- Carbonyl 1,2-transposition through triflate-mediated a-amination
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To date, it remains challenging to selectively migrate a carbonyl oxygen within a given molecular scaffold, especially to an adjacent carbon. In this work, we describe a simple one- or two-pot protocol that transposes a ketone to the vicinal carbon. This approach first converts the ketone to the corresponding alkenyl triflate, which can then undergo the palladium- and norbornene-catalyzed regioselective a-amination and ipso-hydrogenation enabled by a bifunctional hydrogen and nitrogen donor. The resulting "transposed enamine" intermediate can subsequently be hydrolyzed to produce the 1,2-carbonyl-migrated product. This method allows rapid access to unusual bioactive analogs through late-stage functionalization.
- Wu, Zhao,Xu, Xiaolong,Wang, Jianchun,Dong, Guangbin
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p. 734 - 740
(2021/11/16)
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- 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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- 9,10-Dihydroanthracene auto-photooxidation efficiently triggered photo-catalytic oxidation of organic compounds by molecular oxygen under visible light
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The development of mild and efficient process for the selective oxidation of organic compounds by molecular oxygen (O2) can be one of the key technologies for synthesizing oxygenates. This paper discloses an efficient and mild synthesis protocol for the O2-involved ethylbenzene (EB) photooxidation triggered by 910-dihydroanthracene (DHA) auto- photooxidation in acetone under visible light illumination, which can achieve 87.7 percent EB conversion and 99.5 percent acetylacetone (ACP) selectivity under ambient conditions. Also, 62.9 percent EB conversion and 96.3 percent ACP selectivity is obtained in air atmosphere. Furthermore, this protocol has a good adaptability for the photooxidation of other organic substrates such as tetrahydronaphthalene, diphenylmethane, toluene, cyclohexane, cyclohexene, alcohol, methylfuran and thioether to their corresponding oxygenates. A series of control and quenching tests, combined with EPR spectra, suggest that the photo-excited DHA can transfer its photo-electron to O2 to yield a superoxide radical anion (O2??), then DHA is preferentially oxidized to anthraquinone (AQ) by the active O2?? owing to its high reactivity. Finally, the in situ generated AQ as an active photo-catalyst can achieve the photooxidation of EB and other organic compounds by O2. The present photo-autoxidation protocol gives a good example for the O2-based selective oxidation of inert hydrocarbons under mild conditions.
- Chen, Mengke,Deng, Youer,Fu, Zaihui,Hu, Wenwei,Jiang, Dabo,Liu, Yachun,Mao, Feng,Su, Anqun,Yang, Bo,Zhang, Chao
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-
- Lewis Acid Promoted Dearomatization of Naphthols
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Two-step dearomative functionalization of naphthols promoted by Lewis acids and copper(I) catalysis was developed. Initially, Lewis acid complexation inverted the electronic properties of the ring and established an equilibrium with the dearomatized counterpart. Subsequent trapping of the dearomatized intermediate with organometallics as well as organophosphines was demonstrated and provided the corresponding dearomatized products.
- Boldrini, Cosimo,Casti?eira Reis, Marta,Harutyunyan, Syuzanna R.,Kulish, Kirill,Pérez, Juana M.
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supporting information
p. 15843 - 15846
(2020/11/30)
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- Homobenzylic Oxygenation Enabled by Dual Organic Photoredox and Cobalt Catalysis
-
Activation of aliphatic C(sp3)-H bonds in the presence of more activated benzylic C(sp3)-H bonds is often a nontrivial, if not impossible task. Herein we show that leveraging the reactivity of benzylic C(sp3)-H bonds to achieve reactivity at the homobenzylic position can be accomplished using dual organic photoredox/cobalt catalysis. Through a two-part catalytic system, alkyl arenes undergo dehydrogenation followed by an anti-Markovnikov Wacker-type oxidation to grant benzyl ketone products. This formal homobenzylic oxidation is accomplished with high atom economy without the use of directing groups, achieving valuable reactivity that traditionally would require multiple chemical transformations.
- McManus, Joshua B.,Griffin, Jeremy D.,White, Alexander R.,Nicewicz, David A.
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supporting information
p. 10325 - 10330
(2020/07/27)
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- Peroxygenase-Catalysed Epoxidation of Styrene Derivatives in Neat Reaction Media
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Biocatalytic oxyfunctionalisation reactions are traditionally conducted in aqueous media limiting their production yield. Here we report the application of a peroxygenase in neat reaction conditions reaching product concentrations of up to 360 mM.
- Alcalde, Miguel,Arends, Isabel W. C. E.,Hollmann, Frank,Paul, Caroline E.,Rauch, Marine C. R.,Tieves, Florian
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- Sulfur and nitrogen-doped porous cobalt carbon catalyst for high efficient aerobic oxidation of hydrocarbons
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The selective oxidation of hydrocarbons to corresponding ketones under green reaction conditions is of more and more important in chemical processes due to environmental and economic pressure. In this respect, we successfully prepared high efficient sulfur and nitrogen-doped porous cobalt carbon catalyst through a simple but efficient one-pot method. Potassium thiocyanate (KSCN) is using as sulfur source and complexing agent, what's more, KSCN also acts as pore-forming agent to create larger specific surface area. In addition, the as-obtained catalyst shows high catalytic performance for oxidation of hydrocarbons under solvent-free and oxygen as oxidant conditions, especially for ethylbenzene, the conversion is up to 82% with 88% of selectivity for acetophenone, which is an exciting result due to the relative low activity of oxygen in comparison with tert-butyl hydroperoxide as oxidant. This is due to structure defect and Co4S3 by the doping of KSCN in CoNC catalysts, which may result in the improvement of the catalytic performance of the catalysts.
