- Decomposition of amitriptyline hydrochloride in aqueous solution: identification of decomposition products
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The decomposition of amitriptyline hydrochloride upon autoclaving in a buffered solution (pH 6.8) was investigated. Three major decomposition products [3 (propa 1,3 dienyl) 1,2:4,5 dibenzocyclohepta 1,4 diene, dibenzosuberone, and 3 (2 oxoethylidene) 1,2:4,5 dibenzocyclohepta 1,4 diene] were detected and identified by chromatographic and spectroscopic techniques. Evidence is presented that the latter two compounds are formed by further oxidation of 3 (propa 1,3 dienyl) 1,2:4,5 dibenzocyclohepta 1,4 diene, and a possible decomposition pathway is outlined.
- Enever,Li Wan Po,Millard,Shotton
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Read Online
- Productive chloroarene C-Cl bond activation: Palladium/phosphine-catalyzed methods for oxidation of alcohols and hydrodechlorination of chloroarenes
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The palladium/phosphine-catalyzed productive chloroarene C-Cl bond activation provides general, efficient, and functional group friendly methods for the selective oxidation of alcohols and the hydrodechlorination of chloroarenes.
- Bei, Xiaohong,Hagemeyer, Alfred,Volpe, Anthony,Saxton, Robert,Turner, Howard,Guram, Anil S.
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Read Online
- Excited State Carbon Acids: Base Catalysed Photoketonization of Dibenzosuberenol to Dibenzosuberone via Initial C-H Bond Heterolysis from S1
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A new photoreaction, the photoketonization of dibenzosuberenol (1) to dibenzosuberone (2) in aqueous solution, is reported, the mechanism of which is believed to involve initial ionization of the C-H proton at the 5-position (in S1), to generate a 5-hydroxy-5-dibenzosuberenyl (9) carbanion intermediate.
- Wan, Peter,Budac, David,Krogh, Erik
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- Convenient synthesis of 2-(2-phenylethyl)benzoic acid: A key intermediate in the synthesis of dibenzosuberone
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A convenient and improved synthesis of 2-(2-phenylethyl) benzoicacid, a key intermediate in the synthesis of dibenzosuberone is described.
- Ramesha,Roy
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Read Online
- Spectrophotometric determination of amitriptyline hcl in pure and pharmaceutical forms
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Five spectrophotometric methods for determination of Amitriptyline HCl have been developed, validated and applied for the assay of the drug in pharmaceuticals. Methods A, B and C are based on ion pair complexation of drug, in acidic buffers, with triphenylmethane dyes viz., Bromothymol blue (BTB), Bromophenol blue (BPB) and Bromocresol purple (BCP). The complexes are extracted into chloroform and absorbance is measured around at 415 nm as function of concentration of the drug. The stoichiometry of the complex is found 1:1 in each case. Method D depends upon charge transfer complexation of neutralized drug with iodine which produces iodide ion whose absorbance at 366 nm is measured as function of concentration of the drug. This complex, too, has 1:1 composition as determined by Job's method. Method E is developed on the basis of oxidation of the drug with alkaline KMnO4 which generates green colored manganate ion with ?max 610 nm. As the intensity of green color increased with increasing time kinetics of the reaction is followed and calibration curves are constructed by using initial rate and fixed time methods. Excellent recovery studies with high accuracy and precision indicate that the methods can be successfully used in industries for the assay of drug in pure form and pharmaceuticals.
- Susmitha,Thirumalachary,Singh, T.Charan,Venkateshwarlu
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Read Online
- Nafion-H catalysed intramolecular Friedel-Crafts acylation: Formation of cyclic ketones and related heterocycles
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Benzoic acids with suitable substituents bearing phenyl ring in the ortho position undergo cyclization by intramolecular Friedel-Crafts acylation in the presence of Nafion-H, a perfluorinated resinsulfonic acid catalyst. Synthesis of anthraquinone, anthrone, fluorenone, α-tetralone, 1-benzosurberone and heterocycles such as acridone, xanthone etc. is easily achieved in good to excellent yields (82-95%) by this method.
- Olah, George A.,Mathew, Thomas,Farnia, Morteza,Prakash, G. K. Surya,Katherine,Donald
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Read Online
- Phase-Transfer Permanganate Oxidation of Unfunctionalized Benzylic Positions
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The utility of potassium permanganate in a biphasic medium employing a phase-transfer catalyst is described for the selective oxidations of doubly-benzylic secondary carbons to ketones and doubly-benzylic tertiary carbons to alcohols as well as of singly-benzylic secondary alcohols to ketones.
