- Identification of an Asexual Reproduction Inducer of Phytopathogenic and Toxigenic Fusarium
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Asexual and sexual reproduction are the most important biological events in the life cycle of phytopathogenic and toxigenic Fusarium and are responsible for disease epidemics. However, the signaling molecules which induce the asexual reproduction of Fusarium are unknown. Herein we describe the structure elucidation, including the absolute configuration, of Fusarium asexual reproduction inducer (FARI), a new sesquiterpene derivative, by spectroscopic analysis, total synthesis, and conidium-inducing assays of synthetic isomers. We have also uncovered the universality of FARI among Fusarium species. Moreover, a mechanism-of-action study suggested that the Gpmk1 and LaeA signaling pathways are required for conidium formation induced by FARI; conversely, the Mgv1 of mitogen-activated protein kinase is not involved in conidium formation. FARI exhibited conidium-inducing activity at an extremely low dose and high stereoselectivity, which may suggest the presence of a stereospecific target.
- Qi, Jianhua,Cheng, Lihong,Sun, Yujuan,Hirata, Yushi,Ushida, Naoki,Ma, Zhonghua,Osada, Hiroyuki,Nishikawa, Toshio,Xiang, Lan
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- Convenient one-pot synthesis of 4,8-dimethyl-bicyclo[3.3.1)non-7-en-2-ol via platinum/tin catalyzed hydroformylation/cyclization of limonene
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Limonene (1) was converted in one step into two diastereoisomers of 4,8-dimethyl-bicyclo[3.3.1]non-7-en-2-ol (2), useful as perfumes, employing PtCl2(PPh3)2/PPh3/SnCl2 and PtCl2(diphosphine)/PPh3/SnCl2 systems as bifunctional catalysts whose diphosphines were 1,3-bis(diphenylphosphino)propane (dppp) and 1,4-bis(diphenylphosphino)butane (dppb). In the presence of the PtCl2(dppb)/PPh3/SnCl2 system, which was found to be the most promising combination, the selectivity for 2 reached the value of 82% at 95% conversion of 1.
- Dias, Adelson de O.,Augusti, Rodinei,Dos Santos, Eduardo N.,Gusevskaya, Elena V.
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- Pt- and Pd-catalysed limonene hydrogenation in high-density carbon dioxide
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This paper discusses the development of catalytic (Pt, Pd) hydrogenation in high-pressure CO2 to convert limonene into valuable chemicals. It was noticed that varying the catalyst results in product regioselectivity. Platinum as catalyst favours the formation of p-menthane stereoisomers in equimolar quantities whereas palladium as catalyst furnishes trans-p-menthane and cis-p-menthane in 2:1 ratio. These results are in agreement with hydrogenation mechanisms for Pt- and Pd-catalysed reactions. Platinum is a more active catalyst than palladium, but higher activity results in lower chemical stability of the catalyst. Palladium as catalyst usually catalyses limonene isomerisation in the first stage of the process. Pressure tuning of the processes affects termination of the reaction. The flow rate of the reaction mixture through the stationary catalyst bed affects the composition of products; partially hydrogenated limonene is obtained at low flow rates and completely hydrogenated products at high flow rates.
- Bogel-Lukasik, Ewa,Bogel-Lukasik, Rafal,Da Ponte, Manuel Nunes
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- Synthesis of puleganic amides via a catalytically efficient two-step approach
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Puleganic amides display interesting insect-repellent properties. A new synthetic route to this type of amide was developed involving an organocatalytic cyclization and metal-catalyzed hydrogenation in a one-pot protocol. An eco-friendly oxidative amination provided the puleganic amides with only one purification step and acceptable yields.
- Pérez, Ignacio,ávila-Zárraga, José Gustavo
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Read Online
- Cobalt-Catalyzed Desymmetric Isomerization of Exocyclic Olefins
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Chiral cyclic olefins, 1-methylcyclohexenes, are versatile building blocks for the synthesis of pharmaceuticals and natural products. Despite the prevalence of these structural motifs, the development of efficient synthetic methods remains an unmet challenge. Herein we report a novel desymmetric isomerization of exocyclic olefins using a series of newly designed chiral cobalt catalysts, which enables a straightforward construction of chiral 1-methylcyclohexenes with diversified functionalities. The synthetic utility of this methodology is highlighted by a concise and enantioselective synthesis of a natural product, β-bisabolene. The versatility of the reaction products is further demonstrated by multifarious derivatizations.
- Lan, Yu,Liu, Qiang,Liu, Shihan,Liu, Xufang,Rong, Xianle
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supporting information
p. 20633 - 20639
(2021/12/17)
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- Nickel-catalyzed reductive 1,3-diene formation from the cross-coupling of vinyl bromides
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Facile construction of 1,3-dienes building upon cross-electrophile coupling of two open-chain vinyl halides is disclosed in this work, showing moderate chemoselectivities between the terminal bromoalkenes and internal vinyl bromides. The present method is mild and tolerates a range of functional groups and can be applied to the total synthesis of a tobacco fragrance solanone.