- Lin, Xiu,Jie, Shanshan,Liu, Zhigang
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p. 143 - 149
(2018/06/18)
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- Chemoselective Continuous Ru-Catalyzed Hydrogen-Transfer Oppenauer-Type Oxidation of Secondary Alcohols
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A continuous flow method for the selective oxidation of secondary alcohols is reported. The method is based on an Oppenauer-type ruthenium-catalyzed hydrogen-transfer process that uses acetone as both solvent and oxidant. The process utilizes a low loading (1 mol%) of the commercially available ruthenium catalyst [Ru(p-cymene)Cl2]2 and triethylamine as a base and can be successfully applied to a range of different substrates, with a good level of functional group tolerance.
- Labes, Ricardo,Battilocchio, Claudio,Mateos, Carlos,Cumming, Graham R.,De Frutos, Oscar,Rincón, Juan A.,Binder, Kellie,Ley, Steven V.
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supporting information
p. 1419 - 1422
(2017/09/23)
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- Synthetic method of beta-tetralone
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The invention discloses a synthetic method of beta-tetralone. The method comprises the following steps: (1) 1,2-dichloroethane is added into a reaction bottle, and aluminium chloride is added into the reaction bottle with the protection of nitrogen; (2) phenylacetyl chloride is added into the reaction bottle; (3) ethene is introduced into the reaction bottle; (4) the mixture is permitted to stand for separation; (5) products are neutralized with alkali; (6) the products are purified. The method has the advantages of mild condition, and operation convenience; compared with prior art, the reaction temperature is improved, and operationality of the whole process is substantially improved.
- -
-
Paragraph 0027-0055
(2017/08/27)
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- Gold-Catalyzed Oxidation Terminal Alkyne: An Approach to Synthesize Substituted Dihydronaphthalen-2(1H)-ones and Phenanthrenols
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A facile gold-catalyzed oxidation terminal alkynes to synthesize substituted dihydronaphthalen-2(1H)-ones 3 and phenanthrenols 5 was realized. Various useful structures and drug precursors were generated in up to 99% yield under mild condition and low catalyst loading.
- Ling, Hui-Bo,Chen, Zi-Sheng,Yang, Fang,Xu, Bin,Gao, Jin-Ming,Ji, Kegong
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p. 7070 - 7076
(2017/07/15)
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- Anti-Markovnikov Oxidation of β-Alkyl Styrenes with H2O as the Terminal Oxidant
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Oxygenation of alkenes is one of the most straightforward routes for the construction of carbonyl compounds. Wacker oxidation provides a broadly useful strategy to convert the mineral oil into higher value-added carbonyl chemicals. However, the conventional Wacker chemistry remains problematic, such as the poor activity for internal alkenes, the lack of anti-Markovnikov regioselectivity, and the high cost and chemical waste resulted from noble metal catalysts and stoichiometric oxidant. Here, we describe an unprecedented dehydrogenative oxygenation of β-alkyl styrenes and their derivatives with water under external-oxidant-free conditions by utilizing the synergistic effect of photocatalysis and proton-reduction catalysis that can address these challenges. This dual catalytic system possesses the single anti-Markovnikov selectivity due to the property of the visible-light-induced alkene radical cation intermediate.
- Zhang, Guoting,Hu, Xia,Chiang, Chien-Wei,Yi, Hong,Pei, Pengkun,Singh, Atul K.,Lei, Aiwen
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supporting information
p. 12037 - 12040
(2016/09/28)
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- Oxone-acetone mediated Wacker-type oxidation of benzo-fused olefins
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Herein we disclose a novel application of the oxone-acetone combination for the Wacker-type oxidation of indenes and dihydronaphthalenes leading, respectively, to indan-2-ones and 2-tetralones. The amount of the base employed in the reaction seems to switch the reaction path from dioxygenation to Wacker-type oxidation. Control experiments suggest that the reaction is not proceeding via the epoxide route and also that there is no role of trace amounts of metals present in the reagents on the current oxidation.
- Phatake, Ravindra S.,Ramana, Chepuri V.
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supporting information
p. 3868 - 3871
(2015/06/08)
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- The oxidation of alcohols with O-iodoxybenzoic acid (IBX) in aqueous nanomicelles at room temperature
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GMPGS-2000, a nonionic amphiphile composed of Guerbet alcohol (2-octyldodecan-1-ol), MPEG-2000 and succinic acid, has been prepared as an effective nanomicelle forming species for the oxidation of alcohols with 2-iodoxybenzoic acid (IBX) in water at room temperature.
