- Ruthenium-Catalyzed Alkylation of Cyclopropanols with Sulfoxonium Ylides via C-C Bond Cleavage: Formation of Diverse 1,5-Diketones
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A novel ruthenium-catalyzed alkylation of cyclopropanols with sulfoxonium ylides has been developed that affords diverse 1,5-diketones with good efficiency and broad substrate scope. To illustrate the synthetic applications of the obtained 1,5-diketones, aldol and cyclization reactions have been investigated. Preliminary mechanistic studies suggest that this process involves a sequential C C activation and carbene migratory insertion.
- Huang, Xin,Li, Jianglian,He, Hua,Yan, Kaichuan,Lai, Ruizhi,Luo, Yi,Guan, Mei,Wu, Yong
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p. 779 - 787
(2021/10/29)
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- Iron-Catalyzed Ring-Opening Reactions of Cyclopropanols with Alkenes and TBHP: Synthesis of 5-Oxo Peroxides
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The ring opening of cyclopropanols is rarely used in multicomponent reactions. Herein we report the three-component reaction of cyclopropanols with alkenes and tert-butyl hydroperoxide (TBHP) catalyzed by an iron catalyst. This protocol enables the incorporation of both the β-carbonyl fragment and a peroxy unit across the C=C double bond regioselectively, thus allowing an efficient, facile access to 5-oxo peroxides. Modification of the biologically active molecules and various downstream derivatizations of the peroxides are also demonstrated.
- Lou, Chenhao,Wang, Xin,Lv, Leiyang,Li, Zhiping
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p. 7608 - 7612
(2021/10/02)
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- Ruthenium-catalyzed room-temperature coupling of α-keto sulfoxonium ylides and cyclopropanols for δ-diketone synthesis
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Previous transition metal-catalyzed synthesis processes of δ-diketones are plagued by the high cost of the rhodium catalyst and harsh reaction conditions. Herein a low-cost, room temperature ruthenium catalytic method is developed based on the coupling of α-keto sulfoxonium ylides with cyclopropanols. The mild protocol features a broad substrate scope (47 examples) and a high product yield (up to 99%). Mechanistic studies argue against a radical pathway and support a cyclopropanol ring opening, sulfoxonium ylide-derived carbenoid formation, migratory insertion C-C bond formation pathway.
- Fan, Shuaixin,Fang, Lili,Li, Tielei,Wu, Weiping,Zhu, Jin
-
supporting information
p. 7386 - 7389
(2021/08/03)
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- Palladium mediated one-pot synthesis of 3-aryl-cyclohexenones and 1,5-diketones from allyl alcohols and aryl ketones
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One-pot synthesis of Robinson annulated 3-aryl-cyclohexenones from allyl alcohols and ketones using palladium is reported. Long chain aliphatic or aryl substitutions at the C1 position of allyl alcohol result in the formation of 1,5-diketone products. This simple one-pot method avoids the use of highly electrophilic vinyl ketones.
- Samser, Shaikh,Biswal, Priyabrata,Meher, Sushanta Kumar,Venkatasubbaiah, Krishnan
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p. 1386 - 1394
(2021/02/27)
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- Ruthenium-catalyzed alkylation reaction of cyclopropanol and sulfur ylide for synthesis of 1, 5-diketone compounds
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The invention relates to a ruthenium-catalyzed alkylation reaction of cyclopropanol and sulfur ylide, and a series of 1, 5-diketone compounds can be synthesized by the method. According to the method,cyclopropanol is catalyzed by ruthenium to generate beta-carbon elimination ring opening, and safe, stable and easy-to-prepare sulfur ylide is used as a carbene precursor, so that the method has goodapplicability in the field of construction of 1, 5-diketone.
- -
-
Paragraph 0016; 0017
(2020/12/15)
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- Copper-Catalyzed Oxidative Fragmentation of Alkynes with NFSI Provides Aryl Ketones
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A copper-catalyzed oxidative cleavage reaction of alkynes using NFSI and TBHP was described. Various terminal and internal alkyne substrates were employed to render quick access to aryl ketone products in moderate to good yields. NFSI not only functioned as N-centered radical precursors but also engaged in the aryl group migration. Mechanistic studies also suggested the important role of water in the title reactions.
