- Selective Catalytic Synthesis of 1,2- and 8,9-Cyclic Limonene Carbonates as Versatile Building Blocks for Novel Hydroxyurethanes
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The selective catalytic synthesis of limonene-derived monofunctional cyclic carbonates and their subsequent functionalisation via thiol–ene addition and amine ring-opening is reported. A phosphotungstate polyoxometalate catalyst used for limonene epoxidation in the 1,2-position is shown to also be active in cyclic carbonate synthesis, allowing a two-step, one-pot synthesis without intermittent epoxide isolation. When used in conjunction with a classical halide catalyst, the polyoxometalate increased the rate of carbonation in a synergistic double-activation of both substrates. The cis isomer is shown to be responsible for incomplete conversion and by-product formation in commercial mixtures of 1,2-limomene oxide. Carbonation of 8,9-limonene epoxide furnished the 8,9-limonene carbonate for the first time. Both cyclic carbonates underwent thiol–ene addition reactions to yield linked di-monocarbonates, which can be used in linear non-isocyanate polyurethanes synthesis, as shown by their facile ring-opening with N-hexylamine. Thus, the selective catalytic route to monofunctional limonene carbonates gives straightforward access to monomers for novel bio-based polymers.
- Maltby, Katarzyna A.,Hutchby, Marc,Plucinski, Pawel,Davidson, Matthew G.,Hintermair, Ulrich
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supporting information
p. 7405 - 7415
(2020/05/25)
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- Bimetallic Radical Redox-Relay Catalysis for the Isomerization of Epoxides to Allylic Alcohols
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Organic radicals are generally short-lived intermediates with exceptionally high reactivity. Strategically, achieving synthetically useful transformations mediated by organic radicals requires both efficient initiation and selective termination events. Here, we report a new catalytic strategy, namely, bimetallic radical redox-relay, in the regio- and stereoselective rearrangement of epoxides to allylic alcohols. This approach exploits the rich redox chemistry of Ti and Co complexes and merges reductive epoxide ring opening (initiation) with hydrogen atom transfer (termination). Critically, upon effecting key bond-forming and -breaking events, Ti and Co catalysts undergo proton transfer/electron transfer with one another to achieve turnover, thus constituting a truly synergistic dual catalytic system.
- Ye, Ke-Yin,Mccallum, Terry,Lin, Song
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supporting information
(2019/06/24)
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- Combining Photo-Organo Redox- and Enzyme Catalysis Facilitates Asymmetric C-H Bond Functionalization
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In this study, we combined photo-organo redox catalysis and biocatalysis to achieve asymmetric C–H bond functionalization of simple alkane starting materials. The photo-organo catalyst anthraquinone sulfate (SAS) was employed to oxyfunctionalise alkanes to aldehydes and ketones. We coupled this light-driven reaction with asymmetric enzymatic functionalisations to yield chiral hydroxynitriles, amines, acyloins and α-chiral ketones with up to 99 % ee. In addition, we demonstrate functional group interconversion to alcohols, esters and carboxylic acids. The transformations can be performed as concurrent tandem reactions. We identified the degradation of substrates and inhibition of the biocatalysts as limiting factors affecting compatibility, due to reactive oxygen species generated in the photocatalytic step. These incompatibilities were addressed by reaction engineering, such as applying a two-phase system or temporal and spatial separation of the catalysts. Using a selection of eleven starting alkanes, one photo-organo catalyst and 8 diverse biocatalysts, we synthesized 26 products and report for the model compounds benzoin and mandelonitrile > 97 % ee at gram scale.
- Zhang, Wuyuan,Fueyo, Elena Fernandez,Hollmann, Frank,Martin, Laura Leemans,Pesic, Milja,Wardenga, Rainer,H?hne, Matthias,Schmidt, Sandy
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supporting information
p. 80 - 84
(2019/01/04)
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- Creating Hierarchical Pores by Controlled Linker Thermolysis in Multivariate Metal-Organic Frameworks
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Sufficient pore size, appropriate stability, and hierarchical porosity are three prerequisites for open frameworks designed for drug delivery, enzyme immobilization, and catalysis involving large molecules. Herein, we report a powerful and general strategy, linker thermolysis, to construct ultrastable hierarchically porous metal-organic frameworks (HP-MOFs) with tunable pore size distribution. Linker instability, usually an undesirable trait of MOFs, was exploited to create mesopores by generating crystal defects throughout a microporous MOF crystal via thermolysis. The crystallinity and stability of HP-MOFs remain after thermolabile linkers are selectively removed from multivariate metal-organic frameworks (MTV-MOFs) through a decarboxylation process. A domain-based linker spatial distribution was found to be critical for creating hierarchical pores inside MTV-MOFs. Furthermore, linker thermolysis promotes the formation of ultrasmall metal oxide nanoparticles immobilized in an open framework that exhibits high catalytic activity for Lewis acid-catalyzed reactions. Most importantly, this work provides fresh insights into the connection between linker apportionment and vacancy distribution, which may shed light on probing the disordered linker apportionment in multivariate systems, a long-standing challenge in the study of MTV-MOFs.