- Xie, Aming,Zhou, Xiangxiang,Feng, Liandong,Hu, Xinyu,Dong, Wei
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p. 3514 - 3519
(2014/05/06)
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- Organocatalytic oxidation of secondary alcohols using 1,2-Di(1-naphthyl)-1,2-ethanediamine (NEDA)
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Diamine, 1,2-di(1-naphthyl)-1,2-ethanediamine (NEDA), efficiently catalyzes the oxidation of alcohols by using TBHP as an oxidant. Notably, secondary benzyl alcohols are oxidized in almost quantitative yields, and the catalyst also displays high activity towards even hindered cycloaliphatic secondary alcohols. With enantiopure (R,R)-NEDA, oxidative kinetic resolution can be realized and depending on the alcohol ee up to 99% are achieved.
- Al-Hunaiti, Afnan,R?is?nen, Minna,Pihko, Petri,Leskel?, Markku,Repo, Timo
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supporting information
p. 6141 - 6144
(2015/03/30)
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- SBA-15-Functionalized 3-Oxo-ABNO as Recyclable Catalyst for Aerobic Oxidation of Alcohols under Metal-Free Conditions
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The nitroxyl radical 3-oxo-9-azabicyclo [3.3.1]nonane-N-oxyl (3-oxo-ABNO) has been prepared using a simple protocol. This organocatalyst is found to be an efficient catalyst for the aerobic oxidation of a wide variety of alcohols under metal-free conditions. In addition, the preparation and characterization of a supported version of 3-oxo-ABNO on ordered mesoporous silica SBA-15 (SABNO) is described for the first time. The catalyst has been characterized using several techniques including simultaneous thermal analysis (STA), transmission electron microscopy (TEM), and nitrogen sorption analysis. This catalyst exhibits catalytic performance comparable to its homogeneous analogue and much superior catalytic activity in comparison with (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO) for the aerobic oxidation of almost the same range of alcohols under identical reaction conditions. It is also found that SABNO can be conveniently recovered and reused at least 12 times without significant effect on its catalytic efficiency.
- Karimi, Babak,Farhangi, Elham,Vali, Hojatollah,Vahdati, Saleh
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p. 2735 - 2741
(2016/12/23)
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- Ruthenium(IV) porphyrin catalyzed highly selective oxidation of internal alkenes into ketones with Cl2pyNO as terminal oxidant
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A new method for the conversion of internal alkenes into ketones without cleavage of CC bond by using dichlororuthenium(IV) meso-tetrakis(2,6- dichlorophenyl)porphyrin [RuIV(TDCPP)Cl2] as catalyst and 2,6-dichloropyridine N-oxide(Cl2pyNO) as oxidant is developed.
- Wang, Zhi-Ming,Sang, Xue-Ling,Che, Chi-Ming,Chen, Jian
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supporting information
p. 1736 - 1739
(2014/03/21)
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- Rhenium-catalyzed acceptorless dehydrogenative coupling via dual activation of alcohols and carbonyl compounds
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The rhenium hetaphydride complex was found to be a versatile, homogeneous catalyst for dehydrogenative functionalization of alcohol. The dehydrogenative C-C coupling of alcohols and carbonyl compounds was carried out in the absence of base and hydrogen acceptors to afford a series of α,β-unsaturated carbonyl compounds. A possible dual activation pathway was proposed by mechanistic investigations.
- Jin, Hongming,Xie, Jin,Pan, Changduo,Zhu, Zhengbo,Cheng, Yixiang,Zhu, Chengjian
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p. 2195 - 2198
(2013/10/22)
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- Biarylphosphonite gold(I) complexes as superior catalysts for oxidative cyclization of propynyl arenes into indan-2-ones
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Striking gold: A series of variously functionalized propynyl arenes was smoothly converted into indan-2-ones by a new gold(I)-catalyzed oxidative cyclization process. [LAu]NTf2 (Tf=trifluoromethanesulfonyl) is a superior catalyst both in terms of yield and kinetics for the present transformation. Copyright
- Henrion, Guilhem,Chavas, Thomas E. J.,Le Goff, Xavier,Gagosz, Fabien
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supporting information
p. 6277 - 6282
(2013/07/11)
-
- Artificial multi-enzyme networks for the asymmetric amination of sec-alcohols
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Various artificial network designs that involve biocatalysts were tested for the asymmetric amination of sec-alcohols to the corresponding α-chiral primary amines. The artificial systems tested involved three to five redox enzymes and were exemplary of a range of different sec-alcohol substrates. Alcohols were oxidised to the corresponding ketone by an alcohol dehydrogenase. The ketones were subsequently aminated by employing a ω-transaminase. Of special interest were redox-neutral designs in which the hydride abstracted in the oxidation step was reused in the amination step of the cascade. Under optimised conditions up to 91 % conversion of an alcohol to the amine was achieved. Trickle-down effect: The asymmetric amination of sec-alcohols to the corresponding α-chiral primary amines was performed with a biocatalytic cascade whereby the various steps were interconnected through the cofactors/cosubstrates. In a redox-neutral cascade and under optimised conditions, up to 91 % conversion of an alcohol to the amine was achieved. Copyright
- Tauber, Katharina,Fuchs, Michael,Sattler, Johann H.,Pitzer, Julia,Pressnitz, Desiree,Koszelewski, Dominik,Faber, Kurt,Pfeffer, Jan,Haas, Thomas,Kroutil, Wolfgang
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p. 4030 - 4035
(2013/04/10)
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- New methylene homologation method for cyclic ketones
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Teaching new tricks to an old dog: By intercepting adducts between ketones and lithium trimethylsilyldiazomethane, a new Tiffeneau-Demjanov type methylene homologation could be realized in a single-step operation. Among proton sources and Lewis acids, silica gel was found to be the most effective reagent for the protonation of intermediates and their subsequent ring expansion (see scheme). Copyright
- Liu, Huaqing,Sun, Chunrui,Lee, Nam-Kyu,Henry, Roger F.,Lee, Daesung
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p. 11889 - 11893
(2012/10/29)
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- High-performance gold-promoted palladium catalyst towards the hydrogenation of phenol with mesoporous hollow spheres as support
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A high-performance, gold-promoted Pd catalyst with mesoporous hollow silica spheres as support, PdAu/MHSS, was prepared using an impregnation-reduction approach. The catalyst showed 10 times higher activity than commercial Pd/C catalyst and 6 times higher activity than Pd/MHSS catalyst. The conversion of phenol was 100% within 30 min of reaction at 80 °C. The catalyst was characterized by XRD, XPS, and TEM, which revealed that its high performance may result from both the high dispersion of active components on the MHSS, caused by the addition of gold, and the interaction between palladium and gold.