- Sha, Yunfei,Liu, Jiandong,Wang, Liang,Liang, Demin,Wu, Da,Gong, Hegui
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supporting information
p. 4887 - 4890
(2021/06/16)
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- Photo-Initiated Cobalt-Catalyzed Radical Olefin Hydrogenation
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Outer-sphere radical hydrogenation of olefins proceeds via stepwise hydrogen atom transfer (HAT) from transition metal hydride species to the substrate. Typical catalysts exhibit M?H bonds that are either too weak to efficiently activate H2 or too strong to reduce unactivated olefins. This contribution evaluates an alternative approach, that starts from a square-planar cobalt(II) hydride complex. Photoactivation results in Co?H bond homolysis. The three-coordinate cobalt(I) photoproduct binds H2 to give a dihydrogen complex, which is a strong hydrogen atom donor, enabling the stepwise hydrogenation of both styrenes and unactivated aliphatic olefins with H2 via HAT.
- Sang, Sier,Unruh, Tobias,Demeshko, Serhiy,Domenianni, Luis I.,van Leest, Nicolaas P.,Marquetand, Philipp,Schneck, Felix,Würtele, Christian,de Zwart, Felix J.,de Bruin, Bas,González, Leticia,V?hringer, Peter,Schneider, Sven
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p. 16978 - 16989
(2021/08/09)
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- Ambient Hydrogenation and Deuteration of Alkenes Using a Nanostructured Ni-Core–Shell Catalyst
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A general protocol for the selective hydrogenation and deuteration of a variety of alkenes is presented. Key to success for these reactions is the use of a specific nickel-graphitic shell-based core–shell-structured catalyst, which is conveniently prepared by impregnation and subsequent calcination of nickel nitrate on carbon at 450 °C under argon. Applying this nanostructured catalyst, both terminal and internal alkenes, which are of industrial and commercial importance, were selectively hydrogenated and deuterated at ambient conditions (room temperature, using 1 bar hydrogen or 1 bar deuterium), giving access to the corresponding alkanes and deuterium-labeled alkanes in good to excellent yields. The synthetic utility and practicability of this Ni-based hydrogenation protocol is demonstrated by gram-scale reactions as well as efficient catalyst recycling experiments.
- Beller, Matthias,Feng, Lu,Gao, Jie,Jackstell, Ralf,Jagadeesh, Rajenahally V.,Liu, Yuefeng,Ma, Rui
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supporting information
p. 18591 - 18598
(2021/06/28)
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- Tetraalkylammonium Functionalized Hydrochars as Efficient Supports for Palladium Nanocatalysts
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With the aim of preparing bio-sourced supports with enhanced properties in catalysis, we devised an original strategy allowing the immobilization of metal nanoparticles. Thus, size-controlled hydrochars with a high degree of hydroxyl functionalities, from both neat sucrose or modified with acrylic acid (10 wt.%), were derivatized with ether linkers containing ammonium groups. These non-porous carbon-based materials were used as suitable supports for the immobilization of palladium nanoparticles. The catalytic materials were synthesized by reduction of Pd(OAc)2 to Pd(0) under H2 atmosphere in the presence of the corresponding hydrochar, and fully characterized by standard methods. Among the different hydrochar-supported palladium materials, those functionalized with tetraalkylammonium groups afforded heterogeneous catalysts, exhibiting high activity in hydrogenations of different types of substrates (alkynes, alkenes, and carbonyl and nitro derivatives). The most efficient catalyst was recycled up to ten runs without loss of catalytic behavior, in agreement with the unchanged composite materials after catalysis (Transmission Electron Microscopy (TEM) analyses) and the lack of metal leaching in the extracted organic products (no palladium detected by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES)); these systems exhibited enhanced recyclability properties as compared to commercial Pd/C catalyst.
- Duarte, Tiago A. G.,Favier, Isabelle,Pradel, Christian,Martins, Luísa M. D. R. S.,Carvalho, Ana P.,Pla, Daniel,Gómez, Montserrat
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p. 2295 - 2303
(2020/03/23)
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- Biomolecule-derived supported cobalt nanoparticles for hydrogenation of industrial olefins, natural oils and more in water
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Catalytic hydrogenation of olefins using noble metal catalysts or pyrophoric RANEY nickel is of high importance in the chemical industry. From the point of view of green and sustainable chemistry, design and development of Earth-abundant, less toxic, and more environmentally friendly catalysts are highly desirable. Herein, we report the convenient preparation of active cobalt catalysts and their application in hydrogenations of a wide range of terminal and internal carbon-carbon double bonds in water under mild conditions. Catalysts are prepared on multi-gram scale by pyrolysis of cobalt acetate and uracil, guanine, adenine or l-tryptophan. The most active material Co-Ura/C-600 showed good productivity in industrially relevant hydrogenation of diisobutene to isooctane and in natural oil hardening.
