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

The reaction of some functionalised organolithium compounds 2 (easily prepa red by DTBB-catalysed lithiation of isochroman, phthalan and 2.3-dihydroben zofuran) 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 t he expected cross-coupling compounds. These arylation or alkenylation proce sses, which work also with iodinated substrates. are not possible in the ab sence of the zinc or palladium compounds under the same reaction conditions . (C) 2001 Elsevier Science Ltd. All rights reserved.