- Yang, Xu,Du, Li,Liao, Shijun,Li, Yuexia,Song, Huiyu
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scheme or table
p. 29 - 33
(2012/03/26)
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- Stereoselective benzylic hydroxylation of alkylbenzenes and epoxidation of styrene derivatives catalyzed by the peroxygenase of Agrocybe aegerita
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Here we report on the stereoselective benzylic hydroxylation and C1-C2 epoxidation of alkylbenzenes and styrene derivatives, respectively, by a heme-thiolate peroxygenase (EC 1.11.2.1) from the fungus Agrocybe aegerita. Benzylic hydroxylation led exclusively to the (R)-1-phenylalkanols. For (R)-1-phenylethanol, (R)-1-phenylpropanol and (R)-1-tetralol, the ee reached >99%. For longer chain lengths, the enantiomeric excesses (ee) and total turnover numbers (TTN) decreased while the number of by-products, e.g. 1-phenylketones, increased. Epoxidation of straight chain and cyclic styrene derivatives gave a heterogeneous picture and resulted in moderate to excellent ee values and TTN: e.g., in the case of (1R,2S)-cis-β-methylstyrene oxide formation, an ee >99% and a TTN of 110000 was achieved. Hydroxylation and epoxidation were true peroxygenations, which was demonstrated by the incorporation of 18O from H218O2 into the products. The use of fed-batch devices and varying feeding strategies for the substrate and co-substrate turned out to be a suitable approach to optimize peroxygenase catalysis.
- Kluge, Martin,Ullrich, Rene,Scheibner, Katrin,Hofrichter, Martin
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supporting information; experimental part
p. 440 - 446
(2012/04/10)
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- Relative tendency of carbonyl compounds to form enamines
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Equilibria between carbonyl compounds and their enamines (from O-TBDPS-derived prolinol) have been examined by NMR spectroscopy in DMSO-d 6. By comparing the exchange reactions between pairs (enamine A + carbonyl B → carbonyl A + enamine B), a quite general scale of the tendency of carbonyl groups to form enamines has been established. Aldehydes quickly give enamines that are relatively more stable than those of ketones, but there are exceptions to this expected rule; for example, 1,3-dihydroxyacetone acetals or 3,5-dioxacyclohexanones (2-phenyl-1,3-dioxan-5-one and 2,2-dimethyl-1,3- dioxan-5-one) show a greater tendency to afford enamines than many α-substituted aldehydes.
- Sanchez, Dani,Bastida, David,Bures, Jordi,Isart, Carles,Pineda, Oriol,Vilarrasa, Jaume
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supporting information; experimental part
p. 536 - 539
(2012/03/26)
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- Gold(III) complexes catalyze deoximations/transoximations at neutral pH
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Golden solution: A neutral solution of AuBr3, containing [AuBr2(OH)2]- in equilibrium with [AuBr 3(OH)]- and [AuBr4]-, promotes the chemoselective hydrolysis of robust oximes into carbonyl compounds without racemization (see scheme). The food additive diacetyl acts as a NH 2OH-trapping agent, thus avoiding the formation of gold nanoparticles and allows the reaction to run catalytically. Copyright
- Isart, Carles,Bastida, David,Bures, Jordi,Vilarrasa, Jaume
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experimental part
p. 3275 - 3279
(2011/05/12)
-
- Heterogenization of [Cu(2,2′-bpy)Cl2] and [Cu(1,10-phen)Cl2] on polyoxometalates: New catalysts for the selective oxidation of tetralin
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Mononuclear Cu(II) bipyridine (1) and phenantroline complexes (2) were synthesized and immobilized by different procedures on H3PW 12O40 polyoxometalate (POM). Characterization by XRD and SEM-EDX were performed to assess the preservation of the Keggin structure and stoichiometry of the complex. The immobilized complexes were tested as heterogeneous catalysts for the partial oxidation of tetralin (1,2,3,4-tetrahydronaphthalene) using hydrogen peroxide as oxidant in acetonitrile/water as solvent. [Cu(2,2′-bpy)Cl][H2PW 12O40] and [Cu(1,10-phen)Cl][H2PW 12O40] oxidized tetralin at room temperature, with 16 conversion with (2), to 1-tetralone and 2-tetralone with 83 selectivity. However, the selectivity for 1-tetralone was only 56. Different preparation methods for the heterogenization of these complexes on the POM Keggin unit were compared and used to enhance the selectivity to 1-tetralone to 75.