- Pews-Davtyan, Anahit,Scharnagl, Florian Korbinian,Hertrich, Maximilian Franz,Kreyenschulte, Carsten,Bartling, Stephan,Lund, Henrik,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 5104 - 5112
(2019/09/30)
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- Air-Stable α-Diimine Nickel Precatalysts for the Hydrogenation of Hindered, Unactivated Alkenes
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Treatment of a mixture of air-stable nickel(II) bis(octanoate), Ni(O2CC7H15)2, and α-diimine ligand, iPrDI or CyADI (iPrDI = [2,6-iPr2-C6H3N=C(CH3)]2, CyADI = [C6H11N=C(CH3)]2) with pinacolborane (HBPin) generated a highly active catalyst for the hydrogenation of hindered, essentially unfunctionalized alkenes. A range of tri- and tetrasubstituted alkenes was hydrogenated and a benchtop procedure for the hydrogenation of 1-phenyl-1-cyclohexene on a multigram scale was demonstrated and represents an advance in catalyst activity and scope for the nickel-catalyzed hydrogenation of this challenging class of alkenes. Deuteration of 1,2-dimethylindene with the in situ-generated nickel catalyst with iPrDI exclusively furnished the 1,2-syn-d2-dimethylindane. With cyclic trisubstituted alkenes, such as 1-methyl-indene and methylcyclohexene, deuteration with the in situ generated nickel catalyst under 4 atm of D2 produced multiple deuterated isotopologues of the alkanes, signaling chain running processes that are competitive with productive hydrogenation. Stoichiometric studies, titration, and deuterium labeling experiments identified that the borane reagent served the dual role of reducing nickel(II) bis(carboxylate) to the previously reported nickel hydride dimer [(iPrDI)NiH]2 and increasing the observed hydrogenation activity. Performing the catalyst activation procedure with D2 gas and HBPin generated both HD and DBPin, establishing that the borane is involved in H2 activation as judged by 1H and 11B nuclear magnetic resonance spectroscopies.
- Léonard, Nadia G.,Chirik, Paul J.
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p. 342 - 348
(2018/01/17)
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- Inexpensive and rapid hydrogenation catalyst from CuSO4/CoCl2 — Chemoselective reduction of alkenes and alkynes in the presence of benzyl protecting groups
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The simple reduction of a number of alkenes and alkynes was performed with a typical reaction time of 20 min using a copper-cobalt catalytic system. The reduction did not cleave benzyl protecting groups which are usually vulnerable to catalytic hydrogenation reactions. The catalyst can be prepared in situ by reduction of the inexpensive precursor salts CuSO4 and CoCl2 with NaBH4. Sodium borohydride was also used as an easily handled hydrogen source for the catalytic reductions. No pressure, heating or inert atmosphere is required and purification/catalyst removal is achieved using extraction procedures, making this approach simple and efficient.
- Ficker, Mario,Svenningsen, S?ren W.,Larribeau, Thomas,Christensen, J?rn B.
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supporting information
p. 1125 - 1129
(2018/02/21)
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- A Co2B Mediated NaBH4 Reduction Protocol Applicable to a Selection of Functional Groups in Organic Synthesis
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A high-yielding and high-rate reduction method that operates with alkenes, alkynes, azides, nitriles, and nitroarenes was developed and optimized. The method makes use of sodium borohydride reduction of CoSO4 under release of hydrogen along with the formation of Co2B as a nanoparticle material. The produced Co2B activates the various functional groups for hydride reduction. The protocol was proven to operate with an assortment of functional groups to provide good to excellent yields. Furthermore, the reduction method was successfully adapted, implemented, and developed for a continuous flow approach using the multi-jet oscillating disk (MJOD) flow reactor platform at atmospheric pressure.
- Lundevall, Frida Johanne,Elumalai, Vijayaragavan,Drageset, Audun,Totland, Christian,Bj?rsvik, Hans-René
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supporting information
p. 3416 - 3425
(2018/07/29)
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- A Manganese Nanosheet: New Cluster Topology and Catalysis
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While the coordination chemistry of monometallic complexes and the surface characteristics of larger metal particles are well understood, preparations of molecular metallic nanoclusters remain a great challenge. Discrete planar metal clusters constitute nanoscale snapshots of cluster growth but are especially rare owing to the strong preference for three-dimensional structures and rapid aggregation or decomposition. A simple ligand-exchange procedure has led to the formation of a novel heteroleptic Mn6 nanocluster that crystallized in an unprecedented flat-chair topology and exhibited unique magnetic and catalytic properties. Magnetic susceptibility studies documented strong electronic communication between the manganese ions. Reductive activation of the molecular Mn6 cluster enabled catalytic hydrogenations of alkenes, alkynes, and imines.
