35262-43-2Relevant academic research and scientific papers
A Redox-Active Nickel Complex that Acts as an Electron Mediator in Photochemical Giese Reactions
van Leeuwen, Thomas,Buzzetti, Luca,Perego, Luca Alessandro,Melchiorre, Paolo
, p. 4953 - 4957 (2019)
We report a simple protocol for the photochemical Giese addition of C(sp3)-centered radicals to a variety of electron-poor olefins. The chemistry does not require external photoredox catalysts. Instead, it harnesses the excited-state reactivity of 4-alkyl-1,4-dihydropyridines (4-alkyl-DHPs) to generate alkyl radicals. Crucial for reactivity is the use of a catalytic amount of Ni(bpy)32+ (bpy=2,2′-bipyridyl), which acts as an electron mediator to facilitate the redox processes involving fleeting and highly reactive intermediates.
Chiral phosphine-phosphoramidite ester ligand as well as preparation method and application thereof
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Paragraph 0054-0057; 0081-0084; 0089-0090, (2021/05/22)
The invention provides a method for preparing a phosphine-phosphoramidite ester ligand from a chiral beta-aminophosphine intermediate and an application of the phosphine-phosphoramidite ester ligand in an asymmetric reaction. Chiral N-(2-(phosphoryl)-1-phenethyl) amide is prepared from the chiral beta-aminophosphine intermediate through an asymmetric hydrogenation reaction of (Z)-(alpha-aryl-beta-phosphoryl) alkenyl amide, and then hydrolysis reduction. The preparation method comprises the following steps: dissolving newly-prepared chlorinated phosphite in toluene, adding a solution formed by dissolving the chiral phosphine-amine compound and triethylamine in toluene into an ice-water bath according to a molar ratio of the chiral phosphine-amine compound to the chlorinated phosphite to the triethylamine of 1: (1-2): (3-5), heating the reaction solution to 18-25 DEG C, stirring and reacting for 10-30 hours, filtering, and carrying out column chromatography to remove the solvent, and recrystallizing to obtain the required phosphine-phosphoramidite ligand. According to the present invention, the asymmetric hydrogenation reaction of the catalyst formed by the ligand and the metal precursor on the double bonds such as C = C, C = N, C = O and the like can achieve the enantioselectivity of 99%; the catalyst is high in activity, and TON reaches up to 10000.
Metal-free desilylative C-C bond formation by visible-light photoredox catalysis
Uygur, Mustafa,Danelzik, Tobias,García Manche?o, Olga
supporting information, p. 2980 - 2983 (2019/03/26)
A newly developed methodology for the use of organosilanes as radical precursors under metal-free and visible-light conditions is presented. The strong oxidant character of the 9-mesityl-10-methylacridinium salt in its excited state enables the transforma
Photochemical generation of radicals from alkyl electrophiles using a nucleophilic organic catalyst
Schweitzer-Chaput, Bertrand,Horwitz, Matthew A.,de Pedro Beato, Eduardo,Melchiorre, Paolo
, p. 129 - 135 (2018/12/13)
Chemists extensively use free radical reactivity for applications in organic synthesis, materials science, and life science. Traditionally, generating radicals requires strategies that exploit the bond dissociation energy or the redox properties of the precursors. Here, we disclose a photochemical catalytic approach that harnesses different physical properties of the substrate to form carbon radicals. We use a nucleophilic dithiocarbamate anion catalyst, adorned with a well-tailored chromophoric unit, to activate alkyl electrophiles via an SN2 pathway. The resulting photon-absorbing intermediate affords radicals upon homolytic cleavage induced by visible light. This catalytic SN2-based strategy, which exploits a fundamental mechanistic process of ionic chemistry, grants access to open-shell intermediates from a variety of substrates that would be incompatible with or inert to classical radical-generating strategies. We also describe how the method’s mild reaction conditions and high functional group tolerance could be advantageous for developing C–C bond-forming reactions, for streamlining the preparation of a marketed drug, for the late-stage elaboration of biorelevant compounds and for enantioselective radical catalysis.
Modular 1,1′-Ferrocenediyl-cored P-Stereogenic Diphosphines: ′′JDayPhos′′ Series and its Use in Rhodium(I)-Catalyzed Hydrogenation
Poklukar, Ga?per,Stephan, Michel,Mohar, Barbara
supporting information, p. 2566 - 2570 (2018/05/16)
A novel ferrocene-based P-stereogenic diphospine ligand series dubbed JDayPhos was developed, which rhodium(I) complexes of some of its members exhibited excellent enantioselectivity (up to >99% ee) and high activity in asymmetric hydrogenation of β-unsubstituted or -substituted itaconates and α-methylene-γ-oxo-carboxylates. (Figure presented.).