- Boltz,Blanc,Laugel,Pale,Louis
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experimental part
p. 807 - 811
(2012/04/23)
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- Design, synthesis, and in vivo characterization of a novel series of tetralin amino imidazoles as γ-secretase inhibitors: Discovery of PF-3084014
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A novel series of tetralin containing amino imidazoles, derived from modification of the corresponding phenyl acetic acid derivatives is described. Replacement of the amide led to identification of a potent series of tetralin-amino imidazoles with robust central efficacy. The reduction of brain Aβ in guinea pigs in the absence of changes in B-cells suggested a potential therapeutic index with respect to APP processing compared with biomarkers of notch related toxicity. Optimization of the FTOC to plasma concentrations at the brain Aβ EC50 lead to the identification of compound 14f (PF-3084014) which was selected for clinical development.
- Brodney, Michael A.,Auperin, David D.,Becker, Stacey L.,Bronk, Brian S.,Brown, Tracy M.,Coffman, Karen J.,Finley, James E.,Hicks, Carol D.,Karmilowicz, Michael J.,Lanz, Thomas A.,Liston, Dane,Liu, Xingrong,Martin, Barbara-Anne,Nelson, Robert B.,Nolan, Charles E.,Oborski, Christine E.,Parker, Christine P.,Richter, Karl E.G.,Pozdnyakov, Nikolay,Sahagan, Barbara G.,Schachter, Joel B.,Sokolowski, Sharon A.,Tate, Barbara,Wood, Douglas E.,Wood, Kathleen M.,Van Deusen, Jeffrey W.,Zhang, Lei
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scheme or table
p. 2637 - 2640
(2011/06/20)
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- A tuneable bifunctional water-compatible heterogeneous catalyst for the selective aqueous hydrogenation of phenols
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A water-tolerant bifunctional heterogeneous catalyst is able to effectively catalyse the selective hydrogenation of phenol to cyclohexanone in water at atmospheric pressure and room temperature with >99.9% selectivity to cyclohexanone at phenol conversions >99.9%. The catalyst was found to be highly active and reusable, giving identical activities and selectivities after >5 uses. Moreover, this reported simple bifunctional catalyst is also able to hydrogenate a range of substituted phenols in high yields under the investigated aqueous conditions. Copyright
- Liu, Hongli,Li, Yingwei,Luque, Rafael,Jiang, Huanfeng
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supporting information; experimental part
p. 3107 - 3113
(2012/01/02)
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- Copper(II) tetrafluroborate-promoted Meinwald rearrangement reactions of epoxides
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Epoxides undergo a highly efficient Meinwald rearrangement in the presence of catalytic quantities of copper(II) tetrafluoroborate to give carbonyl compounds in high yields and with excellent selectivity. The low toxicity and ease of handling of this reagent make it an attractive alternative to the more corrosive or costly Lewis acids frequently employed.
- Robinson, Mathew W.C.,Pillinger, Kathryn S.,Mabbett, Ian,Timms, David A.,Graham, Andrew E.
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supporting information; experimental part
p. 8377 - 8382
(2010/11/19)
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- A concise method for the synthesis of 2-tetralone by titanium tetrachloride-promoted cyclization of 4-aryl-2-hydroxybutanal diethyl acetal
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4-Aryl-2-hydroxybutanal diethyl acetal, prepared from the reaction of benzyl Grignard reagent and glycidaldehyde diethyl acetal, was treated with titanium tetrachloride to give 2-tetralone in good yield. This highly efficient transformation involves tande
- Hon, Yung-Son,Devulapally, Rammohan
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scheme or table
p. 5713 - 5715
(2009/12/09)
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- TiCl4-promoted intramolecular cyclization of 4-methoxy-5-arylethyl-1,3-dioxolan-2-ones: an expedient method to prepare 2-tetralones
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DABCO is a very effective catalyst in the formation of 4-methoxy-5-arylethyl-1,3-dioxolan-2-ones 12 from the corresponding α-carbonatoaldehyde. Intramolecular cyclization of cyclic carbonates 12 promoted by TiCl4 affords 2-tetralones 13 contain
- Hon, Yung-Son,Devulapally, Rammohan
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experimental part
p. 2831 - 2834
(2009/09/30)
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- Et2Zn-mediated rearrangement of bromohydrins
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(Chemical Equation Presented) A simple and highly efficient method for the rearrangement of bromohydrins mediated by Et2Zn to synthesize carbonyl compounds was described. Various β-bromo alcohols were treated with 0.6 equiv of Et2Zn to form a zinc complex in CH 2Cl2 at room temperature for 2 h, followed by 1,2-migration to give the corresponding carbonyl compounds. This remarkable and clean rearrangement is general for acyclic and cyclic bromohydrins, and a variety of ring-expansive and -contractive carbonyl compounds were obtained in good to excellent yields according to the feature of the starting bromohydrins. The functional group tolerance of organozinc reagents in this reaction will be useful in organic synthesis. The scope and limitations of this rearrangement process were also investigated.