- Chakraborty, Uttam,Reyes-Rodriguez, Efrain,Demeshko, Serhiy,Meyer, Franc,Jacobi von Wangelin, Axel
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supporting information
p. 4970 - 4975
(2018/03/28)
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- Rhodium-catalyzed hydroformylation in γ-valerolactone as a biomass-derived solvent
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Rhodium-catalyzed hydroformylation of styrene, α-methylstyrene, dimethyl itaconate, and (R)-limonene was performed in gamma-valerolactone (GVL) as a proposed biomass-based environmentally benign solvent for hydroformylation referring to toluene as a generally used conventional solvent. Both achiral (triphenylphosphine, 1,3-bis(diphenylphoshino)propane) and enantiopure bidentate phosphine ligands ((S,S)-BDPP, (R)-BINAP, (R)-QUINAP, (R,R)-DIOP, (Rc),(Sp)-JOSIPHOS, (S)-SEGPHOS, (S)-(DM)-SEGPHOS) were investigated in in situ generated Rh-diphosphine catalyst systems. In general, the catalysts' activity in GVL was lower than in toluene; however, remarkable chemo- (>99%) and regioselectivities (>95%) were achieved in GVL under identical conditions. The BDPP-modified Rh-catalyst was recycled for three consecutive cycles; however a decrease in its activity was detected.
- Pongrácz, Péter,Bartal, Brigitta,Kollár, László,Mika, László T.
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p. 140 - 145
(2017/09/12)
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- Alkene Metalates as Hydrogenation Catalysts
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First-row transition-metal complexes hold great potential as catalysts for hydrogenations and related reductive reactions. Homo- and heteroleptic arene/alkene metalates(1?) (M=Co, Fe) are a structurally distinct catalyst class with good activities in hydrogenations of alkenes and alkynes. The first syntheses of the heteroleptic cobaltates [K([18]crown-6)][Co(η4-cod)(η2-styrene)2] (5) and [K([18]crown-6)][Co(η4-dct)(η4-cod)] (6), and the homoleptic complex [K(thf)2][Co(η4-dct)2] (7; dct=dibenzo[a,e]cyclooctatetraene, cod=1,5-cyclooctadiene), are reported. For comparison, two cyclopentadienylferrates(1?) were synthesized according to literature procedures. The isolated and fully characterized monoanionic complexes were competent precatalysts in alkene hydrogenations under mild conditions (2 bar H2, r.t., THF). Mechanistic studies by NMR spectroscopy, ESI mass spectrometry, and poisoning experiments documented the operation of a homogeneous mechanism, which was initiated by facile redox-neutral π-ligand exchange with the substrates followed by H2 activation. The substrate scope of the investigated precatalysts was also extended to polar substrates (ketones and imines).
- Büschelberger, Philipp,G?rtner, Dominik,Reyes-Rodriguez, Efrain,Kreyenschmidt, Friedrich,Koszinowski, Konrad,Jacobi von Wangelin, Axel,Wolf, Robert
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p. 3139 - 3151
(2017/03/13)
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- Symbiotic Transition-Metal and Organocatalysis for Catalytic Ambient Amine Oxidation and Alkene Reduction Reactions
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A new oxidation reaction based on two simple catalysts, namely, alloxan and a CuI salt, is highly effective for the aerobic oxidation and oxidative cross-coupling of amines. The reaction is operationally simple, reaction atmospheres enriched in dioxygen are obviated, and neither catalyst component requires prior synthesis. Mechanistic investigations have been performed and point towards a complex reaction manifold with evidence that supports a catalytic cycle that does not proceed through a quinone-imine step. Additionally, this dual catalyst system is efficient to effect diimide-mediated hydrogenation reactions of alkenes and alkynes, a transformation that has not been reported previously in the context of quinone catalyst systems.
- Murray, Alexander T.,King, Rose,Donnelly, Joseph V. G.,Dowley, Myles J. H.,Tuna, Floriana,Sells, Daniel,John, Matthew P.,Carbery, David R.
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p. 510 - 514
(2016/02/20)
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- A new approach for bio-jet fuel generation from palm oil and limonene in the absence of hydrogen
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The traditional methodology includes a carbon-chain shortening strategy to produce bio-jet fuel from lipids via a two-stage process with hydrogen. Here, we propose a new solution using a carbon-chain filling strategy to convert C10 terpene and lipids to jet fuel ranged hydrocarbons with aromatic hydrocarbon ingredients in the absence of hydrogen.