- Chen, Hanfei,Cheng, Hao,Huang, Yifan,Jin, Chaochao,Song, Weihan,Tan, Chen,Tan, Jiajing,Tang, Lin,Yang, Fang,Zhang, Shuaifei
-
supporting information
(2020/11/03)
-
- Light and oxygen-enabled sodium trifluoromethanesulfinate-mediated selective oxidation of C-H bonds
-
Visible light-induced organic reactions are important chemical transformations in organic chemistry, and their efficiency highly depends on suitable photocatalysts. However, the commonly used photocatalysts are precious transition-metal complexes and elaborate organic dyes, which hamper large-scale production due to high cost. Here, for the first time, we report a novel strategy: light and oxygen-enabled sodium trifluoromethanesulfinate-mediated selective oxidation of C-H bonds, allowing high-value-added aromatic ketones and carboxylic acids to be easily prepared in high-to-excellent yields using readily available alkyl arenes, methyl arenes and aldehydes as materials. The mechanistic investigations showed that the treatment of inexpensive and readily available sodium trifluoromethanesulfinate with oxygen under irradiation of light could in situ form a pentacoordinate sulfide intermediate as an efficient photosensitizer. The method represents a highly efficient, economical and environmentally friendly strategy, and the light and oxygen-enabled sodium trifluoromethanesulfinate photocatalytic system represents a breakthrough in photochemistry. This journal is
- Fu, Hua,Liu, Can,Liu, Yong,Yang, Haijun,Zhu, Xianjin
-
supporting information
p. 4357 - 4363
(2020/07/14)
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- Syntheses of Pyrroles, Pyridines, and Ketonitriles via Catalytic Carbopalladation of Dinitriles
-
The first example of the Pd-catalyzed addition of organoboron reagents to dinitriles, as an efficient means of preparing 2,5-diarylpyrroles and 2,6-diarylpyridines, has been discussed here. Furthermore, the highly selective carbopalladation of dinitriles with organoboron reagents to give long-chain ketonitriles has been developed as well. Based on the broad scope of substrates, excellent functional group tolerance, and use of commercially available substrates, the Pd-catalyzed addition reaction of arylboronic acid and dinitriles is expected to be significant in future synthetic procedures.
- Qi, Linjun,Li, Renhao,Yao, Xinrong,Zhen, Qianqian,Ye, Pengqing,Shao, Yinlin,Chen, Jiuxi
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p. 1097 - 1108
(2020/01/22)
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- Photoredox-Catalyzed Decarboxylative Alkylation of Silyl Enol Ethers to Synthesize Functionalized Aryl Alkyl Ketones
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Photoredox-catalyzed decarboxylative alkylation of silyl enol ethers has been developed. Diverse functionalized aryl alkyl ketones were afforded in modest to good yields using N-(acyloxy)phthalimide as an easy access alkyl radical source under mild and operationally simple conditions. The excellent performance of drug molecules such as fenbufen and indomethacin and naturally occurring carboxylic acids such as stearic acid and dehydrocholic acid further demonstrated the practicability of the reaction.
- Kong, Weiguang,Yu, Changjiang,An, Hejun,Song, Qiuling
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p. 349 - 352
(2018/01/28)
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- Synthetic studies on a series of functionalized pyrylium salts, 4-chloro- and 4-bromophosphinines
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A series of new pyrylium salts that bear sulfonate and phosphonate groups were obtained from the reactions between 2,6-diphenyl-4H-pyran-4-one, sulfonic anhydride, and chlorophosphates, and analyzed spectroscopically. Furthermore, treatment of 2,6-diphenyl-4H-pyran-4-one with phosphoryl chloride or bromide afforded the corresponding 4-chloro- and 4-bromopyrylium tetrafluoroborates in good yield. Subsequently, the synthesis of the corresponding 4-chloro- and 4-bromophosphinines was accomplished by treating the respective chloro- and bromopyrylium tetrafluoroborates with tris(trimethylsilyl)phosphine.