- Li, Lezhen,Cai, Peijie,Guo, Qingxiang,Xue, Song
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p. 3516 - 3522
(2008/09/20)
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- Synthesis of aryl-containing terpenoids based on 1,4-dihydronaphthalene
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Successive transformations including oxidation of 1,4-dihydronaphthalene into 1,2,3,4-tetrahydronaphthalen-2-one, Reformatskii reaction of the latter with methyl bromoacetate, ozonolysis of the Reformatsky reaction product, and Emmons olefination of the aldehyde group in methyl 3-oxo-5-(2-formylphenyl) pentanate thus formed gave analogs of highly active dienoate juvenoids having an aromatic ring in their molecules.
- Kukovinets,Kislitsyn,Zainullin,Mukhamedzyanova,Galin,Abdullin
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p. 362 - 368
(2008/12/22)
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- Discovery of the first nonpeptidic, Small-molecule, highly selective somatostatin receptor subtype 5 antagonists: A chemogenomics approach
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We disclose the first selective, nonpeptidic, small-molecule somatostatin receptor subtype 5 (SST5R) antagonists that were identified by a chemogenomics approach based on the analysis of the homology of amino acids defining the putative consensus drug binding site of SST5R. With this strategy, opioid, histamine, dopamine, and serotonine receptors were identified as the closest neighbors of SST5R. The H1 antagonist astemizole was chosen as a seed structure and subsequently transformed into a SST5 receptor antagonist with nanomolar binding affinity devoid of the original target activity.
- Martin, Rainer E.,Green, Luke G.,Guba, Wolfgang,Kratochwil, Nicole,Christ, Andreas
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p. 6291 - 6294
(2008/03/30)
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- Heteroaryl β-tetralin ureas as novel antagonists of human TRPV1
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We report on a series of α-substituted-β-tetralin-derived and related phenethyl-based isoquinolinyl and hydroxynaphthyl ureas as potent antagonists of the human TRPV1 receptor. The synthesis and Structure-activity relationships (SAR) of the series are described.
- Jetter, Michele C.,Youngman, Mark A.,McNally, James J.,McDonnell, Mark E.,Zhang, Sui-Po,Dubin, Adrienne E.,Nasser, Nadia,Codd, Ellen E.,Flores, Christopher M.,Dax, Scott L.
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p. 6160 - 6163
(2008/03/18)
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- Substrate specificity and reaction mechanism of recombinant styrene oxide isomerase from Pseudomonas putida S12
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To clarify the substrate specificity of the recombinant styrene oxide isomerase, various epoxides were subjected to the reaction. From the substituent effect on the rate of isomerization, the mechanism of the isomerase catalyzed reaction was estimated.
- Miyamoto, Kenji,Okuro, Kou,Ohta, Hiromichi
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p. 3255 - 3257
(2008/02/02)
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- Photochemistry of 1,2-dihydronaphthaiene oxide: Concurrent triplet and singlet processes via singlet excitation
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The photochemistry of 1,2-dihydronaphthalene oxide (254 nm) was reexamined and indan was found to be a primary photoproduct, as well as the traditionally assumed secondary photoproduct. Quenching studies demonstrated that indan, as a primary photoproduct, is derived from a triplet pathway, competing with a singlet route, back to the ground state surface. CASSCF calculations strongly suggest that the triplet pathway consists of a dissociation of the oxirane moiety to give a triplet carbene and aldehyde, which via hydrogen abstraction-decarbonylation-ISC recloses to give indan. Conical intersections corresponding to the presumed 1,2-hydrogen shift and 1,2-alkyl shift to give 2-tetralone and 1-indancarbaldehyde, respectively, were located computationally.
- White, Rick C.,Arney Jr., Benny E.,White, Katherine M.
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p. 8173 - 8177
(2007/10/03)
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- Selective hydrogenation of naphthols to tetralones over supported palladium catalysts in supercritical carbon dioxide solvent
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Naphthols were selectively hydrogenated to the corresponding tetralones over supported palladium metal catalysts in supercritical carbon dioxide solvent. Copyright
- Mine, Eiichi,Hiyoshi, Norihito,Sato, Osamu,Rode, Chandrashekhar V.,Shirai, Masayuki
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p. 780 - 781
(2007/10/03)
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- Highly efficient Meinwald rearrangement reactions of epoxides catalyzed by copper tetrafluoroborate
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Epoxides undergo a highly efficient and selective rearrangement in the presence of catalytic quantities of copper tetrafluoroborate to give carbonyl compounds in excellent yields. The low toxicity and ease of handling of this reagent make it an attractive alternative to the more corrosive Lewis acids frequently employed.
- Robinson, Mathew W.C.,Pillinger, Kathryn S.,Graham, Andrew E.