- Zhang, Jingjing,Zhao, Chen
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supporting information
p. 17249 - 17252
(2015/12/08)
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- Iron-catalyzed olefin hydrogenation at 1 bar H2 with a FeCl3-LiAlH4 catalyst
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The scope and mechanism of a practical protocol for the iron-catalyzed hydrogenation of alkenes and alkynes at 1 bar H2 pressure were studied. The catalyst is formed from cheap chemicals (5 mol% FeCl3-LiAlH4, THF). A homogeneous mechanism operates at early stages of the reaction while active nanoparticles form upon ageing of the catalyst solution. This journal is
- Gieshoff, Tim N.,Villa, Matteo,Welther, Alice,Plois, Markus,Chakraborty, Uttam,Wolf, Robert,Jacobi Von Wangelin, Axel
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supporting information
p. 1408 - 1413
(2015/03/18)
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- Continuous-flow hydrogenation of olefins and nitrobenzenes catalyzed by platinum nanoparticles dispersed in an amphiphilic polymer
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A method for the flow hydrogenation of olefins and nitrobenzenes in a continuous-flow reactor containing platinum nanoparticles dispersed on an amphiphilic polystyrene-poly(ethylene glycol) resin (ARP-Pt) was developed. The hydrogenation of olefins and nitrobenzenes was completed within 31 seconds in the continuous-flow system containing ARP-Pt, giving the corresponding hydrogenated products in up to 99% yield with good chemoselectivity. Moreover, long-term (63-70 h) continuous-flow hydrogenation of styrene and nitrobenzene produced more than ten grams of ethylbenzene and aniline, respectively, without significant loss of catalytic activity. The flow hydrogenation system provides an efficient and practical method for the chemoselective reduction of olefins and nitrobenzenes. This journal is
- Osako, Takao,Torii, Kaoru,Tazawa, Aya,Uozumi, Yasuhiro
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p. 45760 - 45766
(2015/06/08)
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- Microwave assisted bi-functional activation of β-bromo-tert-alcohols
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Microwave-assisted dehydration-oxidation of β-bromo-tert-alcohols to afford 2,3-unsaturated ketones in good yield is reported. The reaction of substrates with DMSO in 1:1 ratio (w/v) is promoted by ZnS in a solvent-free condition. A concurrent bi-functional activation of trans-vicinal bromo- and hydroxyl groups with ZnS is elucidated. This is a new observation under microwave and applies to β-bromo-tert-alcohols derived from 1,4-disubstitued-1-cyclohexenes. It is very useful in the synthesis of 2,3-unsaturated ketones derived from monoterpenes which are valuable flavour compounds. [Figure not available: see fulltext.]
- Kannan, Nandini,Rangaswamy, Manjunatha Javagal,Kemapaiah, Bettadaiah Bheemanakere
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p. 1405 - 1410
(2015/11/09)
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- ENANTIOPURE BASE-METAL CATALYSTS FOR ASYMMETRIC CATALYSIS AND BIS(IMINO)PYRIDINE IRON ALKYL COMPLEXES FOR CATALYSIS
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Disclosed herein are iron, nickel, or cobalt compounds having tridentate ligands, which can have at least one chiral moiety in the molecular structure thereof and the use of these compounds for the hydrogenation and transformation of olefins (preferably prochiral) and alkynes.
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Paragraph 00149
(2013/04/10)
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- COBALT PHOSPHINE ALKYL COMPLEXES FOR THE ASYMMETRIC HYDROGENATION OF ALKENES
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Disclosed herein are manganese, iron, nickel, or cobalt compounds having a bidentate ligand and the use of these compounds for the hydrogenation of alkenes, particularly the asymmetric hydrogenation of prochiral olefins.
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Paragraph 0118; 0119
(2013/11/05)
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- Synthesis of analogues of linckoside B, a new neuritogenic steroid glycoside
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A facile synthetic approach toward six designed analogues (2-7) of linckoside B, a new neuritogenic steroid glycoside isolated from the Okinawan starfish Linckia laevigata, has been developed. The key steroid aglycon was achieved by a dimethylaluminum chloride-mediated 'ene' reaction. A versatile strategy was employed for the construction of glycosidic bonds through Schmidt's procedure using a glycosyl trichloroacetimidate donor.
- Liu, Qingchao,Yu, Yue,Wang, Peng,Li, Yingxia
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p. 3647 - 3661
(2013/11/06)
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- Ligand effect on the catalytic activity of ruthenium nanoparticles in ionic liquids
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Suspensions of small sized (1-2.5 nm) ruthenium nanoparticles (RuNPs) have been obtained by decomposition, under H2, of (η4-1,5- cyclooctadiene)(η6-1,3,5-cyclooctatriene)ruthenium(0), [Ru(COD)(COT)], in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C1C4Im][NTf 2], and in the presence of different compounds acting as ligands: C8H17NH2, PPhH2, PPh2H and H2O. Previous and new liquid NMR experiments showed that the ligands are coordinated or in the proximity to the surface of the RuNPs. Herein is reported how the ligand affects the catalytic performance (activity and selectivity) compared to a ligand-free system of RuNPs, when RuNPs in [C 1C4Im][NTf2] are used as catalysts for the hydrogenation of various unsaturated compounds (1,3-cyclohexadiene, limonene and styrene). It has been observed that σ-donor ligands increase the activity of the nanoparticles, contrarily to π-acceptor ones.
- Salas, Gorka,Campbell, Paul S.,Santini, Catherine C.,Philippot, Karine,Costa Gomes, Margarida F.,Pádua, Agílio A.H.
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p. 13919 - 13926
(2013/01/15)
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- Iron(III) chloride-catalysed aerobic reduction of olefins using aqueous hydrazine at ambient temperature
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A chemoselective reduction of olefins and acetylenes is demonstrated by employing catalytic amounts of ferric chloride hexahydrate (FeCl 3·6 H2O) and aqueous hydrazine (NH 2NH2·H2O) as hydrogen source at room temperature. The reduction is chemoselective and tolerates a variety of reducible functional groups. Unlike other metal-catalysed reduction methods, the present method employs a minimum amount of aqueous hydrazine (1.5-2 equiv.). Also, the scope of this method is demonstrated in the synthesis of ibuprofen in aqueous medium. Copyright
- Lamani, Manjunath,Ravikumara, Guralamata S.,Prabhu, Kandikere Ramaiah
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supporting information; experimental part
p. 1437 - 1442
(2012/07/03)
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- Mild and homogeneous cobalt-catalyzed hydrogenation of C=C, C=O, and C=N bonds
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A cationic cobalt(II)-alkyl complex is an effective precatalyst for hydrogenation of alkenes, aldehydes, ketones, and imines under mild conditions (1-4 atm H2; see scheme). The catalyst shows a high functional-group tolerance across a broad range of substrates. Experiments suggest that the active catalytic species is a cobalt(II)-hydride complex. Copyright
- Zhang, Guoqi,Scott, Brian L.,Hanson, Susan K.