- Gannon, Sharon M.,Krause, Josef G.
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Read Online
- Base-free oxidation of alcohols enabled by nickel(ii)-catalyzed transfer dehydrogenation
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An efficient nickel(ii)-catalyzed transfer dehydrogenation oxidation of alcohols is reported that relies on cyclohexanone as the formal oxidant and does not require the use of an external base. The synthetic utility of this protocol is demonstratedviathe facile oxidation of structurally complicated natural products.
- Ye, Danfeng,Liu, Zhiyuan,Sessler, Jonathan L.,Lei, Chuanhu
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supporting information
p. 11811 - 11814
(2020/10/13)
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- Synthesis of dibenzocycloketones by acyl radical cyclization from aromatic carboxylic acids using methylene blue as a photocatalyst
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An efficient intramolecular radical cyclization reaction via photoredox catalysis was developed for the synthesis of dibenzocycloketone derivatives using methylene blue as a photosensitizer. This strategy could be widely used to synthesize large heterocycles due to the unique reactivity of phosphoranyl radicals formed by a polar/SET crossover between an aromatic carboxylic acid and a phosphine radical cation. Attractive features of this process include generation of an acyl radical by an inexpensive and metal-free photocatalyst, which effectively undergoes a cyclization process.
- Jiang, Hongshuo,Mao, Guijie,Wu, Hongfeng,An, Qi,Zuo, Minghui,Guo, Weihao,Xu, Chunzhao,Sun, Zhizhong,Chu, Wenyi
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supporting information
p. 5368 - 5373
(2019/10/11)
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- Aerobic Oxygenation of Alkylarenes over Ultrafine Transition-Metal-Containing Manganese-Based Oxides
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The oxygenation of alkylarenes to the corresponding aryl ketones is an important reaction, and the development of efficient heterogeneous catalysts that can utilize O2 as the sole oxidant is highly desired. In this study, we developed an efficient alkylarene oxygenation process catalyzed by ultrafine transition-metal-containing Mn-based oxides with spinel or spinel-like structures (M-MnOx, M=Fe, Co, Ni, Cu). These M-MnOx catalysts were prepared by a low-temperature reduction method in 2-propanol-based solutions using tetra-n-butyl ammonium permanganate (TBAMnO4) as the Mn source, and they exhibited high Brunauer–Emmett–Teller surface areas (typically >400 m2 g?1). Using fluorene as the model substrate, the catalytic activities of M-MnOx and Mn3O4 were compared. The catalytic activities of M-MnOx were significantly higher than that of Mn3O4, which demonstrates that the incorporation of transition metals in manganese oxide was critical. Among the series of M-MnOx catalysts examined, Ni-MnOx exhibited the highest catalytic activity for the oxygenation. In addition, the catalytic activity of Ni-MnOx was higher than that of a physical mixture of Mn3O4 and NiO. Furthermore, Ni-MnOx exhibited a broad substrate scope with respect to various types of structurally diverse (hetero)alkylarenes (16 examples). The observed catalysis was truly heterogeneous, and the Ni-MnOx catalyst was reusable for the oxygenation of fluorene at least three times and its high catalytic performance was preserved, for example, the reaction rate, final product yield, and product selectivity. The present Ni-MnOx-catalyzed oxygenation process is possibly initiated by a single-electron oxidation process, and herein a plausible oxygen-transfer mechanism is proposed based on several pieces of experimental evidence.
- Nakai, Satoru,Uematsu, Tsubasa,Ogasawara, Yoshiyuki,Suzuki, Kosuke,Yamaguchi, Kazuya,Mizuno, Noritaka
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p. 1096 - 1106
(2018/01/15)
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- Method for preparing amitriptyline intermediate by using solid acid catalyst
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The invention relates to a method for preparing an amitriptyline intermediate by using a solid acid catalyst. The method for preparing the amitriptyline intermediate by using the solid acid catalyst can effectively solve the problem about green, clean and safe production of the amitriptyline intermediate. The method comprises the steps of adding o-phenethyl benzoic acid and ZSM-5 molecular sievesto a solvent of 5 to 20 times of the total mass of o-phenethyl benzoic acid and ZSM-5 molecular sieves at 0 to 40 DEG C, raising temperature to 60 to 100 DEG C, heating under reflux and stirring for 6to 12 hours, after cooling reaction liquid, filtering under reduced pressure, removing ZSM-5 molecular sieves through filtration, after washing filtrate with water, drying and concentrating to obtaina crude product of 10,11-dihydrodibenzo[a,b]cycloheptene-5-one, and conducting recrystallization with anhydrous ethanol to obtain a pure product of the amitriptyline intermediate. The method for preparing the amitriptyline intermediate can significantly reduce the emission of polluting waste in production, reduce the production cost, and is an innovation in the method for preparing the amitriptyline intermediate.
