3419-74-7Relevant academic research and scientific papers
Visible-Light-Enhanced Cobalt-Catalyzed Hydrogenation: Switchable Catalysis Enabled by Divergence between Thermal and Photochemical Pathways
Mendelsohn, Lauren N.,MacNeil, Connor S.,Tian, Lei,Park, Yoonsu,Scholes, Gregory D.,Chirik, Paul J.
, p. 1351 - 1360 (2021/02/01)
The catalytic hydrogenation activity of the readily prepared, coordinatively saturated cobalt(I) precatalyst, (R,R)-(iPrDuPhos)Co(CO)2H ((R,R)-iPrDuPhos = (+)-1,2-bis[(2R,5R)-2,5-diisopropylphospholano]benzene), is described. While efficient turnover was observed with a range of alkenes upon heating to 100 °C, the catalytic performance of the cobalt catalyst was markedly enhanced upon irradiation with blue light at 35 °C. This improved reactivity enabled hydrogenation of terminal, di-, and trisubstituted alkenes, alkynes, and carbonyl compounds. A combination of deuterium labeling studies, hydrogenation of alkenes containing radical clocks, and experiments probing relative rates supports a hydrogen atom transfer pathway under thermal conditions that is enabled by a relatively weak cobalt-hydrogen bond of 54 kcal/mol. In contrast, data for the photocatalytic reactions support light-induced dissociation of a carbonyl ligand followed by a coordination-insertion sequence where the product is released by combination of a cobalt alkyl intermediate with the starting hydride, (R,R)-(iPrDuPhos)Co(CO)2H. These results demonstrate the versatility of catalysis with Earth-abundant metals as pathways involving open-versus closed-shell intermediates can be switched by the energy source.
Contra-thermodynamic Olefin Isomerization by Chain-Walking Hydrofunctionalization and Formal Retro-hydrofunctionalization
Hanna, Steven,Butcher, Trevor W.,Hartwig, John F.
supporting information, p. 7129 - 7133 (2019/09/12)
We report a contra-thermodynamic isomerization of internal olefins to terminal olefins driven by redox reactions and formation of Si-F bonds. This process involves chain-walking hydrosilylation of internal olefins and subsequent formal retro-hydrosilylation. The process rests upon the high activities of platinum hydrosilylation catalysts for isomerization of metal alkyl intermediates and a new, metal-free process for the conversion of alkylsilanes to alkenes. By this approach, 1,2-disubstituted and trisubstituted olefins are converted to terminal olefins.
Comparative study of the bioconversion process using R-(+)- and S-(-)-limonene as substrates for Fusarium oxysporum 152B
Molina, Gustavo,Bution, Murillo L.,Bicas, Juliano L.,Dolder, Mary Anne Heidi,Pastore, Gláucia M.
, p. 606 - 613 (2015/02/19)
This study compared the bioconversion process of S-(-)-limonene into limonene-1,2-diol with the already established biotransformation of R-(+)-limonene into α-terpineol using the same biocatalyst in both processes, Fusarium oxysporum 152B. The bioconversion of the S-(-)-isomer was tested on cell permeabilisation under anaerobic conditions and using a biphasic system. When submitted to permeabilisation trials, this biocatalyst has shown a relatively high resistance; still, no production of limonene-1,2-diol and a loss of activity of the biocatalyst were observed after intense cell treatment, indicating a complete loss of cell viability. Furthermore, the results showed that this process can be characterised as an aerobic system that was catalysed by limonene-1,2-epoxide hydrolase, had an intracellular nature and was cofactor-dependent because the final product was not detected by an anaerobic process. Finally, this is the first report to characterise the bioconversion of R-(+)- and S-(-)-limonene by cellular detoxification using ultra-structural analysis.