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p. 5919 - 5921
(2007/10/03)
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- 2,6-Dicarboxypyridinium fluorochromate: A mild and efficient reagent for oxidative deprotection of oximes, phenylhydrazones, and semicarbazones to their corresponding carbonyl compounds under solvent-free conditions
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2,6-Dicarboxypyridinium fluorochromate as a new, rapid, and efficient reagent was prepared and used for the oxidative deprotection of oximes, phenylhydrazones, and semicarbazones to their carbonyl analogues under solvent-free conditions at room temperature.
- Tajbakhsh, Mahmood,Hosseinzadeh, Rahman,Ramzanian-Lahmali, Farhad,Sadatshahabi, Marzieh
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p. 1005 - 1009
(2007/10/03)
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- Partial ring hydrogenation of naphthols over supported metal catalysts in supercritical carbon dioxide solvent
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Selective ring hydrogenation of naphthols to tetrahydronaphthols and tetralones proceeded at 323 K over a charcoal supported rhodium catalyst in supercritical carbon dioxide. Copyright
- Mine, Eiichi,Haryu, Eiji,Arai, Kunio,Sato, Takafumi,Sato, Osamu,Sasaki, Akiyoshi,Rode, Chandrashekhar V.,Shirai, Masayuki
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p. 782 - 783
(2007/10/03)
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- Application of [hydroxy(tosyloxy)iodo]benzene in the wittig-ring expansion sequence for the synthesis of β-benzocycloalkenones from α-benzocycloalkenones
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The conversion of α-benzocycloalkenones to homologous β-benzocycloalkenones containing six, seven and eight-membered rings is reported. This was accomplished via a Wittig olefination-oxidative rearrangement sequence using [hydroxy(tosyloxy)iodo]-benzene (HTIB) is the oxidant, that enables the synthesis of regioisomeric pairs of methyl-substituted β-benzocycloalkenones. The incorporation of carbon-13 at C-1 of the β-tetralone nucleus was also demonstrated. The Wittig-HTIB approach is a useful alternative to analogous sequences in which Tl(NO3) 3·3H2O or the Prevost combination (AgNO 3/I2) are employed in the oxidation step.
- Justik, Michael W.,Koser, Gerald F.
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p. 217 - 225
(2007/10/03)
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- Photocatalytic oxidation of alkanes with dioxygen by visible light and copper(II) and iron(III) chlorides: Preference oxidation of alkanes over alcohols and ketones
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Visible light irradiation of alkanes in acetonitrile with CuCl2 and FeCl3 catalysts under atmospheric dioxygen gave the corresponding alcohols and ketones effectively; in these reactions, the total selectivity of the products did not decrease so much with increase of alkane conversion. For example, cyclohexanol and cyclohexanone were formed with ca. 70% selectivity at 50% conversion, because overoxidation of the products took place more slowly than cyclohexane oxidation. The relative reactivity values of cycloalkanes increased as their ring-sizes decreased. In the oxidation of hexane, the reactivity ratio of C1-/C2-/C3-H was found to be 1.0/1.4/1.8 with CuCl2 and 1.0/4.6/6.6 with FeCl3, respectively. Toluene and diphenylmethane were more reactive than cyclohexane with FeCl3, as expected, whereas the alkane was oxidized faster than the benzylic compounds in the separate reaction with CuCl2. Moreover, the alkane oxidation could be comparably performed by sunlight instead of an artificial lamp.
- Takaki, Ken,Yamamoto, Jun,Komeyama, Kimihiro,Kawabata, Tomonori,Takehira, Katsuomi
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p. 2251 - 2255
(2007/10/03)
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- Liquid phase oxidation of alkenes with nitrous oxide to carbonyl compounds
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A variety of substrates including linear, cyclic, heterocyclic alkenes and their derivatives were tested in the liquid phase non-catalytic oxidation with nitrous oxide (N2O). The structure and composition of the alkenes have a significant effect on the reaction selectivity. With many alkenes, N 2O oxidation provides a selective way for the preparation of carbonyl compounds. The generation of carbene (or diazomethane) species is a remarkable feature of the oxidation of terminal alkenes.
- Starokon,Dubkov,Babushkin,Parmon,Panov
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p. 268 - 274
(2007/10/03)
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- Iridium-catalyzed alternative of the Meinwald rearrangement
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A novel and easy to handle procedure for the regioselective rearrangement of epoxides has been developed, based on an iridium catalyst.
- Karamé, Iyad,Tommasino, M. Lorraine,Lemaire, Marc
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p. 7687 - 7689
(2007/10/03)
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- Chemoselective deprotection of 1,3-oxathiolanes using Amberlyst 15 and glyoxylic acid under solvent free conditions
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Carbonyl compounds were regenerated from corresponding 1,3-oxathiolanes via equilibrium exchange with glyoxylic acid and Amberlyst 15 as the heterogeneous catalyst, under solvent free conditions.