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Paragraph 0015; 0019; 0023
(2018/07/15)
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- Catalyst@Metal Hybrids in a One-Pot Multistep Opposing Oxidation and Reduction Reaction Sequence
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We report the feasibility of the catalysis of contrasting reactions, oxidation and reduction, in a multistep process that also involves a condensation reaction all performed with hybrids of catalytic organometallic complexes entrapped within metals ([complex]@metal). Two routes were explored for the multistep process. The first route used a combination of an oxidizing Ir complex entrapped in Ag ([Ir]@Ag) and a reducing Rh complex entrapped in Ag ([Rh]@Ag). The second route used a single composite material, namely, [Ir]@Pd, in which [Ir] acted as the oxidizing catalyst, and Pd was the reducing catalyst. Both routes were efficient for the heterogeneous catalytic oxidation and reduction reaction sequence. Towards the goal of a one-pot multistep oxidation and reduction process, a detailed study of the catalytic alcohol oxidation properties of the heterogeneous [Ir]@Ag and [Ir]@Pd was performed. As the arsenal of available hydrogenation catalysts exceeds by far that of oxidations, this part of the study is, we believe, of general interest in itself, as a new alternative to heterogeneous oxidative catalysis.
- Shapiro, Leora,Avnir, David
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p. 816 - 823
(2017/03/13)
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- Efficient acceptorless dehydrogenation of secondary alcohols to ketones mediated by a PNN-Ru(II) catalyst
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Four types of ruthenium(II) complexes, [fac-PNN]RuH(PPh3)(CO) (A), [fac-PNHN]RuH(η1-BH4)(CO) (B), [fac-PNHN]RuCl2(PPh3) (C) and [fac-PNHN]RuH(η1-BH4)(PPh3) (D) (where PNHN and PNN are N-(2-(diphenylphosphino)ethyl)-5,6,7,8-tetrahydroquinoline-8-amine and its deprotonated derivative), have been synthesized and assessed as catalysts for the acceptorless dehydrogenation of secondary alcohols to afford ketones. It was found that C, in combination with t-BuOK, proved the most effective and versatile catalyst allowing aromatic-, aliphatic- and cycloalkyl-containing alcohols to be efficiently converted to their corresponding ketones with particularly high values of TON achievable. Furthermore, the mechanism for this PNN-Ru mediated process been proposed on the basis of a number of intermediates that have been characterized by EI-MS and NMR spectroscopy. These catalysts show great potential for applications in atom-economic synthesis as well as in the development of organic hydride-based hydrogen storage systems.
- Wang, Zheng,Pan, Bing,Liu, Qingbin,Yue, Erlin,Solan, Gregory A.,Ma, Yanping,Sun, Wen-Hua
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p. 1654 - 1661
(2017/07/13)
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- Highly efficient oxidation of alcohols catalyzed by a porphyrin-inspired manganese complex
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A novel strategy for catalytic oxidation of a variety of benzylic, allylic, propargylic, and aliphatic alcohols to the corresponding aldehydes or ketones by an in situ formed porphyrin-inspired manganese complex in excellent yields (up to 99%) has been successfully developed.