- Nagahora, Noriyoshi,Tokumaru, Hiroshi,Ikaga, Shinpei,Hanada, Takuya,Shioji, Kosei,Okuma, Kentaro
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p. 1880 - 1887
(2018/03/07)
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- Method for manufacturing organic electronic devices
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The present invention relates to a method for manufacturing organic electronic devices including a dipyrannylidene film as an anodic interface layer, the method being carried out in a vacuum and without any exposure to air. The invention also relates to o
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Page/Page column 7
(2017/11/09)
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- Structural and electronic properties of 2,2′,6,6′-tetraphenyl-dipyranylidene and its use as a hole-collecting interfacial layer in organic solar cells
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The accumulation of positive charges at the anodic interface considerably limits the efficiency of photovoltaic solar cells based on polymer/fullerene bulk heterojunctions (BHJs). Interfacial layers (IFLs) such as PEDOT:PSS improve charge injection but ha
- Courté,Alaaeddine,Barth,Tortech,Fichou
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p. 487 - 492
(2017/03/15)
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- Tailoring flavins for visible light photocatalysis: organocatalytic [2+2] cycloadditions mediated by a flavin derivative and visible light
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A new application of flavin derivatives in visible light photocatalysis was found. 1-Butyl-7,8-dimethoxy-3-methylalloxazine, when irradiated by visible light, was shown to allow an efficient cyclobutane ring formation via an intramolecular [2+2] cycloaddition of both styrene dienes, considered as electron-rich substrates, and electron-poor bis(arylenones), presumably proceeding via an energy transfer mechanism.
- Mojr, Viktor,Svobodová, Eva,Straková, Karolína,Nevesely, Tomá?,Chudoba, Josef,Dvo?áková, Hana,Cibulka, Radek
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supporting information
p. 12036 - 12039
(2015/07/28)
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- Methods for the synthesis of chiral sulfur heterocycles and their application in the asymmetric Baylis-Hillman reactions
-
Enantiomerically pure (2S,6S)-2,6-diphenyltetrahydro-2H-thiopyran, (2S)-2-phenyltetrahydro thiophene, and (2S)-2-phenyltetrahydro-2H-thiopyran were prepared in 70-72% yields and with 86-99% ee via cyclization of the corresponding dimesylate in an SN2 cyclization reaction using sodium sulfide nonahydrate. The results on the application of various chiral sulfides in asymmetric Baylis-Hillman reactions are also described.
- Periasamy, Mariappan,Gurubrahamam, Ramani,Muthukumaragopal, Gopal P.
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p. 568 - 574
(2013/06/27)
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- Palladium-catalyzed addition of potassium aryltrifluoroborates to aliphatic nitriles: Synthesis of alkyl aryl ketones, diketone compounds, and 2-arylbenzo[b]furans
-
A palladium-catalyzed addition of potassium aryltrifluoroborates to aliphatic nitriles has been developed, leading to a wide range of alkyl aryl ketones with moderate to excellent yields. Moreover, several dinitriles (e.g., malononitrile, glutaronitrile, and adiponitrile) were applicable to this process for the construction of 1,3-, 1,5-, or 1,6-dicarbonyl compounds. The scope of the developed approach is successfully explored toward the one-step synthesis of 2-arylbenzo[b]furans via sequential addition and intramolecular annulation reactions. The methodology accepted a wide range of substrates and is applicable to library synthesis.
- Wang, Xingyong,Liu, Miaochang,Xu, Long,Wang, Qingzong,Chen, Jiuxi,Ding, Jinchang,Wu, Huayue
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p. 5273 - 5281
(2013/07/26)
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- Palladium-catalysed addition of potassium phenyltrifluoroborate to dinitriles: Synthesis of diketone compounds
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Pd(OAc)2/1,10-phenanthroline-catalysed addition of potassium phenyltrifluoroborate to aliphatic dinitriles in 2-MeTHF has been developed, achieving diphenyl diones in moderate to excellent yields. The scope of the developed approach was successfully explored toward the addition of potassium phenyltrifluoroborate to aromatic dinitriles. Additionally, a plausible pathway for the formation of the diones has been proposed.
