Modular Construction of Fluoroarenes from a New Difluorinated Building Block by Cross‐Coupling/Electrocyclisation/Dehydrofluorination Reactions

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 °C, depending on the central component of the π-system; nonaromatic trienes were most reactive, but even systems that required the temporary dearomatisation of two arenyl subunits 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.

1-(Trimethylsilyl)vinyl MIDA Boronate: A Trifunctional C2 Building Block

“…1 α-Heteroatom-substituted vinyl boronic acid derivatives are of special interest since after coupling, functionalized alkenes are obtained in a regioselective manner; moreover, iterative chemoselective cross-coupling to form polysubstituted alkenes is possible. [2][3][4] Examples of these organoboron compounds include α-and β-(sulfon)amido, [5][6][7][8] α-alkoxy, [9][10][11] α-halogenoboronates, [12][13][14] α-boryl vinyl silanes 7,[15][16][17][18][19][20] and α,α-diboryl alkenes. [21][22][23] Most of these compounds have a boronic acid ester as the boryl moiety, which is prone to oxidation, protodeborylation and polycondensation, and therefore provides limited possibilities for chemical manipulations at other functional groups.…”