- Dai, Wen,Lv, Ying,Wang, Lianyue,Shang, Sensen,Chen, Bo,Li, Guosong,Gao, Shuang
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supporting information
p. 11268 - 11271
(2015/07/07)
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- Multiple organolithium generation in the continuous flow synthesis of amitriptyline
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A continuous flow protocol for the preparation of the tricyclic antidepressant (TCA) amitriptyline is reported. The advantages of flow chemistry when handling organometallic agents as well as when performing reaction with gases are demonstrated. Continuous multilithiation combined with carboxylation and the Parham cyclization, a Grignard addition and thermolytic water elimination by inductive heating are key features of the multistep protocol. Copyright
- Kupracz, Lukas,Kirschning, Andreas
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supporting information
p. 3375 - 3380
(2013/12/04)
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- Iodine-catalyzed disproportionation of aryl-substituted ethers under solvent-free reaction conditions
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Iodine was demonstrated to be an efficient catalyst for disproportionation of aryl-substituted ethers under solvent-free reaction conditions. Variously substituted 1,1,1′,1′-tetraaryldimethyl ethers were transformed into the corresponding diarylketone and diarylmethane derivatives. I 2-catalyzed transformation of 4-methoxyphenyl substituted ethers yielded mono- and dialkylated Friedel-Crafts products as well. Treatment of trityl alkyl and trityl benzyl ethers with a catalytic amount of iodine produced triphenylmethane and the corresponding aldehydes and ketones. The electron-donating substituents facilitated the reaction, while the electron-withdrawing groups retarded it; the difference in reactivity is not very high. Such an observation may be in favour of hydride transfer, predominantly from the less electron rich side of the ether with more stable carbocation formation. With the isotopic studies it was established that a substantial portion of the C-H bond scission took place in the rate-determining step, while the carbonyl oxygen atom originated from the starting ether, and not from the air. The transformation took place under air and under argon, and HI was not a functioning catalyst.
- Jereb, Marjan,Vrazic, Dejan
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p. 1978 - 1999
(2013/05/22)
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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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- Determination of hydride affinities of various aldehydes and ketones in acetonitrile
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Chemical equations presented. The hydride affinities of 21 typical aldehydes and ketones in acetonitrile were determined by using an experimental method, which is valuable for chemists choosing suitable reducing agents to reduce them. The focus of this paper is to introduce a very facile experimental method, which can be used to determine the hydride affinities of various carbonyl compounds in solution.
- Zhu, Xiao-Qing,Chen, Xi,Mei, Lian-Rui
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supporting information; experimental part
p. 2456 - 2459
(2011/07/09)
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- An efficient hydrogenation of various alkenes using scrap automobile catalyst
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An efficient, easy, cheap, convenient, and safe procedure for the reduction of various alkenes to the corresponding alkanes is developed by using scrap automobile catalyst as an efficient hydrogenation catalyst. This procedure not only gives high yields, but also allows recycling of automobile wastes as a catalyst in organic reactions and is representative of green chemistry.
- Zengin, Mustafa,Genc, Hayriye,Demirci, Tuna,Arslan, Mustafa,Kucukislamoglu, Mustafa
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experimental part
p. 2333 - 2335
(2011/05/16)
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- Flow-vacuum pyrolysis of dibenzocycloheptane derivatives on zeolites catalysts. IV
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The pyrolysis of 10,11-dihydro-5H-dibenzo[a,d]cicloheptadien-5-ol (4) and of 5H-dibenzo[a,d]cycloheptatrien-5-ol (5) in flowvacuum conditions (advanced vacuum, inert atmosphere) on zeolites at 300°C is presented. The reaction products were identified by GC/MS using authentic samples and a reaction mechanisms involving cationic species as intermediates were proposed. A comparison with the pyrolysis of the same compounds performed in FVP conditions on quartz is presented.
- Istrati, Daniela,Parvulescu, Luminitza,Popescu, Angela,Mihaiescu, Dan,Badea, Florin
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scheme or table
p. 711 - 714
(2011/10/02)
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- Benzylic carbon oxidation by an in situ formed o-iodoxybenzoic acid (IBX) derivative
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Benzylic C-H bonds are selectively oxidized to the corresponding carbonyl functionalities using catalytic quantities of 2-iodobenzoic acid (2IBAcid) and Oxone. The reported procedure tolerates different functional groups and operates under mild conditions. A radical mechanism is proposed for the transformation and evidence supporting the proposed mechanism is also presented. Georg Thieme Verlag Stuttgart.
- Ojha, Lawanya R.,Kudugunti, Shashi,Maddukuri, Padma P.,Kommareddy, Amitha,Gunna, Meena R.,Dokuparthi, Praveen,Gottam, Hima B.,Botha, Kiran K.,Parapati, Divya R.,Vinod, Thottumkara K.