Amberlyst-15: A reusable heterogeneous catalyst for the dehydration of tertiary alcohols
Frija, Luís M.T.,Afonso, Carlos A.M.
experimental part, p. 7414 - 7421 (2012/09/22)
Tertiary alcohols react under mild conditions in the presence of Amberlyst-15 (dry) (solid-supported sulfonic acid) to give predominantly the most stable alkene in very good yield. The dehydration of tertiary alcohol functionality occurs without observation of rearrangement and polymerization products, and with outstanding substrate tolerance, which include the NHCBz, NHBoc, OSEM, OTBDMS, OBOM and ethylene ketal functional groups. Amberlyst-15 (dry) can be easily recovered from the reaction medium and reused for five cycles, maintaining the catalytic efficiency. In addition, the dehydration can occur under continuous operation.
α-Lithioalkoxysilanes: Applications to alkene synthesis
Bates, Tim F.,Dandekar, Sushama A.,Longlet, Jon J.,Thomas, Ruthanne D.
, p. 13 - 22 (2007/10/03)
α-Lithioalkoxysilanes [RO(Me2)Si]CH(Li)(X), where R=Me or Et and X=H or SiMe3, react with carbonyl compounds in hydrocarbon solution to produce alkenes in moderate to high yield via Peterson-type reactions. For X=SiMe3, the corresponding vinylsilanes are isolated directly following work-up. The reaction is regiospecific and shows fair stereoselectivity. When the carbonyl substrates are cyclic ketones in six- or seven-membered rings, the products are exocyclic alkenes. For X=H, the initial product is a β-hydroxysilane, which is then efficiently converted to the corresponding terminal alkene by heating with sodium acetate in acetic acid. Both types of α-lithioalkoxysilane reagents are amenable to reaction with enolizable carbonyl compounds.
Atom-efficient metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles
Perez,Sestelo,Sarandeses
, p. 4155 - 4160 (2007/10/03)
The novel metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles is described. Triorganoindium compounds (R3In) containing alkyl, vinyl, aryl, and alkynyl groups are efficiently prepared from the correspond
A direct conversion of alkenes to isocyanides
Kitano, Yoshikazu,Chiba, Kazuhiro,Tada, Masahiro
, p. 288 - 290 (2007/10/03)
Treatment of alkenes with silver salts (AgClO4, AgBF4, or AgOTf) and trimethylsilyl cyanide (TMSCN) in dichloromethane followed by hydrolysis affords the corresponding isocyanides directly in high yields. The addition of the isocyano function is carried out in accordance with Markovnikov's rule.
Palladium-catalyzed cross-coupling reactions of triorganoindium compounds with vinyl and aryl triflates or iodides
Perez, Ignacio,Sestelo, Jose Perez,Sarandeses, Luis A.
, p. 1267 - 1269 (2008/02/09)
(matrix presented) A novel palladium-catalyzed cross-coupling reaction of organoindium compounds with vinyl and aryl triflates or iodides is described. The reaction proceeds for alkyl-, vinyl-, alkynyl-, and arylindium compounds in excellent yields and high chemoselectivity without any excess of the organometallic. Remarkably, indium organometallics transfer efficiently the three organic groups attached to the metal.
Transition Metal-catalysed Elimination of Unactivated Sulfones
Gai, Yonghua,Jin, Liren,Julia, Marc,Verpeaux, Jean-Noel
, p. 1625 - 1626 (2007/10/02)
Lithiated tert-butyl alkyl sulfones undergo an easy elimination in the presence of catalytic amounts of bisacetylacetonatopalladium, thus leading to desulfonylated alkenes.
Regioselective dehydration in cyclic system with triphenylphosphine-azodicarboxylate
Iimori,Ohtsuka,Oishi
, p. 1209 - 1212 (2007/10/02)
The regioselective dehydration of cyclohexanol derivatives was achieved by using the Mitsunobu reagent system. The reaction undergoes under mild and neutral conditions. The observed regioselectivity was explained by considering the importance of the orientation of the leaving group at the elimination stage.
