356050-40-3Relevant academic research and scientific papers
Anion radical [2 + 2] cycloaddition as a mechanistic probe: Stoichiometry- and concentration-dependent partitioning of electron-transfer and alkylation pathways in the reaction of the Gilman reagent Me2CuLi·LiI with bis(enones)
Yang, Jingkui,Cauble, David F.,Berro, Adam J.,Bauld, Nathan L.,Krische, Michael J.
, p. 7979 - 7984 (2004)
Exposure of easily reduced aromatic bis(enones) 1a-1e to the methyl Gilman reagent Me2CuLi· LiI at 0°C in tetrahydrofuran solvent provides the products of tandem conjugate addition-Michael cyclization, 2a-2e, along with the products of [2 + 2] cycloaddition, 3a-3e. Complete partitioning of the Gilman alkylation and [2 + 2] cycloaddition pathways may be achieved by adjusting the loading of the Gilman reagent, the rate of addition of the Gilman reagent, and the concentration of the reaction mixture. The Gilman alkylation manifold is favored by the rapid addition of excess Gilman reagent at higher substrate concentrations, while the [2 + 2] cycloaddition manifold is favored by slow addition of the same Gilman reagent at lower concentrations and loadings. Notably, [2 + 2] cycloaddition to form 3a-3e is catalytic in Gilman reagent. Kinetic data reveal that the ratio of 2a and 3a changes such that the cycloaddition pathway becomes dominant upon increased consumption of Gilman reagent. These data suggest a concentration-dependent speciation of the Gilman reagent and differential reactivity of the aggregates present at higher and lower concentrations. While the species present at higher concentration induce Gilman alkylation en route to products 2a-2e, the species present at lower concentration provide products of catalytic [2 + 2] cycloaddition, 3a-3e. Moreover, upon electrochemical reduction of the bis(enones) 1a-1e, or chemically induced single-electron transfer from arene anion radicals, the very same [2 + 2] cycloadducts 3a-3e are formed. The collective data suggest that [2 + 2] cycloadducts 3a-3e arising under Gilman conditions may be products of anion radical chain cyclobutanation that derive via electron transfer (ET) from the Me2CuLi-LiI aggregate(s) present at low concentration. These observations provide a link between the Gilman alkylation reaction and related ET chemistry and suggest these reaction paths are mechanistically distinct. This analysis is made possible by the recent observation that easily reduced bis(enones) are subject to intramolecular [2 + 2] cycloaddition upon cathodic reduction or chemically induced ET from arene anion radicals, and is herewith showcased as a novel method of testing for the intermediacy of enone anion radicals.
Anion radical chain cycloaddition of tethered enones: Intramolecular cyclobutanation and Diels-Alder cycloaddition
Roh, Yeonsuk,Jang, Hye-Young,Lynch, Vincent,Bauld, Nathan L.,Krische, Michael J.
, p. 611 - 613 (2002)
(formula presented) The anion radicals of certain bis(enones), generated by cethodic reduction, are observed to participate in intramolecular cyclobutanation, yielding bicyclo[3.2.0]heptane derivatives through an anion radical chain mechanism. Evidence fo
Polymer-supported, photo-redox catalysts prepared from unimolecular photo-redox catalyst/initiator systems
Peavy, Matthew,Hobbs, Christopher
supporting information, (2021/02/05)
Unimolecular, photo-redox catalyst/initiator systems can effectively synthezise their own polymer-support that can then be used to affect recovery and reuse of the resulting supported catalyst. We show that α-bromo ester-containing Ru(bpy)3- and phenothiazine-derivatives (common photo-redox catalysts) can undergo visible light-facilitated radical polymerizations to form polymer-supported photo-redox catalysts that can facilitate photo-redox [2+2] cycloadditions and metal-free borylations in a recyclable manner.
Photoredox catalysis using infrared light via triplet fusion upconversion
Ravetz, Benjamin D.,Pun, Andrew B.,Churchill, Emily M.,Congreve, Daniel N.,Rovis, Tomislav,Campos, Luis M.