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scheme or table
p. 117 - 121
(2009/05/30)
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- Gold-catalyzed benzylic oxidation to carbonyl compounds
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The gold-catalyzed, mild and general benzylic oxidation toward carbonyl compounds with TBHP as oxidant is described. Corresponding products are obtained in moderate to excellent yields. Crown Copyright
- Li, Huanrong,Li, Zhiping,Shi, Zhangjie
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experimental part
p. 1856 - 1858
(2009/07/04)
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- Mass spectrum fragmentation of 10,11-dIHYDRO-5H-dIBENZO[a,d]cyclohepten-5- one
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The dibenzo[a,d]cycloheptene skeleton is of importance taking into account the presence of this moiety in different compounds having theoretical or practical interest. A key intermediate in the synthesis of such compounds is 10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-one. The study of the MS fragmentation of this ketone may give information about the possible fragmentation of similar compounds. The central seven-member ring leads to a different MS fragmentation pattern, compared with the simple dibenzylic ketone (bcnzophenone). The formation energy (ΔHf) of the molecules and ions resulted during fragmentation have been calculated by the semi-empirical methods AM1, using the package of programmes HyperChem 5.11.
- Stǎnescu, Michaela Dina,Dincǎ, Nicolae,?i?u, Eugen
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p. 669 - 673
(2007/10/03)
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- Bismuth-catalyzed benzylic oxidations with tert-butyl hydroperoxide
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(Chemical Equation Presented) Oxidation of alkyl and cycloalkyl arenes with tert-butyl hydroperoxide catalyzed by bismuth and picolinic acid in pyridine and acetic acid gave the corresponding benzylic ketones (48-99%). Alternatively, oxidation of methyl arenes gave the corresponding substituted benzole acids (50-95%). Preliminary mechanistic studies were consistent with a radical mechanism rather than a bismuth(III)-bismuth(V) cycle.
- Bonvin, Yannick,Callens, Emmanuel,Larrosa, Igor,Henderson, David A.,Oldham, James,Burton, Andrew J.,Barrett, Anthony G. M.
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p. 4549 - 4552
(2007/10/03)
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- Efficient heterogeneous oxidation of alkylarenes with molecular oxygen
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(Chemical Equation Presented) Ru(OH)x/Al2O 3 efficiently catalyzes the heterogeneous aerobic oxygenation or oxidative dehydrogenation of alkylarenes to give the corresponding oxygenated or dehydrogenated products. Catalyst/product separation is very easy, and the recovered catalyst is reusable with retention of the high catalytic performance.
- Kamata, Keigo,Kasai, Jun,Yamaguchi, Kazuya,Mizuno, Noritaka
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p. 3577 - 3580
(2007/10/03)
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- Application of high throughput screening to heterogeneous liquid and gas phase oxidation catalysis
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The application of combinatorial methods to oxidation catalysis in the liquid and gas phases is described. New lead materials have been discovered for the selective liquid phase oxidation of alcohols to aldehydes/ketones catalyzed by vanadium supported on carbon, for the low temperature CO oxidation/ light off for cold start automotive emissions control over supported noble metals and perovskites, for volatile organic compound (VOC) removal using CoCr oxide catalysts, and for the selective gas phase oxidation of propane to acrylic acid and acrylonitrile using mixed metal oxides. Catalyst discovery libraries were screened in 96-well batch reactors, in a rapid serial scanning mass spectrometer and in a massively parallel microfluidic reactor as primary screens. Promising hits were scaled up in conventional autoclaves or in multi-channel fixed bed secondary/ tertiary screening reactors.
- Guram, Anil,Hagemeyer, Alfred,Lugmair, Claus G.,Turner, Howard W.,Volpe Jr., Anthony F.,Weinberg, W. Henry,Yaccato, Karin
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p. 215 - 230
(2007/10/03)
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- Productive utilization of chlorobenzene: Palladium-catalyzed selective oxidation of alcohols
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(Matrix presented) The palladium/ligand-catalyzed activation of chlorobenzene provides a general, efficient, and functional group friendly method for the selective oxidation of alcohols to carbonyl compounds.
- Guram, Anil S.,Bei, Xiaohong,Turner, Howard W.
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p. 2485 - 2487
(2007/10/03)
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- Antitumor dibenzofluorene derivatives
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Dibenzofluorene derivatives having a formula selected from the group consisting of and salts thereof have antitumor activity. At least one of R1-R13in formula (I) or R1-R12in formula (II) is —R14Z. R14is a substituted or unsubstituted amino or amido group having from 1-12 carbon atoms, and Z is a substituted or unsubstituted heterocyclic group having from 1-12 carbon atoms. The remainder of R1-R13in formula (I) or R1-R12in formula (II) are independently selected from the group consisting of hydrogen, hydroxyl, halogen, nitro, substituted or unsubstituted amino or amido groups having from 1-12 carbon atoms, and alkyl groups having 1-12 carbon atoms.