- Feng, Liang,Yuan, Shuai,Zhang, Liang-Liang,Tan, Kui,Li, Jia-Luo,Kirchon, Angelo,Liu, Ling-Mei,Zhang, Peng,Han, Yu,Chabal, Yves J.,Zhou, Hong-Cai
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supporting information
p. 2363 - 2372
(2018/02/19)
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- Pt/Ferric Hydroxyphosphate: An Effective Catalyst for the Selective Hydrogenation of Α,Β-Unsaturated Aldehydes (Ketones) into Α,Β-Unsaturated Alcohols
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Abstract: Four micro (nano)-sized mesoporous ferric hydroxyphosphates (FHP) are synthesized by a reverse microemulsion-solvothermal method, and then are used as supports to prepare supported Pt catalysts. The mean particle diameter of Pt nanoparticles (NPs) was 4.5–4.6?nm. When the four different Pt/FHP catalysts were used into the hydrogenation of α,β-unsaturated aldehydes (ketones) to their corresponding unsaturated alcohols, Pt/FHP (c) catalyst showed better catalytic performance than the other three partners. Under the optimal experimental conditions, several tested α,β-unsaturated aldehydes could be effectively transformed into corresponding unsaturated alcohols over Pt/FHP (c) catalyst. The catalyst could be recycled and reused several times without activity loss. We propose the stronger interaction between the Pt NPs and ferric ions of the FHP (c) are responsible for its good catalytic performance, and this stronger interaction should be rooted in its enhanced Lewis acid strength.
- Liu, Cheng,Luo, Wei,Liu, Junhua,Sun, Lei,Yang, Yue,Liu, Gui,Wang, Fang,Zhong, Wei,Guild, Curtis,Suib, Steven L.
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p. 555 - 563
(2018/01/11)
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- Zeolite Y encaged Ru(III) and Fe(III) complexes for oxidation of styrene, cyclohexene, limonene, and α-pinene: An eye-catching impact of H2SO4 on product selectivity
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A novel Ru(III) and Fe(III) complexes of ligands 1 and/or 2 {where 1 = 2,2'-((1E,1'E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene))diphenol and 2 = 2,2'-((1E,1'E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene)) bis(4-nitrophenol)} have been synthesized as ‘neat’ and zeolite Y encapsulated complexes. These catalysts are characterized by various analytical tools such as FTIR, UV–vis, elemental analysis, ICP-AES, molar conductivity, 1H- and 13C NMR, TGA, SEM, AAS, BET, magnetic susceptibility and powder XRD to endorse the complex formation, absence of peripheral redundant ligands and complexes, conservation of zeolite Y morphology and crystallinity, and the encapsulation of complexes without devastation in the zeolite Y framework. Out of these synthesized catalysts, 5Y is found to be a potent candidate for styrene (Conv. 76.1%, TOF: 2130 h?1), cyclohexene (Conv. 84.4%, TOF: 2351 h?1), limonene (Conv. 81.6%, TOF: 2273 h?1), and α-pinene (Conv. 72.6%, TOF: 2023 h?1) oxidation with high selectivity of respective allylic products excluding the styrene oxidation, which undergoes epoxidation only. The addition of H2SO4 in an identical reaction catalyzed by 5Y not only surge the conversion up to 100% in a short time span with high TOF but also increase the selectivity of respective epoxidation products. This switchover in the selectivities could be credited to the presence of H2SO4 that facilitates the heterolytic [sbnd]O[sbnd]O[sbnd] bond cleavage of metal hydroperoxide and stimulates the epoxidation over allylic oxidation. Furthermore, the results establish that the heterogeneous systems are effortlessly recovered and reused without ample drop in the activity and selectivity.