- Wang, Xingyong,Wang, Qingzong,Chen, Jiuxi,Liu, Miaochang,Ding, Jinchang,Wu, Huayue
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p. 470 - 472
(2013/09/12)
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- Rhodium(II)-catalyzed cyclization of bis(N-tosylhydrazone)s: An efficient approach towards polycyclic aromatic compounds
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Ahead of the PAC: Polycyclic aromatic compounds (PACs) can be easily accessed by the combination of Suzuki-Miyaura cross-coupling and a [Rh 2(OAc)4]-catalyzed carbene reaction using easily available bis(N-tosylhydrazone)s as intermediates (see scheme; Ts=4-toluenesulfonyl). Copyright
- Xia, Ying,Liu, Zhenxing,Xiao, Qing,Qu, Peiyuan,Ge, Rui,Zhang, Yan,Wang, Jianbo
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supporting information; experimental part
p. 5714 - 5717
(2012/07/28)
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- DERIVATIVES OR DIPYRANNYLIDENE TYPE AS ANODE INTERFACE LAYER IN ELECTRONIC DEVICES
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The present invention relates to substrates coated with films comprising compounds of general formula (I) below: and also to the process for manufacturing them and to their use as anode interface layer in electronic devices. The present invention also rel
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Page/Page column 7
(2011/04/25)
-
- Synthesis and viscoelastic behavior of an anionic gemini surfactant in aqueous solution
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A novel anionic Gemini surfactant,sodium dialkylbenzene disulfonate with spacer of -C3H6-, was synthesized and confirmed by 1HNMR,MS and IR. Such Gemini surfactant in dilute aqueous solution without additives was researche
- Wu, By Huijue,Du, Xigang,Lu, Yao,Zhang, Xin,Yang, Zhengyu
-
scheme or table
p. 1355 - 1362
(2011/02/17)
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- Pd(0) or Pd(II)-catalyzed ring-opening reactions of benzylidene- and alkylidenecyclopropyl ketones and aldehydes
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Pd(0) catalyzed reactions of methylenecyclopropyl carbonyl compounds afforded a convenient method for the synthesis of conjugate (E,E)-1,3-diene derivatives 2 in good to excellent yields. Moreover, we also found that Pd(II)-catalyzed reactions of methylen
- Tang, Xiang-Ying,Shi, Min
-
supporting information; experimental part
p. 8863 - 8868
(2009/12/26)
-
- Synthesis and reactivity of imide-derived bisvinyl phosphates. Reactivity of 2,6-disubstituted 1,4-dihydropyridines
-
Symmetrical and unsymmetrical 2,6-disubstituted dihydropyridines were prepared in high yields under mild conditions using the Suzuki and Stille Pd-catalyzed coupling reactions of imide-derived bisvinyl phosphates with a range of aryl, heteroaryl, and alkenyl moieties. The alkylation reaction at C-4 easily afforded original tri- and tetrasubstituted dihydropyridines. Hydrolysis of the latter under acidic condition provided efficiently either open-chain 1,5-diketones or di- or trisubstituted pyridines.
- Mousset, Deborah,Gillaizeau, Isabelle,Sabatie, Andrea,Bouyssou, Pascal,Coudert, Gerard
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p. 5993 - 5999
(2007/10/03)
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- Generation of β-keto radicals from cyclopropanols catalyzed by AgNO3
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Various β-keto radicals are generated from cyclopropanols by treatment with a catalytic amount of AgNO3 and (NH4) 2S2O8 as a reoxidant in the presence of pyridine. Thus, generated β-keto radicals react with alkenes to yield addition products. Copyright
- Chiba, Shunsuke,Cao, Zhengyan,El Bialy, Serry Atta Atta,Narasaka, Koichi
-
-
- Ring-opening of tertiary cyclopropanols derived from β-diketones
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The ring-opening reaction of 1,2-disubstituted cyclopropanols, prepared from β-diketones, mediated by Cu(NO3)2, p-TsOH, and NaOH is reported. The Cu(II)-mediated ring-opening of cyclopropanols gave α-methylene-γ-diketones in good yie
- Li, Le-Zhen,Xiao, Bin,Guo, Qing-Xiang,Xue, Song
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p. 7762 - 7771
(2007/10/03)
-
- Synthesis and fluorescence spectra of Oxa[3.n]phenanthrenophanes
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(Chemical Equation Presented) Novel photostable oxa[3.n](3,9)- and [3.3](3,10)phenanthrenophanes (n = 3, 4) bearing trimethylene-type linkage(s) were successfully synthesized by the intramolecular acid-catalyzed etherification of the corresponding precursor diols. syn-Oxa[3.3](3,10) phenanthrenophane afforded the most red-shifted excimer fluorescence (λmax = 432 nm) among the phenanthrenophanes so far prepared.