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- Selective oxidation of alcohols to aldehydes or ketones
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Alcohols are oxidized to their corresponding ketone or aldehyde using an aryl chloride oxidant and a metal-ligand complex or metal/ligand composition. This reaction is particularly applicable to aromatic alcohols and cyclic and bicyclic aliphatic alcohols.
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- A novel catalytic role of molecular iodine in the oxidation of benzylic alcohols: Microwave-assisted reaction
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Molecular iodine was used to catalyse the oxidation of several benzylic alcohols to the corresponding ketones under the microwave-irradiated method, and the role of iodine was explored.
- Mukhopadhyay,Becker,Banik
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- An anion-induced regio- and chemoselective acylation and its application to the synthesis of an anticancer agent
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Figure presented An efficient Grignard- and organolithium-induced regio- and chemoselective anionic acylation is reported. A number of tricyclic ketones are prepared in good to excellent yields via this method. This method is complementary to the Frieldel-Crafts acylation for electron-deficient substrates. A novel anisole-based Grignard reagent was developed to effect the cyclization of sterically hindered substrates. This novel reagent has been successfully applied to the synthesis of Sch 66336, a candidate for oncologic treatment.
- Poirier, Marc,Chen, Frank,Bernard, Charles,Wong, Yee-Shing,Wu, George G.
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p. 3795 - 3798
(2007/10/03)
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- Benzylic oxidation by sodium bismuthate in acetic acid: A simple method for the synthesis of polycyclic aromatic ketones
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Oxidation of benzylic methylenes in polycyclic systems to the benzylic ketones was carried out with sodium bismuthate in the presence of acetic acid.
- Banik, Bimal K.,Venkatraman,Mukhopadhyay, Chhanda,Becker, Frederick F.
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p. 7247 - 7250
(2007/10/03)
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- Photodecarboxylation of diarylacetic acids in aqueous solution: Enhanced photogeneration of cyclically conjugated eight π electron carbanions
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The photodecarboxylation of a series of diarylacetic acids 1-6 has been studied in aqueous solution. The mechanism of these photodecarboxylations is shown to involve C-C bond heterolysis from the singlet excited state, giving rise to carbanion intermediates. Quantum yields for photodecarboxylation (Φd) are reported at several pH's. Fluorescence quantum yields and lifetimes are reported as a function of pH, and their behavior is consistent with reaction via the carboxylate ions. Rate constants of photodecarboxylation (kdc) are estimated and show a marked dependence on the number of π electrons in the internal cyclic array (ICA). The most reactive compound was suberene-5-carboxylic acid (1) (Φd = 0.60 ± 0.05; kdc ≈ = 6 × 109 s-1), which gives a carbanion intermediate of eight π (4n) electrons in the ICA. The least reactive system was fluorene-9-carboxylic acid (4) (πd = 0.042 ± 0.004; kdc = 8.8 × 106 s-1), which on decarboxylation gives rise to a carbanion with an ICA of six π (4n + 2) electrons. The observed reactivity trend in the excited state is the reverse of that observed in the ground state and appears to demonstrate further the utility of the "4n rule" for predicting the relative reactivity of photochemical reactions giving rise to cyclically conjugated, charged intermediates. The possible theoretical significance of these observations is discussed.
- Krogh, Erik,Wan, Peter
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p. 705 - 712
(2007/10/02)
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- Organic Reactions Catalyzed by Solid Superacids. 5. Perfluorinated Sulfonic Acid Resin (Nafion-H) Catalyzed Intramolecular Friedel-Crafts Acylation
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Nafion-H, a perfluorinated sulfonic acid resin, catalyzed the intramolecular Friedel-Crafts acylation of diarylalkane-2-carboxylic acids and arylalkanoic acids in refluxing p-xylene to provide cyclic ketones.The reactions were clean, and the water that was formed as a byproduct did not deactivate the catalyst.It was also found that the intramolecular acylation of the corresponding acid chlorides occurred under much milder reaction conditions.The mechanism of the reaction is discussed.
- Yamato, Takehiko,Hideshima, Chieko,Prakash, G. K. Surya,Olah, George A.