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supporting information
p. 12102 - 12106
(2013/01/16)
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- Enantiospecific approach to AB-ring system of the diterpenes fusicoccanes
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Enantiospecific synthesis of the AB ring system of 5-8-5 tricyclic diterpenes fusicoccanes has been accomplished, starting from the readily available monoterpene (R)-limonene employing an RCM reaction as the key step.
- Srikrishna,Nagaraju, Gopalasetty
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scheme or table
p. 73 - 76
(2011/04/17)
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- Syntheses of the optically active terpene hydroxyphenylselenides
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The optically active hydroxyphenylselenides derived from the p-menthane, carane, and pinane systems have been obtained. Two methods of hydroxyphenylselenides synthesis have been compared. The first method is based on the reaction of alkenes with N-(phenylseleno)succinimide in the presence of water, and the second from epoxides as a result of the reaction with sodium benzeneselenolate. The influence of the substrate structures on the composition of the obtained products has been demonstrated.
- Scianowski, Jacek,WeLniak, MirosLaw
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scheme or table
p. 1440 - 1447
(2010/03/24)
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- One-pot o-nitrobenzenesulfonylhydrazide (NBSH) formation-diimide alkene reduction protocol
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A one-pot protocol for the formation of 2-nitrobenzenesulfonylhydrazide (NBSH) from commercial reagents and subsequent alkene reduction is presented. The transformation is operationally simple and generally efficient for effecting diimide alkene reductions. A range of 16 substrates have been reduced, highlighting the unique chemoselectivity of diimide as a reduction system.
- Marsh, Barrie J.,Carbery, David R.
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supporting information; experimental part
p. 3186 - 3188
(2009/09/08)
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- Reduction of carbon-carbon double bonds using organocatalytically generated diimide
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(Chemical Equation Presented) An efficient method has been developed for the reduction of carbon-carbon double bonds with diimide, catalytically generated in situ from hydrazine hydrate. The employed catalyst is prepared in one step from riboflavin (vitamin B2). Reactions are carried out in air and are a valuable alternative when metal-catalyzed hydrogenations are problematic.
- Smit, Christian,Fraaije, Marco W.,Minnaard, Adriaan J.
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supporting information; experimental part
p. 9482 - 9485
(2009/04/06)
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- Highly selective hydrogenation of multiple carbon-carbon bonds promoted by nickel(0) nanoparticles
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A new method for the highly stereoselective cis semihydrogenation of internal alkynes, semihydrogenation of terminal alkynes, reduction of dienes to alkenes, and reduction of alkynes and alkenes to alkanes is described based on in situ generated both Ni(0) nanoparticles and molecular hydrogen.
- Alonso, Francisco,Osante, I?aki,Yus, Miguel
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- Determination of the absolute configuration of quercivorol, (1S,4R)-p-menth-2-en-1-ol, an aggregation pheromone of the ambrosia beetle Platypus quercivorus (Coleoptera: Platypodidae)
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A pair of enantiomers of trans-p-menth-2-en-1-ol, an aggregation pheromone of Platypus quercivorus, was synthesized from (S)- and (R)-limonene. The retention time of the aggregation pheromone from the insect coincided with that of (1S,4R)-p-menth-2-en-1-ol synthesized from (S)-limonene from GC analyses with a chiral column, enabling the absolute configuration of the aggregation pheromone to be determined as (1S,4R).
- Kashiwagi, Takehiro,Nakashima, Tadakazu,Tebayashi, Shin-Ich,Kim, Chul-Sa
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p. 2544 - 2546
(2008/02/08)
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- ROMPgel-supported tris(triphenylphosphine)rhodium(I) chloride: A selective hydrogenation catalyst for parallel synthesis
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ROMPgel-supported tris(triphenylphosphine)rhodium(I) chloride has been prepared and the immobilised catalyst has been effectively employed in selective hydrogenations of a variety of alkenes and terminal alkynes.
- ?rstad, Erik,Barrett, Anthony G. M.,Tedeschi, Livio
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p. 2703 - 2707
(2007/10/03)
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- Stereoselective synthesis of (6R)- and (6S)-diosphenol and Ψ-diosphenol
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Methods are discussed for the stereoselective synthesis of the (R)-and (S)-enantiomers of the diosphenols (5)-(8) by utilizing the commercially available stereoisomers (9), (12), (23) and (25) of carvone and limonene, respectively, as chiral starting materials.