- Nakamura, Yosuke,Yamazaki, Takuzo,Nishimura, Jun
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p. 3259 - 3262
(2007/10/03)
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- Mercuric triflate-catalyzed synthesis of 2-methylfurans from 1-alkyn-5-ones
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(Chemical Equation Presented) 2-Methylfurans were prepared by an effective cyclization of 1-alkyn-5-ones in the presence of mercuric triflate as the catalyst under very mild reaction conditions with high catalytic turnover up to 100 times. Benzene, toluen
- Imagawa, Hiroshi,Kurisaki, Takahiro,Nishizawa, Mugio
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p. 3679 - 3681
(2007/10/03)
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- Electrooxidative formation of 1,2-diaroylcyclopropanes from 1,3-diaroylpropanes in the presence of KI
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Various 1,2-diaroylcyclopropanes were obtained in good yields by the indirect electrochemical oxidation of 1,3-diaroylpropanes in the presence of catalytic amounts of KI under very mild conditions.
- Okimoto, Mitsuhiro,Takahashi, Yukio,Kakuchi, Toyoji
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p. 207 - 208
(2007/10/03)
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- Synthesis, Fe(II)-induced degradation, and antimalarial activities of 1,5-diaryl-6,7-dioxabicyclo[3.2.2]nonanes: Direct evidence for nucleophilic O-1,2-aryl shifts
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1,5-Diaryl-6,7-dioxabicyclo[3.2.2]nonanes 1a-d (1a: Ar=p-FC6H4, 1b: Ar=Ph, 1c: Ar=p-MeC6H4, 1d: Ar=p-MeOC6H4) were prepared by a modified method of photo-electron transfer oxygenation, and the reactions of 1 with FeBr2 were investigated under various conditions. The Fe(II)-induced degradation of 1 afforded various rearrangement products and fragmentation products through competitive single electron transfer (SET) and Lewis acid pathways. Direct evidence for the O-1,2-aryl shift was obtained by the isolation of rearrangement products, 1-aryloxy-5-aryl-8-oxabicyclo[3.2.1]octanes 8. The degradation mechanism was proposed and the in vitro antimalarial activities were also evaluated.
- Kamata, Masaki,Ohta, Motoko,Komatsu, Ken-Ichi,Kim, Hye-Sook,Wataya, Yusuke
-
p. 2063 - 2067
(2007/10/03)
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- Novel photo-rearrangement of 1,5-di(p-methoxyphenyl)-6,7-dioxabicyclo[3.2.2]nonane through an O-neophyl-type 1,2-aryl shift: Evidence for a 1,6-dioxyl diradical intermediate
-
Photolysis and thermolysis of 1,5-diaryl-6,7-dioxabicyclo[3.2.2]nonane 1a-c (a: Ar=p-MeOC6H4, b: Ar=p-MeC6H4, c: Ar=Ph) were investigated. (p-Methoxyphenyl)-substituted 1a underwent a novel photo-initiated O-neophyl-type 1,2-aryl shift to afford 1-(p-methoxyphenyl)oxy-5-(p-methoxyphenyl)-8-oxabicyclo[3.2.1]octane 7a along with a small amount of 1-(p-methoxyphenyl)-3-(2-(4′-methoxyphenyl)tetrahydrofuran-2-yl) propan-1-one 4a through an 1,6-dioxyl diradical intermediate, while the thermolysis mainly afforded the 1,5-di(p-methoxyphenyl)pentan-1,5-dione 5a and 1,4-di(p-methoxyphenyl)butan-1,4-dione 8a.
- Kamata, Masaki,Komatsu, Ken-Ichi
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p. 9027 - 9030
(2007/10/03)
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- The preparation of 1,3-dizincapropanes via a boron-zinc transmetallation
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The reaction of 1,3-diethylborylpropane and the corresponding 3-mercurio derivatives were prepared by hydroboration of the allylic precursor and were treated with diethylzinc leading to the corresponding 1,3-bimetallic reagents which, based on their sharp
- Bhanu Prasad, Appana S.,Eick, Holger,Knochel, Paul
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p. 133 - 139
(2007/10/03)
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- Lewis Acid-Promoted Disproportionation Reaction of Aromatic Vinyl Ethers and Acetals and Its Application to the Synthesis of Paracotoin
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Aromatic vinyl ethers and acetals underwent a novel addition-fragmentation reaction affording olefins and esters in the presence of a Lewis acid. This reaction was applied to intramolecular cyclization reaction, giving five or six membered ring compounds in good yields. Paracotoin, an intermediate in the biosynthesis of shikimic acid, was synthesized using this cyclization reaction as the key step.
