- Scalability of microwave-assisted organic synthesis. From single-mode to multimode parallel batch reactors
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The direct scalability of microwave-assisted organic synthesis (MAOS) in a prototype laboratory-scale multimode microwave batch reactor is investigated. Several different organic reactions have been scaled-up typically from 1 mmol to 100 mmol scale. The transformations include multicomponent chemistries (Biginelli dihydropyrimidine and Kindler thioamide synthesis), transition metal-catalyzed carbon - carbon cross-coupling protocols (Heck and Negishi reactions), solid-phase organic synthesis, and Diels - Alder cycloaddition reactions using gaseous reagents in prepressurized reaction vessels. A range of different solvents (high and low microwave absorbing), Pd catalysts (homogeneous and heterogeneous), and varying reaction times and temperatures have been explored in these investigations. In all cases, it was possible to achieve similar isolated product yields on going from a small scale (ca. 5 mL processing volume) to a larger scale (max 500 mL volume) without changing the previously optimized reaction conditions (direct scalability). The prototype, benchtop multimode microwave reactor used in the present study allows parallel processing in either quartz or PTFE-TFM vessels with maximum operating limits of 300°C and 80 bar of pressure. The system features magnetic stirring in all vessels, complete on-line monitoring of temperature, pressure and microwave power, and the ability to maintain inert or reactive gas atmosphere.
- Stadler, Alexander,Yousefi, Behrooz H.,Dallinger, Doris,Walla, Peter,Van Der Eycken, Erik,Kaval, Nadya,Kappe, C. Oliver
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- Cobalt-Catalyzed Oxidative Homocoupling of Arylzinc Species
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A novel procedure for the synthesis of functionalized symmetrical biaryl compounds is described. The reaction proceeds via the oxidative homocoupling of arylzinc species formed by cobalt catalysis in the presence of air or p-benzoquinone depending on the nature of the functional group.
- Bourne-Branchu, Yann,Moncomble, Aurélien,Corpet, Martin,Danoun, Gregory,Gosmini, Corinne
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p. 3352 - 3356
(2016/09/12)
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- Microwave-assisted Negishi and Kumada cross-coupling reactions of aryl chlorides
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Rapid Pd or Ni-catalyzed microwave-accelerated Negishi and Kumada cross-coupling reactions of aryl chlorides in solution and on solid phase are reported.
- Walla, Peter,Kappe, C. Oliver
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p. 564 - 565
(2007/10/03)
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- Preparation of aromatic organozinc compounds and composition therefor
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The invention relates to a technique for preparing aromatic organozinc compounds and to a composition therefore. This composition constitutes a reactant that can be used to carry out the synthesis of organozinc compounds, and comprises a cobalt salt, a zinc salt, a polar aprotic solvent and elemental zinc in divided form, the elemental zinc being in solid form, the other elements being in a form dissolved in the solvent. Application to organic synthesis.
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- New chemical synthesis of functionalized arylzinc compounds from aromatic or thienyl bromides under mild conditions using a simple cobalt catalyst and zinc dust
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A new chemical method for the preparation of arylzinc intermediates is described in acetonitrile, on the basis of the activation of aryl bromides by low-valent cobalt species arising from the reduction of cobalt halide by zinc dust. This procedure allows for the synthesis of a variety of functionalized aryl- and thienylzinc species in good to excellent yields. The versatility and the simplicity of that original method represent an alternative to most known procedures.
- Fillon, Hyacinthe,Gosmini, Corinne,Perichon, Jacques
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p. 3867 - 3870
(2007/10/03)
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