- Schneider, David F,Viljoen, Murray S
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p. 5307 - 5315
(2007/10/03)
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- Stereocontrolled synthesis of contignasterol's side chain
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The four models of the contignasterol's side chains (2-5) have been stereospecifically prepared. The key reaction in the synthesis is a dimethylaluminum chloride-mediated 'ene' reaction between the steroid derivative 6 and the pseudo-enantiomeric aldehydes 7 and 8.
- Izzo, Irene,Pironti, Vincenza,Monica, Carmela Della,Sodano, Guido,De Riccardis, Francesco
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p. 8977 - 8980
(2007/10/03)
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- Terpenes to terpenes through "Push-Pull" cyclopropanes: Enantioselective construction of germacrane, eudesmane and 'copa' sesquiterpenoid skeleta from (+)-limonene
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'Push-Pull' cyclopropane derivatives of the type 3 and 4 readily obtainable from (+)-limonene 7 via dichloroketene cycloaddition and base-mediated ring contraction-rearrangement have been elaborated to mono-, bi- and tricyclic skeleta present in germacrane, eudesmane and 'copa' sesquiterpenoids, respectively. Our methodology provides stereo- and enantioselective entry into these ring systems from a readily available monoterpene chiron.
- Mehta, Goverdhan,Acharyulu, Palle V.R.
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p. 201 - 204
(2007/10/03)
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- A New Strategy for the α-Vinylation of Ketones : Application to an Enantioselective Synthesis of Sesquiterpene (+)-α-Elemene
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A new, simple and preparatively useful protocol for the construction of α-vinyl ketones, particularly those bearing a quaternary carbon centre, from the corresponding alkenes has been devised. Our four-step strategy consists of dichloroketene addition, base catalysed ring contraction to 'push-pull' cyclopropane esters, reduction and eliminative cyclopropane fragmentation to unravel the α-vinyl ketone moiety. The generality of this approach has been demonstrated with a few representative olefins and good regio- and stereocontrol has been observed. As an application of this methodology, an enantioselective synthesis of sesquiterpene hydrocarbon (+)-α-elemene (42) from R-(+)-limonene (43) has been accomplished.
- Mehta, Goverdhan,Acharyulu, Palle V. R.
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p. 601 - 612
(2007/10/03)
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- Terpenes to Terpenes. Stereo- and Enantio-selective Synthesis of (+)-α-Elemene and a Short Route to a Versatile Diquinane Chiron
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Syntheses of sesquiterpene (+)-α-elemene from monoterpenes (+)-limonene and (+)-2-carene following a new strategy are reported.
- Mehta, Goverdhan,Acharyulu, Palle V. R.
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p. 2759 - 2760
(2007/10/02)
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- ENANTIOMERIC COMPOSITION OF MONOTERPENE HYDROCARBONS FROM THE LIVERWORT CONOCEPHALUM CONICUM
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Volatiles from the essential oil of the liverwort Conocephalum conicum were analysed.The chirality of the monoterpene hydrocarbons was studied by two-dimensional gas chromatography.All compounds except β-phellandrene showed high optical purity.For the identification of enantiomers, (+)-β-phellandrene and (-)-α-thujene were prepared from (+)-limonene and (+)-sabinene, respectively.Key Word Index: Conocephalum conicum; Hepaticae; liverwort; monoterpene hydrocarbons; (+)-β-phellandrene; (-)-α-thujene; chiral composition
- Valterova, Irena,Unelius, C. Rikard,Vrkoc, Jan,Norin, Torbjoern
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p. 3121 - 3124
(2007/10/02)
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- Synthesis and Absolute Configuration of the Antiparasitic Furanosesquiterpenes (-)-Furodysin and (-)-Furodysinin. Camphor as a Six-Membered Ring Chiral Pool Template
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The syntheses of (-)-furodysin ((-2)-2a) and (-)-furodysinin ((-)-3a) in four steps starting from (+)-9-bromocamphor (18) has been accomplished, thus establishing the absolute configuration of these and related metabolites.This was made possible by the unexpected exo selectivity in the aldol condensation of camphor-like enolates with aldehydes.This has been found to be a general phenomenon in the camphor system.Further, anionic fragmentation of the C1-C7 bond of camphor derivatives has allowed access to synthetic intermediates containing functionalized six-memberedrings, thus opening up avenues from camphor to a new class of chiral pool elements not currently available from chiral pool substances.
- Vaillancourt, Valerie,Agharahimi, Mohamad R.,Sundram, Uma N.,Richou, Olivier,Faulkner, D. John,Albizati, Kim F.
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p. 378 - 387
(2007/10/02)
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- TOTAL SYNTHESIS OF (-)-PERIPLANONE-B, NATURAL MAJOR SEX-EXCITANT PHEROMONE OF THE AMERICAN COCKROACH, PERIPLANETA AMERICANA
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The total synthesis of (-)-periplanone-B 1, the major sex excitant and attractant pheromone of the American cockroach was accomplished starting from (+)-dihydrolimonene 2.Intramolecular alkylation of the substituted α-phenylthioacrylate 10 gave rise to the (E)-cyclodecene 11.Second key reaction was the reductive elimination of vicinal phenylthiobenzoate 14 to provide the cojugated diene 15.Overall yield of 1 through 28 steps was 0.5 percent.