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p. 3955 - 3957
(2007/10/02)
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- Synthesis of o-Substituted Phenols by Criegee Rearrangement of Benzylic Hydroperoxides
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9-Phenylthioxanthen-9-ol, 10,10-dimethyl-9-phenyl-9,10-dihydroanthracen-9-ol, and 9-arylfluoren-9-ols undergo Criegee-type rearrangements when treated with hydrogen peroxide and acid to generate substituted benzophenones from the first two substrates, and monoesters of biphenyl-2,2'-diol from the fluorenes via subsequent Bayer-Villiger oxidation of the intermediate 2'-aroylbiphenyl-2-ol. 5-Phenyl-10,11-dihydrodibenzocyclohepten-5-ol and its dehydroderivative gave the corresponding heptanone and heptenone on treatment with acid and hydrogen peroxide.Prolonged reaction of the 5-phenyldibenzohepten-5-ol afforded products arising from oxidation of the double bond.
- Taljaard, Benjamin,Goosen, Andre,McCleland, Cedric W.
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p. 931 - 934
(2007/10/02)
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- Contrasting Photosolvolytic Reactivities of 9-Fluorenol vs 5-Suberenol Derivatives. Enhanced Rate of Formation of Cyclically Conjugated Four ? Carbocations in the Excited State
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The photosolvolysis of 9-fluorenol (1) and several of its derivatives, as well as related systems, has been studied in aqueous methanol and acetonitrile solutions.The primary aim of this study was to examine the effect of the internal cyclic array (ICA) of these compounds in promoting photosolvolysis with respect to the number of ? electrons available in the ICA.It was observed that 9-fluorenol derivatives photosolvolyze much more efficiently than any of the related systems studied in this work.In contrast, ground-state 9-fluorenol derivatives are the least reactive systems with respect to solvolysis.Quantum yields for methyl ether formation for photosolvolysis in 50percent MeOH-H2O are reported for 1-3.Rate constants for solvent-assisted photodehydroxylation (ks) are calculated on the basis of the proposed mechanism of heterolytic C-OH bond rupture in the primary photochemical step and are in the range (1.3-1.6)x1E10 s-1 for 1-3.
- Wan, Peter,Krogh, Erik
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p. 4887 - 4895
(2007/10/02)
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- A PPACTICAL CATALYTIC PROCEDURE FOR OXIDATION OF ALCOHOLS INTO ALDEHYDES OR KETONES WITH RuCl3/Water and Ca(OCl)2 or NaIO4
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Ruthenium complexes catalyze the oxidation of alcohols to the corresponding ketones or aldehydes when Ca(OCl)2 or NaIO4 are used as oxygen donors in the presence of water (5 - 10 equiv.).The reactions take place at room temperature affording products in yields of 45 - 80percent.
- Genet, J. P.,Pons, D.,Juge, S.
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p. 1721 - 1726
(2007/10/02)
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- Generation and Transient Spectroscopy of Substituted Diaryl Carbonyl Oxides
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Spectroscopic and kinetic parameters for a variety of substituted diaryl carbonyl oxides in solution at room temperature are reported.These species are generated by direct reaction of oxygen with the triplet carbene derived from the corresponding diazo compound or by reaction of the diazo compound with singlet oxygen.Typically, diaryl-substituted carbonyl oxides have absorption maxima in the 400-450-nm region and decay with second-order kinetics.For example, the parent benzophenone oxide (λmax 410 nm) can be formed by reaction of the carbene with oxygen (kO2 5.0E9 M-1s-1) or by reaction of singlet oxygen with the diazo precursor (kD = 1.0E9 M-1s-1).It decays by-self-reaction with k = 1.33E7 M-1s-1 in acetonitrile and can be readily scavenged by aldehydes, e.g. for acetaldehyde k3 = 3.1E6 M-1s-1.
- Scaiano, J. C.,McGimpsey, W. G.,Casal, H. L.