- Chavan,Soni,Kamat
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p. 1251 - 1252
(2007/10/03)
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- Half-sandwich chloro complexes as ligands for RuCl2L2 (L = PR3, alkene): Syntheses, structures, and catalytic activity of new homo- and heterobimetallic complexes
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Homo- and heterobimetallic complexes, in which half-sandwich complexes of ruthenium(II), rhodium(III), and iridium(III) are connected via three chloro bridges to RuCl2(PPh3)2, have been synthesized. The complexes were obtained in quantitative yields by reaction of [(cymene)RuCl(μ-Cl)]2 or [Cp*MCl(μ-Cl)]2 (M = Rh, Ir) with [(PPh3)2ClRu(μ-Cl)3Ru(Me2CO) (PPh3)2] (2). The crystal structure of 2 has been determined by X-ray analysis. Evidence that half-sandwich chloro complexes are generally suited for stabilizing RuCl2L2 fragments is provided by the synthesis of complexes [(cymene)Ru(μ-Cl)3RuCl(dppb)] [dppb = 1,4-bis(diphenylphosphanyl)butane] and [(cymene)Ru(μ-Cl)3RuCl(cod)] (cod = 1,5-cyclooctadiene), both of which have been structurally characterized. The abilities of all the complexes to catalyze the oxidation of secondary alcohols with 2-butanone have been investigated. The complex [Cp*Rh(μ-Cl)3RuCl(PPh3)2] has proved to be highly active, displaying a performance superior to that of previously known catalysts such as [RuCl2(PPh3)3]. Using a substrate/catalyst ratio of 500:1, initial turnover frequencies of up to 3400 h-1 were observed. The potential of these types of bimetallic complexes to act as catalysts for other reactions is discussed.
- Da Silva, Ana C.,Piotrowski, Holger,Mayer, Peter,Polborn, Kurt,Severin, Kay
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p. 685 - 691
(2007/10/03)
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- Asymmetric epoxidation with a photoactivated [Ru(salen)] complex
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(Nitrosyl)(salen)ruthenium(II) complex 1 was found to serve as an efficient catalyst for the epoxidation of conjugated olefins under photoirradiation, with 2,6-dichloropyridine N-oxide (2) or tetramethylpyrazine N,N′-dioxide as a stoichiometric oxidant. High enantioselectivity was achieved irrespective of the substitution pattern of olefins. The choice of solvent depends on stability of the resulting epoxides: high enantioselectivity is generally observed in the reaction with ethereal solvents, but use of benzene is recommended when the resulting epoxides are acid-sensitive.
- Nakata, Kenya,Takeda, Tsuyoshi,Mihara, Jun,Hamada, Tetsuya,Irie, Ryo,Katsuki, Tsutomu
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p. 3776 - 3782
(2007/10/03)
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- Bismuth(III) oxide perchlorate promoted rearrangement of epoxides to aldehydes and ketones
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Aryl-substituted epoxides and aliphatic epoxides with a tertiary epoxide carbon undergo smooth rearrangement in the presence of 10-50 mol% bismuth(III) oxide perchlorate, BiOClO4·XH2O, to give carbonyl compounds. The rearrangement is regioselective with aryl substituted epoxides and a single carbonyl compound arising from cleavage of benzylic C-O bond is formed. BiOClO4·XH2O is relatively non-toxic, insensitive to air and inexpensive, making this catalyst an attractive alternative to more corrosive and toxic Lewis acids such as BF3·Et2O or INCl3 currently used to effect epoxide rearrangements. (C) 2000 Elsevier Science Ltd.
- Anderson, Andrew M.,Blazek, Jesse M.,Garg, Parie,Payne, Brian J.,Mohan, Ram S.
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p. 1527 - 1530
(2007/10/03)
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- Photo-controlled Lewis acidity: Chiral (ON)Ru-salen catalyzed hetero Diels-Alder reaction and kinetic resolution of racemic epoxides
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(ON+)(Salen)ruthenium(II) complex 1 serves as a chiral Lewis acid catalyst for asymmetric hetero Diels-Alder reaction and for kinetic resolution of racemic epoxides when the reactions were carried out under sunlight coming through windows or incandescent light.
- Mihara, Jun,Hamada, Tetsuya,Takeda, Tsuyoshi,Irie, Ryo,Katsuki, Tsutomu
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p. 1160 - 1162
(2007/10/03)
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- Electronic effects on enol acidity and keto-enol equilibrium constants for ring-substituted 2-tetralones
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Equilibrium constants for the ionization of a variety of phenyl-substituted 2-tetralones (pK(a)(K)), for the ionization of their enols (pK(a)(E)), and for keto-enol tautomerization (PK(E)) were determined. Hammett plots of pK(a)(K) and pK(a)(E) vs. σ are linear with slopes (-ρ) of -1.66 ± 0.06 and -0.90 ± 0.03, respectively, except for deviations of the points corresponding to 6-nitro-2-tetralone (1b) and its enol. We have previously attributed the negative deviation of 1b from the correlation for the acidities of the ketones obtained with the more limited set of data to the lack of a free electron pair on C-1 of the free tetralone (Nevy et al.). The negative deviation of the point for 1b from the correlation for the acidities of the enols suggests that charge transfer from the hydroxyl group of the enol to the nitro group is less important than it is for phenols. This study represents the first systematic study of electronic effects on equilibria among ketone, enol, and enolate in aqueous solution.
- Yao,Pollack
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p. 634 - 638
(2007/10/03)
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