A new application of (polyfluoroorgano)trifluoroborate salts: the palladium-catalysed cross-coupling reaction with substituted benzenediazonium tetrafluoroborates

For the first time (polyfluoroorgano)trifluoroborate salts, namely K[C6F5BF3], K[C6HF4BF3] (all three isomers), K[3,4,5-C6H2F3BF3], and K[CF2CFBF3] were principally applied as reagents to Pd-catalysed cross-coupling reactions. A series of polyfluorinated biphenyls C6H5−nFn–C6H4X-4′ were obtained from K[C6H5−nFnBF3] and the substrates [4-XC6H4N2][BF4] in the presence of Pd catalysts. The influence of the number and the position of the fluorine atoms in the (polyfluorophenyl)trifluoroborate salts on the reactivity in the coupling reaction was elucidated. In addition to (polyfluorophenyl)trifluoroborate salts, the cross-coupling was expanded to a first example of a perfluoroalkenyl reagent. K[CF2CFBF3] reacted with [4-FC6H4N2][BF4] and formed CF2CF–C6H4F-4.