- Gong, Young Dae,Tanaka, Hiroko,Iwasawa, Nobuharu,Narasaka, Koichi
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p. 2181 - 2185
(2007/10/03)
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- Oxidative Cleavage of vic-Diols Using Copper(II) Bromide-Lithium t-Butoxide: A New Route to Unsymmetrical 1,5- and 1,6-Diketones
-
Unsymmetrical 1,6-diketones were obtained by the copper(II) bromide-lithium t-butoxide oxidation of 1,2-disubstituted 1,2-cyclohexanediols. The diols were easily prepared by the addition of Grignard reagents to 2-trimethylsiloxy-2-cyelohexenone followed by the hydrolysis and treatment of the resulting 2-hydroxycyclohexanones with the second Grignard reagents. Similarly, 1,5-Diketones were obtained using 2-trimethylsiloxy-2-cyclopentenone as a starting material.
- Fujiwara, Tooru,Tsuruta, Yumiko,Arizono, Ko-Ichi,Takeda, Takeshi
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p. 962 - 964
(2007/10/03)
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- Synthese von 1,3-Dizinkverbindungen ueber Bor-Zink-Austausch
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Keywords: Borverbindungen; 1,5-Dizinkacycloocyan; Zinkverbindungen
- Eick, Holger,Knochel, Paul
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p. 229 - 231
(2007/10/03)
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- Photoinduced Electron Transfer (PET) cyclization and photooxygenation of 2,6-diaryl-1,6-heptadienes and 2,7-diaryl-1,7-octadienes
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The 2,6-diaryl-substituted 1,6-heptadienes 3a-c and the 2,7-diaryl-substituted 1,7-octadienes 4a-b were cleanly converted into the corresponding anellated cyclobutanes 5 and 6, resp., when irradiated under photoelectron-transfer conditions (9,10-dicyanoanthracene in acetonitrile). Only for 4c did the rearranged compound 7c become the dominant photoproduct. Oxygen trapping experiments with formation of endoperoxides 8, 9 were successful in the case of the electron-rich substrates 3b, c and 4c. VCH Verlagsgesellschaft mbH, 1996.
- Griesbeck, Axel G.,Sadlek, Oliver,Polborn, Kurt
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p. 545 - 549
(2007/10/03)
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- Mechanism-based design of simple, symmetrical, easily prepared, potent antimalarial endoperoxides
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Mechanism-based design, two-step synthesis, and in vitro antimalarial testing showed thermally stable, crystalline, bicyclic endoperoxides 2a and 2b to be potent antimalarials. Their reduction by FeBr2 proceeds via oxy-radicals and then carbon
- Posner, Gary H.,Wang, Dasong,Gonzalez, Lluisa,Tao, Xueliang,Cumming, Jared N.,Klinedinst, Donna,Shapiro, Theresa A.
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p. 815 - 818
(2007/10/03)
-
- Highly Selective Aldol Reaction of Dibenzoylmethanes with Formaldehyde Catalyzed by Cobalt Schiff Base Complex under Neutral Conditions
-
Coordinatively saturated hydroxocobalt(III) Schiff base complexes catalyze highly selective aldol reaction of dibenzoylmethanes with formaldehyde in methanol to give 1,3-dibenzoylpropanes, resulting from retro-Claisen reaction of 1,1,3,3-tetrabenzoylpropanes, which are obtained quantitatively in dichlorometane.Coordinatively saturated cobalt(III) Schiff base complexes ligating a substrate anion as a monodentate ligand is found to be the reactive species.