- Godhani, Dinesh R.,Nakum, Haresh D.,Parmar, Digvijaysinh K.,Mehta, Jignasu P.,Desai, Nisheeth C.
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p. 223 - 237
(2016/12/09)
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- Fe/EuroPh catalysts for limonene oxidation to 1,2-epoxylimonene, its diol, carveol, carvone and perillyl alcohol
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The catalysts in the form of an activated carbon EuroPh supported Fe were prepared and characterized structurally and chemically by XRD, nitrogen sorption, FESEM, EDX, and ICP-AES methods. The active phase was magnetite Fe3O4. The concentration of Fe in the catalysts was equal to 0.68, 1.32, 2.64 wt%. The catalytic activity of the obtained catalysts was examined in limonene oxidation with hydrogen peroxide and tert-butyl hydroperoxide as oxidants. The studies were carried out in a batch reactor. The catalytic activity of the recovered catalysts was also tested. The research showed that all from the studied catalysts were active in the limonene oxidation. As a result of limonene oxidation the following products were mainly obtained: 1,2-epoxylimonene diol, carveol, carvone and perillyl alcohol - products with a great importance. The reused catalysts were characterized by considerably lover activity in the limonene oxidation than in the first run, especially when the oxidation was performed with t-butyl hydroperoxide.
- Mlodzik, Jacek,Wrblewska, Agnieszka,Makuch, Edyta,Wrbel, Rafal J.,Michalkiewicz, Beata
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p. 111 - 120
(2016/04/26)
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- Hydrophobic effect of silica functionalized with silylated Ti-salicylaldimine complex on limonene oxidation by aqueous hydrogen peroxide
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This research work describes the effect of hydrophobicity in inducing the diffusion of alkene substrates to the catalytic active sites. The aim of this research is to improve the catalytic activity by tailoring the degree of hydrophobicity of the catalyst. Silica functionalized with solid non-silylated Ti-salicylaldimine complex was prepared at room temperature by mixing imine ligand and Ti(IV) sulphate solution. The amorphous, solid complex formed was further silylated with octadecyltrimethoxysilane (OTMS) to induce hydrophobicity. The composition of the resulting silica functionalized with silylated Ti-salicylaldimine complex was varied with Ti:OTMS molar ratio in the range of 1:1/4 to 1:4 at room temperature. The successful attachment of alkylsilyl groups to silica functionalized with Ti-salicylaldimine complex was proven by the FTIR and 29Si solid state NMR spectra. The FTIR spectra showed increasing peak area for sp 3 C-H stretching mode (ca. 2919 cm-1 and 2850 cm-1) and decreasing peak area for Si-OH band with increasing amount of OTMS. TGA showed less water content with higher amount of alkylsilyl groups in the catalyst. This is in agreement with the lower kinetic rate of water adsorption capacity for the hydrophobic catalysts prepared. It was observed that the hydrophobic, silica functionalized with silylated Ti-salicylaldimine complex exhibited higher substrate conversion and reusability compared to the non-silylated catalyst.
- Yuan, Lai Sin,Chandren, Sheela,Efendi, Jon,Ho, Chin Siong,Nur, Hadi
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p. 1905 - 1917
(2015/12/30)
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- Synthesis, spectral investigation and catalytic aspects of entrapped VO(IV) and Cu(II) complexes into the supercages of zeolite-Y
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VO(IV) and Cu(II) complexes with Schiff base ligand derived from 1-phenyl-3-methyl-4-formyl-2-pyrazolin-5-one (PMFP) and 2-amino phenol have been synthesized as their neat and entrapped complexes into the supercages of zeolite-Y. The compounds were characterized by chemical analysis (ICP-OES and elemental), electronic and/or UV reflectance spectra, FTIR spectroscopy, X-ray powder diffraction patterns, SEMs, BET and thermogravimetric (TG) analysis. All the prepared catalysts were tested on the liquid phase limonene oxidation reaction, using 30% H2O2 as an oxidant. Limonene glycol, carveol, carvone and limonene 1,2-epoxide were the main products obtained. It was observed that zeolite-Y entrapped complexes exhibited higher catalytic activity than neat complexes. The catalysts undergo no metal leaching and can be easily recovered and reused. The use of inexpensive catalyst and oxidant are significant practical advantages of this environmentally friendly process.
