Nickel or Iron Catalysed Carbon-Carbon Coupling Reaction of Arylenes, Alkenes and Alkines
Organozinc compounds of the type R1—Ar1—ZnY (1) can be reacted with different functionalized aryl halides R2—Ar2—X (2) in the presence of catalytic amounts of Ni or Fe in a polar solvent or solvent mixture to form polyfunctional biaryles of the type R1—Ar1—Ar2—R2 (3). Organozinc compounds of the type (1) can be represented by the transmetallation reaction of functionalized aryl magnesium halides or lithium aryl compounds with e.g. ZnBr2.
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Page/Page column 15
(2010/08/07)
Microwave-assisted Suzuki coupling reactions with an encapsulated palladium catalyst for batch and continuous-flow transformations
This article describes the design, optimisation and development of a Suzuki cross-coupling protocol mediated by an efficient palladium-en-capsulated catalyst (Pd EnCat) under microwave irradiation. The methodology has been used in both batch mode for classical library preparation and in continuous-flow applications furnishing multigram quantities of material. Described is a method that uses direct focused microwave heating whilst applying an external cooling source. This enables a lower than normal bulk temperature to be maintained throughout the reaction period leading to significant improvements in the overall yield and purity of the reaction products. Additional aspects of this novel heating protocol are discussed in relation to the prolonged lifetime and enhanced reactivity of the immobilised catalyst system.
Baxendale, Ian R.,Griffiths-Jones, Charlotte M.,Ley, Steven V.,Tranmer, Geoffrey K.
p. 4407 - 4416
(2008/02/07)
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