- Maruyama, Kazushige,Kubo, Katsunobu,Toda, Yukinobu,Kawase, Kazuhiko,Mashino, Takahiro,Nishinaga, Akira
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p. 5609 - 5612
(2007/10/02)
-
- Photochemistry of nonconjugated diketones: internal self-quenching and energy transfer
-
The triplet state behavior of nine α,ο-dibenzoylalkanes indicates the occurrence of a rapid quenching interaction between the two carbonyl groups.This quenching is fastest (k=3E7 s-1) in dibenzoylbutane, is slightly slower (ca.E7 s-1) in dibenzoylethane, dibenzoylpentane, and 2,2-dibenzoylpropane, but is absent in 1,3-dibenzoylpropane.It also occurs in several "mixed" 1,4-diaroylbutanes incorporating p-ethylbenzoyl or p-methoxybenzoyl chromophores.This internal self-quenching is interpreted as the intramolecular counterpart of the well-know bimolecular self-quenching of aryl ketones, although no exact mechanism can be proposed.Such internal quenching does not occur as rapidly, if at all, in three "turned around" diketones: δ-(p-acetylphenyl)valerophenone, δ-(p-acetylphenoxy)valerophenone, and γ-(p-acetylphenoxy)butyrophenone.This fact, together with the varying rates of internal self-quenching in the dibenzoylalkanes, indicates the necessity for a very specific and close orientation of the two carbonyl groups for self-quenching.In the mixed diketones containing a p-alkylbenzoyl group, triplet excitation appears to be fully equilibrated between the two chromophores.However, in those containing a p-methoxybenzoyl group, excitation does not fully equilibrate before triplet decay, as evidenced by different quenching efficiencies for products from the two carbonyls.Analysis indicates intramolecular energy transfer rate constants -1.These are sufficiently lower than in other bichromophoric systems to suggest relatively slow energy hopping in the polymers of phenyl vinyl ketone.Key words: nonconjugated diketones, dibenzoylalkanes, sefl-quenching, energy transfer, triplet ketones.
- Wagner, Peter J.,Frerking, Harlan W. Jr.
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p. 2047 - 2061
(2007/10/03)
-
- Electron-transfer induced intramolecular [2+2] cycloaddition of 2,6-diarylhepta-1,6-dienes
-
Intramolecular [2+2] cycloaddition of 2,6-diaryl-1,6-heptadienes 1a-c to bicycloheptanes 2 can be induced by electron-transfer photosensitization with 9,10-dicyanoanthracene. A stepwise mechanism involving cyclic 1,4-cation radical 3 has been proposed based on the trapping experiments.
- Takahashi,Okitsu,Ando,Miyashi
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p. 3953 - 3956
(2007/10/02)
-
- Photoaddition of styrene on certain β-polyketones
-
The irradiation of 1,5-diphenylpentane-1,3,5-trione 1 and 1-phenylhexane-1,3,5-trione 2 at λ > 290 nm with styrene gives products of double photo-addition: 1,2,6,9-tetraphenylnonane-1,5,9-trione 5 and 1,2,6-triphenyldecane-1,5,9-trione 6, respectively.Under the same conditions with λ > 220 nm, 2-(3-oxo-3-phenylpropionyl)indane-1,3-dione 3 and 2-(3-oxobutyryl)indane-1,3-dione 4 give only products of simple photoaddition: 4-(3-oxo-3-phenylpropionyl)-2-phenylbenzocycloheptane-1,5-dione 7 and 4-(3-oxobutyryl)-2-phenylbenzocycloheptane-1,5-dione 8, respectively.The regiospecificity previously observed with the β-diketones is not a general rule for these β-triketones.The phenyl group in position 6 (products 5 and 6) is not in the α-position of the benzoyl group.The δ-triketones obtained are characterized using β-diketonic models, which are prepared by a simple sequence.Observations of products 7 and 8 show that styrene reacts with the cyclic enol only.This work may be considered as a model study for the prediction of the behavior of triketones 1, 2, 3 and 4 in the side chain of polymeric compounds.Keywords: photoaddition / styrene / β-polyketones / stereoselectivity
- Mansri, Ali,Casals, Pierre-Francois,Fan, Bo Tao,Lapluye, Gerard
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p. 247 - 252
(2007/10/02)
-
- Generation of β-Carbonyl Radicals from Cyclopropanol Derivatives by the Oxidation with Manganese(III) 2-Pyridinecarboxylate and Their Reactions with Electron-Rich and -Deficient Olefins
-
Various β-carbonyl radicals are generated oxidatively from cyclopropanol derivatives by the use of manganese(III) 2-pyridinecarboxylate (Mn(pic)3).These β-carbonyl radicals react with electron-rich olefins such as conjugated silyl enol ethers, a ketene th
- Iwasawa, Nobuharu,Hayakawa, Satoshi,Funahashi, Masahiro,Isobe, Koichi,Narasaka, Koichi
