIUM-ZINC SYSTEM. A NEW SYNTHESIS OF DIARYL KETONES AND DIARYL-α-DIKETONES
-
Diaryliodonium salts react with carbon monoxide, in the presence of zinc and a catalytic amount of palladium acetate, to give a mixture of the corresponding diaryl ketones and diaryl-α-diketones under mild conditions.
- Uchiyama, Masaharu,Suzuki, Takehiko,Yamazaki, Yasuo
-
p. 1201 - 1202
(2007/10/02)
-