- Modi, Chetan K.,Gade, Bhagyashree G.,Chudasama, Jiten A.,Parmar, Digvijay K.,Nakum, Haresh D.,Patel, Arun L.
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p. 174 - 184
(2015/01/30)
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- Catalytic oxidation of limonene over zeolite-Y entrapped oxovanadium (IV) complexes as heterogeneous catalysts
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A series of VO(IV) complexes with Schiff base ligands derived from vanillin thiophene-2-carboxylic hydrazone (VTCH), vanillin furoic-2-carboxylic hydrazone (VFCH), salicylaldehyde thiophene-2-carboxylic hydrazone (H2STCH) and/or salicylaldehyde furoic-2-carboxylic hydrazone (H2SFCH) have been synthesized as neat and their entrapped complexes into the nanopores of zeolite-Y. These materials were characterized by several techniques: chemical analysis (ICP-OES and elemental) and spectroscopic methods (FT-IR, electronic, XRD, SEMs and BET). All the prepared catalysts were tested over the liquid phase limonene oxidation reaction, using t-butyl hydroperoxide (TBHP) and/or 30% H2O2 as oxidants. Limonene glycol, carveol and carvone were the main products obtained. It was observed that zeolite-Y based entrapped complexes exhibited higher catalytic activity than neat VO(IV) complexes. These zeolite-Y based entrapped complexes are stable and recyclable under current reaction conditions. Amongst them, [VO(VTCH)2]-Y showed higher catalytic activity (97.7%) with limonene glycol (45.1%), selectivity.
- Modi, Chetan K.,Chudasama, Jiten A.,Nakum, Haresh D.,Parmar, Digvijaysinh K.,Patel, Arun L.
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p. 151 - 161
(2014/11/27)
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- COMPLEX CATALYSTS BASED ON AMINO-PHOSPHINE LIGANDS FOR HYDROGENATION AND DEHYDROGENATION PROCESSES
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The present application discloses novel PWNN and PWNWP metal catalysts for organic chemical syntheses including hydrogenation (reduction) of unsaturated compounds or dehydrogenation of substrates. The range of hydrogenation substrate compounds includes esters, lactones, enals, enones, enolates, oils and fats, resulting in alcohols, enols, diols, and triols as reaction products. The catalysts of current application can be used to catalyze a hydrogenation reaction under solvent free conditions. The present catalysts also allow the hydrogenation to proceed without added base, and it can be used in place of the conventional reduction methods employing hydrides of the main-group elements. Furthermore, the catalysts of the present application can catalyze a dehydrogenation reaction under homogenous and/or acceptorless conditions. As such, the catalysts provided herein can be useful in substantially reducing cost and improving the environmental profile of manufacturing processes for a variety of chemicals.
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Page/Page column 39; 40; 41; 42
(2014/09/29)
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- Electrochemical intramolecular aminooxygenation of unactivated alkenes
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An electrochemical approach to the intramolecular aminooxygenation of unactivated alkenes has been developed. This process is based on the addition of nitrogen-centered radicals, generated through electrochemical oxidation, to alkenes followed by trapping of the cyclized radical intermediate with 2,2,6,6-tetramethylpiperidine-N-oxyl radical (TEMPO). Difunctionalization of a variety of alkenes with easily available carbamates/amides and TEMPO affords aminooxygenation products in high yields and with excellent trans selectivity for cyclic systems (d.r. up to>20:1). The approach provides a much-needed complementary route to existing cis-selective methods.
- Xu, Fan,Zhu, Lin,Zhu, Shaobin,Yan, Xiaomei,Xu, Hai-Chao
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supporting information
p. 12740 - 12744
(2015/03/30)
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- New fungi for whole-cell biotransformation of carvone enantiomers. Novel p-menthane-2,8,9-triols production
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The microbial biotransformation of carvone enantiomers by Lasiodiplodia theobromae, Trichoderma harzianum and Mucor circinelloides was investigated. Biotransformation experiments were conducted using growing or resting fungi cells and the products were an
- Nunes, Fátima M.,Dos Santos, Gabriel F.,Saraiva, Natália N.,Trapp, Marília A.,De Mattos, Marcos C.,Oliveira, Maria Da Concei??o F.,Rodrigues-Filho, Edson
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- Lanthanide replacement in organic synthesis: Luche-type reduction of α,β-unsaturated ketones in the presence of calcium triflate
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Development of a calcium-mediated regioselective 1,2-reduction of challenging α,β-unsaturated ketones, such as 2-cyclopententone, is reported. The corresponding allylic alcohols are obtained in very good regioselectivities using Ca(OTf)2 and NaBH4. Furthermore, we have shown that our method can stereoselectively reduce aziridinyl ketones.