Selective Palladium-Catalyzed Carbonylation of Alkynes: An Atom-Economic Synthesis of 1,4-Dicarboxylic Acid Diesters
Liu, Jiawang,Dong, Kaiwu,Franke, Robert,Neumann, Helfried,Jackstell, Ralf,Beller, Matthias
supporting information, p. 10282 - 10288 (2018/08/03)
A class of novel diphosphine ligands bearing pyridine substituents was designed and synthesized for the first time. The resulting palladium complexes of L1 allow for chemo- and regioselective dialkoxycarbonylation of various aromatic and aliphatic alkynes affording a wide range of 1,4-dicarboxylic acid diesters in high yields and selectivities. Kinetic studies suggest the generation of 1,4-dicarboxylic acid diesters via cascade hydroesterification of the corresponding alkynes. Based on these investigations, the chemo- and regioselectivities of alkyne carbonylations can be controlled as shown by switching the ligand from L1 to L3 or L9 to give α,β-unsaturated esters.
Photocatalytic Radical Alkylation of Electrophilic Olefins by Benzylic and Alkylic Zinc-Sulfinates
Gualandi, Andrea,Mazzarella, Daniele,Ortega-Martínez, Aitor,Mengozzi, Luca,Calcinelli, Fabio,Matteucci, Elia,Monti, Filippo,Armaroli, Nicola,Sambri, Letizia,Cozzi, Pier Giorgio
, p. 5357 - 5362 (2017/08/17)
Alkyl radicals are obtained by photocatalytic oxidation of readily prepared or commercially available zinc sulfinates. The convenient benzylation and alkylation of a variety of electron-poor olefins triggered by the iridium(III) complex 6 Ir[dF(CF3)ppy]2(dtbbpy)PF6 as photocatalyst is described. Moreover, it is shown that zinc sulfinates can be used for facile nonradical sulfonylation reactions with highly electrophilic Michael acceptors.
PROCESS FOR DOUBLE CARBONYLATION OF ALLYL ETHERS TO CORRESPONDING DIESTERS
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Paragraph 0095; 0104, (2017/07/14)
The invention relates to a process for doubly carbonylating allyl ethers to the corresponding diesters, wherein a linear or branched allyl ether is reacted with a linear or branched alkanol (alcohol) with supply of CO and in the presence of a catalytic system composed of a palladium complex and at least one organic phosphorus ligand and in the presence of a hydrogen halide selected from HCl, HBr and HI.
A highly efficient Pd/CuI-catalyzed oxidative alkoxycarbonylation of α-olefins to unsaturated esters
Maffei, Mathias,Giacoia, Gabriele,Mancuso, Raffaella,Gabriele, Bartolo,Motti, Elena,Costa, Mirco,Della Ca’, Nicola
, p. 435 - 443 (2016/12/16)
A new protocol for the alkoxycarbonylation of α-olefins to the corresponding unsaturated esters has been developed. Differently substituted styrenes were selectively converted to cinnamate derivatives, via C[sbnd]H bond functionalization. Various palladium sources, including heterogeneous ones, in combination with CuI exhibited a high catalytic efficiency using oxygen as the most cheap oxidant. Monocarbonylated products were obtained in good yields and high chemoselectivity working with a low CO pressure (2 atm) and an excess of air (35 atm) avoiding in this way explosion risks. Commercial cinnamate derivatives were prepared in good to excellent yields by this very simple one-pot procedure.
Decatungstate photocatalyzed benzylation of alkenes with alkylaromatics
Qrareya, Hisham,Ravelli, Davide,Fagnoni, Maurizio,Albini, Angelo
supporting information, p. 2891 - 2899 (2014/03/21)
The direct benzylation of electrophilic al-kenes with alkylbenzenes has been achieved by decatungstate photocatalysis in a high ionic strength medium (5:1 acetonitrile/water mixed solvents, 0.5 M lithium perchlorate). The reaction has been extended to ring-substituted (Cl, F, CN) toluenes and further alkylbenzenes. Intramolecular selectivity (p-cymene, 4-methylanisole) and deuteration effects support the atom transfer character of the process that, however, requires a sufficient stabilization of the intermediate polar exciplex to occur. The reactivity of the deca-tungstate anion is compared with that of aromatic ketones, the benchmark of photochemical hydrogen/ electron transfer processes.
