Modular construction of fluoroarenes from a new difluorinated building block via cross-coupling/electrocyclisation/ dehydrofluorination reactions

Percy, Jonathan M. and Emerson, Helena and Fyfe, James W. B. and Kennedy, Alan R. and Maciuk, Sergej and Orr, David and Rathouska, Lucie and Redmond, Joanna M. and Wilson, Peter G. (2016) Modular construction of fluoroarenes from a new difluorinated building block via cross-coupling/electrocyclisation/ dehydrofluorination reactions. Chemistry - A European Journal, 22 (34). pp. 12166-12175. ISSN 0947-6539

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    Abstract

    Palladium-catalysed coupling reactions based on a novel and easy-to-synthesise difluorinated organotrifluoroborate were used to assemble precursors to 6π-electrocyclisations of three different types. Electrocyclisations took place at temperatures between 90 and 240 oC, depending on the central component of the π-system; non-aromatic trienes were most reactive, but even systems which required the temporary dearomatisation of two arenyl sub-units underwent electrocyclisation, albeit at elevated temperatures. Photochemical conditions were effective for these more demanding reactions. The package of methods delivered a structurally-diverse set of fluorinated arenes, spanning a 20 kcal mol-1 range of reactivity, by a flexible route.