- Kitahara, Takeshi,Mori, Masataka,Mori, Kenji
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p. 2689 - 2700
(2007/10/02)
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- Highly Reactive Organolanthanides. A Mechanistic Study of Catalytic Olefin Hydrogenation by Bis(pentamethylcyclopentadienyl) and Related 4f Complexes
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The organolanthanides (Cp'2MH)2, Cp'=η5-(CH3)5C5, M=La, Nd, Sm, and Lu, and (Me2SiCp''2MH)2, Cp''=η5-(CH3)4C5, M=Nd, Sm, and Lu are highly active catalysts for olefin hydrogenation.In the case of 1-hexene -> n-hexane, activities decrease in the order Cp'2Lu > Cp'2Sm > Cp'2Nd > Me2SiCp''2Lu > Cp'2La > Me2SiCp''2Sm > Me2SiCp''2Nd, with Nt for the most active catalyst exceeding 120 000 h-1 at 25 deg C and 1 atm of H2.Under the conditions employed, the rate law is ν α 0 suggesting rapid, exothermic Lanthanide-H/olefin addition and rate-limiting M-C hydrogenolysis.When D2 uptake is not mass-transport-limited the predominant product is hexane-1,2-d2.For all catalysts except (Cp'2LuH)2, cyclohexene hydrogenation (to yield predominantly cyclohexane-1,2-d2 under D2 in a non-mass-transport-limited regime) obeys the rate law ν α 1/20, suggesting rate-limiting Lanthanide-H/olefin addition.For Cp'2Lu, the rate law is ν α 0, suggesting rate-limiting (Lu-H)2/olefin addition or that the hydride dimer is largely dissociated under these conditions.The relative activities are less than for 1-hexene and follow the order (Me2SiCp''2NdH)2 > Me2SiCp''2SmH)2 > (Cp'2LaH)2 >/= (Cp'2NdH)2 > (Me2SiCp''2LuH)2 >/= (Cp'2SmH)2.Addition of THF significantly decreases the rate both of 1-hexene hydrogenation and (more so) cyclohexene hydrogenation.For all catalysts examined, 3-hexyne hydrogenation follows a two-stage rate law ν α 0 (3-hexine -> cis-3-hexene) and ν α 1/20 (cis-3-hexene -> n-hexane) except for (Cp'2LuH)2 where ν α 0.The rate laws and relative activity trends for trans-2-hexene and trans-3-hexene hydrogenation parallel those for 1-hexene, while cis-2-hexene behaves like cis-3-hexene.While the present olefin and acetylene hydrogenation catalysis can be understood largely on the basis of established or reasonably extrapolated organo-f-element reactivity and bond enthalpy patterns, the steps in the catalytic cycles must proceed with remarkably low activation energies and must be coupled with high efficiency.
- Jeske, Gerald,Lauke, Harald,Mauermann, Heiko,Schumann, Herbert,Marks, Tobin J.
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p. 8111 - 8118
(2007/10/02)
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- Synthesis and Chiroptical Properties of Some Piperidin-2-ones
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The synthesis of optically pure (R)-(+)-4-isopropylpiperidin-2-one, (R)-(+)-4-isopropyl-4-methylpiperidin-2-one, and (R)-(+)-5-methylpiperidin-2-one in high yields from monocyclic terpene precursors are described.The CD spectra of these compounds are reported, and the chiroptical properties of δ-lactams are examined in terms of current theories for the amide chromophore.It is concluded that slight, conformationally induced nonplanarity of the amide chromophore is responsible for signs of the longest wavelenght bands in the CD spectra of these and related compounds.
- Jackman, L. M.,Webb, R. Lee,Yick, H. C.
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p. 1824 - 1831
(2007/10/02)
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- Spiroannelation via Intramolecular Ketocarbenoid Addition. Stereocontrolled Synthesis of (-)-Acorenone B and (+/-)-α-Chamigrene
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The spirobicyclic structures of (+/-)-α-chamigrene (7) and (-)-acorenone B (6) were synthesized by means of a copper-catalyzed, intramolecular cycloaddition of diazo ketones 25 and 47, respectively.The former was prepared from 4-methyl-4-(p-methoxyphenyl)pentanoic acid (8) and the latter was obtained in optically active form from (R)-(+)-limonene (35).Reduction of 26 with lithium in ammonia gave 27, which was transformed to (+/-)-α-chamigrene (7) via olefin 30 and carbinol 32.The tricyclic ketone 53, from 47, was converted via olefin 55 to spiroketone 56.Interoduction of the conjugated olefin afforded (-)-acorenone B (6).Alternatively, 53 was reduced with lithium in ammonia to 54 and this, through a parallel sequence, was taken to (-)-4-epiacorenone B (67).
- White, James D.,Ruppert, John F.,Avery, Mitchell A.,Torii, Sigeru,Nokami, Junzo
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p. 1813 - 1821
(2007/10/02)
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