, p. 343 - 346 (2019/01/26)
Recent advances in photoredox catalysis have made it possible to achieve various challenging synthetic transformations, polymerizations and surface modifications1–3. All of these reactions require ultraviolet- or visible-light stimuli; however,
TRIPLET FUSION UPCONVERSION FOR INFRARED-SENSITIZED PHOTOREDOX CHEMISTRY
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Paragraph 0125, (2019/09/20)
Various exemplary photoreactions can be provided, including reactions generally based on triplet-triplet annihilation upconversion. Representative photosensitizers include PdPc(OBu)8 and PtTPTNP. Representative annihilators include FDPP and TTBP. Such exe
Flavin Photocatalysts for Visible-Light [2+2] Cycloadditions: Structure, Reactivity and Reaction Mechanism
Mojr, Viktor,Pitrová, Gabriela,Straková, Karolína,Pruka?a, Dorota,Brazevic, Sabina,Svobodová, Eva,Hoskovcová, Irena,Burdziński, Gotard,Slanina, Tomá?,Sikorski, Marek,Cibulka, Radek
, p. 849 - 858 (2018/01/27)
New photocatalysts from the flavin family were found to mediate the [2+2] photocycloaddition reaction. 3-Butyl-10-methyl-5-deazaflavin (3 a) and 1-butyl-7,8-dimethoxy-3-methylalloxazine (2 e), if irradiated by visible light, were shown to allow an efficie
Metal-Organic Layers Catalyze Photoreactions without Pore Size and Diffusion Limitations
Xu, Ruoyu,Drake, Tasha,Lan, Guangxu,Lin, Wenbin
supporting information, p. 15772 - 15776 (2018/10/02)
Metal-organic frameworks (MOFs) have emerged as promising single-site solid catalysts for organic reactions. However, MOF catalysts suffer from pore size limitation and slow diffusion, which are detrimental for photoreactions. Metal-organic layers (MOLs)
Visible Light [2+2] Photocycloaddition Mediated by Flavin Derivative Immobilized on Mesoporous Silica
?pa?ková, Jessica,Svobodová, Eva,Hartman, Tomá?,Stibor, Ivan,Kopecká, Jitka,Cibulková, Jana,Chudoba, Josef,Cibulka, Radek
, p. 1177 - 1181 (2017/04/14)
7,8-Dimethoxy-3-methylalloxazine was immobilized on mesoporous silica (MCM-41) to provide a heterogenized flavin photocatalyst. Thus, the prepared heterogeneous catalyst 2 was found to sensitize the visible light [2+2] cycloaddition of various types of di
Visible light mediated photoredox reactions catalyzed by recyclable PIB-bound ruthenium photoredox catalysts
Liang, Yannan,Bergbreiter, David E.
, p. 215 - 221 (2015/12/31)
This report describes the preparation of a PIB-bound Ru(ii)-bipyridine complex [Ru(PIB-bpy)3Cl2], and its use as a recyclable photoredox catalyst to carry out both oxidative C-C bond cleavage of aldehydes and [2 + 2] cycloaddition of bis(enone)s. While this polymer-supported Ru catalyst could be successfully recovered and reused for 5 cycles with no loss of catalytic activity and with leaching levels of ca. 1% of the charged catalyst for these reactions, other reactions like photodimerization or alkyl halide synthesis that require a more polar solvent medium for successful reactions of the low molecular weight catalyst proceeded either with varying selectivity or in low yield because of solubility limitations of the PIB-supported catalyst in the more polar solvents that are often used for this chemistry.
Tailoring flavins for visible light photocatalysis: organocatalytic [2+2] cycloadditions mediated by a flavin derivative and visible light
Mojr, Viktor,Svobodová, Eva,Straková, Karolína,Nevesely, Tomá?,Chudoba, Josef,Dvo?áková, Hana,Cibulka, Radek
, p. 12036 - 12039 (2015/07/28)
A new application of flavin derivatives in visible light photocatalysis was found. 1-Butyl-7,8-dimethoxy-3-methylalloxazine, when irradiated by visible light, was shown to allow an efficient cyclobutane ring formation via an intramolecular [2+2] cycloaddition of both styrene dienes, considered as electron-rich substrates, and electron-poor bis(arylenones), presumably proceeding via an energy transfer mechanism.
