4065-80-9Relevant academic research and scientific papers
A Vinyl Cyclopropane Ring Expansion and Iridium-Catalyzed Hydrogen Borrowing Cascade
Cheong, Choon Boon,Christensen, Kirsten E.,Donohoe, Timothy J.,Frost, James R.,Wübbolt, Simon
supporting information, p. 11339 - 11344 (2020/05/25)
A vinyl cyclopropane rearrangement embedded in an iridium-catalyzed hydrogen borrowing reaction enabled the formation of substituted stereo-defined cyclopentanes from Ph* methyl ketone and cyclopropyl alcohols. Mechanistic studies provide evidence for the ring-expansion reaction being the result of a cascade based on oxidation of the cyclopropyl alcohols, followed by aldol condensation with the pentamethyl phenyl-substituted ketone to form an enone containing the vinyl cyclopropane. Subsequent single electron transfer (SET) to this system initiates a rearrangement, and the catalytic cycle is completed by reduction of the new enone. This process allows for the efficient formation of diversely substituted cyclopentanes as well as the construction of complex bicyclic carbon skeletons containing up to four contiguous stereocentres, all with high diastereoselectivity.
Bimetallic Radical Redox-Relay Catalysis for the Isomerization of Epoxides to Allylic Alcohols
Ye, Ke-Yin,Mccallum, Terry,Lin, Song
supporting information, (2019/06/24)
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.
Demystifying Cp2Ti(H)Cl and Its Enigmatic Role in the Reactions of Epoxides with Cp2TiCl
Gordon, Jonathan,Hildebrandt, Sven,Dewese, Kendra R.,Klare, Sven,Gans?uer, Andreas,Rajanbabu,Nugent, William A.
supporting information, p. 4801 - 4809 (2019/01/08)
The role of Cp2Ti(H)Cl in the reactions of Cp2TiCl with trisubstituted epoxides has been investigated in a combined experimental and computational study. Although Cp2Ti(H)Cl has generally been regarded as a robust species, its decomposition to Cp2TiCl and molecular hydrogen was found to be exothermic (ΔG = -11 kcal/mol when the effects of THF solvation are considered). In laboratory studies, Cp2Ti(H)Cl was generated using the reaction of 1,2-epoxy-1-methylcyclohexane with Cp2TiCl as a model. Rapid evolution of hydrogen gas was demonstrated, indicating that Cp2Ti(H)Cl is indeed a thermally unstable molecule, which undergoes intermolecular reductive elimination of hydrogen under the reaction conditions. The stoichiometry of the reaction (Cp2TiCl:epoxide = 1:1) and the quantity of hydrogen produced (1 mol per 2 mol of epoxide) is consistent with this assertion. The diminished yield of allylic alcohol from these reactions under the conditions of protic versus aprotic catalysis can be understood in terms of the predominant titanium(III) present in solution. Under the conditions of protic catalysis, Cp2TiCl complexes with collidine hydrochloride and the titanium(III) center is less available for "cross-disproportionation" with carbon-centered radicals; this leads to byproducts from radical capture by hydrogen atom transfer, resulting in a saturated alcohol.
Spiro-compound, and preparation method and application thereof
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Paragraph 0111; 0119; 0120; 0121, (2017/02/17)
The invention relates to the fields of medicinal chemistry and pharmacotherapeutics, and discloses a spiro-compound as shown in the following general formula, and a preparation method and application thereof. A bioactivity screening result shows that the
Enhancement of the photoinduced oxidation activity of a ruthenium(II) complex anchored on silica-coated silver nanoparticles by localized surface plasmon resonance
Mori, Kohsuke,Kawashima, Masayoshi,Che, Michel,Yamashita, Hiromi
scheme or table, p. 8598 - 8601 (2011/01/09)
Plasmonic photocatalyst: Anchoring the dye [Ru(bpy)3] 2+ (bpy=2,2-bipyridine) on the surface of Ag nanoparticles coated with a thin SiO2 layer (see picture) afforded a photocatalyst whose phosphorescence emission and photoinduced oxidation activity in the selective liquid-phase oxidation of styrene are efficiently enhanced through interaction with the localized surface plasmon resonance of the core Ag nanoparticles.
Studies towards the taming of the 'carbocation' in the regioselective ring opening of epoxides to allylic alcohols
Chapman, Helen A.,Herbal, Karim,Motherwell, William B.
experimental part, p. 595 - 598 (2010/09/15)
Regioselective isomerisation of epoxides to allylic alcohols can be achieved using p-toluenesulfonic acid in the presence of 1,3- dimethylimidazolidin-2-one. Georg Thieme Verlag Stuttgart.
Glycol-modified molybdate catalysts for efficient singlet oxygen generation from hydrogen peroxide
Wahlen, Joos,De Vos, Dirk,Jary, Walther,Alsters, Paul,Jacobs, Pierre
, p. 2333 - 2335 (2008/02/11)
Pretreatment of molybdate-exchanged layered double hydroxides in polyalcohols such as ethylene glycol affords heterogeneous catalysts showing largely improved oxidant efficiency compared to the unmodified materials. The Royal Society of Chemistry.
Confined space-controlled hydroperoxidation of trisubstituted alkenes adsorbed on pentasil zeolites
Chen, Yu-Zhe,Wu, Li-Zhu,Zhang, Li-Ping,Tung, Chen-Ho
, p. 4676 - 4681 (2007/10/03)
Photosensitized oxidation of trialkylalkenes 2-methyl-2-pentene (1), 1-methylcyclohexene (2), trans-3-methyl-2-pentene (3), cis-3-methyl-2-pentene (4), and 2-methyl-2-butene (5) included in the internal framework of Na-ZSM-5 zeolites was investigated. The zeolite samples having adsorbed the alkenes were suspended in isooctane, and the sensitizer, tetraphenylporphyrin (TPP), was dissolved in the solution. Singlet oxygen produced in the solution diffused into the internal framework of the zeolites and reacted with alkenes. For all the substrates studied, the ene-type allylic hydroperoxides were obtained in a highly regioselective manner. The regiochemistry for 1-4 in favor of the allylic hydrogen abstraction from the largest substituents is in contrast to their photooxidation within the dye-supported zeolite Na-Y, where the secondary hydroperoxides are preferentially produced. The tight confinement of the alkenes within the narrow channels of the ZSM-5 zeolites is likely to be responsible for this selectivity.
AlEt3-promoted eliminative ring-opening of β-hydroxy epoxides: Highly stereoselective synthesis of terminal α-hydroxy olefins
Wang, Fei,Wang, Shao Hua,Tu, Yong Qiang,Ren, Shi Kuo
, p. 2189 - 2193 (2007/10/03)
AlEt3-promoted eliminative ring-opening of β-epoxy alcohols leading to α-hydroxy olefins is reported. This eliminative ring-opening reaction is shown to be highly stereoselective, thus providing an alternative asymmetric synthesis for α-hydroxy olefins.
Novel conversion of 1,2-disubstituted cis-epoxides to one-carbon homologated allylic alcohols using dimethylsulfonium methylide
Alcaraz, Lilian,Cridland, Andrew,Kinchin, Elizabeth
, p. 4051 - 4053 (2007/10/03)
matrix presented The treatment of cis-epoxides with an excess of dimethylsulfonium methylide affords one-carbon homologated allylic alcohols in good to excellent yields.