- Forkel, Nina V.,Henderson, David A.,Fuchter, Matthew J.
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supporting information; scheme or table
p. 2129 - 2132
(2012/09/08)
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- Synthetic studies on C14 cembranoids: Synthesis of C4-12 fragment of sarcophytonolides E-G and L and C5-11 fragment of sarcophytonolide L
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An efficient stereoselective synthesis of C4-12 fragment of the cembranoids, sarcophytonolides E-G and L and C5-11 fragment of sarcophytonolide L is described. The C4-12 building block is efficiently assembled starting from chiral pool material (R)-carvon
- Fernandes, Rodney A.,Ingle, Arun B.
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scheme or table
p. 458 - 460
(2011/02/26)
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- Selective synthesis of carvone and cryptomerlone from α-pinene
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Carvone and cryptomerlone were synthesized selectively using electrochemical oxidation of α-pinene in the key step. 2006 Springer Science+Business Media, Inc.
- Macaev,Vlad,Gudima
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p. 301 - 303
(2008/02/07)
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- Cross-coupling reactions of hypervalent siloxane derivatives: An alternative to stille and Suzuki couplings
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Palladium-catalyzed cross-coupling of phenyl, vinyl, and allyl siloxane derivatives proceeded in good to excellent yield with aryl iodides, electron-deficient aryl bromides, and allylic benzoates. Methyl and 2,2,2-trifluoroethyl siloxane derivatives can be employed in the coupling reaction. Electron-donating and -withdrawing groups are tolerated on the aryl halide without affecting the coupling. The scope and limitations of this alternative to Stille and Suzuki couplings is outlined.
- Mowery, Molly E.,DeShong, Philip
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p. 1684 - 1688
(2007/10/03)
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- An efficient method for the reductive transposition of allylic alcohols
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The Mitsunobu reaction of allylic alcohols with o- nitrobenzenesulfonylhydrazine (NBSH) as nucleophile proceeds at -30 °C with invertive displacement; warming the resultant N-allylic sulfonylhydrazine derivative to 23 °C then leads to allylic diazene formation followed by sigmatropic elimination of dinitrogen. This one-step method for reductive 1,3-transposition is shown to be efficient and highly regio- and stereocontrolled within a wide range of allylic alcohol substrates.
- Myers, Andrew G.,Zheng, Bin
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p. 4841 - 4844
(2007/10/03)
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- The oxidation of allylic methylene groups under FeIII-TBHP and FeIII-TBHP-PA conditions
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Oxidation of allylic methylene groups under FeIII-TBHP (FeIII-t-butyl hydroperoxide) and FeIII-TBHP-PA (FeIII-t-butyl hydroperoxide-picolinic acid) conditions gave α- and γ-ketonization products.
- Barton, Derek H. R.,Wang, Tie-Lin
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p. 4307 - 4310
(2007/10/02)
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- Molybdenum oxadiene catalysts for the chemoselective hydrosilylation of α,β-unsaturated ketones and aldehydes
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Carbonyl molybdenum and tungsten oxadiene complexes exhibit high catalytic activity in hydrosilation of unsaturated ketones and aldehydes, even those geometrically fixed in s-trans-arrangement, using PhSiH3 and Ph2SiH2. In the case of 4-phenylbut-3-en-2-one as substrate, variable chemoselectivity is observed depending on the specific catalyst employed.
- Schmidt, Thomas
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p. 3513 - 3516
(2007/10/02)
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- SELECTIVE REDUCTION OF α,β-UNSATURATED KETONES WITH POTASSIUM TRIPHENYLBOROHYDRIDE
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Potassium triphenylborohydride is an excellent 1,4-reducing agent for acyclic enones and β-unsubstituted cyclohexenones, and shows a greater tendency for 1,4-reduction than K-Selectride for β-substituted cyclohexenones and aromatic enones.
- Kim, Kwan Eung,Park, Soo Bong,Yoon, Nung Min
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