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p. 1612 - 1616
(2007/10/02)
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- Carbene Cation Radicals: The Kinetics of Their Formation from Diazoalkane Cation Radicals and Their Reactions
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The unimolecular decomposition reacions of trhree diazoalkane (diazodiphenylmethane and related compounds) cation radicals were studied in acetonitrile, methanol, and mixed solvent.Kinetic studies, using transient electrochemical methods, show that the reaction rates are insensitive to solvent, the presence of nucleophiles, and the nature and concentration of electrolytes.At temperatures above 300 K the competing second-order reactions, observed to minor extents at lower temperatures, were insignificant.Arrhenius activation energies were observed to be the order of 16 kcal/mol with entropies of activation close to zero.It is suggested that the rate-determining step in all cases is unimolecular loss of dinitrogen (reaction i) to generate the reactive carbene cation radicals.The carbene cation radicals show reaction patterns that exhibit both electrophilic and Ar2C=N2.+ -> Ar2C.++N2 radical-like facets.In acetonitrile complex reaction mixtures were obtained suggesting that the carbene cation radicals react rather indiscriminately.In more nucleophilic methanol, the major products were Ar2C(OMe)2, Ar2C=O, and Ar2CHOMe in proportions depending strongly on the structure of the carbene cation radical.
- Parker, Vernon D.,Bethell, Donald
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p. 5066 - 5072
(2007/10/02)
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- Evidence for the Formation of ?-Dianions of 9-Fluorenone and 10,11-Dihydro-5H-dibenzocyclohepten-5-one from 1H NMR and CNDO Charge Distributions
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It was demonstrated on the basis of reactivity, 1H NMR and CNDO charge distributions that the ?-dianions of 9-fluorenone and 10,11-dihydro-5H-dibenzocyclohepten-5-one were formed from the corresponding neutral precursors in contact with sodium or potassium in dimethoxyethane or tetrahydrofuran at low temperature in vacuo.
- Hirayama, Masatoshi,Suzuki, Hideto,Ohhata, Hiroshi
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p. 413 - 416
(2007/10/02)
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- Ketene. Part 23. Conformational Control of the Addition Reactions of Ketenes with N-Phenylnitrones
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X-Ray analysis shows that the nitrone group in (5a) is not distorted, disproving a previous explanation for the formation of oxazolidinones rather than indolones in the reactions with ketenes.Nitrone (5c) reacts with dimethylketene and diphenylketene to form oxazolidinones (6c,d) whereas nitrones (5d) and (5e) under similar conditions form indolone derivatives (9).Oxazolidinone formation by the reaction of ketenes with nitrones (5a-c) results from restricted rotation about the N-phenyl bond preventing the -migration (3) -> (4), which precedes indolone formation.
- Falshaw, Christopher P.,Hashi, Nur A.,Taylor, Giles A.
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p. 1837 - 1844
(2007/10/02)
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- Transformations in the Dibenzocyclopentene Series
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The synthesis of 5-aminomethyl-5-hydroxy-5H-dibenzocycloheptene derivatives 3 was accomplished by two separate routes.The first route involves the reaction of 4 with Corey's Reagent followed by reaction with either amines or hydrazines.The reaction products with hydrazines (e.g. 6) were hydrogenolyzed, either with hydrogen in the presence of platinum, or with hydrazine in the presence of Raney nickel to yield 3.The second route to these compounds (3) proceeds by a Reformatsky reaction on 4 followed by acid-hydrazide formation and Curtius degradationn of 8 to afford spirooxazolidones 9.Compound 9 can be alkylated on nitrogen (10), and either 9 or 10 hydrolyzed to give target compounds 3.
- Coppola, Gary M.,Hardtmann, Goetz .,Koletar, Gabor,Kroin, Stanley
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- Reactions of Superoxide Ion with Hydrocarbons activated by the Tricarbonylchromium Unit
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The complexation of a Cr(CO)3 unit to certain aromatic hydrocarbons enhances the benzylic position towards attack by superoxide ion in dimethyl sulphoxide; ketones thus produced are also obtainable by treatment of the corresponding benzylic anion complexes with molecular oxygen.
- Top, Siden,Jaouen, Gerard,McGlinchey, Michael
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p. 643 - 644
(2007/10/02)
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- The mild rhodium(I), and phase transfer catalyzed, dehydrogenation of benzylic alcohols
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Benzylic alcohols can be dehydrogenated to carbonyl compounds by phase transfer catalyzed reaction (8 M NaOH, benzene, and PhCH2N(C2H5)3+Cl- as the catalyst) in the presence of catalytic amounts of chlorodicarbonylrhodium(I) dimer.Evidence is presented for the intermediacy of ortho-metalated complexes in these reactions.
- Alper, Howard,Hachem, Khaled,Gambarotta, Sandro
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p. 1599 - 1601
(2007/10/02)
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