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p. 819 - 827
(2007/10/02)
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- Catalyst composition
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Catalyst compositions based upon a. a Group IVA metal compound of the general formula (Cp)pMeX4-pwherein Cp represents identical or different cyclopentadienyl groups which may be substituted with one or more hydrocarbyl groups with t
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- Masked Lithium Bishomoenolates: Useful Intermediates in Organic Synthesis
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The lithiation of the chloro ketals 9 with lithium naphthalenide at -78 deg C led to the corresponding masked lithium bishomoenolates 4, which are stable species under these conditions and react with different electrophilic reagents (H2O, D2O, i-PrCOH, Ph
- Ramon, Diego J.,Yus, Miguel
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p. 3825 - 3831
(2007/10/02)
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- Generation of β-Keto Radicals from Cyclopropanol Derivatives by the Use of Manganese(III) 2-Pyridinecarboxylate as an Oxidant and Their Reactions with Olefins
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Various β-keto radicals are generated from cyclopropanol derivates such as 1- or 2-substituted cyclopropanols and a cyclopropanone hemiacetal by the use of manganese(III) 2-pyridinecarboxylate, and their reactions with electron-rich olefins give cross-addition products in good yields.
- Iwasawa, Nobuharu,Hayakawa, Satoshi,Isobe, Koichi,Narasaka, Koichi
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p. 1193 - 1196
(2007/10/02)
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- REACTIONS OF 2-METHYLENE-1,3-DICARBONYL COMPOUNDS WITH FURAN
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The mono- and/or di-substituted furans (2 and 3) were synthesized by the reaction of 2-methylene-1,3-dicarbonyl compounds (1) with furan under moderate selectivity.
- Yamauchi, Masashige,Shirota, Miwa,Watanabe, Toshio
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p. 1699 - 1704
(2007/10/02)
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- A Novel Route to Phenyl-substituted Pyridines by the Reaction of N-(1-Phenylvinyl)iminophosphoranes with α,β-Unsaturated Ketones
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The N-(1-phenylvinyl)iminotriphenylphosphorane or N-(1-phenylvinyl)iminotributylphosphorane reacted with α,β-unsaturated ketones to undergo a novel C-C bond formation followed by aza-Wittig reaction to result in the formation of phenyl-substituted pyridines.
- Kobayashi, Tomoshige,Nitta, Makoto
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p. 1549 - 1552
(2007/10/02)
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- ONE-METHYLENE INCORPORATED DIMERIZATION REACTION OF KETONE ENOLATES. 1. A NEW ROUTE TO 1,5-DIKETONES FROM KETONES HAVING α-ACTIVE HYDROGEN ON ONE SIDE
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A novel reaction of ketone enolate with dimethylformamide (DMF) to give 1,5-diketone has been found.It is a dimerization of ketone enolates accompanying the incorporation of one-methylene from DMF.
- Kiyooka, Syun-ichi,Yamashita, Tsuneo,Tashiro, Jun-ichi,Takano, Kazuyuki,Uchio, Yasuto
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p. 5629 - 5632
(2007/10/02)
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- Photochemistry of 1,5-Diaryl-1,5-diketones
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The photochemistry of ketones 1-3 has been examined in solution at room temperature by using quantum yield and laser flash photolysis techniques.Triplet energy migration between the two chromophores leads to complete excitation equilibration.In the case of 3, two triplet states have been characterized, reflecting the syn and anti conformations of the o-methylbenzoyl chromophore.The biradicals produced in the triplet decay have lifetimes of ca. 50 ns in wet acetonitrile, for 1 and 2 and 430 ns in the case of 3, where it results from abstraction of the benzylic hydrogens.Biradicals are produced from 2 with a quantum yield of 1.0; however, the product yields are considerably lower, even in polar hydroxylic solvents.The effect is attributed to strong intramolecular hydrogen bonding in the biradical.
- Bays, J. P.,Encinas, M. V.,Small, R. D.,Scaiano, J. C.
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p. 727 - 734
(2007/10/02)
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