Negishi cross-coupling with functionalised organozinc compounds prepared by lithium–zinc transmetallation

The reaction of some functionalised organolithium compounds 2 (easily prepared by DTBB-catalysed lithiation of isochroman, phthalan and 2,3-dihydrobenzofuran) with an equimolecular amount of zinc bromide followed by reaction with an aryl or alkenyl bromide in the presence of a catalytic amount of Pd(PPh3)4 or Pd(PPh3)2(OAc)2 (5 mol%) under THF reflux overnight gave the expected cross-coupling compounds. These arylation or alkenylation processes, which work also with iodinated substrates, are not possible in the absence of the zinc or palladium compounds under the same reaction conditions.